Merge tag 'tty-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial updates from Greg KH:
 "Here is the "big" set of tty/serial driver patches for 5.2-rc1.

  It's really pretty small, not much happening in this portion of the
  kernel at the moment. When the "highlight" is the movement of the
  documentation from .txt to .rst files, it's a good merge window.

  There's a number of small fixes and updates over the various serial
  drivers, and a new "tty null" driver for those embedded systems that
  like to make things even smaller and not break things.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (45 commits)
  tty: serial: add driver for the SiFive UART
  dt-bindings: serial: add documentation for the SiFive UART driver
  serial: uartps: Add support for cts-override
  dt-bindings: xilinx-uartps: Add support for cts-override
  serial: milbeaut_usio: Fix error handling in probe and remove
  tty: rocket: deprecate the rp_ioctl
  tty: rocket: Remove RCPK_GET_STRUCT ioctl
  tty: update obsolete termios comment
  tty: serial_core: fix error code returned by uart_register_driver()
  serial: 8250-mtk: modify baudrate setting
  serial: 8250-mtk: add follow control
  docs: serial: convert docs to ReST and rename to *.rst
  serial: 8250_exar: Adjust IOT2000 matching
  TTY: serial_core, add ->install
  serial: Fix using plain integer instead of Null pointer
  tty:serial_core: Spelling mistake
  tty: Add NULL TTY driver
  tty: vt: keyboard: Allow Unicode compose base char
  Revert "tty: fix NULL pointer issue when tty_port ops is not set"
  serial: Add Milbeaut serial control
  ...

42 files changed, 2606 insertions, 120 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index fbeb71953526..05dbfdb9f4af 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -75,7 +75,7 @@ struct ports_driver_data {
 	/* All the console devices handled by this driver */
 	struct list_head consoles;
 };
-static struct ports_driver_data pdrvdata;
+static struct ports_driver_data pdrvdata = { .next_vtermno = 1};
 
 static DEFINE_SPINLOCK(pdrvdata_lock);
 static DECLARE_COMPLETION(early_console_added);
@@ -1394,6 +1394,7 @@ static int add_port(struct ports_device *portdev, u32 id)
 	port->async_queue = NULL;
 
 	port->cons.ws.ws_row = port->cons.ws.ws_col = 0;
+	port->cons.vtermno = 0;
 
 	port->host_connected = port->guest_connected = false;
 	port->stats = (struct port_stats) { 0 };
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index e0a04bfc873e..3b1d312bb175 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 config TTY
 	bool "Enable TTY" if EXPERT
 	default y
@@ -83,7 +84,6 @@ config HW_CONSOLE
 config VT_HW_CONSOLE_BINDING
        bool "Support for binding and unbinding console drivers"
        depends on HW_CONSOLE
-       default n
        ---help---
          The virtual terminal is the device that interacts with the physical
          terminal through console drivers. On these systems, at least one
@@ -175,7 +175,7 @@ config ROCKETPORT
 	  This driver supports Comtrol RocketPort and RocketModem PCI boards.   
           These boards provide 2, 4, 8, 16, or 32 high-speed serial ports or
           modems.  For information about the RocketPort/RocketModem  boards
-          and this driver read <file:Documentation/serial/rocket.txt>.
+          and this driver read <file:Documentation/serial/rocket.rst>.
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called rocket.
@@ -193,7 +193,7 @@ config CYCLADES
 	  your Linux box, for instance in order to become a dial-in server.
 
 	  For information about the Cyclades-Z card, read
-	  <file:Documentation/serial/README.cycladesZ>.
+	  <file:Documentation/serial/cyclades_z.rst>.
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called cyclades.
@@ -312,7 +312,6 @@ config N_GSM
 config TRACE_ROUTER
 	tristate "Trace data router for MIPI P1149.7 cJTAG standard"
 	depends on TRACE_SINK
-	default n
 	help
 	  The trace router uses the Linux tty line discipline framework to
 	  route trace data coming from a tty port (say UART for example) to
@@ -328,7 +327,6 @@ config TRACE_ROUTER
 
 config TRACE_SINK
 	tristate "Trace data sink for MIPI P1149.7 cJTAG standard"
-	default n
 	help
 	  The trace sink uses the Linux line discipline framework to receive
 	  trace data coming from the trace router line discipline driver
@@ -376,6 +374,20 @@ config PPC_EARLY_DEBUG_EHV_BC_HANDLE
 	  there simply will be no early console output.  This is true also
 	  if you don't boot under a hypervisor at all.
 
+config NULL_TTY
+	tristate "NULL TTY driver"
+	help
+	  Say Y here if you want a NULL TTY which simply discards messages.
+
+	  This is useful to allow userspace applications which expect a console
+	  device to work without modifications even when no console is
+	  available or desired.
+
+	  In order to use this driver, you should redirect the console to this
+	  TTY, or boot the kernel with console=ttynull.
+
+	  If unsure, say N.
+
 config GOLDFISH_TTY
 	tristate "Goldfish TTY Driver"
 	depends on GOLDFISH
diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
index c72cafdf32b4..020b1cd9294f 100644
--- a/drivers/tty/Makefile
+++ b/drivers/tty/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_ISI)		+= isicom.o
 obj-$(CONFIG_MOXA_INTELLIO)	+= moxa.o
 obj-$(CONFIG_MOXA_SMARTIO)	+= mxser.o
 obj-$(CONFIG_NOZOMI)		+= nozomi.o
+obj-$(CONFIG_NULL_TTY)	        += ttynull.o
 obj-$(CONFIG_ROCKETPORT)	+= rocket.o
 obj-$(CONFIG_SYNCLINK_GT)	+= synclink_gt.o
 obj-$(CONFIG_SYNCLINKMP)	+= synclinkmp.o
diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
index 4293c172e120..4d22b911111f 100644
--- a/drivers/tty/hvc/Kconfig
+++ b/drivers/tty/hvc/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 if TTY
 
 config HVC_DRIVER
@@ -24,7 +25,6 @@ config HVC_CONSOLE
 config HVC_OLD_HVSI
 	bool "Old driver for pSeries serial port (/dev/hvsi*)"
 	depends on HVC_CONSOLE
-	default n
 
 config HVC_OPAL
 	bool "OPAL Console support"
@@ -73,7 +73,6 @@ config HVC_UDBG
        bool "udbg based fake hypervisor console"
        depends on PPC
        select HVC_DRIVER
-       default n
        help
          This is meant to be used during HW bring up or debugging when
 	 no other console mechanism exist but udbg, to get you a quick
diff --git a/drivers/tty/ipwireless/Makefile b/drivers/tty/ipwireless/Makefile
index fe2e1730986b..a665d021e24d 100644
--- a/drivers/tty/ipwireless/Makefile
+++ b/drivers/tty/ipwireless/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for the IPWireless driver
 #
diff --git a/drivers/tty/ipwireless/main.c b/drivers/tty/ipwireless/main.c
index 3475e841ef5c..4c18bbfe1a92 100644
--- a/drivers/tty/ipwireless/main.c
+++ b/drivers/tty/ipwireless/main.c
@@ -114,6 +114,10 @@ static int ipwireless_probe(struct pcmcia_device *p_dev, void *priv_data)
 
 	ipw->common_memory = ioremap(p_dev->resource[2]->start,
 				resource_size(p_dev->resource[2]));
+	if (!ipw->common_memory) {
+		ret = -ENOMEM;
+		goto exit1;
+	}
 	if (!request_mem_region(p_dev->resource[2]->start,
 				resource_size(p_dev->resource[2]),
 				IPWIRELESS_PCCARD_NAME)) {
@@ -134,6 +138,10 @@ static int ipwireless_probe(struct pcmcia_device *p_dev, void *priv_data)
 
 	ipw->attr_memory = ioremap(p_dev->resource[3]->start,
 				resource_size(p_dev->resource[3]));
+	if (!ipw->attr_memory) {
+		ret = -ENOMEM;
+		goto exit3;
+	}
 	if (!request_mem_region(p_dev->resource[3]->start,
 				resource_size(p_dev->resource[3]),
 				IPWIRELESS_PCCARD_NAME)) {
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 9cdb0fa3c4bf..f9c584244f72 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -550,9 +550,9 @@ static ssize_t process_output_block(struct tty_struct *tty,
 	mutex_lock(&ldata->output_lock);
 
 	space = tty_write_room(tty);
-	if (!space) {
+	if (space <= 0) {
 		mutex_unlock(&ldata->output_lock);
-		return 0;
+		return space;
 	}
 	if (nr > space)
 		nr = space;
diff --git a/drivers/tty/rocket.c b/drivers/tty/rocket.c
index 27aeca30eeae..5ba6816ebf81 100644
--- a/drivers/tty/rocket.c
+++ b/drivers/tty/rocket.c
@@ -1283,23 +1283,29 @@ static int rp_ioctl(struct tty_struct *tty,
 		return -ENXIO;
 
 	switch (cmd) {
-	case RCKP_GET_STRUCT:
-		if (copy_to_user(argp, info, sizeof (struct r_port)))
-			ret = -EFAULT;
-		break;
 	case RCKP_GET_CONFIG:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_GET_CONFIG option is deprecated\n");
 		ret = get_config(info, argp);
 		break;
 	case RCKP_SET_CONFIG:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_SET_CONFIG option is deprecated\n");
 		ret = set_config(tty, info, argp);
 		break;
 	case RCKP_GET_PORTS:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_GET_PORTS option is deprecated\n");
 		ret = get_ports(info, argp);
 		break;
 	case RCKP_RESET_RM2:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_RESET_RM2 option is deprecated\n");
 		ret = reset_rm2(info, argp);
 		break;
 	case RCKP_GET_VERSION:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_GET_VERSION option is deprecated\n");
 		ret = get_version(info, argp);
 		break;
 	default:
diff --git a/drivers/tty/rocket.h b/drivers/tty/rocket.h
index d0560203f215..d62ed6587f32 100644
--- a/drivers/tty/rocket.h
+++ b/drivers/tty/rocket.h
@@ -71,7 +71,6 @@ struct rocket_version {
 /*
  * Rocketport ioctls -- "RP"
  */
-#define RCKP_GET_STRUCT		0x00525001
 #define RCKP_GET_CONFIG		0x00525002
 #define RCKP_SET_CONFIG		0x00525003
 #define RCKP_GET_PORTS		0x00525004
diff --git a/drivers/tty/serdev/Kconfig b/drivers/tty/serdev/Kconfig
index 1dbc8352e027..46ae732bfc68 100644
--- a/drivers/tty/serdev/Kconfig
+++ b/drivers/tty/serdev/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Serial bus device driver configuration
 #
diff --git a/drivers/tty/serdev/Makefile b/drivers/tty/serdev/Makefile
index 0cbdb9444d9d..078417e5b068 100644
--- a/drivers/tty/serdev/Makefile
+++ b/drivers/tty/serdev/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 serdev-objs := core.o
 
 obj-$(CONFIG_SERIAL_DEV_BUS) += serdev.o
diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 0089aa305ef9..edd6dfe055bf 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -361,12 +361,15 @@ static const struct exar8250_platform iot2040_platform = {
 	.register_gpio = iot2040_register_gpio,
 };
 
+/*
+ * For SIMATIC IOT2000, only IOT2040 and its variants have the Exar device,
+ * IOT2020 doesn't have. Therefore it is sufficient to match on the common
+ * board name after the device was found.
+ */
 static const struct dmi_system_id exar_platforms[] = {
 	{
 		.matches = {
 			DMI_EXACT_MATCH(DMI_BOARD_NAME, "SIMATIC IOT2000"),
-			DMI_EXACT_MATCH(DMI_BOARD_ASSET_TAG,
-					"6ES7647-0AA00-1YA2"),
 		},
 		.driver_data = (void *)&iot2040_platform,
 	},
diff --git a/drivers/tty/serial/8250/8250_fintek.c b/drivers/tty/serial/8250/8250_fintek.c
index 79a4958b3f5c..31c91c2f8c6e 100644
--- a/drivers/tty/serial/8250/8250_fintek.c
+++ b/drivers/tty/serial/8250/8250_fintek.c
@@ -303,8 +303,9 @@ static void fintek_8250_goto_highspeed(struct uart_8250_port *uart,
 	}
 }
 
-void fintek_8250_set_termios(struct uart_port *port, struct ktermios *termios,
-			struct ktermios *old)
+static void fintek_8250_set_termios(struct uart_port *port,
+				    struct ktermios *termios,
+				    struct ktermios *old)
 {
 	struct fintek_8250 *pdata = port->private_data;
 	unsigned int baud = tty_termios_baud_rate(termios);
diff --git a/drivers/tty/serial/8250/8250_men_mcb.c b/drivers/tty/serial/8250/8250_men_mcb.c
index 127017cc41d9..02c5aff58a74 100644
--- a/drivers/tty/serial/8250/8250_men_mcb.c
+++ b/drivers/tty/serial/8250/8250_men_mcb.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index c1fdbc0b6840..417c7c810df9 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -21,15 +21,32 @@
 
 #include "8250.h"
 
-#define UART_MTK_HIGHS		0x09	/* Highspeed register */
-#define UART_MTK_SAMPLE_COUNT	0x0a	/* Sample count register */
-#define UART_MTK_SAMPLE_POINT	0x0b	/* Sample point register */
+#define MTK_UART_HIGHS		0x09	/* Highspeed register */
+#define MTK_UART_SAMPLE_COUNT	0x0a	/* Sample count register */
+#define MTK_UART_SAMPLE_POINT	0x0b	/* Sample point register */
 #define MTK_UART_RATE_FIX	0x0d	/* UART Rate Fix Register */
-
+#define MTK_UART_ESCAPE_DAT	0x10	/* Escape Character register */
+#define MTK_UART_ESCAPE_EN	0x11	/* Escape Enable register */
 #define MTK_UART_DMA_EN		0x13	/* DMA Enable register */
+#define MTK_UART_RXTRI_AD	0x14	/* RX Trigger address */
+#define MTK_UART_FRACDIV_L	0x15	/* Fractional divider LSB address */
+#define MTK_UART_FRACDIV_M	0x16	/* Fractional divider MSB address */
+#define MTK_UART_IER_XOFFI	0x20	/* Enable XOFF character interrupt */
+#define MTK_UART_IER_RTSI	0x40	/* Enable RTS Modem status interrupt */
+#define MTK_UART_IER_CTSI	0x80	/* Enable CTS Modem status interrupt */
+
+#define MTK_UART_EFR_EN		0x10	/* Enable enhancement feature */
+#define MTK_UART_EFR_RTS	0x40	/* Enable hardware rx flow control */
+#define MTK_UART_EFR_CTS	0x80	/* Enable hardware tx flow control */
+#define MTK_UART_EFR_NO_SW_FC	0x0	/* no sw flow control */
+#define MTK_UART_EFR_XON1_XOFF1	0xa	/* XON1/XOFF1 as sw flow control */
+#define MTK_UART_EFR_XON2_XOFF2	0x5	/* XON2/XOFF2 as sw flow control */
+#define MTK_UART_EFR_SW_FC_MASK	0xf	/* Enable CTS Modem status interrupt */
+#define MTK_UART_EFR_HW_FC	(MTK_UART_EFR_RTS | MTK_UART_EFR_CTS)
 #define MTK_UART_DMA_EN_TX	0x2
 #define MTK_UART_DMA_EN_RX	0x5
 
+#define MTK_UART_ESCAPE_CHAR	0x77	/* Escape char added under sw fc */
 #define MTK_UART_TX_SIZE	UART_XMIT_SIZE
 #define MTK_UART_RX_SIZE	0x8000
 #define MTK_UART_TX_TRIGGER	1
@@ -46,6 +63,7 @@ enum dma_rx_status {
 struct mtk8250_data {
 	int			line;
 	unsigned int		rx_pos;
+	unsigned int		clk_count;
 	struct clk		*uart_clk;
 	struct clk		*bus_clk;
 	struct uart_8250_dma	*dma;
@@ -54,6 +72,13 @@ struct mtk8250_data {
 #endif
 };
 
+/* flow control mode */
+enum {
+	MTK_UART_FC_NONE,
+	MTK_UART_FC_SW,
+	MTK_UART_FC_HW,
+};
+
 #ifdef CONFIG_SERIAL_8250_DMA
 static void mtk8250_rx_dma(struct uart_8250_port *up);
 
@@ -192,13 +217,89 @@ static void mtk8250_shutdown(struct uart_port *port)
 	return serial8250_do_shutdown(port);
 }
 
+static void mtk8250_disable_intrs(struct uart_8250_port *up, int mask)
+{
+	serial_out(up, UART_IER, serial_in(up, UART_IER) & (~mask));
+}
+
+static void mtk8250_enable_intrs(struct uart_8250_port *up, int mask)
+{
+	serial_out(up, UART_IER, serial_in(up, UART_IER) | mask);
+}
+
+static void mtk8250_set_flow_ctrl(struct uart_8250_port *up, int mode)
+{
+	struct uart_port *port = &up->port;
+	int lcr = serial_in(up, UART_LCR);
+
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, UART_EFR, UART_EFR_ECB);
+	serial_out(up, UART_LCR, lcr);
+	lcr = serial_in(up, UART_LCR);
+
+	switch (mode) {
+	case MTK_UART_FC_NONE:
+		serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
+		serial_out(up, MTK_UART_ESCAPE_EN, 0x00);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+		serial_out(up, UART_EFR, serial_in(up, UART_EFR) &
+			(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK)));
+		serial_out(up, UART_LCR, lcr);
+		mtk8250_disable_intrs(up, MTK_UART_IER_XOFFI |
+			MTK_UART_IER_RTSI | MTK_UART_IER_CTSI);
+		break;
+
+	case MTK_UART_FC_HW:
+		serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
+		serial_out(up, MTK_UART_ESCAPE_EN, 0x00);
+		serial_out(up, UART_MCR, UART_MCR_RTS);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+		/*enable hw flow control*/
+		serial_out(up, UART_EFR, MTK_UART_EFR_HW_FC |
+			(serial_in(up, UART_EFR) &
+			(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK))));
+
+		serial_out(up, UART_LCR, lcr);
+		mtk8250_disable_intrs(up, MTK_UART_IER_XOFFI);
+		mtk8250_enable_intrs(up, MTK_UART_IER_CTSI | MTK_UART_IER_RTSI);
+		break;
+
+	case MTK_UART_FC_SW:	/*MTK software flow control */
+		serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
+		serial_out(up, MTK_UART_ESCAPE_EN, 0x01);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+		/*enable sw flow control */
+		serial_out(up, UART_EFR, MTK_UART_EFR_XON1_XOFF1 |
+			(serial_in(up, UART_EFR) &
+			(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK))));
+
+		serial_out(up, UART_XON1, START_CHAR(port->state->port.tty));
+		serial_out(up, UART_XOFF1, STOP_CHAR(port->state->port.tty));
+		serial_out(up, UART_LCR, lcr);
+		mtk8250_disable_intrs(up, MTK_UART_IER_CTSI|MTK_UART_IER_RTSI);
+		mtk8250_enable_intrs(up, MTK_UART_IER_XOFFI);
+		break;
+	default:
+		break;
+	}
+}
+
 static void
 mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
 			struct ktermios *old)
 {
+	unsigned short fraction_L_mapping[] = {
+		0, 1, 0x5, 0x15, 0x55, 0x57, 0x57, 0x77, 0x7F, 0xFF, 0xFF
+	};
+	unsigned short fraction_M_mapping[] = {
+		0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 3
+	};
 	struct uart_8250_port *up = up_to_u8250p(port);
+	unsigned int baud, quot, fraction;
 	unsigned long flags;
-	unsigned int baud, quot;
+	int mode;
 
 #ifdef CONFIG_SERIAL_8250_DMA
 	if (up->dma) {
@@ -214,7 +315,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
 	serial8250_do_set_termios(port, termios, old);
 
 	/*
-	 * Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS)
+	 * Mediatek UARTs use an extra highspeed register (MTK_UART_HIGHS)
 	 *
 	 * We need to recalcualte the quot register, as the claculation depends
 	 * on the vaule in the highspeed register.
@@ -230,18 +331,11 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
 				  port->uartclk / 16 / UART_DIV_MAX,
 				  port->uartclk);
 
-	if (baud <= 115200) {
-		serial_port_out(port, UART_MTK_HIGHS, 0x0);
+	if (baud < 115200) {
+		serial_port_out(port, MTK_UART_HIGHS, 0x0);
 		quot = uart_get_divisor(port, baud);
-	} else if (baud <= 576000) {
-		serial_port_out(port, UART_MTK_HIGHS, 0x2);
-
-		/* Set to next lower baudrate supported */
-		if ((baud == 500000) || (baud == 576000))
-			baud = 460800;
-		quot = DIV_ROUND_UP(port->uartclk, 4 * baud);
 	} else {
-		serial_port_out(port, UART_MTK_HIGHS, 0x3);
+		serial_port_out(port, MTK_UART_HIGHS, 0x3);
 		quot = DIV_ROUND_UP(port->uartclk, 256 * baud);
 	}
 
@@ -258,18 +352,40 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
 	/* reset DLAB */
 	serial_port_out(port, UART_LCR, up->lcr);
 
-	if (baud > 460800) {
+	if (baud >= 115200) {
 		unsigned int tmp;
 
-		tmp = DIV_ROUND_CLOSEST(port->uartclk, quot * baud);
-		serial_port_out(port, UART_MTK_SAMPLE_COUNT, tmp - 1);
-		serial_port_out(port, UART_MTK_SAMPLE_POINT,
-					(tmp - 2) >> 1);
+		tmp = (port->uartclk / (baud *  quot)) - 1;
+		serial_port_out(port, MTK_UART_SAMPLE_COUNT, tmp);
+		serial_port_out(port, MTK_UART_SAMPLE_POINT,
+					(tmp >> 1) - 1);
+
+		/*count fraction to set fractoin register */
+		fraction = ((port->uartclk  * 100) / baud / quot) % 100;
+		fraction = DIV_ROUND_CLOSEST(fraction, 10);
+		serial_port_out(port, MTK_UART_FRACDIV_L,
+						fraction_L_mapping[fraction]);
+		serial_port_out(port, MTK_UART_FRACDIV_M,
+						fraction_M_mapping[fraction]);
 	} else {
-		serial_port_out(port, UART_MTK_SAMPLE_COUNT, 0x00);
-		serial_port_out(port, UART_MTK_SAMPLE_POINT, 0xff);
+		serial_port_out(port, MTK_UART_SAMPLE_COUNT, 0x00);
+		serial_port_out(port, MTK_UART_SAMPLE_POINT, 0xff);
+		serial_port_out(port, MTK_UART_FRACDIV_L, 0x00);
+		serial_port_out(port, MTK_UART_FRACDIV_M, 0x00);
 	}
 
+	if ((termios->c_cflag & CRTSCTS) && (!(termios->c_iflag & CRTSCTS)))
+		mode = MTK_UART_FC_HW;
+	else if (termios->c_iflag & CRTSCTS)
+		mode = MTK_UART_FC_SW;
+	else
+		mode = MTK_UART_FC_NONE;
+
+	mtk8250_set_flow_ctrl(up, mode);
+
+	if (uart_console(port))
+		up->port.cons->cflag = termios->c_cflag;
+
 	spin_unlock_irqrestore(&port->lock, flags);
 	/* Don't rewrite B0 */
 	if (tty_termios_baud_rate(termios))
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 15c2c5463835..296115f6a4d8 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # The 8250/16550 serial drivers.  You shouldn't be in this list unless
 # you somehow have an implicit or explicit dependency on SERIAL_8250.
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 72966bc0ac76..0d31251e04cc 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Serial device configuration
 #
@@ -369,7 +370,6 @@ config SERIAL_MAX310X
 	depends on SPI_MASTER
 	select SERIAL_CORE
 	select REGMAP_SPI if SPI_MASTER
-	default n
 	help
 	  This selects support for an advanced UART from Maxim (Dallas).
 	  Supported ICs are MAX3107, MAX3108, MAX3109, MAX14830.
@@ -652,7 +652,6 @@ config SERIAL_MUX_CONSOLE
 config PDC_CONSOLE
 	bool "PDC software console support"
 	depends on PARISC && !SERIAL_MUX && VT
-	default n
 	help
 	  Saying Y here will enable the software based PDC console to be 
 	  used as the system console.  This is useful for machines in 
@@ -1095,6 +1094,30 @@ config SERIAL_OMAP_CONSOLE
 	  your boot loader about how to pass options to the kernel at
 	  boot time.)
 
+config SERIAL_SIFIVE
+	tristate "SiFive UART support"
+	depends on OF
+	select SERIAL_CORE
+	help
+	  Select this option if you are building a kernel for a device that
+	  contains a SiFive UART IP block.  This type of UART is present on
+	  SiFive FU540 SoCs, among others.
+
+config SERIAL_SIFIVE_CONSOLE
+	bool "Console on SiFive UART"
+	depends on SERIAL_SIFIVE=y
+	select SERIAL_CORE_CONSOLE
+	help
+	  Select this option if you would like to use a SiFive UART as the
+	  system console.
+
+	  Even if you say Y here, the currently visible virtual console
+	  (/dev/tty0) will still be used as the system console by default, but
+	  you can alter that using a kernel command line option such as
+	  "console=ttySIFx". (Try "man bootparam" or see the documentation of
+	  your boot loader about how to pass options to the kernel at
+	  boot time.)
+
 config SERIAL_LANTIQ
 	bool "Lantiq serial driver"
 	depends on LANTIQ
@@ -1109,7 +1132,6 @@ config SERIAL_QE
 	depends on QUICC_ENGINE
 	select SERIAL_CORE
 	select FW_LOADER
-	default n
 	help
 	  This driver supports the QE serial ports on Freescale embedded
 	  PowerPC that contain a QUICC Engine.
@@ -1582,6 +1604,32 @@ config SERIAL_RDA_CONSOLE
 	  Say 'Y' here if you wish to use the RDA8810PL UART as the system
 	  console. Only earlycon is implemented currently.
 
+config SERIAL_MILBEAUT_USIO
+	tristate "Milbeaut USIO/UART serial port support"
+	depends on ARCH_MILBEAUT || (COMPILE_TEST && OF)
+	default ARCH_MILBEAUT
+	select SERIAL_CORE
+	help
+	  This selects the USIO/UART IP found in Socionext Milbeaut SoCs.
+
+config SERIAL_MILBEAUT_USIO_PORTS
+	int "Maximum number of CSIO/UART ports (1-8)"
+	range 1 8
+	depends on SERIAL_MILBEAUT_USIO
+	default "4"
+
+config SERIAL_MILBEAUT_USIO_CONSOLE
+	bool "Support for console on MILBEAUT USIO/UART serial port"
+	depends on SERIAL_MILBEAUT_USIO=y
+	default y
+	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
+	help
+	  Say 'Y' here if you wish to use a USIO/UART of Socionext Milbeaut
+	  SoCs as the system console (the system console is the device which
+	  receives all kernel messages and warnings and which allows logins in
+	  single user mode).
+
 endmenu
 
 config SERIAL_MCTRL_GPIO
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 40b702aaa85e..79c3d513db7e 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -92,6 +92,8 @@ obj-$(CONFIG_SERIAL_PIC32)	+= pic32_uart.o
 obj-$(CONFIG_SERIAL_MPS2_UART)	+= mps2-uart.o
 obj-$(CONFIG_SERIAL_OWL)	+= owl-uart.o
 obj-$(CONFIG_SERIAL_RDA)	+= rda-uart.o
+obj-$(CONFIG_SERIAL_MILBEAUT_USIO) += milbeaut_usio.o
+obj-$(CONFIG_SERIAL_SIFIVE)	+= sifive.o
 
 # GPIOLIB helpers for modem control lines
 obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/cpm_uart/Makefile b/drivers/tty/serial/cpm_uart/Makefile
index 896a5d57881c..3f3a6ed02ed4 100644
--- a/drivers/tty/serial/cpm_uart/Makefile
+++ b/drivers/tty/serial/cpm_uart/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for the Motorola 8xx FEC ethernet controller
 #
diff --git a/drivers/tty/serial/jsm/Makefile b/drivers/tty/serial/jsm/Makefile
index 705d1ff6fdeb..4f2dbada7741 100644
--- a/drivers/tty/serial/jsm/Makefile
+++ b/drivers/tty/serial/jsm/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for Jasmine adapter
 #
diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c
new file mode 100644
index 000000000000..949ab7efc4fc
--- /dev/null
+++ b/drivers/tty/serial/milbeaut_usio.c
@@ -0,0 +1,614 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Socionext Inc.
+ */
+
+#if defined(CONFIG_SERIAL_MILBEAUT_USIO_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+#define USIO_NAME		"mlb-usio-uart"
+#define USIO_UART_DEV_NAME	"ttyUSI"
+
+static struct uart_port mlb_usio_ports[CONFIG_SERIAL_MILBEAUT_USIO_PORTS];
+
+#define RX	0
+#define TX	1
+static int mlb_usio_irq[CONFIG_SERIAL_MILBEAUT_USIO_PORTS][2];
+
+#define MLB_USIO_REG_SMR		0
+#define MLB_USIO_REG_SCR		1
+#define MLB_USIO_REG_ESCR		2
+#define MLB_USIO_REG_SSR		3
+#define MLB_USIO_REG_DR			4
+#define MLB_USIO_REG_BGR		6
+#define MLB_USIO_REG_FCR		12
+#define MLB_USIO_REG_FBYTE		14
+
+#define MLB_USIO_SMR_SOE		BIT(0)
+#define MLB_USIO_SMR_SBL		BIT(3)
+#define MLB_USIO_SCR_TXE		BIT(0)
+#define MLB_USIO_SCR_RXE		BIT(1)
+#define MLB_USIO_SCR_TBIE		BIT(2)
+#define MLB_USIO_SCR_TIE		BIT(3)
+#define MLB_USIO_SCR_RIE		BIT(4)
+#define MLB_USIO_SCR_UPCL		BIT(7)
+#define MLB_USIO_ESCR_L_8BIT		0
+#define MLB_USIO_ESCR_L_5BIT		1
+#define MLB_USIO_ESCR_L_6BIT		2
+#define MLB_USIO_ESCR_L_7BIT		3
+#define MLB_USIO_ESCR_P			BIT(3)
+#define MLB_USIO_ESCR_PEN		BIT(4)
+#define MLB_USIO_ESCR_FLWEN		BIT(7)
+#define MLB_USIO_SSR_TBI		BIT(0)
+#define MLB_USIO_SSR_TDRE		BIT(1)
+#define MLB_USIO_SSR_RDRF		BIT(2)
+#define MLB_USIO_SSR_ORE		BIT(3)
+#define MLB_USIO_SSR_FRE		BIT(4)
+#define MLB_USIO_SSR_PE			BIT(5)
+#define MLB_USIO_SSR_REC		BIT(7)
+#define MLB_USIO_SSR_BRK		BIT(8)
+#define MLB_USIO_FCR_FE1		BIT(0)
+#define MLB_USIO_FCR_FE2		BIT(1)
+#define MLB_USIO_FCR_FCL1		BIT(2)
+#define MLB_USIO_FCR_FCL2		BIT(3)
+#define MLB_USIO_FCR_FSET		BIT(4)
+#define MLB_USIO_FCR_FTIE		BIT(9)
+#define MLB_USIO_FCR_FDRQ		BIT(10)
+#define MLB_USIO_FCR_FRIIE		BIT(11)
+
+static void mlb_usio_stop_tx(struct uart_port *port)
+{
+	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FTIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) & ~MLB_USIO_SCR_TBIE,
+	       port->membase + MLB_USIO_REG_SCR);
+}
+
+static void mlb_usio_tx_chars(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+	int count;
+
+	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FTIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) &
+	       ~(MLB_USIO_SCR_TIE | MLB_USIO_SCR_TBIE),
+	       port->membase + MLB_USIO_REG_SCR);
+
+	if (port->x_char) {
+		writew(port->x_char, port->membase + MLB_USIO_REG_DR);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		mlb_usio_stop_tx(port);
+		return;
+	}
+
+	count = port->fifosize -
+		(readw(port->membase + MLB_USIO_REG_FBYTE) & 0xff);
+
+	do {
+		writew(xmit->buf[xmit->tail], port->membase + MLB_USIO_REG_DR);
+
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+
+	} while (--count > 0);
+
+	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FDRQ,
+	       port->membase + MLB_USIO_REG_FCR);
+
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) | MLB_USIO_SCR_TBIE,
+	       port->membase + MLB_USIO_REG_SCR);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit))
+		mlb_usio_stop_tx(port);
+}
+
+static void mlb_usio_start_tx(struct uart_port *port)
+{
+	u16 fcr = readw(port->membase + MLB_USIO_REG_FCR);
+
+	writew(fcr | MLB_USIO_FCR_FTIE, port->membase + MLB_USIO_REG_FCR);
+	if (!(fcr & MLB_USIO_FCR_FDRQ))
+		return;
+
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) | MLB_USIO_SCR_TBIE,
+	       port->membase + MLB_USIO_REG_SCR);
+
+	if (readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TBI)
+		mlb_usio_tx_chars(port);
+}
+
+static void mlb_usio_stop_rx(struct uart_port *port)
+{
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) & ~MLB_USIO_SCR_RIE,
+	       port->membase + MLB_USIO_REG_SCR);
+}
+
+static void mlb_usio_enable_ms(struct uart_port *port)
+{
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) |
+	       MLB_USIO_SCR_RIE | MLB_USIO_SCR_RXE,
+	       port->membase + MLB_USIO_REG_SCR);
+}
+
+static void mlb_usio_rx_chars(struct uart_port *port)
+{
+	struct tty_port *ttyport = &port->state->port;
+	unsigned long flag = 0;
+	char ch = 0;
+	u8 status;
+	int max_count = 2;
+
+	while (max_count--) {
+		status = readb(port->membase + MLB_USIO_REG_SSR);
+
+		if (!(status & MLB_USIO_SSR_RDRF))
+			break;
+
+		if (!(status & (MLB_USIO_SSR_ORE | MLB_USIO_SSR_FRE |
+				MLB_USIO_SSR_PE))) {
+			ch = readw(port->membase + MLB_USIO_REG_DR);
+			flag = TTY_NORMAL;
+			port->icount.rx++;
+			if (uart_handle_sysrq_char(port, ch))
+				continue;
+			uart_insert_char(port, status, MLB_USIO_SSR_ORE,
+					 ch, flag);
+			continue;
+		}
+		if (status & MLB_USIO_SSR_PE)
+			port->icount.parity++;
+		if (status & MLB_USIO_SSR_ORE)
+			port->icount.overrun++;
+		status &= port->read_status_mask;
+		if (status & MLB_USIO_SSR_BRK) {
+			flag = TTY_BREAK;
+			ch = 0;
+		} else
+			if (status & MLB_USIO_SSR_PE) {
+				flag = TTY_PARITY;
+				ch = 0;
+			} else
+				if (status & MLB_USIO_SSR_FRE) {
+					flag = TTY_FRAME;
+					ch = 0;
+				}
+		if (flag)
+			uart_insert_char(port, status, MLB_USIO_SSR_ORE,
+					 ch, flag);
+
+		writeb(readb(port->membase + MLB_USIO_REG_SSR) |
+				MLB_USIO_SSR_REC,
+				port->membase + MLB_USIO_REG_SSR);
+
+		max_count = readw(port->membase + MLB_USIO_REG_FBYTE) >> 8;
+		writew(readw(port->membase + MLB_USIO_REG_FCR) |
+		       MLB_USIO_FCR_FE2 | MLB_USIO_FCR_FRIIE,
+		port->membase + MLB_USIO_REG_FCR);
+	}
+
+	tty_flip_buffer_push(ttyport);
+}
+
+static irqreturn_t mlb_usio_rx_irq(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+
+	spin_lock(&port->lock);
+	mlb_usio_rx_chars(port);
+	spin_unlock(&port->lock);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t mlb_usio_tx_irq(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+
+	spin_lock(&port->lock);
+	if (readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TBI)
+		mlb_usio_tx_chars(port);
+	spin_unlock(&port->lock);
+
+	return IRQ_HANDLED;
+}
+
+static unsigned int mlb_usio_tx_empty(struct uart_port *port)
+{
+	return (readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TBI) ?
+		TIOCSER_TEMT : 0;
+}
+
+static void mlb_usio_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+static unsigned int mlb_usio_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
+
+}
+
+static void mlb_usio_break_ctl(struct uart_port *port, int break_state)
+{
+}
+
+static int mlb_usio_startup(struct uart_port *port)
+{
+	const char *portname = to_platform_device(port->dev)->name;
+	unsigned long flags;
+	int ret, index = port->line;
+	unsigned char  escr;
+
+	ret = request_irq(mlb_usio_irq[index][RX], mlb_usio_rx_irq,
+				0, portname, port);
+	if (ret)
+		return ret;
+	ret = request_irq(mlb_usio_irq[index][TX], mlb_usio_tx_irq,
+				0, portname, port);
+	if (ret) {
+		free_irq(mlb_usio_irq[index][RX], port);
+		return ret;
+	}
+
+	escr = readb(port->membase + MLB_USIO_REG_ESCR);
+	if (of_property_read_bool(port->dev->of_node, "auto-flow-control"))
+		escr |= MLB_USIO_ESCR_FLWEN;
+	spin_lock_irqsave(&port->lock, flags);
+	writeb(0, port->membase + MLB_USIO_REG_SCR);
+	writeb(escr, port->membase + MLB_USIO_REG_ESCR);
+	writeb(MLB_USIO_SCR_UPCL, port->membase + MLB_USIO_REG_SCR);
+	writeb(MLB_USIO_SSR_REC, port->membase + MLB_USIO_REG_SSR);
+	writew(0, port->membase + MLB_USIO_REG_FCR);
+	writew(MLB_USIO_FCR_FCL1 | MLB_USIO_FCR_FCL2,
+	       port->membase + MLB_USIO_REG_FCR);
+	writew(MLB_USIO_FCR_FE1 | MLB_USIO_FCR_FE2 | MLB_USIO_FCR_FRIIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writew(0, port->membase + MLB_USIO_REG_FBYTE);
+	writew(BIT(12), port->membase + MLB_USIO_REG_FBYTE);
+
+	writeb(MLB_USIO_SCR_TXE  | MLB_USIO_SCR_RIE | MLB_USIO_SCR_TBIE |
+	       MLB_USIO_SCR_RXE, port->membase + MLB_USIO_REG_SCR);
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return 0;
+}
+
+static void mlb_usio_shutdown(struct uart_port *port)
+{
+	int index = port->line;
+
+	free_irq(mlb_usio_irq[index][RX], port);
+	free_irq(mlb_usio_irq[index][TX], port);
+}
+
+static void mlb_usio_set_termios(struct uart_port *port,
+			struct ktermios *termios, struct ktermios *old)
+{
+	unsigned int escr, smr = MLB_USIO_SMR_SOE;
+	unsigned long flags, baud, quot;
+
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		escr = MLB_USIO_ESCR_L_5BIT;
+		break;
+	case CS6:
+		escr = MLB_USIO_ESCR_L_6BIT;
+		break;
+	case CS7:
+		escr = MLB_USIO_ESCR_L_7BIT;
+		break;
+	case CS8:
+	default:
+		escr = MLB_USIO_ESCR_L_8BIT;
+		break;
+	}
+
+	if (termios->c_cflag & CSTOPB)
+		smr |= MLB_USIO_SMR_SBL;
+
+	if (termios->c_cflag & PARENB) {
+		escr |= MLB_USIO_ESCR_PEN;
+		if (termios->c_cflag & PARODD)
+			escr |= MLB_USIO_ESCR_P;
+	}
+	/* Set hard flow control */
+	if (of_property_read_bool(port->dev->of_node, "auto-flow-control") ||
+			(termios->c_cflag & CRTSCTS))
+		escr |= MLB_USIO_ESCR_FLWEN;
+
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk);
+	if (baud > 1)
+		quot = port->uartclk / baud - 1;
+	else
+		quot = 0;
+
+	spin_lock_irqsave(&port->lock, flags);
+	uart_update_timeout(port, termios->c_cflag, baud);
+	port->read_status_mask = MLB_USIO_SSR_ORE | MLB_USIO_SSR_RDRF |
+				 MLB_USIO_SSR_TDRE;
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= MLB_USIO_SSR_FRE | MLB_USIO_SSR_PE;
+
+	port->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		port->ignore_status_mask |= MLB_USIO_SSR_FRE | MLB_USIO_SSR_PE;
+	if ((termios->c_iflag & IGNBRK) && (termios->c_iflag & IGNPAR))
+		port->ignore_status_mask |= MLB_USIO_SSR_ORE;
+	if ((termios->c_cflag & CREAD) == 0)
+		port->ignore_status_mask |= MLB_USIO_SSR_RDRF;
+
+	writeb(0, port->membase + MLB_USIO_REG_SCR);
+	writeb(MLB_USIO_SCR_UPCL, port->membase + MLB_USIO_REG_SCR);
+	writeb(MLB_USIO_SSR_REC, port->membase + MLB_USIO_REG_SSR);
+	writew(0, port->membase + MLB_USIO_REG_FCR);
+	writeb(smr, port->membase + MLB_USIO_REG_SMR);
+	writeb(escr, port->membase + MLB_USIO_REG_ESCR);
+	writew(quot, port->membase + MLB_USIO_REG_BGR);
+	writew(0, port->membase + MLB_USIO_REG_FCR);
+	writew(MLB_USIO_FCR_FCL1 | MLB_USIO_FCR_FCL2 | MLB_USIO_FCR_FE1 |
+	       MLB_USIO_FCR_FE2 | MLB_USIO_FCR_FRIIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writew(0, port->membase + MLB_USIO_REG_FBYTE);
+	writew(BIT(12), port->membase + MLB_USIO_REG_FBYTE);
+	writeb(MLB_USIO_SCR_RIE | MLB_USIO_SCR_RXE | MLB_USIO_SCR_TBIE |
+	       MLB_USIO_SCR_TXE, port->membase + MLB_USIO_REG_SCR);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *mlb_usio_type(struct uart_port *port)
+{
+	return ((port->type == PORT_MLB_USIO) ? USIO_NAME : NULL);
+}
+
+static void mlb_usio_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE)
+		port->type = PORT_MLB_USIO;
+}
+
+static const struct uart_ops mlb_usio_ops = {
+	.tx_empty	= mlb_usio_tx_empty,
+	.set_mctrl	= mlb_usio_set_mctrl,
+	.get_mctrl	= mlb_usio_get_mctrl,
+	.stop_tx	= mlb_usio_stop_tx,
+	.start_tx	= mlb_usio_start_tx,
+	.stop_rx	= mlb_usio_stop_rx,
+	.enable_ms	= mlb_usio_enable_ms,
+	.break_ctl	= mlb_usio_break_ctl,
+	.startup	= mlb_usio_startup,
+	.shutdown	= mlb_usio_shutdown,
+	.set_termios	= mlb_usio_set_termios,
+	.type		= mlb_usio_type,
+	.config_port	= mlb_usio_config_port,
+};
+
+#ifdef CONFIG_SERIAL_MILBEAUT_USIO_CONSOLE
+
+static void mlb_usio_console_putchar(struct uart_port *port, int c)
+{
+	while (!(readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TDRE))
+		cpu_relax();
+
+	writew(c, port->membase + MLB_USIO_REG_DR);
+}
+
+static void mlb_usio_console_write(struct console *co, const char *s,
+			       unsigned int count)
+{
+	struct uart_port *port = &mlb_usio_ports[co->index];
+
+	uart_console_write(port, s, count, mlb_usio_console_putchar);
+}
+
+static int __init mlb_usio_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port;
+	int baud = 115200;
+	int parity = 'n';
+	int flow = 'n';
+	int bits = 8;
+
+	if (co->index >= CONFIG_SERIAL_MILBEAUT_USIO_PORTS)
+		return -ENODEV;
+
+	port = &mlb_usio_ports[co->index];
+	if (!port->membase)
+		return -ENODEV;
+
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	if (of_property_read_bool(port->dev->of_node, "auto-flow-control"))
+		flow = 'r';
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+
+static struct uart_driver mlb_usio_uart_driver;
+static struct console mlb_usio_console = {
+	.name   = USIO_UART_DEV_NAME,
+	.write  = mlb_usio_console_write,
+	.device = uart_console_device,
+	.setup  = mlb_usio_console_setup,
+	.flags  = CON_PRINTBUFFER,
+	.index  = -1,
+	.data   = &mlb_usio_uart_driver,
+};
+
+static int __init mlb_usio_console_init(void)
+{
+	register_console(&mlb_usio_console);
+	return 0;
+}
+console_initcall(mlb_usio_console_init);
+
+
+static void mlb_usio_early_console_write(struct console *co, const char *s,
+					u_int count)
+{
+	struct earlycon_device *dev = co->data;
+
+	uart_console_write(&dev->port, s, count, mlb_usio_console_putchar);
+}
+
+static int __init mlb_usio_early_console_setup(struct earlycon_device *device,
+						const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+	device->con->write = mlb_usio_early_console_write;
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(mlb_usio, "socionext,milbeaut-usio-uart",
+			mlb_usio_early_console_setup);
+
+#define USIO_CONSOLE	(&mlb_usio_console)
+#else
+#define USIO_CONSOLE	NULL
+#endif
+
+static struct  uart_driver mlb_usio_uart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= USIO_NAME,
+	.dev_name	= USIO_UART_DEV_NAME,
+	.cons           = USIO_CONSOLE,
+	.nr		= CONFIG_SERIAL_MILBEAUT_USIO_PORTS,
+};
+
+static int mlb_usio_probe(struct platform_device *pdev)
+{
+	struct clk *clk = devm_clk_get(&pdev->dev, NULL);
+	struct uart_port *port;
+	struct resource *res;
+	int index = 0;
+	int ret;
+
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "Missing clock\n");
+		return PTR_ERR(clk);
+	}
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Clock enable failed: %d\n", ret);
+		return ret;
+	}
+	of_property_read_u32(pdev->dev.of_node, "index", &index);
+	port = &mlb_usio_ports[index];
+
+	port->private_data = (void *)clk;
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res == NULL) {
+		dev_err(&pdev->dev, "Missing regs\n");
+		ret = -ENODEV;
+		goto failed;
+	}
+	port->membase = devm_ioremap(&pdev->dev, res->start,
+				resource_size(res));
+
+	ret = platform_get_irq_byname(pdev, "rx");
+	mlb_usio_irq[index][RX] = ret;
+
+	ret = platform_get_irq_byname(pdev, "tx");
+	mlb_usio_irq[index][TX] = ret;
+
+	port->irq = mlb_usio_irq[index][RX];
+	port->uartclk = clk_get_rate(clk);
+	port->fifosize = 128;
+	port->iotype = UPIO_MEM32;
+	port->flags = UPF_BOOT_AUTOCONF | UPF_SPD_VHI;
+	port->line = index;
+	port->ops = &mlb_usio_ops;
+	port->dev = &pdev->dev;
+
+	ret = uart_add_one_port(&mlb_usio_uart_driver, port);
+	if (ret) {
+		dev_err(&pdev->dev, "Adding port failed: %d\n", ret);
+		goto failed;
+	}
+	return 0;
+
+failed:
+	clk_disable_unprepare(clk);
+
+	return ret;
+}
+
+static int mlb_usio_remove(struct platform_device *pdev)
+{
+	struct uart_port *port = &mlb_usio_ports[pdev->id];
+	struct clk *clk = port->private_data;
+
+	uart_remove_one_port(&mlb_usio_uart_driver, port);
+	clk_disable_unprepare(clk);
+
+	return 0;
+}
+
+static const struct of_device_id mlb_usio_dt_ids[] = {
+	{ .compatible = "socionext,milbeaut-usio-uart" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mlb_usio_dt_ids);
+
+static struct platform_driver mlb_usio_driver = {
+	.probe          = mlb_usio_probe,
+	.remove         = mlb_usio_remove,
+	.driver         = {
+		.name   = USIO_NAME,
+		.of_match_table = mlb_usio_dt_ids,
+	},
+};
+
+static int __init mlb_usio_init(void)
+{
+	int ret = uart_register_driver(&mlb_usio_uart_driver);
+
+	if (ret) {
+		pr_err("%s: uart registration failed: %d\n", __func__, ret);
+		return ret;
+	}
+	ret = platform_driver_register(&mlb_usio_driver);
+	if (ret) {
+		uart_unregister_driver(&mlb_usio_uart_driver);
+		pr_err("%s: drv registration failed: %d\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit mlb_usio_exit(void)
+{
+	platform_driver_unregister(&mlb_usio_driver);
+	uart_unregister_driver(&mlb_usio_uart_driver);
+}
+
+module_init(mlb_usio_init);
+module_exit(mlb_usio_exit);
+
+MODULE_AUTHOR("SOCIONEXT");
+MODULE_DESCRIPTION("MILBEAUT_USIO/UART Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index a31db15cd7c0..7d3ae31cc720 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -14,9 +14,9 @@
 #include <linux/device.h>
 #include <linux/gpio/driver.h>
 #include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
 #include <linux/module.h>
-#include <linux/of.h>
-#include <linux/of_device.h>
+#include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/serial_core.h>
 #include <linux/serial.h>
@@ -1179,7 +1179,8 @@ static int sc16is7xx_probe(struct device *dev,
 			   struct regmap *regmap, int irq, unsigned long flags)
 {
 	struct sched_param sched_param = { .sched_priority = MAX_RT_PRIO / 2 };
-	unsigned long freq, *pfreq = dev_get_platdata(dev);
+	unsigned long freq = 0, *pfreq = dev_get_platdata(dev);
+	u32 uartclk = 0;
 	int i, ret;
 	struct sc16is7xx_port *s;
 
@@ -1193,10 +1194,17 @@ static int sc16is7xx_probe(struct device *dev,
 		return -ENOMEM;
 	}
 
+	/* Always ask for fixed clock rate from a property. */
+	device_property_read_u32(dev, "clock-frequency", &uartclk);
+
 	s->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(s->clk)) {
+		if (uartclk)
+			freq = uartclk;
 		if (pfreq)
 			freq = *pfreq;
+		if (freq)
+			dev_dbg(dev, "Clock frequency: %luHz\n", freq);
 		else
 			return PTR_ERR(s->clk);
 	} else {
@@ -1384,13 +1392,9 @@ static int sc16is7xx_spi_probe(struct spi_device *spi)
 		return ret;
 
 	if (spi->dev.of_node) {
-		const struct of_device_id *of_id =
-			of_match_device(sc16is7xx_dt_ids, &spi->dev);
-
-		if (!of_id)
+		devtype = device_get_match_data(&spi->dev);
+		if (!devtype)
 			return -ENODEV;
-
-		devtype = (struct sc16is7xx_devtype *)of_id->data;
 	} else {
 		const struct spi_device_id *id_entry = spi_get_device_id(spi);
 
@@ -1426,7 +1430,7 @@ MODULE_DEVICE_TABLE(spi, sc16is7xx_spi_id_table);
 static struct spi_driver sc16is7xx_spi_uart_driver = {
 	.driver = {
 		.name		= SC16IS7XX_NAME,
-		.of_match_table	= of_match_ptr(sc16is7xx_dt_ids),
+		.of_match_table	= sc16is7xx_dt_ids,
 	},
 	.probe		= sc16is7xx_spi_probe,
 	.remove		= sc16is7xx_spi_remove,
@@ -1445,13 +1449,9 @@ static int sc16is7xx_i2c_probe(struct i2c_client *i2c,
 	struct regmap *regmap;
 
 	if (i2c->dev.of_node) {
-		const struct of_device_id *of_id =
-				of_match_device(sc16is7xx_dt_ids, &i2c->dev);
-
-		if (!of_id)
+		devtype = device_get_match_data(&i2c->dev);
+		if (!devtype)
 			return -ENODEV;
-
-		devtype = (struct sc16is7xx_devtype *)of_id->data;
 	} else {
 		devtype = (struct sc16is7xx_devtype *)id->driver_data;
 		flags = IRQF_TRIGGER_FALLING;
@@ -1484,7 +1484,7 @@ MODULE_DEVICE_TABLE(i2c, sc16is7xx_i2c_id_table);
 static struct i2c_driver sc16is7xx_i2c_uart_driver = {
 	.driver = {
 		.name		= SC16IS7XX_NAME,
-		.of_match_table	= of_match_ptr(sc16is7xx_dt_ids),
+		.of_match_table	= sc16is7xx_dt_ids,
 	},
 	.probe		= sc16is7xx_i2c_probe,
 	.remove		= sc16is7xx_i2c_remove,
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 351843f847c0..83f4dd0bfd74 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -130,9 +130,6 @@ static void uart_start(struct tty_struct *tty)
 	struct uart_port *port;
 	unsigned long flags;
 
-	if (!state)
-		return;
-
 	port = uart_port_lock(state, flags);
 	__uart_start(tty);
 	uart_port_unlock(port, flags);
@@ -730,9 +727,6 @@ static void uart_unthrottle(struct tty_struct *tty)
 	upstat_t mask = UPSTAT_SYNC_FIFO;
 	struct uart_port *port;
 
-	if (!state)
-		return;
-
 	port = uart_port_ref(state);
 	if (!port)
 		return;
@@ -1514,7 +1508,7 @@ static void uart_set_termios(struct tty_struct *tty,
 	}
 
 	uart_change_speed(tty, state, old_termios);
-	/* reload cflag from termios; port driver may have overriden flags */
+	/* reload cflag from termios; port driver may have overridden flags */
 	cflag = tty->termios.c_cflag;
 
 	/* Handle transition to B0 status */
@@ -1747,6 +1741,16 @@ static void uart_dtr_rts(struct tty_port *port, int raise)
 	uart_port_deref(uport);
 }
 
+static int uart_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+	struct uart_driver *drv = driver->driver_state;
+	struct uart_state *state = drv->state + tty->index;
+
+	tty->driver_data = state;
+
+	return tty_standard_install(driver, tty);
+}
+
 /*
  * Calls to uart_open are serialised by the tty_lock in
  *   drivers/tty/tty_io.c:tty_open()
@@ -1759,11 +1763,8 @@ static void uart_dtr_rts(struct tty_port *port, int raise)
  */
 static int uart_open(struct tty_struct *tty, struct file *filp)
 {
-	struct uart_driver *drv = tty->driver->driver_state;
-	int retval, line = tty->index;
-	struct uart_state *state = drv->state + line;
-
-	tty->driver_data = state;
+	struct uart_state *state = tty->driver_data;
+	int retval;
 
 	retval = tty_port_open(&state->port, tty, filp);
 	if (retval > 0)
@@ -2448,6 +2449,7 @@ static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
 #endif
 
 static const struct tty_operations uart_ops = {
+	.install	= uart_install,
 	.open		= uart_open,
 	.close		= uart_close,
 	.write		= uart_write,
@@ -2505,7 +2507,7 @@ static const struct tty_port_operations uart_port_ops = {
 int uart_register_driver(struct uart_driver *drv)
 {
 	struct tty_driver *normal;
-	int i, retval;
+	int i, retval = -ENOMEM;
 
 	BUG_ON(drv->state);
 
@@ -2557,7 +2559,7 @@ int uart_register_driver(struct uart_driver *drv)
 out_kfree:
 	kfree(drv->state);
 out:
-	return -ENOMEM;
+	return retval;
 }
 
 /**
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
new file mode 100644
index 000000000000..be4687814353
--- /dev/null
+++ b/drivers/tty/serial/sifive.c
@@ -0,0 +1,1056 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * SiFive UART driver
+ * Copyright (C) 2018 Paul Walmsley <paul@pwsan.com>
+ * Copyright (C) 2018-2019 SiFive
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Based partially on:
+ * - drivers/tty/serial/pxa.c
+ * - drivers/tty/serial/amba-pl011.c
+ * - drivers/tty/serial/uartlite.c
+ * - drivers/tty/serial/omap-serial.c
+ * - drivers/pwm/pwm-sifive.c
+ *
+ * See the following sources for further documentation:
+ * - Chapter 19 "Universal Asynchronous Receiver/Transmitter (UART)" of
+ *   SiFive FE310-G000 v2p3
+ * - The tree/master/src/main/scala/devices/uart directory of
+ *   https://github.com/sifive/sifive-blocks/
+ *
+ * The SiFive UART design is not 8250-compatible.  The following common
+ * features are not supported:
+ * - Word lengths other than 8 bits
+ * - Break handling
+ * - Parity
+ * - Flow control
+ * - Modem signals (DSR, RI, etc.)
+ * On the other hand, the design is free from the baggage of the 8250
+ * programming model.
+ */
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+/*
+ * Register offsets
+ */
+
+/* TXDATA */
+#define SIFIVE_SERIAL_TXDATA_OFFS		0x0
+#define SIFIVE_SERIAL_TXDATA_FULL_SHIFT		31
+#define SIFIVE_SERIAL_TXDATA_FULL_MASK		(1 << SIFIVE_SERIAL_TXDATA_FULL_SHIFT)
+#define SIFIVE_SERIAL_TXDATA_DATA_SHIFT		0
+#define SIFIVE_SERIAL_TXDATA_DATA_MASK		(0xff << SIFIVE_SERIAL_TXDATA_DATA_SHIFT)
+
+/* RXDATA */
+#define SIFIVE_SERIAL_RXDATA_OFFS		0x4
+#define SIFIVE_SERIAL_RXDATA_EMPTY_SHIFT	31
+#define SIFIVE_SERIAL_RXDATA_EMPTY_MASK		(1 << SIFIVE_SERIAL_RXDATA_EMPTY_SHIFT)
+#define SIFIVE_SERIAL_RXDATA_DATA_SHIFT		0
+#define SIFIVE_SERIAL_RXDATA_DATA_MASK		(0xff << SIFIVE_SERIAL_RXDATA_DATA_SHIFT)
+
+/* TXCTRL */
+#define SIFIVE_SERIAL_TXCTRL_OFFS		0x8
+#define SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT	16
+#define SIFIVE_SERIAL_TXCTRL_TXCNT_MASK		(0x7 << SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT)
+#define SIFIVE_SERIAL_TXCTRL_NSTOP_SHIFT	1
+#define SIFIVE_SERIAL_TXCTRL_NSTOP_MASK		(1 << SIFIVE_SERIAL_TXCTRL_NSTOP_SHIFT)
+#define SIFIVE_SERIAL_TXCTRL_TXEN_SHIFT		0
+#define SIFIVE_SERIAL_TXCTRL_TXEN_MASK		(1 << SIFIVE_SERIAL_TXCTRL_TXEN_SHIFT)
+
+/* RXCTRL */
+#define SIFIVE_SERIAL_RXCTRL_OFFS		0xC
+#define SIFIVE_SERIAL_RXCTRL_RXCNT_SHIFT	16
+#define SIFIVE_SERIAL_RXCTRL_RXCNT_MASK		(0x7 << SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT)
+#define SIFIVE_SERIAL_RXCTRL_RXEN_SHIFT		0
+#define SIFIVE_SERIAL_RXCTRL_RXEN_MASK		(1 << SIFIVE_SERIAL_RXCTRL_RXEN_SHIFT)
+
+/* IE */
+#define SIFIVE_SERIAL_IE_OFFS			0x10
+#define SIFIVE_SERIAL_IE_RXWM_SHIFT		1
+#define SIFIVE_SERIAL_IE_RXWM_MASK		(1 << SIFIVE_SERIAL_IE_RXWM_SHIFT)
+#define SIFIVE_SERIAL_IE_TXWM_SHIFT		0
+#define SIFIVE_SERIAL_IE_TXWM_MASK		(1 << SIFIVE_SERIAL_IE_TXWM_SHIFT)
+
+/* IP */
+#define SIFIVE_SERIAL_IP_OFFS			0x14
+#define SIFIVE_SERIAL_IP_RXWM_SHIFT		1
+#define SIFIVE_SERIAL_IP_RXWM_MASK		(1 << SIFIVE_SERIAL_IP_RXWM_SHIFT)
+#define SIFIVE_SERIAL_IP_TXWM_SHIFT		0
+#define SIFIVE_SERIAL_IP_TXWM_MASK		(1 << SIFIVE_SERIAL_IP_TXWM_SHIFT)
+
+/* DIV */
+#define SIFIVE_SERIAL_DIV_OFFS			0x18
+#define SIFIVE_SERIAL_DIV_DIV_SHIFT		0
+#define SIFIVE_SERIAL_DIV_DIV_MASK		(0xffff << SIFIVE_SERIAL_IP_DIV_SHIFT)
+
+/*
+ * Config macros
+ */
+
+/*
+ * SIFIVE_SERIAL_MAX_PORTS: maximum number of UARTs on a device that can
+ *                          host a serial console
+ */
+#define SIFIVE_SERIAL_MAX_PORTS			8
+
+/*
+ * SIFIVE_DEFAULT_BAUD_RATE: default baud rate that the driver should
+ *                           configure itself to use
+ */
+#define SIFIVE_DEFAULT_BAUD_RATE		115200
+
+/* SIFIVE_SERIAL_NAME: our driver's name that we pass to the operating system */
+#define SIFIVE_SERIAL_NAME			"sifive-serial"
+
+/* SIFIVE_TTY_PREFIX: tty name prefix for SiFive serial ports */
+#define SIFIVE_TTY_PREFIX			"ttySIF"
+
+/* SIFIVE_TX_FIFO_DEPTH: depth of the TX FIFO (in bytes) */
+#define SIFIVE_TX_FIFO_DEPTH			8
+
+/* SIFIVE_RX_FIFO_DEPTH: depth of the TX FIFO (in bytes) */
+#define SIFIVE_RX_FIFO_DEPTH			8
+
+#if (SIFIVE_TX_FIFO_DEPTH != SIFIVE_RX_FIFO_DEPTH)
+#error Driver does not support configurations with different TX, RX FIFO sizes
+#endif
+
+/*
+ *
+ */
+
+/**
+ * sifive_serial_port - driver-specific data extension to struct uart_port
+ * @port: struct uart_port embedded in this struct
+ * @dev: struct device *
+ * @ier: shadowed copy of the interrupt enable register
+ * @clkin_rate: input clock to the UART IP block.
+ * @baud_rate: UART serial line rate (e.g., 115200 baud)
+ * @clk_notifier: clock rate change notifier for upstream clock changes
+ *
+ * Configuration data specific to this SiFive UART.
+ */
+struct sifive_serial_port {
+	struct uart_port	port;
+	struct device		*dev;
+	unsigned char		ier;
+	unsigned long		clkin_rate;
+	unsigned long		baud_rate;
+	struct clk		*clk;
+	struct notifier_block	clk_notifier;
+};
+
+/*
+ * Structure container-of macros
+ */
+
+#define port_to_sifive_serial_port(p) (container_of((p), \
+						    struct sifive_serial_port, \
+						    port))
+
+#define notifier_to_sifive_serial_port(nb) (container_of((nb), \
+							 struct sifive_serial_port, \
+							 clk_notifier))
+
+/*
+ * Forward declarations
+ */
+static void sifive_serial_stop_tx(struct uart_port *port);
+
+/*
+ * Internal functions
+ */
+
+/**
+ * __ssp_early_writel() - write to a SiFive serial port register (early)
+ * @port: pointer to a struct uart_port record
+ * @offs: register address offset from the IP block base address
+ * @v: value to write to the register
+ *
+ * Given a pointer @port to a struct uart_port record, write the value
+ * @v to the IP block register address offset @offs.  This function is
+ * intended for early console use.
+ *
+ * Context: Intended to be used only by the earlyconsole code.
+ */
+static void __ssp_early_writel(u32 v, u16 offs, struct uart_port *port)
+{
+	writel_relaxed(v, port->membase + offs);
+}
+
+/**
+ * __ssp_early_readl() - read from a SiFive serial port register (early)
+ * @port: pointer to a struct uart_port record
+ * @offs: register address offset from the IP block base address
+ *
+ * Given a pointer @port to a struct uart_port record, read the
+ * contents of the IP block register located at offset @offs from the
+ * IP block base and return it.  This function is intended for early
+ * console use.
+ *
+ * Context: Intended to be called only by the earlyconsole code or by
+ *          __ssp_readl() or __ssp_writel() (in this driver)
+ *
+ * Returns: the register value read from the UART.
+ */
+static u32 __ssp_early_readl(struct uart_port *port, u16 offs)
+{
+	return readl_relaxed(port->membase + offs);
+}
+
+/**
+ * __ssp_writel() - write to a SiFive serial port register
+ * @v: value to write to the register
+ * @offs: register address offset from the IP block base address
+ * @ssp: pointer to a struct sifive_serial_port record
+ *
+ * Write the value @v to the IP block register located at offset @offs from the
+ * IP block base, given a pointer @ssp to a struct sifive_serial_port record.
+ *
+ * Context: Any context.
+ */
+static void __ssp_writel(u32 v, u16 offs, struct sifive_serial_port *ssp)
+{
+	__ssp_early_writel(v, offs, &ssp->port);
+}
+
+/**
+ * __ssp_readl() - read from a SiFive serial port register
+ * @ssp: pointer to a struct sifive_serial_port record
+ * @offs: register address offset from the IP block base address
+ *
+ * Read the contents of the IP block register located at offset @offs from the
+ * IP block base, given a pointer @ssp to a struct sifive_serial_port record.
+ *
+ * Context: Any context.
+ *
+ * Returns: the value of the UART register
+ */
+static u32 __ssp_readl(struct sifive_serial_port *ssp, u16 offs)
+{
+	return __ssp_early_readl(&ssp->port, offs);
+}
+
+/**
+ * sifive_serial_is_txfifo_full() - is the TXFIFO full?
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Read the transmit FIFO "full" bit, returning a non-zero value if the
+ * TX FIFO is full, or zero if space remains.  Intended to be used to prevent
+ * writes to the TX FIFO when it's full.
+ *
+ * Returns: SIFIVE_SERIAL_TXDATA_FULL_MASK (non-zero) if the transmit FIFO
+ * is full, or 0 if space remains.
+ */
+static int sifive_serial_is_txfifo_full(struct sifive_serial_port *ssp)
+{
+	return __ssp_readl(ssp, SIFIVE_SERIAL_TXDATA_OFFS) &
+		SIFIVE_SERIAL_TXDATA_FULL_MASK;
+}
+
+/**
+ * __ssp_transmit_char() - enqueue a byte to transmit onto the TX FIFO
+ * @ssp: pointer to a struct sifive_serial_port
+ * @ch: character to transmit
+ *
+ * Enqueue a byte @ch onto the transmit FIFO, given a pointer @ssp to the
+ * struct sifive_serial_port * to transmit on.  Caller should first check to
+ * ensure that the TXFIFO has space; see sifive_serial_is_txfifo_full().
+ *
+ * Context: Any context.
+ */
+static void __ssp_transmit_char(struct sifive_serial_port *ssp, int ch)
+{
+	__ssp_writel(ch, SIFIVE_SERIAL_TXDATA_OFFS, ssp);
+}
+
+/**
+ * __ssp_transmit_chars() - enqueue multiple bytes onto the TX FIFO
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Transfer up to a TX FIFO size's worth of characters from the Linux serial
+ * transmit buffer to the SiFive UART TX FIFO.
+ *
+ * Context: Any context.  Expects @ssp->port.lock to be held by caller.
+ */
+static void __ssp_transmit_chars(struct sifive_serial_port *ssp)
+{
+	struct circ_buf *xmit = &ssp->port.state->xmit;
+	int count;
+
+	if (ssp->port.x_char) {
+		__ssp_transmit_char(ssp, ssp->port.x_char);
+		ssp->port.icount.tx++;
+		ssp->port.x_char = 0;
+		return;
+	}
+	if (uart_circ_empty(xmit) || uart_tx_stopped(&ssp->port)) {
+		sifive_serial_stop_tx(&ssp->port);
+		return;
+	}
+	count = SIFIVE_TX_FIFO_DEPTH;
+	do {
+		__ssp_transmit_char(ssp, xmit->buf[xmit->tail]);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		ssp->port.icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+	} while (--count > 0);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&ssp->port);
+
+	if (uart_circ_empty(xmit))
+		sifive_serial_stop_tx(&ssp->port);
+}
+
+/**
+ * __ssp_enable_txwm() - enable transmit watermark interrupts
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Enable interrupt generation when the transmit FIFO watermark is reached
+ * on the SiFive UART referred to by @ssp.
+ */
+static void __ssp_enable_txwm(struct sifive_serial_port *ssp)
+{
+	if (ssp->ier & SIFIVE_SERIAL_IE_TXWM_MASK)
+		return;
+
+	ssp->ier |= SIFIVE_SERIAL_IE_TXWM_MASK;
+	__ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+}
+
+/**
+ * __ssp_enable_rxwm() - enable receive watermark interrupts
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Enable interrupt generation when the receive FIFO watermark is reached
+ * on the SiFive UART referred to by @ssp.
+ */
+static void __ssp_enable_rxwm(struct sifive_serial_port *ssp)
+{
+	if (ssp->ier & SIFIVE_SERIAL_IE_RXWM_MASK)
+		return;
+
+	ssp->ier |= SIFIVE_SERIAL_IE_RXWM_MASK;
+	__ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+}
+
+/**
+ * __ssp_disable_txwm() - disable transmit watermark interrupts
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Disable interrupt generation when the transmit FIFO watermark is reached
+ * on the UART referred to by @ssp.
+ */
+static void __ssp_disable_txwm(struct sifive_serial_port *ssp)
+{
+	if (!(ssp->ier & SIFIVE_SERIAL_IE_TXWM_MASK))
+		return;
+
+	ssp->ier &= ~SIFIVE_SERIAL_IE_TXWM_MASK;
+	__ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+}
+
+/**
+ * __ssp_disable_rxwm() - disable receive watermark interrupts
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Disable interrupt generation when the receive FIFO watermark is reached
+ * on the UART referred to by @ssp.
+ */
+static void __ssp_disable_rxwm(struct sifive_serial_port *ssp)
+{
+	if (!(ssp->ier & SIFIVE_SERIAL_IE_RXWM_MASK))
+		return;
+
+	ssp->ier &= ~SIFIVE_SERIAL_IE_RXWM_MASK;
+	__ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+}
+
+/**
+ * __ssp_receive_char() - receive a byte from the UART
+ * @ssp: pointer to a struct sifive_serial_port
+ * @is_empty: char pointer to return whether the RX FIFO is empty
+ *
+ * Try to read a byte from the SiFive UART RX FIFO, referenced by
+ * @ssp, and to return it.  Also returns the RX FIFO empty bit in
+ * the char pointed to by @ch.  The caller must pass the byte back to the
+ * Linux serial layer if needed.
+ *
+ * Returns: the byte read from the UART RX FIFO.
+ */
+static char __ssp_receive_char(struct sifive_serial_port *ssp, char *is_empty)
+{
+	u32 v;
+	u8 ch;
+
+	v = __ssp_readl(ssp, SIFIVE_SERIAL_RXDATA_OFFS);
+
+	if (!is_empty)
+		WARN_ON(1);
+	else
+		*is_empty = (v & SIFIVE_SERIAL_RXDATA_EMPTY_MASK) >>
+			SIFIVE_SERIAL_RXDATA_EMPTY_SHIFT;
+
+	ch = (v & SIFIVE_SERIAL_RXDATA_DATA_MASK) >>
+		SIFIVE_SERIAL_RXDATA_DATA_SHIFT;
+
+	return ch;
+}
+
+/**
+ * __ssp_receive_chars() - receive multiple bytes from the UART
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Receive up to an RX FIFO's worth of bytes from the SiFive UART referred
+ * to by @ssp and pass them up to the Linux serial layer.
+ *
+ * Context: Expects ssp->port.lock to be held by caller.
+ */
+static void __ssp_receive_chars(struct sifive_serial_port *ssp)
+{
+	unsigned char ch;
+	char is_empty;
+	int c;
+
+	for (c = SIFIVE_RX_FIFO_DEPTH; c > 0; --c) {
+		ch = __ssp_receive_char(ssp, &is_empty);
+		if (is_empty)
+			break;
+
+		ssp->port.icount.rx++;
+		uart_insert_char(&ssp->port, 0, 0, ch, TTY_NORMAL);
+	}
+
+	spin_unlock(&ssp->port.lock);
+	tty_flip_buffer_push(&ssp->port.state->port);
+	spin_lock(&ssp->port.lock);
+}
+
+/**
+ * __ssp_update_div() - calculate the divisor setting by the line rate
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Calculate the appropriate value of the clock divisor for the UART
+ * and target line rate referred to by @ssp and write it into the
+ * hardware.
+ */
+static void __ssp_update_div(struct sifive_serial_port *ssp)
+{
+	u16 div;
+
+	div = DIV_ROUND_UP(ssp->clkin_rate, ssp->baud_rate) - 1;
+
+	__ssp_writel(div, SIFIVE_SERIAL_DIV_OFFS, ssp);
+}
+
+/**
+ * __ssp_update_baud_rate() - set the UART "baud rate"
+ * @ssp: pointer to a struct sifive_serial_port
+ * @rate: new target bit rate
+ *
+ * Calculate the UART divisor value for the target bit rate @rate for the
+ * SiFive UART described by @ssp and program it into the UART.  There may
+ * be some error between the target bit rate and the actual bit rate implemented
+ * by the UART due to clock ratio granularity.
+ */
+static void __ssp_update_baud_rate(struct sifive_serial_port *ssp,
+				   unsigned int rate)
+{
+	if (ssp->baud_rate == rate)
+		return;
+
+	ssp->baud_rate = rate;
+	__ssp_update_div(ssp);
+}
+
+/**
+ * __ssp_set_stop_bits() - set the number of stop bits
+ * @ssp: pointer to a struct sifive_serial_port
+ * @nstop: 1 or 2 (stop bits)
+ *
+ * Program the SiFive UART referred to by @ssp to use @nstop stop bits.
+ */
+static void __ssp_set_stop_bits(struct sifive_serial_port *ssp, char nstop)
+{
+	u32 v;
+
+	if (nstop < 1 || nstop > 2) {
+		WARN_ON(1);
+		return;
+	}
+
+	v = __ssp_readl(ssp, SIFIVE_SERIAL_TXCTRL_OFFS);
+	v &= ~SIFIVE_SERIAL_TXCTRL_NSTOP_MASK;
+	v |= (nstop - 1) << SIFIVE_SERIAL_TXCTRL_NSTOP_SHIFT;
+	__ssp_writel(v, SIFIVE_SERIAL_TXCTRL_OFFS, ssp);
+}
+
+/**
+ * __ssp_wait_for_xmitr() - wait for an empty slot on the TX FIFO
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Delay while the UART TX FIFO referred to by @ssp is marked as full.
+ *
+ * Context: Any context.
+ */
+static void __maybe_unused __ssp_wait_for_xmitr(struct sifive_serial_port *ssp)
+{
+	while (sifive_serial_is_txfifo_full(ssp))
+		udelay(1); /* XXX Could probably be more intelligent here */
+}
+
+/*
+ * Linux serial API functions
+ */
+
+static void sifive_serial_stop_tx(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_disable_txwm(ssp);
+}
+
+static void sifive_serial_stop_rx(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_disable_rxwm(ssp);
+}
+
+static void sifive_serial_start_tx(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_enable_txwm(ssp);
+}
+
+static irqreturn_t sifive_serial_irq(int irq, void *dev_id)
+{
+	struct sifive_serial_port *ssp = dev_id;
+	u32 ip;
+
+	spin_lock(&ssp->port.lock);
+
+	ip = __ssp_readl(ssp, SIFIVE_SERIAL_IP_OFFS);
+	if (!ip) {
+		spin_unlock(&ssp->port.lock);
+		return IRQ_NONE;
+	}
+
+	if (ip & SIFIVE_SERIAL_IP_RXWM_MASK)
+		__ssp_receive_chars(ssp);
+	if (ip & SIFIVE_SERIAL_IP_TXWM_MASK)
+		__ssp_transmit_chars(ssp);
+
+	spin_unlock(&ssp->port.lock);
+
+	return IRQ_HANDLED;
+}
+
+static unsigned int sifive_serial_tx_empty(struct uart_port *port)
+{
+	return TIOCSER_TEMT;
+}
+
+static unsigned int sifive_serial_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR;
+}
+
+static void sifive_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	/* IP block does not support these signals */
+}
+
+static void sifive_serial_break_ctl(struct uart_port *port, int break_state)
+{
+	/* IP block does not support sending a break */
+}
+
+static int sifive_serial_startup(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_enable_rxwm(ssp);
+
+	return 0;
+}
+
+static void sifive_serial_shutdown(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_disable_rxwm(ssp);
+	__ssp_disable_txwm(ssp);
+}
+
+/**
+ * sifive_serial_clk_notifier() - clock post-rate-change notifier
+ * @nb: pointer to the struct notifier_block, from the notifier code
+ * @event: event mask from the notifier code
+ * @data: pointer to the struct clk_notifier_data from the notifier code
+ *
+ * On the V0 SoC, the UART IP block is derived from the CPU clock source
+ * after a synchronous divide-by-two divider, so any CPU clock rate change
+ * requires the UART baud rate to be updated.  This presumably could corrupt any
+ * serial word currently being transmitted or received.  It would probably
+ * be better to stop receives and transmits, then complete the baud rate
+ * change, then re-enable them.
+ */
+static int sifive_serial_clk_notifier(struct notifier_block *nb,
+				      unsigned long event, void *data)
+{
+	struct clk_notifier_data *cnd = data;
+	struct sifive_serial_port *ssp = notifier_to_sifive_serial_port(nb);
+
+	if (event == POST_RATE_CHANGE && ssp->clkin_rate != cnd->new_rate) {
+		ssp->clkin_rate = cnd->new_rate;
+		__ssp_update_div(ssp);
+	}
+
+	return NOTIFY_OK;
+}
+
+static void sifive_serial_set_termios(struct uart_port *port,
+				      struct ktermios *termios,
+				      struct ktermios *old)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+	unsigned long flags;
+	u32 v, old_v;
+	int rate;
+	char nstop;
+
+	if ((termios->c_cflag & CSIZE) != CS8)
+		dev_err_once(ssp->port.dev, "only 8-bit words supported\n");
+	if (termios->c_iflag & (INPCK | PARMRK))
+		dev_err_once(ssp->port.dev, "parity checking not supported\n");
+	if (termios->c_iflag & BRKINT)
+		dev_err_once(ssp->port.dev, "BREAK detection not supported\n");
+
+	/* Set number of stop bits */
+	nstop = (termios->c_cflag & CSTOPB) ? 2 : 1;
+	__ssp_set_stop_bits(ssp, nstop);
+
+	/* Set line rate */
+	rate = uart_get_baud_rate(port, termios, old, 0, ssp->clkin_rate / 16);
+	__ssp_update_baud_rate(ssp, rate);
+
+	spin_lock_irqsave(&ssp->port.lock, flags);
+
+	/* Update the per-port timeout */
+	uart_update_timeout(port, termios->c_cflag, rate);
+
+	ssp->port.read_status_mask = 0;
+
+	/* Ignore all characters if CREAD is not set */
+	v = __ssp_readl(ssp, SIFIVE_SERIAL_RXCTRL_OFFS);
+	old_v = v;
+	if ((termios->c_cflag & CREAD) == 0)
+		v &= SIFIVE_SERIAL_RXCTRL_RXEN_MASK;
+	else
+		v |= SIFIVE_SERIAL_RXCTRL_RXEN_MASK;
+	if (v != old_v)
+		__ssp_writel(v, SIFIVE_SERIAL_RXCTRL_OFFS, ssp);
+
+	spin_unlock_irqrestore(&ssp->port.lock, flags);
+}
+
+static void sifive_serial_release_port(struct uart_port *port)
+{
+}
+
+static int sifive_serial_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+static void sifive_serial_config_port(struct uart_port *port, int flags)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	ssp->port.type = PORT_SIFIVE_V0;
+}
+
+static int sifive_serial_verify_port(struct uart_port *port,
+				     struct serial_struct *ser)
+{
+	return -EINVAL;
+}
+
+static const char *sifive_serial_type(struct uart_port *port)
+{
+	return port->type == PORT_SIFIVE_V0 ? "SiFive UART v0" : NULL;
+}
+
+/*
+ * Early console support
+ */
+
+#ifdef CONFIG_SERIAL_EARLYCON
+static void early_sifive_serial_putc(struct uart_port *port, int c)
+{
+	while (__ssp_early_readl(port, SIFIVE_SERIAL_TXDATA_OFFS) &
+	       SIFIVE_SERIAL_TXDATA_FULL_MASK)
+		cpu_relax();
+
+	__ssp_early_writel(c, SIFIVE_SERIAL_TXDATA_OFFS, port);
+}
+
+static void early_sifive_serial_write(struct console *con, const char *s,
+				      unsigned int n)
+{
+	struct earlycon_device *dev = con->data;
+	struct uart_port *port = &dev->port;
+
+	uart_console_write(port, s, n, early_sifive_serial_putc);
+}
+
+static int __init early_sifive_serial_setup(struct earlycon_device *dev,
+					    const char *options)
+{
+	struct uart_port *port = &dev->port;
+
+	if (!port->membase)
+		return -ENODEV;
+
+	dev->con->write = early_sifive_serial_write;
+
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(sifive, "sifive,uart0", early_sifive_serial_setup);
+OF_EARLYCON_DECLARE(sifive, "sifive,fu540-c000-uart0",
+		    early_sifive_serial_setup);
+#endif /* CONFIG_SERIAL_EARLYCON */
+
+/*
+ * Linux console interface
+ */
+
+#ifdef CONFIG_SERIAL_SIFIVE_CONSOLE
+
+static struct sifive_serial_port *sifive_serial_console_ports[SIFIVE_SERIAL_MAX_PORTS];
+
+static void sifive_serial_console_putchar(struct uart_port *port, int ch)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_wait_for_xmitr(ssp);
+	__ssp_transmit_char(ssp, ch);
+}
+
+static void sifive_serial_console_write(struct console *co, const char *s,
+					unsigned int count)
+{
+	struct sifive_serial_port *ssp = sifive_serial_console_ports[co->index];
+	unsigned long flags;
+	unsigned int ier;
+	int locked = 1;
+
+	if (!ssp)
+		return;
+
+	local_irq_save(flags);
+	if (ssp->port.sysrq)
+		locked = 0;
+	else if (oops_in_progress)
+		locked = spin_trylock(&ssp->port.lock);
+	else
+		spin_lock(&ssp->port.lock);
+
+	ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
+	__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
+
+	uart_console_write(&ssp->port, s, count, sifive_serial_console_putchar);
+
+	__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+
+	if (locked)
+		spin_unlock(&ssp->port.lock);
+	local_irq_restore(flags);
+}
+
+static int __init sifive_serial_console_setup(struct console *co, char *options)
+{
+	struct sifive_serial_port *ssp;
+	int baud = SIFIVE_DEFAULT_BAUD_RATE;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (co->index < 0 || co->index >= SIFIVE_SERIAL_MAX_PORTS)
+		return -ENODEV;
+
+	ssp = sifive_serial_console_ports[co->index];
+	if (!ssp)
+		return -ENODEV;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(&ssp->port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver sifive_serial_uart_driver;
+
+static struct console sifive_serial_console = {
+	.name		= SIFIVE_TTY_PREFIX,
+	.write		= sifive_serial_console_write,
+	.device		= uart_console_device,
+	.setup		= sifive_serial_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &sifive_serial_uart_driver,
+};
+
+static int __init sifive_console_init(void)
+{
+	register_console(&sifive_serial_console);
+	return 0;
+}
+
+console_initcall(sifive_console_init);
+
+static void __ssp_add_console_port(struct sifive_serial_port *ssp)
+{
+	sifive_serial_console_ports[ssp->port.line] = ssp;
+}
+
+static void __ssp_remove_console_port(struct sifive_serial_port *ssp)
+{
+	sifive_serial_console_ports[ssp->port.line] = 0;
+}
+
+#define SIFIVE_SERIAL_CONSOLE	(&sifive_serial_console)
+
+#else
+
+#define SIFIVE_SERIAL_CONSOLE	NULL
+
+static void __ssp_add_console_port(struct sifive_serial_port *ssp)
+{}
+static void __ssp_remove_console_port(struct sifive_serial_port *ssp)
+{}
+
+#endif
+
+static const struct uart_ops sifive_serial_uops = {
+	.tx_empty	= sifive_serial_tx_empty,
+	.set_mctrl	= sifive_serial_set_mctrl,
+	.get_mctrl	= sifive_serial_get_mctrl,
+	.stop_tx	= sifive_serial_stop_tx,
+	.start_tx	= sifive_serial_start_tx,
+	.stop_rx	= sifive_serial_stop_rx,
+	.break_ctl	= sifive_serial_break_ctl,
+	.startup	= sifive_serial_startup,
+	.shutdown	= sifive_serial_shutdown,
+	.set_termios	= sifive_serial_set_termios,
+	.type		= sifive_serial_type,
+	.release_port	= sifive_serial_release_port,
+	.request_port	= sifive_serial_request_port,
+	.config_port	= sifive_serial_config_port,
+	.verify_port	= sifive_serial_verify_port,
+};
+
+static struct uart_driver sifive_serial_uart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= SIFIVE_SERIAL_NAME,
+	.dev_name	= SIFIVE_TTY_PREFIX,
+	.nr		= SIFIVE_SERIAL_MAX_PORTS,
+	.cons		= SIFIVE_SERIAL_CONSOLE,
+};
+
+static int sifive_serial_probe(struct platform_device *pdev)
+{
+	struct sifive_serial_port *ssp;
+	struct resource *mem;
+	struct clk *clk;
+	void __iomem *base;
+	int irq, id, r;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "could not acquire interrupt\n");
+		return -EPROBE_DEFER;
+	}
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(base)) {
+		dev_err(&pdev->dev, "could not acquire device memory\n");
+		return PTR_ERR(base);
+	}
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "unable to find controller clock\n");
+		return PTR_ERR(clk);
+	}
+
+	id = of_alias_get_id(pdev->dev.of_node, "serial");
+	if (id < 0) {
+		dev_err(&pdev->dev, "missing aliases entry\n");
+		return id;
+	}
+
+#ifdef CONFIG_SERIAL_SIFIVE_CONSOLE
+	if (id > SIFIVE_SERIAL_MAX_PORTS) {
+		dev_err(&pdev->dev, "too many UARTs (%d)\n", id);
+		return -EINVAL;
+	}
+#endif
+
+	ssp = devm_kzalloc(&pdev->dev, sizeof(*ssp), GFP_KERNEL);
+	if (!ssp)
+		return -ENOMEM;
+
+	ssp->port.dev = &pdev->dev;
+	ssp->port.type = PORT_SIFIVE_V0;
+	ssp->port.iotype = UPIO_MEM;
+	ssp->port.irq = irq;
+	ssp->port.fifosize = SIFIVE_TX_FIFO_DEPTH;
+	ssp->port.ops = &sifive_serial_uops;
+	ssp->port.line = id;
+	ssp->port.mapbase = mem->start;
+	ssp->port.membase = base;
+	ssp->dev = &pdev->dev;
+	ssp->clk = clk;
+	ssp->clk_notifier.notifier_call = sifive_serial_clk_notifier;
+
+	r = clk_notifier_register(ssp->clk, &ssp->clk_notifier);
+	if (r) {
+		dev_err(&pdev->dev, "could not register clock notifier: %d\n",
+			r);
+		goto probe_out1;
+	}
+
+	/* Set up clock divider */
+	ssp->clkin_rate = clk_get_rate(ssp->clk);
+	ssp->baud_rate = SIFIVE_DEFAULT_BAUD_RATE;
+	__ssp_update_div(ssp);
+
+	platform_set_drvdata(pdev, ssp);
+
+	/* Enable transmits and set the watermark level to 1 */
+	__ssp_writel((1 << SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT) |
+		     SIFIVE_SERIAL_TXCTRL_TXEN_MASK,
+		     SIFIVE_SERIAL_TXCTRL_OFFS, ssp);
+
+	/* Enable receives and set the watermark level to 0 */
+	__ssp_writel((0 << SIFIVE_SERIAL_RXCTRL_RXCNT_SHIFT) |
+		     SIFIVE_SERIAL_RXCTRL_RXEN_MASK,
+		     SIFIVE_SERIAL_RXCTRL_OFFS, ssp);
+
+	r = request_irq(ssp->port.irq, sifive_serial_irq, ssp->port.irqflags,
+			dev_name(&pdev->dev), ssp);
+	if (r) {
+		dev_err(&pdev->dev, "could not attach interrupt: %d\n", r);
+		goto probe_out2;
+	}
+
+	__ssp_add_console_port(ssp);
+
+	r = uart_add_one_port(&sifive_serial_uart_driver, &ssp->port);
+	if (r != 0) {
+		dev_err(&pdev->dev, "could not add uart: %d\n", r);
+		goto probe_out3;
+	}
+
+	return 0;
+
+probe_out3:
+	__ssp_remove_console_port(ssp);
+	free_irq(ssp->port.irq, ssp);
+probe_out2:
+	clk_notifier_unregister(ssp->clk, &ssp->clk_notifier);
+probe_out1:
+	return r;
+}
+
+static int sifive_serial_remove(struct platform_device *dev)
+{
+	struct sifive_serial_port *ssp = platform_get_drvdata(dev);
+
+	__ssp_remove_console_port(ssp);
+	uart_remove_one_port(&sifive_serial_uart_driver, &ssp->port);
+	free_irq(ssp->port.irq, ssp);
+	clk_notifier_unregister(ssp->clk, &ssp->clk_notifier);
+
+	return 0;
+}
+
+static const struct of_device_id sifive_serial_of_match[] = {
+	{ .compatible = "sifive,fu540-c000-uart0" },
+	{ .compatible = "sifive,uart0" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sifive_serial_of_match);
+
+static struct platform_driver sifive_serial_platform_driver = {
+	.probe		= sifive_serial_probe,
+	.remove		= sifive_serial_remove,
+	.driver		= {
+		.name	= SIFIVE_SERIAL_NAME,
+		.of_match_table = of_match_ptr(sifive_serial_of_match),
+	},
+};
+
+static int __init sifive_serial_init(void)
+{
+	int r;
+
+	r = uart_register_driver(&sifive_serial_uart_driver);
+	if (r)
+		goto init_out1;
+
+	r = platform_driver_register(&sifive_serial_platform_driver);
+	if (r)
+		goto init_out2;
+
+	return 0;
+
+init_out2:
+	uart_unregister_driver(&sifive_serial_uart_driver);
+init_out1:
+	return r;
+}
+
+static void __exit sifive_serial_exit(void)
+{
+	platform_driver_unregister(&sifive_serial_platform_driver);
+	uart_unregister_driver(&sifive_serial_uart_driver);
+}
+
+module_init(sifive_serial_init);
+module_exit(sifive_serial_exit);
+
+MODULE_DESCRIPTION("SiFive UART serial driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Paul Walmsley <paul@pwsan.com>");
diff --git a/drivers/tty/serial/sn_console.c b/drivers/tty/serial/sn_console.c
index fe9170731c16..283493358a62 100644
--- a/drivers/tty/serial/sn_console.c
+++ b/drivers/tty/serial/sn_console.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * C-Brick Serial Port (and console) driver for SGI Altix machines.
  *
diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 1891a45ac05d..73d71a4e6c0c 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -10,6 +10,9 @@
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/dma/sprd-dma.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
@@ -75,6 +78,7 @@
 
 /* control register 1 */
 #define SPRD_CTL1		0x001C
+#define SPRD_DMA_EN		BIT(15)
 #define RX_HW_FLOW_CTL_THLD	BIT(6)
 #define RX_HW_FLOW_CTL_EN	BIT(7)
 #define TX_HW_FLOW_CTL_EN	BIT(8)
@@ -86,6 +90,7 @@
 #define THLD_TX_EMPTY		0x40
 #define THLD_TX_EMPTY_SHIFT	8
 #define THLD_RX_FULL		0x40
+#define THLD_RX_FULL_MASK	GENMASK(6, 0)
 
 /* config baud rate register */
 #define SPRD_CLKD0		0x0024
@@ -100,15 +105,38 @@
 #define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
 #define SPRD_IMSR_BREAK_DETECT	BIT(7)
 #define SPRD_IMSR_TIMEOUT	BIT(13)
+#define SPRD_DEFAULT_SOURCE_CLK	26000000
+
+#define SPRD_RX_DMA_STEP	1
+#define SPRD_RX_FIFO_FULL	1
+#define SPRD_TX_FIFO_FULL	0x20
+#define SPRD_UART_RX_SIZE	(UART_XMIT_SIZE / 4)
+
+struct sprd_uart_dma {
+	struct dma_chan *chn;
+	unsigned char *virt;
+	dma_addr_t phys_addr;
+	dma_cookie_t cookie;
+	u32 trans_len;
+	bool enable;
+};
 
 struct sprd_uart_port {
 	struct uart_port port;
 	char name[16];
+	struct clk *clk;
+	struct sprd_uart_dma tx_dma;
+	struct sprd_uart_dma rx_dma;
+	dma_addr_t pos;
+	unsigned char *rx_buf_tail;
 };
 
 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
 static int sprd_ports_num;
 
+static int sprd_start_dma_rx(struct uart_port *port);
+static int sprd_tx_dma_config(struct uart_port *port);
+
 static inline unsigned int serial_in(struct uart_port *port,
 				     unsigned int offset)
 {
@@ -139,45 +167,389 @@ static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	/* nothing to do */
 }
 
-static void sprd_stop_tx(struct uart_port *port)
+static void sprd_stop_rx(struct uart_port *port)
 {
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
 	unsigned int ien, iclr;
 
+	if (sp->rx_dma.enable)
+		dmaengine_terminate_all(sp->rx_dma.chn);
+
 	iclr = serial_in(port, SPRD_ICLR);
 	ien = serial_in(port, SPRD_IEN);
 
-	iclr |= SPRD_IEN_TX_EMPTY;
-	ien &= ~SPRD_IEN_TX_EMPTY;
+	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
+	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
 
-	serial_out(port, SPRD_ICLR, iclr);
 	serial_out(port, SPRD_IEN, ien);
+	serial_out(port, SPRD_ICLR, iclr);
 }
 
-static void sprd_start_tx(struct uart_port *port)
+static void sprd_uart_dma_enable(struct uart_port *port, bool enable)
 {
-	unsigned int ien;
+	u32 val = serial_in(port, SPRD_CTL1);
 
-	ien = serial_in(port, SPRD_IEN);
-	if (!(ien & SPRD_IEN_TX_EMPTY)) {
-		ien |= SPRD_IEN_TX_EMPTY;
-		serial_out(port, SPRD_IEN, ien);
+	if (enable)
+		val |= SPRD_DMA_EN;
+	else
+		val &= ~SPRD_DMA_EN;
+
+	serial_out(port, SPRD_CTL1, val);
+}
+
+static void sprd_stop_tx_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+	struct dma_tx_state state;
+	u32 trans_len;
+
+	dmaengine_pause(sp->tx_dma.chn);
+
+	dmaengine_tx_status(sp->tx_dma.chn, sp->tx_dma.cookie, &state);
+	if (state.residue) {
+		trans_len = state.residue - sp->tx_dma.phys_addr;
+		xmit->tail = (xmit->tail + trans_len) & (UART_XMIT_SIZE - 1);
+		port->icount.tx += trans_len;
+		dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
+				 sp->tx_dma.trans_len, DMA_TO_DEVICE);
 	}
+
+	dmaengine_terminate_all(sp->tx_dma.chn);
+	sp->tx_dma.trans_len = 0;
 }
 
-static void sprd_stop_rx(struct uart_port *port)
+static int sprd_tx_buf_remap(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+
+	sp->tx_dma.trans_len =
+		CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+
+	sp->tx_dma.phys_addr = dma_map_single(port->dev,
+					      (void *)&(xmit->buf[xmit->tail]),
+					      sp->tx_dma.trans_len,
+					      DMA_TO_DEVICE);
+	return dma_mapping_error(port->dev, sp->tx_dma.phys_addr);
+}
+
+static void sprd_complete_tx_dma(void *data)
+{
+	struct uart_port *port = (struct uart_port *)data;
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
+			 sp->tx_dma.trans_len, DMA_TO_DEVICE);
+
+	xmit->tail = (xmit->tail + sp->tx_dma.trans_len) & (UART_XMIT_SIZE - 1);
+	port->icount.tx += sp->tx_dma.trans_len;
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit) || sprd_tx_buf_remap(port) ||
+	    sprd_tx_dma_config(port))
+		sp->tx_dma.trans_len = 0;
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int sprd_uart_dma_submit(struct uart_port *port,
+				struct sprd_uart_dma *ud, u32 trans_len,
+				enum dma_transfer_direction direction,
+				dma_async_tx_callback callback)
+{
+	struct dma_async_tx_descriptor *dma_des;
+	unsigned long flags;
+
+	flags = SPRD_DMA_FLAGS(SPRD_DMA_CHN_MODE_NONE,
+			       SPRD_DMA_NO_TRG,
+			       SPRD_DMA_FRAG_REQ,
+			       SPRD_DMA_TRANS_INT);
+
+	dma_des = dmaengine_prep_slave_single(ud->chn, ud->phys_addr, trans_len,
+					      direction, flags);
+	if (!dma_des)
+		return -ENODEV;
+
+	dma_des->callback = callback;
+	dma_des->callback_param = port;
+
+	ud->cookie = dmaengine_submit(dma_des);
+	if (dma_submit_error(ud->cookie))
+		return dma_submit_error(ud->cookie);
+
+	dma_async_issue_pending(ud->chn);
+
+	return 0;
+}
+
+static int sprd_tx_dma_config(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	u32 burst = sp->tx_dma.trans_len > SPRD_TX_FIFO_FULL ?
+		SPRD_TX_FIFO_FULL : sp->tx_dma.trans_len;
+	int ret;
+	struct dma_slave_config cfg = {
+		.dst_addr = port->mapbase + SPRD_TXD,
+		.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.src_maxburst = burst,
+	};
+
+	ret = dmaengine_slave_config(sp->tx_dma.chn, &cfg);
+	if (ret < 0)
+		return ret;
+
+	return sprd_uart_dma_submit(port, &sp->tx_dma, sp->tx_dma.trans_len,
+				    DMA_MEM_TO_DEV, sprd_complete_tx_dma);
+}
+
+static void sprd_start_tx_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+
+	if (port->x_char) {
+		serial_out(port, SPRD_TXD, port->x_char);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		sprd_stop_tx_dma(port);
+		return;
+	}
+
+	if (sp->tx_dma.trans_len)
+		return;
+
+	if (sprd_tx_buf_remap(port) || sprd_tx_dma_config(port))
+		sp->tx_dma.trans_len = 0;
+}
+
+static void sprd_rx_full_thld(struct uart_port *port, u32 thld)
+{
+	u32 val = serial_in(port, SPRD_CTL2);
+
+	val &= ~THLD_RX_FULL_MASK;
+	val |= thld & THLD_RX_FULL_MASK;
+	serial_out(port, SPRD_CTL2, val);
+}
+
+static int sprd_rx_alloc_buf(struct sprd_uart_port *sp)
+{
+	sp->rx_dma.virt = dma_alloc_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
+					     &sp->rx_dma.phys_addr, GFP_KERNEL);
+	if (!sp->rx_dma.virt)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void sprd_rx_free_buf(struct sprd_uart_port *sp)
+{
+	if (sp->rx_dma.virt)
+		dma_free_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
+				  sp->rx_dma.virt, sp->rx_dma.phys_addr);
+
+}
+
+static int sprd_rx_dma_config(struct uart_port *port, u32 burst)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct dma_slave_config cfg = {
+		.src_addr = port->mapbase + SPRD_RXD,
+		.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.src_maxburst = burst,
+	};
+
+	return dmaengine_slave_config(sp->rx_dma.chn, &cfg);
+}
+
+static void sprd_uart_dma_rx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct tty_port *tty = &port->state->port;
+
+	port->icount.rx += sp->rx_dma.trans_len;
+	tty_insert_flip_string(tty, sp->rx_buf_tail, sp->rx_dma.trans_len);
+	tty_flip_buffer_push(tty);
+}
+
+static void sprd_uart_dma_irq(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct dma_tx_state state;
+	enum dma_status status;
+
+	status = dmaengine_tx_status(sp->rx_dma.chn,
+				     sp->rx_dma.cookie, &state);
+	if (status == DMA_ERROR)
+		sprd_stop_rx(port);
+
+	if (!state.residue && sp->pos == sp->rx_dma.phys_addr)
+		return;
+
+	if (!state.residue) {
+		sp->rx_dma.trans_len = SPRD_UART_RX_SIZE +
+			sp->rx_dma.phys_addr - sp->pos;
+		sp->pos = sp->rx_dma.phys_addr;
+	} else {
+		sp->rx_dma.trans_len = state.residue - sp->pos;
+		sp->pos = state.residue;
+	}
+
+	sprd_uart_dma_rx(port);
+	sp->rx_buf_tail += sp->rx_dma.trans_len;
+}
+
+static void sprd_complete_rx_dma(void *data)
+{
+	struct uart_port *port = (struct uart_port *)data;
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct dma_tx_state state;
+	enum dma_status status;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	status = dmaengine_tx_status(sp->rx_dma.chn,
+				     sp->rx_dma.cookie, &state);
+	if (status != DMA_COMPLETE) {
+		sprd_stop_rx(port);
+		spin_unlock_irqrestore(&port->lock, flags);
+		return;
+	}
+
+	if (sp->pos != sp->rx_dma.phys_addr) {
+		sp->rx_dma.trans_len =  SPRD_UART_RX_SIZE +
+			sp->rx_dma.phys_addr - sp->pos;
+		sprd_uart_dma_rx(port);
+		sp->rx_buf_tail += sp->rx_dma.trans_len;
+	}
+
+	if (sprd_start_dma_rx(port))
+		sprd_stop_rx(port);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int sprd_start_dma_rx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	int ret;
+
+	if (!sp->rx_dma.enable)
+		return 0;
+
+	sp->pos = sp->rx_dma.phys_addr;
+	sp->rx_buf_tail = sp->rx_dma.virt;
+	sprd_rx_full_thld(port, SPRD_RX_FIFO_FULL);
+	ret = sprd_rx_dma_config(port, SPRD_RX_DMA_STEP);
+	if (ret)
+		return ret;
+
+	return sprd_uart_dma_submit(port, &sp->rx_dma, SPRD_UART_RX_SIZE,
+				    DMA_DEV_TO_MEM, sprd_complete_rx_dma);
+}
+
+static void sprd_release_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+
+	sprd_uart_dma_enable(port, false);
+
+	if (sp->rx_dma.enable)
+		dma_release_channel(sp->rx_dma.chn);
+
+	if (sp->tx_dma.enable)
+		dma_release_channel(sp->tx_dma.chn);
+
+	sp->tx_dma.enable = false;
+	sp->rx_dma.enable = false;
+}
+
+static void sprd_request_dma(struct uart_port *port)
 {
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+
+	sp->tx_dma.enable = true;
+	sp->rx_dma.enable = true;
+
+	sp->tx_dma.chn = dma_request_chan(port->dev, "tx");
+	if (IS_ERR(sp->tx_dma.chn)) {
+		dev_err(port->dev, "request TX DMA channel failed, ret = %ld\n",
+			PTR_ERR(sp->tx_dma.chn));
+		sp->tx_dma.enable = false;
+	}
+
+	sp->rx_dma.chn = dma_request_chan(port->dev, "rx");
+	if (IS_ERR(sp->rx_dma.chn)) {
+		dev_err(port->dev, "request RX DMA channel failed, ret = %ld\n",
+			PTR_ERR(sp->rx_dma.chn));
+		sp->rx_dma.enable = false;
+	}
+}
+
+static void sprd_stop_tx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
+						 port);
 	unsigned int ien, iclr;
 
+	if (sp->tx_dma.enable) {
+		sprd_stop_tx_dma(port);
+		return;
+	}
+
 	iclr = serial_in(port, SPRD_ICLR);
 	ien = serial_in(port, SPRD_IEN);
 
-	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
-	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
+	iclr |= SPRD_IEN_TX_EMPTY;
+	ien &= ~SPRD_IEN_TX_EMPTY;
 
 	serial_out(port, SPRD_IEN, ien);
 	serial_out(port, SPRD_ICLR, iclr);
 }
 
+static void sprd_start_tx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
+						 port);
+	unsigned int ien;
+
+	if (sp->tx_dma.enable) {
+		sprd_start_tx_dma(port);
+		return;
+	}
+
+	ien = serial_in(port, SPRD_IEN);
+	if (!(ien & SPRD_IEN_TX_EMPTY)) {
+		ien |= SPRD_IEN_TX_EMPTY;
+		serial_out(port, SPRD_IEN, ien);
+	}
+}
+
 /* The Sprd serial does not support this function. */
 static void sprd_break_ctl(struct uart_port *port, int break_state)
 {
@@ -218,9 +590,16 @@ static int handle_lsr_errors(struct uart_port *port,
 
 static inline void sprd_rx(struct uart_port *port)
 {
+	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
+						 port);
 	struct tty_port *tty = &port->state->port;
 	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;
 
+	if (sp->rx_dma.enable) {
+		sprd_uart_dma_irq(port);
+		return;
+	}
+
 	while ((serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK) &&
 	       max_count--) {
 		lsr = serial_in(port, SPRD_LSR);
@@ -304,6 +683,25 @@ static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static void sprd_uart_dma_startup(struct uart_port *port,
+				  struct sprd_uart_port *sp)
+{
+	int ret;
+
+	sprd_request_dma(port);
+	if (!(sp->rx_dma.enable || sp->tx_dma.enable))
+		return;
+
+	ret = sprd_start_dma_rx(port);
+	if (ret) {
+		sp->rx_dma.enable = false;
+		dma_release_channel(sp->rx_dma.chn);
+		dev_warn(port->dev, "fail to start RX dma mode\n");
+	}
+
+	sprd_uart_dma_enable(port, true);
+}
+
 static int sprd_startup(struct uart_port *port)
 {
 	int ret = 0;
@@ -332,6 +730,9 @@ static int sprd_startup(struct uart_port *port)
 	/* allocate irq */
 	sp = container_of(port, struct sprd_uart_port, port);
 	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
+
+	sprd_uart_dma_startup(port, sp);
+
 	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
 			       IRQF_SHARED, sp->name, port);
 	if (ret) {
@@ -346,7 +747,9 @@ static int sprd_startup(struct uart_port *port)
 	/* enable interrupt */
 	spin_lock_irqsave(&port->lock, flags);
 	ien = serial_in(port, SPRD_IEN);
-	ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
+	ien |= SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
+	if (!sp->rx_dma.enable)
+		ien |= SPRD_IEN_RX_FULL;
 	serial_out(port, SPRD_IEN, ien);
 	spin_unlock_irqrestore(&port->lock, flags);
 
@@ -355,6 +758,7 @@ static int sprd_startup(struct uart_port *port)
 
 static void sprd_shutdown(struct uart_port *port)
 {
+	sprd_release_dma(port);
 	serial_out(port, SPRD_IEN, 0);
 	serial_out(port, SPRD_ICLR, ~0);
 	devm_free_irq(port->dev, port->irq, port);
@@ -491,6 +895,22 @@ static int sprd_verify_port(struct uart_port *port, struct serial_struct *ser)
 	return 0;
 }
 
+static void sprd_pm(struct uart_port *port, unsigned int state,
+		unsigned int oldstate)
+{
+	struct sprd_uart_port *sup =
+		container_of(port, struct sprd_uart_port, port);
+
+	switch (state) {
+	case UART_PM_STATE_ON:
+		clk_prepare_enable(sup->clk);
+		break;
+	case UART_PM_STATE_OFF:
+		clk_disable_unprepare(sup->clk);
+		break;
+	}
+}
+
 static const struct uart_ops serial_sprd_ops = {
 	.tx_empty = sprd_tx_empty,
 	.get_mctrl = sprd_get_mctrl,
@@ -507,6 +927,7 @@ static const struct uart_ops serial_sprd_ops = {
 	.request_port = sprd_request_port,
 	.config_port = sprd_config_port,
 	.verify_port = sprd_verify_port,
+	.pm = sprd_pm,
 };
 
 #ifdef CONFIG_SERIAL_SPRD_CONSOLE
@@ -668,6 +1089,43 @@ static int sprd_remove(struct platform_device *dev)
 	if (!sprd_ports_num)
 		uart_unregister_driver(&sprd_uart_driver);
 
+	sprd_rx_free_buf(sup);
+
+	return 0;
+}
+
+static int sprd_clk_init(struct uart_port *uport)
+{
+	struct clk *clk_uart, *clk_parent;
+	struct sprd_uart_port *u = sprd_port[uport->line];
+
+	clk_uart = devm_clk_get(uport->dev, "uart");
+	if (IS_ERR(clk_uart)) {
+		dev_warn(uport->dev, "uart%d can't get uart clock\n",
+			 uport->line);
+		clk_uart = NULL;
+	}
+
+	clk_parent = devm_clk_get(uport->dev, "source");
+	if (IS_ERR(clk_parent)) {
+		dev_warn(uport->dev, "uart%d can't get source clock\n",
+			 uport->line);
+		clk_parent = NULL;
+	}
+
+	if (!clk_uart || clk_set_parent(clk_uart, clk_parent))
+		uport->uartclk = SPRD_DEFAULT_SOURCE_CLK;
+	else
+		uport->uartclk = clk_get_rate(clk_uart);
+
+	u->clk = devm_clk_get(uport->dev, "enable");
+	if (IS_ERR(u->clk)) {
+		if (PTR_ERR(u->clk) != -EPROBE_DEFER)
+			dev_err(uport->dev, "uart%d can't get enable clock\n",
+				uport->line);
+		return PTR_ERR(u->clk);
+	}
+
 	return 0;
 }
 
@@ -675,7 +1133,6 @@ static int sprd_probe(struct platform_device *pdev)
 {
 	struct resource *res;
 	struct uart_port *up;
-	struct clk *clk;
 	int irq;
 	int index;
 	int ret;
@@ -704,9 +1161,9 @@ static int sprd_probe(struct platform_device *pdev)
 	up->ops = &serial_sprd_ops;
 	up->flags = UPF_BOOT_AUTOCONF;
 
-	clk = devm_clk_get(&pdev->dev, NULL);
-	if (!IS_ERR_OR_NULL(clk))
-		up->uartclk = clk_get_rate(clk);
+	ret = sprd_clk_init(up);
+	if (ret)
+		return ret;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	up->membase = devm_ioremap_resource(&pdev->dev, res);
@@ -722,6 +1179,14 @@ static int sprd_probe(struct platform_device *pdev)
 	}
 	up->irq = irq;
 
+	/*
+	 * Allocate one dma buffer to prepare for receive transfer, in case
+	 * memory allocation failure at runtime.
+	 */
+	ret = sprd_rx_alloc_buf(sprd_port[index]);
+	if (ret)
+		return ret;
+
 	if (!sprd_ports_num) {
 		ret = uart_register_driver(&sprd_uart_driver);
 		if (ret < 0) {
diff --git a/drivers/tty/serial/ucc_uart.c b/drivers/tty/serial/ucc_uart.c
index 2b6376e6e5ad..6e3c66ab0e62 100644
--- a/drivers/tty/serial/ucc_uart.c
+++ b/drivers/tty/serial/ucc_uart.c
@@ -1081,7 +1081,7 @@ static int qe_uart_verify_port(struct uart_port *port,
 }
 /* UART operations
  *
- * Details on these functions can be found in Documentation/serial/driver
+ * Details on these functions can be found in Documentation/serial/driver.rst
  */
 static const struct uart_ops qe_uart_pops = {
 	.tx_empty       = qe_uart_tx_empty,
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 74089f5e5b53..605354fd60b1 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -193,6 +193,7 @@ struct cdns_uart {
 	int			id;
 	struct notifier_block	clk_rate_change_nb;
 	u32			quirks;
+	bool cts_override;
 };
 struct cdns_platform_data {
 	u32 quirks;
@@ -1000,6 +1001,11 @@ static void cdns_uart_config_port(struct uart_port *port, int flags)
  */
 static unsigned int cdns_uart_get_mctrl(struct uart_port *port)
 {
+	struct cdns_uart *cdns_uart_data = port->private_data;
+
+	if (cdns_uart_data->cts_override)
+		return 0;
+
 	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 }
 
@@ -1007,6 +1013,10 @@ static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 	u32 val;
 	u32 mode_reg;
+	struct cdns_uart *cdns_uart_data = port->private_data;
+
+	if (cdns_uart_data->cts_override)
+		return;
 
 	val = readl(port->membase + CDNS_UART_MODEMCR);
 	mode_reg = readl(port->membase + CDNS_UART_MR);
@@ -1665,6 +1675,8 @@ static int cdns_uart_probe(struct platform_device *pdev)
 		console_port = NULL;
 #endif
 
+	cdns_uart_data->cts_override = of_property_read_bool(pdev->dev.of_node,
+							     "cts-override");
 	return 0;
 
 err_out_pm_disable:
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index fa0ce7dd9e24..59e82e6d776d 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -208,7 +208,7 @@ static struct sysrq_key_op sysrq_showlocks_op = {
 #endif
 
 #ifdef CONFIG_SMP
-static DEFINE_SPINLOCK(show_lock);
+static DEFINE_RAW_SPINLOCK(show_lock);
 
 static void showacpu(void *dummy)
 {
@@ -218,10 +218,10 @@ static void showacpu(void *dummy)
 	if (idle_cpu(smp_processor_id()))
 		return;
 
-	spin_lock_irqsave(&show_lock, flags);
+	raw_spin_lock_irqsave(&show_lock, flags);
 	pr_info("CPU%d:\n", smp_processor_id());
 	show_stack(NULL, NULL);
-	spin_unlock_irqrestore(&show_lock, flags);
+	raw_spin_unlock_irqrestore(&show_lock, flags);
 }
 
 static void sysrq_showregs_othercpus(struct work_struct *dummy)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 5fa250157025..033ac7e6a70d 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1173,7 +1173,7 @@ static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
  *	tty_init_termios	-  helper for termios setup
  *	@tty: the tty to set up
  *
- *	Initialise the termios structures for this tty. Thus runs under
+ *	Initialise the termios structure for this tty. This runs under
  *	the tty_mutex currently so we can be relaxed about ordering.
  */
 
diff --git a/drivers/tty/tty_jobctrl.c b/drivers/tty/tty_jobctrl.c
index c4ecd66fafef..f8ed50a16848 100644
--- a/drivers/tty/tty_jobctrl.c
+++ b/drivers/tty/tty_jobctrl.c
@@ -44,7 +44,7 @@ int __tty_check_change(struct tty_struct *tty, int sig)
 	tty_pgrp = tty->pgrp;
 	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 
-	if (tty_pgrp && pgrp != tty->pgrp) {
+	if (tty_pgrp && pgrp != tty_pgrp) {
 		if (is_ignored(sig)) {
 			if (sig == SIGTTIN)
 				ret = -EIO;
@@ -313,7 +313,7 @@ void disassociate_ctty(int on_exit)
 	read_unlock(&tasklist_lock);
 }
 
-/**
+/*
  *
  *	no_tty	- Ensure the current process does not have a controlling tty
  */
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index a9e12b3bc31d..044c3cbdcfa4 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -325,7 +325,7 @@ static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)
 		if (tty && C_HUPCL(tty))
 			tty_port_lower_dtr_rts(port);
 
-		if (port->ops && port->ops->shutdown)
+		if (port->ops->shutdown)
 			port->ops->shutdown(port);
 	}
 out:
@@ -398,7 +398,7 @@ EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
  */
 int tty_port_carrier_raised(struct tty_port *port)
 {
-	if (!port->ops || !port->ops->carrier_raised)
+	if (port->ops->carrier_raised == NULL)
 		return 1;
 	return port->ops->carrier_raised(port);
 }
@@ -414,7 +414,7 @@ EXPORT_SYMBOL(tty_port_carrier_raised);
  */
 void tty_port_raise_dtr_rts(struct tty_port *port)
 {
-	if (port->ops && port->ops->dtr_rts)
+	if (port->ops->dtr_rts)
 		port->ops->dtr_rts(port, 1);
 }
 EXPORT_SYMBOL(tty_port_raise_dtr_rts);
@@ -429,7 +429,7 @@ EXPORT_SYMBOL(tty_port_raise_dtr_rts);
  */
 void tty_port_lower_dtr_rts(struct tty_port *port)
 {
-	if (port->ops && port->ops->dtr_rts)
+	if (port->ops->dtr_rts)
 		port->ops->dtr_rts(port, 0);
 }
 EXPORT_SYMBOL(tty_port_lower_dtr_rts);
@@ -684,7 +684,7 @@ int tty_port_open(struct tty_port *port, struct tty_struct *tty,
 
 	if (!tty_port_initialized(port)) {
 		clear_bit(TTY_IO_ERROR, &tty->flags);
-		if (port->ops && port->ops->activate) {
+		if (port->ops->activate) {
 			int retval = port->ops->activate(port, tty);
 			if (retval) {
 				mutex_unlock(&port->mutex);
diff --git a/drivers/tty/ttynull.c b/drivers/tty/ttynull.c
new file mode 100644
index 000000000000..17f05b7eb6d3
--- /dev/null
+++ b/drivers/tty/ttynull.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Axis Communications AB
+ *
+ * Based on ttyprintk.c:
+ *  Copyright (C) 2010 Samo Pogacnik
+ */
+
+#include <linux/console.h>
+#include <linux/module.h>
+#include <linux/tty.h>
+
+static const struct tty_port_operations ttynull_port_ops;
+static struct tty_driver *ttynull_driver;
+static struct tty_port ttynull_port;
+
+static int ttynull_open(struct tty_struct *tty, struct file *filp)
+{
+	return tty_port_open(&ttynull_port, tty, filp);
+}
+
+static void ttynull_close(struct tty_struct *tty, struct file *filp)
+{
+	tty_port_close(&ttynull_port, tty, filp);
+}
+
+static void ttynull_hangup(struct tty_struct *tty)
+{
+	tty_port_hangup(&ttynull_port);
+}
+
+static int ttynull_write(struct tty_struct *tty, const unsigned char *buf,
+			 int count)
+{
+	return count;
+}
+
+static int ttynull_write_room(struct tty_struct *tty)
+{
+	return 65536;
+}
+
+static const struct tty_operations ttynull_ops = {
+	.open = ttynull_open,
+	.close = ttynull_close,
+	.hangup = ttynull_hangup,
+	.write = ttynull_write,
+	.write_room = ttynull_write_room,
+};
+
+static struct tty_driver *ttynull_device(struct console *c, int *index)
+{
+	*index = 0;
+	return ttynull_driver;
+}
+
+static struct console ttynull_console = {
+	.name = "ttynull",
+	.device = ttynull_device,
+};
+
+static int __init ttynull_init(void)
+{
+	struct tty_driver *driver;
+	int ret;
+
+	driver = tty_alloc_driver(1,
+		TTY_DRIVER_RESET_TERMIOS |
+		TTY_DRIVER_REAL_RAW |
+		TTY_DRIVER_UNNUMBERED_NODE);
+	if (IS_ERR(driver))
+		return PTR_ERR(driver);
+
+	tty_port_init(&ttynull_port);
+	ttynull_port.ops = &ttynull_port_ops;
+
+	driver->driver_name = "ttynull";
+	driver->name = "ttynull";
+	driver->type = TTY_DRIVER_TYPE_CONSOLE;
+	driver->init_termios = tty_std_termios;
+	driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET;
+	tty_set_operations(driver, &ttynull_ops);
+	tty_port_link_device(&ttynull_port, driver, 0);
+
+	ret = tty_register_driver(driver);
+	if (ret < 0) {
+		put_tty_driver(driver);
+		tty_port_destroy(&ttynull_port);
+		return ret;
+	}
+
+	ttynull_driver = driver;
+	register_console(&ttynull_console);
+
+	return 0;
+}
+
+static void __exit ttynull_exit(void)
+{
+	unregister_console(&ttynull_console);
+	tty_unregister_driver(ttynull_driver);
+	put_tty_driver(ttynull_driver);
+	tty_port_destroy(&ttynull_port);
+}
+
+module_init(ttynull_init);
+module_exit(ttynull_exit);
+
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/tty/vcc.c b/drivers/tty/vcc.c
index 58b454c34560..d2a1e1228c82 100644
--- a/drivers/tty/vcc.c
+++ b/drivers/tty/vcc.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /* vcc.c: sun4v virtual channel concentrator
  *
  * Copyright (C) 2017 Oracle. All rights reserved.
diff --git a/drivers/tty/vt/.gitignore b/drivers/tty/vt/.gitignore
index 83683a2d8e6a..9b38b85f9d9a 100644
--- a/drivers/tty/vt/.gitignore
+++ b/drivers/tty/vt/.gitignore
@@ -1,2 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
 consolemap_deftbl.c
 defkeymap.c
diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
index 7c7ada0b3ea0..b28aa0d289f8 100644
--- a/drivers/tty/vt/consolemap.c
+++ b/drivers/tty/vt/consolemap.c
@@ -542,7 +542,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
 	if (!ct)
 		return 0;
 
-	unilist = memdup_user(list, ct * sizeof(struct unipair));
+	unilist = vmemdup_user(list, ct * sizeof(struct unipair));
 	if (IS_ERR(unilist))
 		return PTR_ERR(unilist);
 
@@ -641,7 +641,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
 
 out_unlock:
 	console_unlock();
-	kfree(unilist);
+	kvfree(unilist);
 	return err;
 }
 
@@ -743,7 +743,7 @@ int con_get_unimap(struct vc_data *vc, ushort ct, ushort __user *uct, struct uni
 	struct uni_pagedir *p;
 	struct unipair *unilist;
 
-	unilist = kmalloc_array(ct, sizeof(struct unipair), GFP_KERNEL);
+	unilist = kvmalloc_array(ct, sizeof(struct unipair), GFP_KERNEL);
 	if (!unilist)
 		return -ENOMEM;
 
@@ -775,7 +775,7 @@ int con_get_unimap(struct vc_data *vc, ushort ct, ushort __user *uct, struct uni
 	if (copy_to_user(list, unilist, min(ect, ct) * sizeof(struct unipair)))
 		ret = -EFAULT;
 	put_user(ect, uct);
-	kfree(unilist);
+	kvfree(unilist);
 	return ret ? ret : (ect <= ct) ? 0 : -ENOMEM;
 }
 
diff --git a/drivers/tty/vt/cp437.uni b/drivers/tty/vt/cp437.uni
index bc6163484f62..a1991904c559 100644
--- a/drivers/tty/vt/cp437.uni
+++ b/drivers/tty/vt/cp437.uni
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Unicode table for IBM Codepage 437.  Note that there are many more
 # substitutions that could be conceived (for example, thick-line
diff --git a/drivers/tty/vt/defkeymap.c_shipped b/drivers/tty/vt/defkeymap.c_shipped
index d2208dfe3f67..c7095fb7d2d1 100644
--- a/drivers/tty/vt/defkeymap.c_shipped
+++ b/drivers/tty/vt/defkeymap.c_shipped
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /* Do not edit this file! It was automatically generated by   */
 /*    loadkeys --mktable defkeymap.map > defkeymap.c          */
 
diff --git a/drivers/tty/vt/defkeymap.map b/drivers/tty/vt/defkeymap.map
index 50b30cace261..37f1ac6ddfb9 100644
--- a/drivers/tty/vt/defkeymap.map
+++ b/drivers/tty/vt/defkeymap.map
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 # Default kernel keymap. This uses 7 modifier combinations.
 keymaps 0-2,4-5,8,12
 # Change the above line into
diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index 88312c6c92cc..515fc095e3b4 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -123,6 +123,7 @@ static const int NR_TYPES = ARRAY_SIZE(max_vals);
 static struct input_handler kbd_handler;
 static DEFINE_SPINLOCK(kbd_event_lock);
 static DEFINE_SPINLOCK(led_lock);
+static DEFINE_SPINLOCK(func_buf_lock); /* guard 'func_buf'  and friends */
 static unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];	/* keyboard key bitmap */
 static unsigned char shift_down[NR_SHIFT];		/* shift state counters.. */
 static bool dead_key_next;
@@ -1449,7 +1450,7 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
 						KBD_UNICODE, &param);
 		if (rc != NOTIFY_STOP)
 			if (down && !raw_mode)
-				to_utf8(vc, keysym);
+				k_unicode(vc, keysym, !down);
 		return;
 	}
 
@@ -1990,11 +1991,12 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
 	char *p;
 	u_char *q;
 	u_char __user *up;
-	int sz;
+	int sz, fnw_sz;
 	int delta;
 	char *first_free, *fj, *fnw;
 	int i, j, k;
 	int ret;
+	unsigned long flags;
 
 	if (!capable(CAP_SYS_TTY_CONFIG))
 		perm = 0;
@@ -2037,7 +2039,14 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
 			goto reterr;
 		}
 
+		fnw = NULL;
+		fnw_sz = 0;
+		/* race aginst other writers */
+		again:
+		spin_lock_irqsave(&func_buf_lock, flags);
 		q = func_table[i];
+
+		/* fj pointer to next entry after 'q' */
 		first_free = funcbufptr + (funcbufsize - funcbufleft);
 		for (j = i+1; j < MAX_NR_FUNC && !func_table[j]; j++)
 			;
@@ -2045,10 +2054,12 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
 			fj = func_table[j];
 		else
 			fj = first_free;
-
+		/* buffer usage increase by new entry */
 		delta = (q ? -strlen(q) : 1) + strlen(kbs->kb_string);
+
 		if (delta <= funcbufleft) { 	/* it fits in current buf */
 		    if (j < MAX_NR_FUNC) {
+			/* make enough space for new entry at 'fj' */
 			memmove(fj + delta, fj, first_free - fj);
 			for (k = j; k < MAX_NR_FUNC; k++)
 			    if (func_table[k])
@@ -2061,20 +2072,28 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
 		    sz = 256;
 		    while (sz < funcbufsize - funcbufleft + delta)
 		      sz <<= 1;
-		    fnw = kmalloc(sz, GFP_KERNEL);
-		    if(!fnw) {
-		      ret = -ENOMEM;
-		      goto reterr;
+		    if (fnw_sz != sz) {
+		      spin_unlock_irqrestore(&func_buf_lock, flags);
+		      kfree(fnw);
+		      fnw = kmalloc(sz, GFP_KERNEL);
+		      fnw_sz = sz;
+		      if (!fnw) {
+			ret = -ENOMEM;
+			goto reterr;
+		      }
+		      goto again;
 		    }
 
 		    if (!q)
 		      func_table[i] = fj;
+		    /* copy data before insertion point to new location */
 		    if (fj > funcbufptr)
 			memmove(fnw, funcbufptr, fj - funcbufptr);
 		    for (k = 0; k < j; k++)
 		      if (func_table[k])
 			func_table[k] = fnw + (func_table[k] - funcbufptr);
 
+		    /* copy data after insertion point to new location */
 		    if (first_free > fj) {
 			memmove(fnw + (fj - funcbufptr) + delta, fj, first_free - fj);
 			for (k = j; k < MAX_NR_FUNC; k++)
@@ -2087,7 +2106,9 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
 		    funcbufleft = funcbufleft - delta + sz - funcbufsize;
 		    funcbufsize = sz;
 		}
+		/* finally insert item itself */
 		strcpy(func_table[i], kbs->kb_string);
+		spin_unlock_irqrestore(&func_buf_lock, flags);
 		break;
 	}
 	ret = 0;
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index 160f46115aaa..1f042346e722 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
  * Provide access to virtual console memory.
- * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
+ * /dev/vcs: the screen as it is being viewed right now (possibly scrolled)
  * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
  *            [minor: N]
  *
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index fb6f1c93e5c2..fdd12f8c3deb 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -4180,8 +4180,6 @@ void do_blank_screen(int entering_gfx)
 		return;
 	}
 
-	if (blank_state != blank_normal_wait)
-		return;
 	blank_state = blank_off;
 
 	/* don't blank graphics */