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authorLukas Wunner <lukas@wunner.de>2021-12-28 18:22:00 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-12-30 13:23:44 +0100
commitb4a29b94804c4774f22555651296b838df6ec0e4 (patch)
tree941ce02678fe2d72628c8bd9d4428b1ce100f985 /drivers/tty
parentd3b3404df318504ec084213ab1065b73f49b0f1d (diff)
serial: 8250: Move Alpha-specific quirk out of the core
struct uart_8250_port contains mcr_mask and mcr_force members whose sole purpose is to work around an Alpha-specific quirk. This code doesn't belong in the core where it is executed by everyone else, so move it to a proper ->set_mctrl callback which is used on the affected Alpha machine only. The quirk was introduced in January 1995: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/diff/drivers/char/serial.c?h=1.1.83 The members in struct uart_8250_port were added in 2002: https://git.kernel.org/history/history/c/4524aad27854 The quirk applies to non-PCI Alphas and arch/alpha/Kconfig specifies "select FORCE_PCI if !ALPHA_JENSEN". So apparently the only affected machine is the EISA-based Jensen that Linus was working on back then: https://lore.kernel.org/all/CAHk-=wj1JWZ3sCrGz16nxEj7=0O+srMg6Ah3iPTDXSPKEws_SA@mail.gmail.com/ Up until now the quirk is not applied unless CONFIG_PCI is disabled. If users forget to do that or run a generic Alpha kernel, the serial ports aren't usable on Jensen. Avoid by confining the quirk to CONFIG_ALPHA_JENSEN instead of !CONFIG_PCI. On generic Alpha kernels, auto-detect at runtime whether the quirk needs to be applied. Cc: Russell King <rmk+kernel@armlinux.org.uk> Cc: Ulrich Teichert <krypton@ulrich-teichert.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Lukas Wunner <lukas@wunner.de> Link: https://lore.kernel.org/r/b83d069cb516549b8a5420e097bb6bdd806f36fc.1640695609.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/8250/8250.h12
-rw-r--r--drivers/tty/serial/8250/8250_alpha.c21
-rw-r--r--drivers/tty/serial/8250/8250_core.c9
-rw-r--r--drivers/tty/serial/8250/8250_port.c2
-rw-r--r--drivers/tty/serial/8250/Makefile2
-rw-r--r--drivers/tty/serial/sunsu.c3
6 files changed, 32 insertions, 17 deletions
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 6473361525d1..db784ace25d8 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -241,16 +241,8 @@ static inline int serial8250_in_MCR(struct uart_8250_port *up)
return mctrl;
}
-#if defined(__alpha__) && !defined(CONFIG_PCI)
-/*
- * Digital did something really horribly wrong with the OUT1 and OUT2
- * lines on at least some ALPHA's. The failure mode is that if either
- * is cleared, the machine locks up with endless interrupts.
- */
-#define ALPHA_KLUDGE_MCR (UART_MCR_OUT2 | UART_MCR_OUT1)
-#else
-#define ALPHA_KLUDGE_MCR 0
-#endif
+bool alpha_jensen(void);
+void alpha_jensen_set_mctrl(struct uart_port *port, unsigned int mctrl);
#ifdef CONFIG_SERIAL_8250_PNP
int serial8250_pnp_init(void);
diff --git a/drivers/tty/serial/8250/8250_alpha.c b/drivers/tty/serial/8250/8250_alpha.c
new file mode 100644
index 000000000000..58e70328aa4d
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_alpha.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <asm/machvec.h>
+#include "8250.h"
+
+bool alpha_jensen(void)
+{
+ return !strcmp(alpha_mv.vector_name, "Jensen");
+}
+
+void alpha_jensen_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+ /*
+ * Digital did something really horribly wrong with the OUT1 and OUT2
+ * lines on Alpha Jensen. The failure mode is that if either is
+ * cleared, the machine locks up with endless interrupts.
+ */
+ mctrl |= TIOCM_OUT1 | TIOCM_OUT2;
+
+ serial8250_do_set_mctrl(port, mctrl);
+}
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 1ce193daea7f..01d30f6ed8fb 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -509,11 +509,10 @@ static void __init serial8250_isa_init_ports(void)
up->ops = &univ8250_driver_ops;
- /*
- * ALPHA_KLUDGE_MCR needs to be killed.
- */
- up->mcr_mask = ~ALPHA_KLUDGE_MCR;
- up->mcr_force = ALPHA_KLUDGE_MCR;
+ if (IS_ENABLED(CONFIG_ALPHA_JENSEN) ||
+ (IS_ENABLED(CONFIG_ALPHA_GENERIC) && alpha_jensen()))
+ port->set_mctrl = alpha_jensen_set_mctrl;
+
serial8250_set_defaults(up);
}
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 7e7e67dea0ad..2abb3de11a48 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2026,7 +2026,7 @@ void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl)
mcr = serial8250_TIOCM_to_MCR(mctrl);
- mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr;
+ mcr |= up->mcr;
serial8250_out_MCR(up, mcr);
}
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 4e4913e0e4d2..bee908f99ea0 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -5,6 +5,8 @@
obj-$(CONFIG_SERIAL_8250) += 8250.o 8250_base.o
8250-y := 8250_core.o
+8250-$(CONFIG_ALPHA_GENERIC) += 8250_alpha.o
+8250-$(CONFIG_ALPHA_JENSEN) += 8250_alpha.o
8250-$(CONFIG_SERIAL_8250_PNP) += 8250_pnp.o
8250_base-y := 8250_port.o
8250_base-$(CONFIG_SERIAL_8250_DMA) += 8250_dma.o
diff --git a/drivers/tty/serial/sunsu.c b/drivers/tty/serial/sunsu.c
index 425a016f9db7..98b2f4fb9a99 100644
--- a/drivers/tty/serial/sunsu.c
+++ b/drivers/tty/serial/sunsu.c
@@ -127,7 +127,8 @@ static void serial_out(struct uart_sunsu_port *up, int offset, int value)
* gate outputs a logical one. Since we use level triggered interrupts
* we have lockup and watchdog reset. We cannot mask IRQ because
* keyboard shares IRQ with us (Word has it as Bob Smelik's design).
- * This problem is similar to what Alpha people suffer, see serial.c.
+ * This problem is similar to what Alpha people suffer, see
+ * 8250_alpha.c.
*/
if (offset == UART_MCR)
value |= UART_MCR_OUT2;