diff options
Diffstat (limited to 'drivers/tty/serial/stm32-usart.c')
| -rw-r--r-- | drivers/tty/serial/stm32-usart.c | 739 |
1 files changed, 739 insertions, 0 deletions
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c new file mode 100644 index 000000000000..4a6eab6da63e --- /dev/null +++ b/drivers/tty/serial/stm32-usart.c @@ -0,0 +1,739 @@ +/* + * Copyright (C) Maxime Coquelin 2015 + * Author: Maxime Coquelin <mcoquelin.stm32@gmail.com> + * License terms: GNU General Public License (GPL), version 2 + * + * Inspired by st-asc.c from STMicroelectronics (c) + */ + +#if defined(CONFIG_SERIAL_STM32_USART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ) +#define SUPPORT_SYSRQ +#endif + +#include <linux/module.h> +#include <linux/serial.h> +#include <linux/console.h> +#include <linux/sysrq.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/irq.h> +#include <linux/tty.h> +#include <linux/tty_flip.h> +#include <linux/delay.h> +#include <linux/spinlock.h> +#include <linux/pm_runtime.h> +#include <linux/of.h> +#include <linux/of_platform.h> +#include <linux/serial_core.h> +#include <linux/clk.h> + +#define DRIVER_NAME "stm32-usart" + +/* Register offsets */ +#define USART_SR 0x00 +#define USART_DR 0x04 +#define USART_BRR 0x08 +#define USART_CR1 0x0c +#define USART_CR2 0x10 +#define USART_CR3 0x14 +#define USART_GTPR 0x18 + +/* USART_SR */ +#define USART_SR_PE BIT(0) +#define USART_SR_FE BIT(1) +#define USART_SR_NF BIT(2) +#define USART_SR_ORE BIT(3) +#define USART_SR_IDLE BIT(4) +#define USART_SR_RXNE BIT(5) +#define USART_SR_TC BIT(6) +#define USART_SR_TXE BIT(7) +#define USART_SR_LBD BIT(8) +#define USART_SR_CTS BIT(9) +#define USART_SR_ERR_MASK (USART_SR_LBD | USART_SR_ORE | \ + USART_SR_FE | USART_SR_PE) +/* Dummy bits */ +#define USART_SR_DUMMY_RX BIT(16) + +/* USART_DR */ +#define USART_DR_MASK GENMASK(8, 0) + +/* USART_BRR */ +#define USART_BRR_DIV_F_MASK GENMASK(3, 0) +#define USART_BRR_DIV_M_MASK GENMASK(15, 4) +#define USART_BRR_DIV_M_SHIFT 4 + +/* USART_CR1 */ +#define USART_CR1_SBK BIT(0) +#define USART_CR1_RWU BIT(1) +#define USART_CR1_RE BIT(2) +#define USART_CR1_TE BIT(3) +#define USART_CR1_IDLEIE BIT(4) +#define USART_CR1_RXNEIE BIT(5) +#define USART_CR1_TCIE BIT(6) +#define USART_CR1_TXEIE BIT(7) +#define USART_CR1_PEIE BIT(8) +#define USART_CR1_PS BIT(9) +#define USART_CR1_PCE BIT(10) +#define USART_CR1_WAKE BIT(11) +#define USART_CR1_M BIT(12) +#define USART_CR1_UE BIT(13) +#define USART_CR1_OVER8 BIT(15) +#define USART_CR1_IE_MASK GENMASK(8, 4) + +/* USART_CR2 */ +#define USART_CR2_ADD_MASK GENMASK(3, 0) +#define USART_CR2_LBDL BIT(5) +#define USART_CR2_LBDIE BIT(6) +#define USART_CR2_LBCL BIT(8) +#define USART_CR2_CPHA BIT(9) +#define USART_CR2_CPOL BIT(10) +#define USART_CR2_CLKEN BIT(11) +#define USART_CR2_STOP_2B BIT(13) +#define USART_CR2_STOP_MASK GENMASK(13, 12) +#define USART_CR2_LINEN BIT(14) + +/* USART_CR3 */ +#define USART_CR3_EIE BIT(0) +#define USART_CR3_IREN BIT(1) +#define USART_CR3_IRLP BIT(2) +#define USART_CR3_HDSEL BIT(3) +#define USART_CR3_NACK BIT(4) +#define USART_CR3_SCEN BIT(5) +#define USART_CR3_DMAR BIT(6) +#define USART_CR3_DMAT BIT(7) +#define USART_CR3_RTSE BIT(8) +#define USART_CR3_CTSE BIT(9) +#define USART_CR3_CTSIE BIT(10) +#define USART_CR3_ONEBIT BIT(11) + +/* USART_GTPR */ +#define USART_GTPR_PSC_MASK GENMASK(7, 0) +#define USART_GTPR_GT_MASK GENMASK(15, 8) + +#define DRIVER_NAME "stm32-usart" +#define STM32_SERIAL_NAME "ttyS" +#define STM32_MAX_PORTS 6 + +struct stm32_port { + struct uart_port port; + struct clk *clk; + bool hw_flow_control; +}; + +static struct stm32_port stm32_ports[STM32_MAX_PORTS]; +static struct uart_driver stm32_usart_driver; + +static void stm32_stop_tx(struct uart_port *port); + +static inline struct stm32_port *to_stm32_port(struct uart_port *port) +{ + return container_of(port, struct stm32_port, port); +} + +static void stm32_set_bits(struct uart_port *port, u32 reg, u32 bits) +{ + u32 val; + + val = readl_relaxed(port->membase + reg); + val |= bits; + writel_relaxed(val, port->membase + reg); +} + +static void stm32_clr_bits(struct uart_port *port, u32 reg, u32 bits) +{ + u32 val; + + val = readl_relaxed(port->membase + reg); + val &= ~bits; + writel_relaxed(val, port->membase + reg); +} + +static void stm32_receive_chars(struct uart_port *port) +{ + struct tty_port *tport = &port->state->port; + unsigned long c; + u32 sr; + char flag; + + if (port->irq_wake) + pm_wakeup_event(tport->tty->dev, 0); + + while ((sr = readl_relaxed(port->membase + USART_SR)) & USART_SR_RXNE) { + sr |= USART_SR_DUMMY_RX; + c = readl_relaxed(port->membase + USART_DR); + flag = TTY_NORMAL; + port->icount.rx++; + + if (sr & USART_SR_ERR_MASK) { + if (sr & USART_SR_LBD) { + port->icount.brk++; + if (uart_handle_break(port)) + continue; + } else if (sr & USART_SR_ORE) { + port->icount.overrun++; + } else if (sr & USART_SR_PE) { + port->icount.parity++; + } else if (sr & USART_SR_FE) { + port->icount.frame++; + } + + sr &= port->read_status_mask; + + if (sr & USART_SR_LBD) + flag = TTY_BREAK; + else if (sr & USART_SR_PE) + flag = TTY_PARITY; + else if (sr & USART_SR_FE) + flag = TTY_FRAME; + } + + if (uart_handle_sysrq_char(port, c)) + continue; + uart_insert_char(port, sr, USART_SR_ORE, c, flag); + } + + spin_unlock(&port->lock); + tty_flip_buffer_push(tport); + spin_lock(&port->lock); +} + +static void stm32_transmit_chars(struct uart_port *port) +{ + struct circ_buf *xmit = &port->state->xmit; + + if (port->x_char) { + writel_relaxed(port->x_char, port->membase + USART_DR); + port->x_char = 0; + port->icount.tx++; + return; + } + + if (uart_tx_stopped(port)) { + stm32_stop_tx(port); + return; + } + + if (uart_circ_empty(xmit)) { + stm32_stop_tx(port); + return; + } + + writel_relaxed(xmit->buf[xmit->tail], port->membase + USART_DR); + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); + port->icount.tx++; + + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(port); + + if (uart_circ_empty(xmit)) + stm32_stop_tx(port); +} + +static irqreturn_t stm32_interrupt(int irq, void *ptr) +{ + struct uart_port *port = ptr; + u32 sr; + + spin_lock(&port->lock); + + sr = readl_relaxed(port->membase + USART_SR); + + if (sr & USART_SR_RXNE) + stm32_receive_chars(port); + + if (sr & USART_SR_TXE) + stm32_transmit_chars(port); + + spin_unlock(&port->lock); + + return IRQ_HANDLED; +} + +static unsigned int stm32_tx_empty(struct uart_port *port) +{ + return readl_relaxed(port->membase + USART_SR) & USART_SR_TXE; +} + +static void stm32_set_mctrl(struct uart_port *port, unsigned int mctrl) +{ + if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS)) + stm32_set_bits(port, USART_CR3, USART_CR3_RTSE); + else + stm32_clr_bits(port, USART_CR3, USART_CR3_RTSE); +} + +static unsigned int stm32_get_mctrl(struct uart_port *port) +{ + /* This routine is used to get signals of: DCD, DSR, RI, and CTS */ + return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS; +} + +/* Transmit stop */ +static void stm32_stop_tx(struct uart_port *port) +{ + stm32_clr_bits(port, USART_CR1, USART_CR1_TXEIE); +} + +/* There are probably characters waiting to be transmitted. */ +static void stm32_start_tx(struct uart_port *port) +{ + struct circ_buf *xmit = &port->state->xmit; + + if (uart_circ_empty(xmit)) + return; + + stm32_set_bits(port, USART_CR1, USART_CR1_TXEIE | USART_CR1_TE); +} + +/* Throttle the remote when input buffer is about to overflow. */ +static void stm32_throttle(struct uart_port *port) +{ + unsigned long flags; + + spin_lock_irqsave(&port->lock, flags); + stm32_clr_bits(port, USART_CR1, USART_CR1_RXNEIE); + spin_unlock_irqrestore(&port->lock, flags); +} + +/* Unthrottle the remote, the input buffer can now accept data. */ +static void stm32_unthrottle(struct uart_port *port) +{ + unsigned long flags; + + spin_lock_irqsave(&port->lock, flags); + stm32_set_bits(port, USART_CR1, USART_CR1_RXNEIE); + spin_unlock_irqrestore(&port->lock, flags); +} + +/* Receive stop */ +static void stm32_stop_rx(struct uart_port *port) +{ + stm32_clr_bits(port, USART_CR1, USART_CR1_RXNEIE); +} + +/* Handle breaks - ignored by us */ +static void stm32_break_ctl(struct uart_port *port, int break_state) +{ +} + +static int stm32_startup(struct uart_port *port) +{ + const char *name = to_platform_device(port->dev)->name; + u32 val; + int ret; + + ret = request_irq(port->irq, stm32_interrupt, IRQF_NO_SUSPEND, + name, port); + if (ret) + return ret; + + val = USART_CR1_RXNEIE | USART_CR1_TE | USART_CR1_RE; + stm32_set_bits(port, USART_CR1, val); + + return 0; +} + +static void stm32_shutdown(struct uart_port *port) +{ + u32 val; + + val = USART_CR1_TXEIE | USART_CR1_RXNEIE | USART_CR1_TE | USART_CR1_RE; + stm32_set_bits(port, USART_CR1, val); + + free_irq(port->irq, port); +} + +static void stm32_set_termios(struct uart_port *port, struct ktermios *termios, + struct ktermios *old) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + unsigned int baud; + u32 usartdiv, mantissa, fraction, oversampling; + tcflag_t cflag = termios->c_cflag; + u32 cr1, cr2, cr3; + unsigned long flags; + + if (!stm32_port->hw_flow_control) + cflag &= ~CRTSCTS; + + baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 8); + + spin_lock_irqsave(&port->lock, flags); + + /* Stop serial port and reset value */ + writel_relaxed(0, port->membase + USART_CR1); + + cr1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE | USART_CR1_RXNEIE; + cr2 = 0; + cr3 = 0; + + if (cflag & CSTOPB) + cr2 |= USART_CR2_STOP_2B; + + if (cflag & PARENB) { + cr1 |= USART_CR1_PCE; + if ((cflag & CSIZE) == CS8) + cr1 |= USART_CR1_M; + } + + if (cflag & PARODD) + cr1 |= USART_CR1_PS; + + port->status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS); + if (cflag & CRTSCTS) { + port->status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS; + cr3 |= USART_CR3_CTSE; + } + + usartdiv = DIV_ROUND_CLOSEST(port->uartclk, baud); + + /* + * The USART supports 16 or 8 times oversampling. + * By default we prefer 16 times oversampling, so that the receiver + * has a better tolerance to clock deviations. + * 8 times oversampling is only used to achieve higher speeds. + */ + if (usartdiv < 16) { + oversampling = 8; + stm32_set_bits(port, USART_CR1, USART_CR1_OVER8); + } else { + oversampling = 16; + stm32_clr_bits(port, USART_CR1, USART_CR1_OVER8); + } + + mantissa = (usartdiv / oversampling) << USART_BRR_DIV_M_SHIFT; + fraction = usartdiv % oversampling; + writel_relaxed(mantissa | fraction, port->membase + USART_BRR); + + uart_update_timeout(port, cflag, baud); + + port->read_status_mask = USART_SR_ORE; + if (termios->c_iflag & INPCK) + port->read_status_mask |= USART_SR_PE | USART_SR_FE; + if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK)) + port->read_status_mask |= USART_SR_LBD; + + /* Characters to ignore */ + port->ignore_status_mask = 0; + if (termios->c_iflag & IGNPAR) + port->ignore_status_mask = USART_SR_PE | USART_SR_FE; + if (termios->c_iflag & IGNBRK) { + port->ignore_status_mask |= USART_SR_LBD; + /* + * If we're ignoring parity and break indicators, + * ignore overruns too (for real raw support). + */ + if (termios->c_iflag & IGNPAR) + port->ignore_status_mask |= USART_SR_ORE; + } + + /* Ignore all characters if CREAD is not set */ + if ((termios->c_cflag & CREAD) == 0) + port->ignore_status_mask |= USART_SR_DUMMY_RX; + + writel_relaxed(cr3, port->membase + USART_CR3); + writel_relaxed(cr2, port->membase + USART_CR2); + writel_relaxed(cr1, port->membase + USART_CR1); + + spin_unlock_irqrestore(&port->lock, flags); +} + +static const char *stm32_type(struct uart_port *port) +{ + return (port->type == PORT_STM32) ? DRIVER_NAME : NULL; +} + +static void stm32_release_port(struct uart_port *port) +{ +} + +static int stm32_request_port(struct uart_port *port) +{ + return 0; +} + +static void stm32_config_port(struct uart_port *port, int flags) +{ + if (flags & UART_CONFIG_TYPE) + port->type = PORT_STM32; +} + +static int +stm32_verify_port(struct uart_port *port, struct serial_struct *ser) +{ + /* No user changeable parameters */ + return -EINVAL; +} + +static void stm32_pm(struct uart_port *port, unsigned int state, + unsigned int oldstate) +{ + struct stm32_port *stm32port = container_of(port, + struct stm32_port, port); + unsigned long flags = 0; + + switch (state) { + case UART_PM_STATE_ON: + clk_prepare_enable(stm32port->clk); + break; + case UART_PM_STATE_OFF: + spin_lock_irqsave(&port->lock, flags); + stm32_clr_bits(port, USART_CR1, USART_CR1_UE); + spin_unlock_irqrestore(&port->lock, flags); + clk_disable_unprepare(stm32port->clk); + break; + } +} + +static const struct uart_ops stm32_uart_ops = { + .tx_empty = stm32_tx_empty, + .set_mctrl = stm32_set_mctrl, + .get_mctrl = stm32_get_mctrl, + .stop_tx = stm32_stop_tx, + .start_tx = stm32_start_tx, + .throttle = stm32_throttle, + .unthrottle = stm32_unthrottle, + .stop_rx = stm32_stop_rx, + .break_ctl = stm32_break_ctl, + .startup = stm32_startup, + .shutdown = stm32_shutdown, + .set_termios = stm32_set_termios, + .pm = stm32_pm, + .type = stm32_type, + .release_port = stm32_release_port, + .request_port = stm32_request_port, + .config_port = stm32_config_port, + .verify_port = stm32_verify_port, +}; + +static int stm32_init_port(struct stm32_port *stm32port, + struct platform_device *pdev) +{ + struct uart_port *port = &stm32port->port; + struct resource *res; + int ret; + + port->iotype = UPIO_MEM; + port->flags = UPF_BOOT_AUTOCONF; + port->ops = &stm32_uart_ops; + port->dev = &pdev->dev; + port->irq = platform_get_irq(pdev, 0); + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + port->membase = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(port->membase)) + return PTR_ERR(port->membase); + port->mapbase = res->start; + + spin_lock_init(&port->lock); + + stm32port->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(stm32port->clk)) + return PTR_ERR(stm32port->clk); + + /* Ensure that clk rate is correct by enabling the clk */ + ret = clk_prepare_enable(stm32port->clk); + if (ret) + return ret; + + stm32port->port.uartclk = clk_get_rate(stm32port->clk); + if (!stm32port->port.uartclk) + ret = -EINVAL; + + clk_disable_unprepare(stm32port->clk); + + return ret; +} + +static struct stm32_port *stm32_of_get_stm32_port(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + int id; + + if (!np) + return NULL; + + id = of_alias_get_id(np, "serial"); + if (id < 0) + id = 0; + + if (WARN_ON(id >= STM32_MAX_PORTS)) + return NULL; + + stm32_ports[id].hw_flow_control = of_property_read_bool(np, + "auto-flow-control"); + stm32_ports[id].port.line = id; + return &stm32_ports[id]; +} + +#ifdef CONFIG_OF +static const struct of_device_id stm32_match[] = { + { .compatible = "st,stm32-usart", }, + { .compatible = "st,stm32-uart", }, + {}, +}; + +MODULE_DEVICE_TABLE(of, stm32_match); +#endif + +static int stm32_serial_probe(struct platform_device *pdev) +{ + int ret; + struct stm32_port *stm32port; + + stm32port = stm32_of_get_stm32_port(pdev); + if (!stm32port) + return -ENODEV; + + ret = stm32_init_port(stm32port, pdev); + if (ret) + return ret; + + ret = uart_add_one_port(&stm32_usart_driver, &stm32port->port); + if (ret) + return ret; + + platform_set_drvdata(pdev, &stm32port->port); + + return 0; +} + +static int stm32_serial_remove(struct platform_device *pdev) +{ + struct uart_port *port = platform_get_drvdata(pdev); + + return uart_remove_one_port(&stm32_usart_driver, port); +} + + +#ifdef CONFIG_SERIAL_STM32_CONSOLE +static void stm32_console_putchar(struct uart_port *port, int ch) +{ + while (!(readl_relaxed(port->membase + USART_SR) & USART_SR_TXE)) + cpu_relax(); + + writel_relaxed(ch, port->membase + USART_DR); +} + +static void stm32_console_write(struct console *co, const char *s, unsigned cnt) +{ + struct uart_port *port = &stm32_ports[co->index].port; + unsigned long flags; + u32 old_cr1, new_cr1; + int locked = 1; + + local_irq_save(flags); + if (port->sysrq) + locked = 0; + else if (oops_in_progress) + locked = spin_trylock(&port->lock); + else + spin_lock(&port->lock); + + /* Save and disable interrupts */ + old_cr1 = readl_relaxed(port->membase + USART_CR1); + new_cr1 = old_cr1 & ~USART_CR1_IE_MASK; + writel_relaxed(new_cr1, port->membase + USART_CR1); + + uart_console_write(port, s, cnt, stm32_console_putchar); + + /* Restore interrupt state */ + writel_relaxed(old_cr1, port->membase + USART_CR1); + + if (locked) + spin_unlock(&port->lock); + local_irq_restore(flags); +} + +static int stm32_console_setup(struct console *co, char *options) +{ + struct stm32_port *stm32port; + int baud = 9600; + int bits = 8; + int parity = 'n'; + int flow = 'n'; + + if (co->index >= STM32_MAX_PORTS) + return -ENODEV; + + stm32port = &stm32_ports[co->index]; + + /* + * This driver does not support early console initialization + * (use ARM early printk support instead), so we only expect + * this to be called during the uart port registration when the + * driver gets probed and the port should be mapped at that point. + */ + if (stm32port->port.mapbase == 0 || stm32port->port.membase == NULL) + return -ENXIO; + + if (options) + uart_parse_options(options, &baud, &parity, &bits, &flow); + + return uart_set_options(&stm32port->port, co, baud, parity, bits, flow); +} + +static struct console stm32_console = { + .name = STM32_SERIAL_NAME, + .device = uart_console_device, + .write = stm32_console_write, + .setup = stm32_console_setup, + .flags = CON_PRINTBUFFER, + .index = -1, + .data = &stm32_usart_driver, +}; + +#define STM32_SERIAL_CONSOLE (&stm32_console) + +#else +#define STM32_SERIAL_CONSOLE NULL +#endif /* CONFIG_SERIAL_STM32_CONSOLE */ + +static struct uart_driver stm32_usart_driver = { + .driver_name = DRIVER_NAME, + .dev_name = STM32_SERIAL_NAME, + .major = 0, + .minor = 0, + .nr = STM32_MAX_PORTS, + .cons = STM32_SERIAL_CONSOLE, +}; + +static struct platform_driver stm32_serial_driver = { + .probe = stm32_serial_probe, + .remove = stm32_serial_remove, + .driver = { + .name = DRIVER_NAME, + .of_match_table = of_match_ptr(stm32_match), + }, +}; + +static int __init usart_init(void) +{ + static char banner[] __initdata = "STM32 USART driver initialized"; + int ret; + + pr_info("%s\n", banner); + + ret = uart_register_driver(&stm32_usart_driver); + if (ret) + return ret; + + ret = platform_driver_register(&stm32_serial_driver); + if (ret) + uart_unregister_driver(&stm32_usart_driver); + + return ret; +} + +static void __exit usart_exit(void) +{ + platform_driver_unregister(&stm32_serial_driver); + uart_unregister_driver(&stm32_usart_driver); +} + +module_init(usart_init); +module_exit(usart_exit); + +MODULE_ALIAS("platform:" DRIVER_NAME); +MODULE_DESCRIPTION("STMicroelectronics STM32 serial port driver"); +MODULE_LICENSE("GPL v2"); |