/* * Copyright (C) Maxime Coquelin 2015 * Author: Maxime Coquelin * License terms: GNU General Public License (GPL), version 2 * * Inspired by st-asc.c from STMicroelectronics (c) */ #if defined(CONFIG_SERIAL_STM32_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ) #define SUPPORT_SYSRQ #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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, 0, 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");