diff options
Diffstat (limited to 'drivers/tty/serial/mps2-uart.c')
| -rw-r--r-- | drivers/tty/serial/mps2-uart.c | 625 |
1 files changed, 625 insertions, 0 deletions
diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c new file mode 100644 index 000000000000..da9e27d3c263 --- /dev/null +++ b/drivers/tty/serial/mps2-uart.c @@ -0,0 +1,625 @@ +/* + * Copyright (C) 2015 ARM Limited + * + * Author: Vladimir Murzin <vladimir.murzin@arm.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * TODO: support for SysRq + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/bitops.h> +#include <linux/clk.h> +#include <linux/console.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of_device.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/serial_core.h> +#include <linux/tty_flip.h> +#include <linux/types.h> + +#define SERIAL_NAME "ttyMPS" +#define DRIVER_NAME "mps2-uart" +#define MAKE_NAME(x) (DRIVER_NAME # x) + +#define UARTn_DATA 0x00 + +#define UARTn_STATE 0x04 +#define UARTn_STATE_TX_FULL BIT(0) +#define UARTn_STATE_RX_FULL BIT(1) +#define UARTn_STATE_TX_OVERRUN BIT(2) +#define UARTn_STATE_RX_OVERRUN BIT(3) + +#define UARTn_CTRL 0x08 +#define UARTn_CTRL_TX_ENABLE BIT(0) +#define UARTn_CTRL_RX_ENABLE BIT(1) +#define UARTn_CTRL_TX_INT_ENABLE BIT(2) +#define UARTn_CTRL_RX_INT_ENABLE BIT(3) +#define UARTn_CTRL_TX_OVERRUN_INT_ENABLE BIT(4) +#define UARTn_CTRL_RX_OVERRUN_INT_ENABLE BIT(5) + +#define UARTn_INT 0x0c +#define UARTn_INT_TX BIT(0) +#define UARTn_INT_RX BIT(1) +#define UARTn_INT_TX_OVERRUN BIT(2) +#define UARTn_INT_RX_OVERRUN BIT(3) + +#define UARTn_BAUDDIV 0x10 +#define UARTn_BAUDDIV_MASK GENMASK(20, 0) + +/* + * Helpers to make typical enable/disable operations more readable. + */ +#define UARTn_CTRL_TX_GRP (UARTn_CTRL_TX_ENABLE |\ + UARTn_CTRL_TX_INT_ENABLE |\ + UARTn_CTRL_TX_OVERRUN_INT_ENABLE) + +#define UARTn_CTRL_RX_GRP (UARTn_CTRL_RX_ENABLE |\ + UARTn_CTRL_RX_INT_ENABLE |\ + UARTn_CTRL_RX_OVERRUN_INT_ENABLE) + +#define MPS2_MAX_PORTS 3 + +struct mps2_uart_port { + struct uart_port port; + struct clk *clk; + unsigned int tx_irq; + unsigned int rx_irq; +}; + +static inline struct mps2_uart_port *to_mps2_port(struct uart_port *port) +{ + return container_of(port, struct mps2_uart_port, port); +} + +static void mps2_uart_write8(struct uart_port *port, u8 val, unsigned int off) +{ + struct mps2_uart_port *mps_port = to_mps2_port(port); + + writeb(val, mps_port->port.membase + off); +} + +static u8 mps2_uart_read8(struct uart_port *port, unsigned int off) +{ + struct mps2_uart_port *mps_port = to_mps2_port(port); + + return readb(mps_port->port.membase + off); +} + +static void mps2_uart_write32(struct uart_port *port, u32 val, unsigned int off) +{ + struct mps2_uart_port *mps_port = to_mps2_port(port); + + writel_relaxed(val, mps_port->port.membase + off); +} + +static unsigned int mps2_uart_tx_empty(struct uart_port *port) +{ + u8 status = mps2_uart_read8(port, UARTn_STATE); + + return (status & UARTn_STATE_TX_FULL) ? 0 : TIOCSER_TEMT; +} + +static void mps2_uart_set_mctrl(struct uart_port *port, unsigned int mctrl) +{ +} + +static unsigned int mps2_uart_get_mctrl(struct uart_port *port) +{ + return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR; +} + +static void mps2_uart_stop_tx(struct uart_port *port) +{ + u8 control = mps2_uart_read8(port, UARTn_CTRL); + + control &= ~UARTn_CTRL_TX_INT_ENABLE; + + mps2_uart_write8(port, control, UARTn_CTRL); +} + +static void mps2_uart_tx_chars(struct uart_port *port) +{ + struct circ_buf *xmit = &port->state->xmit; + + while (!(mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_TX_FULL)) { + if (port->x_char) { + mps2_uart_write8(port, port->x_char, UARTn_DATA); + port->x_char = 0; + port->icount.tx++; + continue; + } + + if (uart_circ_empty(xmit) || uart_tx_stopped(port)) + break; + + mps2_uart_write8(port, xmit->buf[xmit->tail], UARTn_DATA); + xmit->tail = (xmit->tail + 1) % UART_XMIT_SIZE; + port->icount.tx++; + } + + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(port); + + if (uart_circ_empty(xmit)) + mps2_uart_stop_tx(port); +} + +static void mps2_uart_start_tx(struct uart_port *port) +{ + u8 control = mps2_uart_read8(port, UARTn_CTRL); + + control |= UARTn_CTRL_TX_INT_ENABLE; + + mps2_uart_write8(port, control, UARTn_CTRL); + + /* + * We've just unmasked the TX IRQ and now slow-starting via + * polling; if there is enough data to fill up the internal + * write buffer in one go, the TX IRQ should assert, at which + * point we switch to fully interrupt-driven TX. + */ + + mps2_uart_tx_chars(port); +} + +static void mps2_uart_stop_rx(struct uart_port *port) +{ + u8 control = mps2_uart_read8(port, UARTn_CTRL); + + control &= ~UARTn_CTRL_RX_GRP; + + mps2_uart_write8(port, control, UARTn_CTRL); +} + +static void mps2_uart_break_ctl(struct uart_port *port, int ctl) +{ +} + +static void mps2_uart_rx_chars(struct uart_port *port) +{ + struct tty_port *tport = &port->state->port; + + while (mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_RX_FULL) { + u8 rxdata = mps2_uart_read8(port, UARTn_DATA); + + port->icount.rx++; + tty_insert_flip_char(&port->state->port, rxdata, TTY_NORMAL); + } + + tty_flip_buffer_push(tport); +} + +static irqreturn_t mps2_uart_rxirq(int irq, void *data) +{ + struct uart_port *port = data; + u8 irqflag = mps2_uart_read8(port, UARTn_INT); + + if (unlikely(!(irqflag & UARTn_INT_RX))) + return IRQ_NONE; + + spin_lock(&port->lock); + + mps2_uart_write8(port, UARTn_INT_RX, UARTn_INT); + mps2_uart_rx_chars(port); + + spin_unlock(&port->lock); + + return IRQ_HANDLED; +} + +static irqreturn_t mps2_uart_txirq(int irq, void *data) +{ + struct uart_port *port = data; + u8 irqflag = mps2_uart_read8(port, UARTn_INT); + + if (unlikely(!(irqflag & UARTn_INT_TX))) + return IRQ_NONE; + + spin_lock(&port->lock); + + mps2_uart_write8(port, UARTn_INT_TX, UARTn_INT); + mps2_uart_tx_chars(port); + + spin_unlock(&port->lock); + + return IRQ_HANDLED; +} + +static irqreturn_t mps2_uart_oerrirq(int irq, void *data) +{ + irqreturn_t handled = IRQ_NONE; + struct uart_port *port = data; + u8 irqflag = mps2_uart_read8(port, UARTn_INT); + + spin_lock(&port->lock); + + if (irqflag & UARTn_INT_RX_OVERRUN) { + struct tty_port *tport = &port->state->port; + + mps2_uart_write8(port, UARTn_INT_RX_OVERRUN, UARTn_INT); + port->icount.overrun++; + tty_insert_flip_char(tport, 0, TTY_OVERRUN); + tty_flip_buffer_push(tport); + handled = IRQ_HANDLED; + } + + /* + * It's never been seen in practice and it never *should* happen since + * we check if there is enough room in TX buffer before sending data. + * So we keep this check in case something suspicious has happened. + */ + if (irqflag & UARTn_INT_TX_OVERRUN) { + mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT); + handled = IRQ_HANDLED; + } + + spin_unlock(&port->lock); + + return handled; +} + +static int mps2_uart_startup(struct uart_port *port) +{ + struct mps2_uart_port *mps_port = to_mps2_port(port); + u8 control = mps2_uart_read8(port, UARTn_CTRL); + int ret; + + control &= ~(UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP); + + mps2_uart_write8(port, control, UARTn_CTRL); + + ret = request_irq(mps_port->rx_irq, mps2_uart_rxirq, 0, + MAKE_NAME(-rx), mps_port); + if (ret) { + dev_err(port->dev, "failed to register rxirq (%d)\n", ret); + return ret; + } + + ret = request_irq(mps_port->tx_irq, mps2_uart_txirq, 0, + MAKE_NAME(-tx), mps_port); + if (ret) { + dev_err(port->dev, "failed to register txirq (%d)\n", ret); + goto err_free_rxirq; + } + + ret = request_irq(port->irq, mps2_uart_oerrirq, IRQF_SHARED, + MAKE_NAME(-overrun), mps_port); + + if (ret) { + dev_err(port->dev, "failed to register oerrirq (%d)\n", ret); + goto err_free_txirq; + } + + control |= UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP; + + mps2_uart_write8(port, control, UARTn_CTRL); + + return 0; + +err_free_txirq: + free_irq(mps_port->tx_irq, mps_port); +err_free_rxirq: + free_irq(mps_port->rx_irq, mps_port); + + return ret; +} + +static void mps2_uart_shutdown(struct uart_port *port) +{ + struct mps2_uart_port *mps_port = to_mps2_port(port); + u8 control = mps2_uart_read8(port, UARTn_CTRL); + + control &= ~(UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP); + + mps2_uart_write8(port, control, UARTn_CTRL); + + free_irq(mps_port->rx_irq, mps_port); + free_irq(mps_port->tx_irq, mps_port); + free_irq(port->irq, mps_port); +} + +static void +mps2_uart_set_termios(struct uart_port *port, struct ktermios *termios, + struct ktermios *old) +{ + unsigned long flags; + unsigned int baud, bauddiv; + + termios->c_cflag &= ~(CRTSCTS | CMSPAR); + termios->c_cflag &= ~CSIZE; + termios->c_cflag |= CS8; + termios->c_cflag &= ~PARENB; + termios->c_cflag &= ~CSTOPB; + + baud = uart_get_baud_rate(port, termios, old, + DIV_ROUND_CLOSEST(port->uartclk, UARTn_BAUDDIV_MASK), + DIV_ROUND_CLOSEST(port->uartclk, 16)); + + bauddiv = DIV_ROUND_CLOSEST(port->uartclk, baud); + + spin_lock_irqsave(&port->lock, flags); + + uart_update_timeout(port, termios->c_cflag, baud); + mps2_uart_write32(port, bauddiv, UARTn_BAUDDIV); + + spin_unlock_irqrestore(&port->lock, flags); + + if (tty_termios_baud_rate(termios)) + tty_termios_encode_baud_rate(termios, baud, baud); +} + +static const char *mps2_uart_type(struct uart_port *port) +{ + return (port->type == PORT_MPS2UART) ? DRIVER_NAME : NULL; +} + +static void mps2_uart_release_port(struct uart_port *port) +{ +} + +static int mps2_uart_request_port(struct uart_port *port) +{ + return 0; +} + +static void mps2_uart_config_port(struct uart_port *port, int type) +{ + if (type & UART_CONFIG_TYPE && !mps2_uart_request_port(port)) + port->type = PORT_MPS2UART; +} + +static int mps2_uart_verify_port(struct uart_port *port, struct serial_struct *serinfo) +{ + return -EINVAL; +} + +static const struct uart_ops mps2_uart_pops = { + .tx_empty = mps2_uart_tx_empty, + .set_mctrl = mps2_uart_set_mctrl, + .get_mctrl = mps2_uart_get_mctrl, + .stop_tx = mps2_uart_stop_tx, + .start_tx = mps2_uart_start_tx, + .stop_rx = mps2_uart_stop_rx, + .break_ctl = mps2_uart_break_ctl, + .startup = mps2_uart_startup, + .shutdown = mps2_uart_shutdown, + .set_termios = mps2_uart_set_termios, + .type = mps2_uart_type, + .release_port = mps2_uart_release_port, + .request_port = mps2_uart_request_port, + .config_port = mps2_uart_config_port, + .verify_port = mps2_uart_verify_port, +}; + +static struct mps2_uart_port mps2_uart_ports[MPS2_MAX_PORTS]; + +#ifdef CONFIG_SERIAL_MPS2_UART_CONSOLE +static void mps2_uart_console_putchar(struct uart_port *port, int ch) +{ + while (mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_TX_FULL) + cpu_relax(); + + mps2_uart_write8(port, ch, UARTn_DATA); +} + +static void mps2_uart_console_write(struct console *co, const char *s, unsigned int cnt) +{ + struct uart_port *port = &mps2_uart_ports[co->index].port; + + uart_console_write(port, s, cnt, mps2_uart_console_putchar); +} + +static int mps2_uart_console_setup(struct console *co, char *options) +{ + struct mps2_uart_port *mps_port; + int baud = 9600; + int bits = 8; + int parity = 'n'; + int flow = 'n'; + + if (co->index < 0 || co->index >= MPS2_MAX_PORTS) + return -ENODEV; + + mps_port = &mps2_uart_ports[co->index]; + + if (options) + uart_parse_options(options, &baud, &parity, &bits, &flow); + + return uart_set_options(&mps_port->port, co, baud, parity, bits, flow); +} + +static struct uart_driver mps2_uart_driver; + +static struct console mps2_uart_console = { + .name = SERIAL_NAME, + .device = uart_console_device, + .write = mps2_uart_console_write, + .setup = mps2_uart_console_setup, + .flags = CON_PRINTBUFFER, + .index = -1, + .data = &mps2_uart_driver, +}; + +#define MPS2_SERIAL_CONSOLE (&mps2_uart_console) + +static void mps2_early_putchar(struct uart_port *port, int ch) +{ + while (readb(port->membase + UARTn_STATE) & UARTn_STATE_TX_FULL) + cpu_relax(); + + writeb((unsigned char)ch, port->membase + UARTn_DATA); +} + +static void mps2_early_write(struct console *con, const char *s, unsigned int n) +{ + struct earlycon_device *dev = con->data; + + uart_console_write(&dev->port, s, n, mps2_early_putchar); +} + +static int __init mps2_early_console_setup(struct earlycon_device *device, + const char *opt) +{ + if (!device->port.membase) + return -ENODEV; + + device->con->write = mps2_early_write; + + return 0; +} + +OF_EARLYCON_DECLARE(mps2, "arm,mps2-uart", mps2_early_console_setup); + +#else +#define MPS2_SERIAL_CONSOLE NULL +#endif + +static struct uart_driver mps2_uart_driver = { + .driver_name = DRIVER_NAME, + .dev_name = SERIAL_NAME, + .nr = MPS2_MAX_PORTS, + .cons = MPS2_SERIAL_CONSOLE, +}; + +static struct mps2_uart_port *mps2_of_get_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 >= MPS2_MAX_PORTS)) + return NULL; + + mps2_uart_ports[id].port.line = id; + return &mps2_uart_ports[id]; +} + +static int mps2_init_port(struct mps2_uart_port *mps_port, + struct platform_device *pdev) +{ + struct resource *res; + int ret; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + mps_port->port.membase = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(mps_port->port.membase)) + return PTR_ERR(mps_port->port.membase); + + mps_port->port.mapbase = res->start; + mps_port->port.mapsize = resource_size(res); + + mps_port->rx_irq = platform_get_irq(pdev, 0); + mps_port->tx_irq = platform_get_irq(pdev, 1); + mps_port->port.irq = platform_get_irq(pdev, 2); + + mps_port->port.iotype = UPIO_MEM; + mps_port->port.flags = UPF_BOOT_AUTOCONF; + mps_port->port.fifosize = 1; + mps_port->port.ops = &mps2_uart_pops; + mps_port->port.dev = &pdev->dev; + + mps_port->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(mps_port->clk)) + return PTR_ERR(mps_port->clk); + + ret = clk_prepare_enable(mps_port->clk); + if (ret) + return ret; + + mps_port->port.uartclk = clk_get_rate(mps_port->clk); + + clk_disable_unprepare(mps_port->clk); + + return ret; +} + +static int mps2_serial_probe(struct platform_device *pdev) +{ + struct mps2_uart_port *mps_port; + int ret; + + mps_port = mps2_of_get_port(pdev); + if (!mps_port) + return -ENODEV; + + ret = mps2_init_port(mps_port, pdev); + if (ret) + return ret; + + ret = uart_add_one_port(&mps2_uart_driver, &mps_port->port); + if (ret) + return ret; + + platform_set_drvdata(pdev, mps_port); + + return 0; +} + +static int mps2_serial_remove(struct platform_device *pdev) +{ + struct mps2_uart_port *mps_port = platform_get_drvdata(pdev); + + uart_remove_one_port(&mps2_uart_driver, &mps_port->port); + + return 0; +} + +#ifdef CONFIG_OF +static const struct of_device_id mps2_match[] = { + { .compatible = "arm,mps2-uart", }, + {}, +}; +MODULE_DEVICE_TABLE(of, mps2_match); +#endif + +static struct platform_driver mps2_serial_driver = { + .probe = mps2_serial_probe, + .remove = mps2_serial_remove, + + .driver = { + .name = DRIVER_NAME, + .of_match_table = of_match_ptr(mps2_match), + }, +}; + +static int __init mps2_uart_init(void) +{ + int ret; + + ret = uart_register_driver(&mps2_uart_driver); + if (ret) + return ret; + + ret = platform_driver_register(&mps2_serial_driver); + if (ret) + uart_unregister_driver(&mps2_uart_driver); + + return ret; +} +module_init(mps2_uart_init); + +static void __exit mps2_uart_exit(void) +{ + platform_driver_unregister(&mps2_serial_driver); + uart_unregister_driver(&mps2_uart_driver); +} +module_exit(mps2_uart_exit); + +MODULE_AUTHOR("Vladimir Murzin <vladimir.murzin@arm.com>"); +MODULE_DESCRIPTION("MPS2 UART driver"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:" DRIVER_NAME); 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