altera_uart.c

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/*
 * altera_uart.c -- Altera UART driver
 *
 * Based on mcf.c -- Freescale ColdFire UART driver
 *
 * (C) Copyright 2003-2007, Greg Ungerer <[email protected]>
 * (C) Copyright 2008, Thomas Chou <[email protected]>
 * (C) Copyright 2010, Tobias Klauser <[email protected]>
 *
 * 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.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/console.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/io.h>
#include <linux/altera_uart.h>

#define DRV_NAME "altera_uart"
#define SERIAL_ALTERA_MAJOR 204
#define SERIAL_ALTERA_MINOR 213

/*
 * Altera UART register definitions according to the Nios UART datasheet:
 * http://www.altera.com/literature/ds/ds_nios_uart.pdf
 */

#define ALTERA_UART_SIZE        32

#define ALTERA_UART_RXDATA_REG      0
#define ALTERA_UART_TXDATA_REG      4
#define ALTERA_UART_STATUS_REG      8
#define ALTERA_UART_CONTROL_REG     12
#define ALTERA_UART_DIVISOR_REG     16
#define ALTERA_UART_EOP_REG     20

#define ALTERA_UART_STATUS_PE_MSK   0x0001  /* parity error */
#define ALTERA_UART_STATUS_FE_MSK   0x0002  /* framing error */
#define ALTERA_UART_STATUS_BRK_MSK  0x0004  /* break */
#define ALTERA_UART_STATUS_ROE_MSK  0x0008  /* RX overrun error */
#define ALTERA_UART_STATUS_TOE_MSK  0x0010  /* TX overrun error */
#define ALTERA_UART_STATUS_TMT_MSK  0x0020  /* TX shift register state */
#define ALTERA_UART_STATUS_TRDY_MSK 0x0040  /* TX ready */
#define ALTERA_UART_STATUS_RRDY_MSK 0x0080  /* RX ready */
#define ALTERA_UART_STATUS_E_MSK    0x0100  /* exception condition */
#define ALTERA_UART_STATUS_DCTS_MSK 0x0400  /* CTS logic-level change */
#define ALTERA_UART_STATUS_CTS_MSK  0x0800  /* CTS logic state */
#define ALTERA_UART_STATUS_EOP_MSK  0x1000  /* EOP written/read */

                        /* Enable interrupt on... */
#define ALTERA_UART_CONTROL_PE_MSK  0x0001  /* ...parity error */
#define ALTERA_UART_CONTROL_FE_MSK  0x0002  /* ...framing error */
#define ALTERA_UART_CONTROL_BRK_MSK 0x0004  /* ...break */
#define ALTERA_UART_CONTROL_ROE_MSK 0x0008  /* ...RX overrun */
#define ALTERA_UART_CONTROL_TOE_MSK 0x0010  /* ...TX overrun */
#define ALTERA_UART_CONTROL_TMT_MSK 0x0020  /* ...TX shift register empty */
#define ALTERA_UART_CONTROL_TRDY_MSK    0x0040  /* ...TX ready */
#define ALTERA_UART_CONTROL_RRDY_MSK    0x0080  /* ...RX ready */
#define ALTERA_UART_CONTROL_E_MSK   0x0100  /* ...exception*/

#define ALTERA_UART_CONTROL_TRBK_MSK    0x0200  /* TX break */
#define ALTERA_UART_CONTROL_DCTS_MSK    0x0400  /* Interrupt on CTS change */
#define ALTERA_UART_CONTROL_RTS_MSK 0x0800  /* RTS signal */
#define ALTERA_UART_CONTROL_EOP_MSK 0x1000  /* Interrupt on EOP */

/*
 * Local per-uart structure.
 */
struct altera_uart {
    struct uart_port port;
    struct timer_list tmr;
    unsigned int sigs;  /* Local copy of line sigs */
    unsigned short imr; /* Local IMR mirror */
};

static u32 altera_uart_readl(struct uart_port *port, int reg)
{
    return readl(port->membase + (reg << port->regshift));
}

static void altera_uart_writel(struct uart_port *port, u32 dat, int reg)
{
    writel(dat, port->membase + (reg << port->regshift));
}

static unsigned int altera_uart_tx_empty(struct uart_port *port)
{
    return (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
        ALTERA_UART_STATUS_TMT_MSK) ? TIOCSER_TEMT : 0;
}

static unsigned int altera_uart_get_mctrl(struct uart_port *port)
{
    struct altera_uart *pp = container_of(port, struct altera_uart, port);
    unsigned int sigs;

    sigs = (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
         ALTERA_UART_STATUS_CTS_MSK) ? TIOCM_CTS : 0;
    sigs |= (pp->sigs & TIOCM_RTS);

    return sigs;
}

static void altera_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
{
    struct altera_uart *pp = container_of(port, struct altera_uart, port);

    pp->sigs = sigs;
    if (sigs & TIOCM_RTS)
        pp->imr |= ALTERA_UART_CONTROL_RTS_MSK;
    else
        pp->imr &= ~ALTERA_UART_CONTROL_RTS_MSK;
    altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
}

static void altera_uart_start_tx(struct uart_port *port)
{
    struct altera_uart *pp = container_of(port, struct altera_uart, port);

    pp->imr |= ALTERA_UART_CONTROL_TRDY_MSK;
    altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
}

static void altera_uart_stop_tx(struct uart_port *port)
{
    struct altera_uart *pp = container_of(port, struct altera_uart, port);

    pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
    altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
}

static void altera_uart_stop_rx(struct uart_port *port)
{
    struct altera_uart *pp = container_of(port, struct altera_uart, port);

    pp->imr &= ~ALTERA_UART_CONTROL_RRDY_MSK;
    altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
}

static void altera_uart_break_ctl(struct uart_port *port, int break_state)
{
    struct altera_uart *pp = container_of(port, struct altera_uart, port);
    unsigned long flags;

    spin_lock_irqsave(&port->lock, flags);
    if (break_state == -1)
        pp->imr |= ALTERA_UART_CONTROL_TRBK_MSK;
    else
        pp->imr &= ~ALTERA_UART_CONTROL_TRBK_MSK;
    altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
    spin_unlock_irqrestore(&port->lock, flags);
}

static void altera_uart_enable_ms(struct uart_port *port)
{
}

static void altera_uart_set_termios(struct uart_port *port,
                    struct ktermios *termios,
                    struct ktermios *old)
{
    unsigned long flags;
    unsigned int baud, baudclk;

    baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
    baudclk = port->uartclk / baud;

    if (old)
        tty_termios_copy_hw(termios, old);
    tty_termios_encode_baud_rate(termios, baud, baud);

    spin_lock_irqsave(&port->lock, flags);
    uart_update_timeout(port, termios->c_cflag, baud);
    altera_uart_writel(port, baudclk, ALTERA_UART_DIVISOR_REG);
    spin_unlock_irqrestore(&port->lock, flags);
}

static void altera_uart_rx_chars(struct altera_uart *pp)
{
    struct uart_port *port = &pp->port;
    unsigned char ch, flag;
    unsigned short status;

    while ((status = altera_uart_readl(port, ALTERA_UART_STATUS_REG)) &
           ALTERA_UART_STATUS_RRDY_MSK) {
        ch = altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
        flag = TTY_NORMAL;
        port->icount.rx++;

        if (status & ALTERA_UART_STATUS_E_MSK) {
            altera_uart_writel(port, status,
                       ALTERA_UART_STATUS_REG);

            if (status & ALTERA_UART_STATUS_BRK_MSK) {
                port->icount.brk++;
                if (uart_handle_break(port))
                    continue;
            } else if (status & ALTERA_UART_STATUS_PE_MSK) {
                port->icount.parity++;
            } else if (status & ALTERA_UART_STATUS_ROE_MSK) {
                port->icount.overrun++;
            } else if (status & ALTERA_UART_STATUS_FE_MSK) {
                port->icount.frame++;
            }

            status &= port->read_status_mask;

            if (status & ALTERA_UART_STATUS_BRK_MSK)
                flag = TTY_BREAK;
            else if (status & ALTERA_UART_STATUS_PE_MSK)
                flag = TTY_PARITY;
            else if (status & ALTERA_UART_STATUS_FE_MSK)
                flag = TTY_FRAME;
        }

        if (uart_handle_sysrq_char(port, ch))
            continue;
        uart_insert_char(port, status, ALTERA_UART_STATUS_ROE_MSK, ch,
                 flag);
    }

    tty_flip_buffer_push(port->state->port.tty);
}

static void altera_uart_tx_chars(struct altera_uart *pp)
{
    struct uart_port *port = &pp->port;
    struct circ_buf *xmit = &port->state->xmit;

    if (port->x_char) {
        /* Send special char - probably flow control */
        altera_uart_writel(port, port->x_char, ALTERA_UART_TXDATA_REG);
        port->x_char = 0;
        port->icount.tx++;
        return;
    }

    while (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
           ALTERA_UART_STATUS_TRDY_MSK) {
        if (xmit->head == xmit->tail)
            break;
        altera_uart_writel(port, xmit->buf[xmit->tail],
               ALTERA_UART_TXDATA_REG);
        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 (xmit->head == xmit->tail) {
        pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
        altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
    }
}

static irqreturn_t altera_uart_interrupt(int irq, void *data)
{
    struct uart_port *port = data;
    struct altera_uart *pp = container_of(port, struct altera_uart, port);
    unsigned int isr;

    isr = altera_uart_readl(port, ALTERA_UART_STATUS_REG) & pp->imr;

    spin_lock(&port->lock);
    if (isr & ALTERA_UART_STATUS_RRDY_MSK)
        altera_uart_rx_chars(pp);
    if (isr & ALTERA_UART_STATUS_TRDY_MSK)
        altera_uart_tx_chars(pp);
    spin_unlock(&port->lock);

    return IRQ_RETVAL(isr);
}

static void altera_uart_timer(unsigned long data)
{
    struct uart_port *port = (void *)data;
    struct altera_uart *pp = container_of(port, struct altera_uart, port);

    altera_uart_interrupt(0, port);
    mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
}

static void altera_uart_config_port(struct uart_port *port, int flags)
{
    port->type = PORT_ALTERA_UART;

    /* Clear mask, so no surprise interrupts. */
    altera_uart_writel(port, 0, ALTERA_UART_CONTROL_REG);
    /* Clear status register */
    altera_uart_writel(port, 0, ALTERA_UART_STATUS_REG);
}

static int altera_uart_startup(struct uart_port *port)
{
    struct altera_uart *pp = container_of(port, struct altera_uart, port);
    unsigned long flags;
    int ret;

    if (!port->irq) {
        setup_timer(&pp->tmr, altera_uart_timer, (unsigned long)port);
        mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
        return 0;
    }

    ret = request_irq(port->irq, altera_uart_interrupt, 0,
            DRV_NAME, port);
    if (ret) {
        pr_err(DRV_NAME ": unable to attach Altera UART %d "
               "interrupt vector=%d\n", port->line, port->irq);
        return ret;
    }

    spin_lock_irqsave(&port->lock, flags);

    /* Enable RX interrupts now */
    pp->imr = ALTERA_UART_CONTROL_RRDY_MSK;
    writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);

    spin_unlock_irqrestore(&port->lock, flags);

    return 0;
}

static void altera_uart_shutdown(struct uart_port *port)
{
    struct altera_uart *pp = container_of(port, struct altera_uart, port);
    unsigned long flags;

    spin_lock_irqsave(&port->lock, flags);

    /* Disable all interrupts now */
    pp->imr = 0;
    writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);

    spin_unlock_irqrestore(&port->lock, flags);

    if (port->irq)
        free_irq(port->irq, port);
    else
        del_timer_sync(&pp->tmr);
}

static const char *altera_uart_type(struct uart_port *port)
{
    return (port->type == PORT_ALTERA_UART) ? "Altera UART" : NULL;
}

static int altera_uart_request_port(struct uart_port *port)
{
    /* UARTs always present */
    return 0;
}

static void altera_uart_release_port(struct uart_port *port)
{
    /* Nothing to release... */
}

static int altera_uart_verify_port(struct uart_port *port,
                   struct serial_struct *ser)
{
    if ((ser->type != PORT_UNKNOWN) && (ser->type != PORT_ALTERA_UART))
        return -EINVAL;
    return 0;
}

#ifdef CONFIG_CONSOLE_POLL
static int altera_uart_poll_get_char(struct uart_port *port)
{
    while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
         ALTERA_UART_STATUS_RRDY_MSK))
        cpu_relax();

    return altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
}

static void altera_uart_poll_put_char(struct uart_port *port, unsigned char c)
{
    while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
         ALTERA_UART_STATUS_TRDY_MSK))
        cpu_relax();

    altera_uart_writel(port, c, ALTERA_UART_TXDATA_REG);
}
#endif

/*
 *  Define the basic serial functions we support.
 */
static struct uart_ops altera_uart_ops = {
    .tx_empty   = altera_uart_tx_empty,
    .get_mctrl  = altera_uart_get_mctrl,
    .set_mctrl  = altera_uart_set_mctrl,
    .start_tx   = altera_uart_start_tx,
    .stop_tx    = altera_uart_stop_tx,
    .stop_rx    = altera_uart_stop_rx,
    .enable_ms  = altera_uart_enable_ms,
    .break_ctl  = altera_uart_break_ctl,
    .startup    = altera_uart_startup,
    .shutdown   = altera_uart_shutdown,
    .set_termios    = altera_uart_set_termios,
    .type       = altera_uart_type,
    .request_port   = altera_uart_request_port,
    .release_port   = altera_uart_release_port,
    .config_port    = altera_uart_config_port,
    .verify_port    = altera_uart_verify_port,
#ifdef CONFIG_CONSOLE_POLL
    .poll_get_char  = altera_uart_poll_get_char,
    .poll_put_char  = altera_uart_poll_put_char,
#endif
};

static struct altera_uart altera_uart_ports[CONFIG_SERIAL_ALTERA_UART_MAXPORTS];

#if defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)

static void altera_uart_console_putc(struct uart_port *port, const char c)
{
    while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
         ALTERA_UART_STATUS_TRDY_MSK))
        cpu_relax();

    writel(c, port->membase + ALTERA_UART_TXDATA_REG);
}

static void altera_uart_console_write(struct console *co, const char *s,
                      unsigned int count)
{
    struct uart_port *port = &(altera_uart_ports + co->index)->port;

    for (; count; count--, s++) {
        altera_uart_console_putc(port, *s);
        if (*s == '\n')
            altera_uart_console_putc(port, '\r');
    }
}

static int __init altera_uart_console_setup(struct console *co, char *options)
{
    struct uart_port *port;
    int baud = CONFIG_SERIAL_ALTERA_UART_BAUDRATE;
    int bits = 8;
    int parity = 'n';
    int flow = 'n';

    if (co->index < 0 || co->index >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
        return -EINVAL;
    port = &altera_uart_ports[co->index].port;
    if (!port->membase)
        return -ENODEV;

    if (options)
        uart_parse_options(options, &baud, &parity, &bits, &flow);

    return uart_set_options(port, co, baud, parity, bits, flow);
}

static struct uart_driver altera_uart_driver;

static struct console altera_uart_console = {
    .name   = "ttyAL",
    .write  = altera_uart_console_write,
    .device = uart_console_device,
    .setup  = altera_uart_console_setup,
    .flags  = CON_PRINTBUFFER,
    .index  = -1,
    .data   = &altera_uart_driver,
};

static int __init altera_uart_console_init(void)
{
    register_console(&altera_uart_console);
    return 0;
}

console_initcall(altera_uart_console_init);

#define ALTERA_UART_CONSOLE (&altera_uart_console)

#else

#define ALTERA_UART_CONSOLE NULL

#endif /* CONFIG_ALTERA_UART_CONSOLE */

/*
 *  Define the altera_uart UART driver structure.
 */
static struct uart_driver altera_uart_driver = {
    .owner      = THIS_MODULE,
    .driver_name    = DRV_NAME,
    .dev_name   = "ttyAL",
    .major      = SERIAL_ALTERA_MAJOR,
    .minor      = SERIAL_ALTERA_MINOR,
    .nr     = CONFIG_SERIAL_ALTERA_UART_MAXPORTS,
    .cons       = ALTERA_UART_CONSOLE,
};

#ifdef CONFIG_OF
static int altera_uart_get_of_uartclk(struct platform_device *pdev,
                      struct uart_port *port)
{
    int len;
    const __be32 *clk;

    clk = of_get_property(pdev->dev.of_node, "clock-frequency", &len);
    if (!clk || len < sizeof(__be32))
        return -ENODEV;

    port->uartclk = be32_to_cpup(clk);

    return 0;
}
#else
static int altera_uart_get_of_uartclk(struct platform_device *pdev,
                      struct uart_port *port)
{
    return -ENODEV;
}
#endif /* CONFIG_OF */

static int __devinit altera_uart_probe(struct platform_device *pdev)
{
    struct altera_uart_platform_uart *platp = pdev->dev.platform_data;
    struct uart_port *port;
    struct resource *res_mem;
    struct resource *res_irq;
    int i = pdev->id;
    int ret;

    /* if id is -1 scan for a free id and use that one */
    if (i == -1) {
        for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS; i++)
            if (altera_uart_ports[i].port.mapbase == 0)
                break;
    }

    if (i < 0 || i >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
        return -EINVAL;

    port = &altera_uart_ports[i].port;

    res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (res_mem)
        port->mapbase = res_mem->start;
    else if (platp)
        port->mapbase = platp->mapbase;
    else
        return -EINVAL;

    res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
    if (res_irq)
        port->irq = res_irq->start;
    else if (platp)
        port->irq = platp->irq;

    /* Check platform data first so we can override device node data */
    if (platp)
        port->uartclk = platp->uartclk;
    else {
        ret = altera_uart_get_of_uartclk(pdev, port);
        if (ret)
            return ret;
    }

    port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
    if (!port->membase)
        return -ENOMEM;

    if (platp)
        port->regshift = platp->bus_shift;
    else
        port->regshift = 0;

    port->line = i;
    port->type = PORT_ALTERA_UART;
    port->iotype = SERIAL_IO_MEM;
    port->ops = &altera_uart_ops;
    port->flags = UPF_BOOT_AUTOCONF;

    platform_set_drvdata(pdev, port);

    uart_add_one_port(&altera_uart_driver, port);

    return 0;
}

static int __devexit altera_uart_remove(struct platform_device *pdev)
{
    struct uart_port *port = platform_get_drvdata(pdev);

    if (port) {
        uart_remove_one_port(&altera_uart_driver, port);
        platform_set_drvdata(pdev, NULL);
        port->mapbase = 0;
    }

    return 0;
}

#ifdef CONFIG_OF
static struct of_device_id altera_uart_match[] = {
    { .compatible = "ALTR,uart-1.0", },
    {},
};
MODULE_DEVICE_TABLE(of, altera_uart_match);
#endif /* CONFIG_OF */

static struct platform_driver altera_uart_platform_driver = {
    .probe  = altera_uart_probe,
    .remove = __devexit_p(altera_uart_remove),
    .driver = {
        .name       = DRV_NAME,
        .owner      = THIS_MODULE,
        .of_match_table = of_match_ptr(altera_uart_match),
    },
};

static int __init altera_uart_init(void)
{
    int rc;

    rc = uart_register_driver(&altera_uart_driver);
    if (rc)
        return rc;
    rc = platform_driver_register(&altera_uart_platform_driver);
    if (rc) {
        uart_unregister_driver(&altera_uart_driver);
        return rc;
    }
    return 0;
}

static void __exit altera_uart_exit(void)
{
    platform_driver_unregister(&altera_uart_platform_driver);
    uart_unregister_driver(&altera_uart_driver);
}

module_init(altera_uart_init);
module_exit(altera_uart_exit);

MODULE_DESCRIPTION("Altera UART driver");
MODULE_AUTHOR("Thomas Chou <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);
MODULE_ALIAS_CHARDEV_MAJOR(SERIAL_ALTERA_MAJOR);