altera_jtaguart.c

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/*
 * altera_jtaguart.c -- Altera JTAG 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/interrupt.h>
#include <linux/module.h>
#include <linux/console.h>
#include <linux/of.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/io.h>
#include <linux/altera_jtaguart.h>

#define DRV_NAME "altera_jtaguart"

/*
 * Altera JTAG UART register definitions according to the Altera JTAG UART
 * datasheet: http://www.altera.com/literature/hb/nios2/n2cpu_nii51009.pdf
 */

#define ALTERA_JTAGUART_SIZE            8

#define ALTERA_JTAGUART_DATA_REG        0

#define ALTERA_JTAGUART_DATA_DATA_MSK       0x000000FF
#define ALTERA_JTAGUART_DATA_RVALID_MSK     0x00008000
#define ALTERA_JTAGUART_DATA_RAVAIL_MSK     0xFFFF0000
#define ALTERA_JTAGUART_DATA_RAVAIL_OFF     16

#define ALTERA_JTAGUART_CONTROL_REG     4

#define ALTERA_JTAGUART_CONTROL_RE_MSK      0x00000001
#define ALTERA_JTAGUART_CONTROL_WE_MSK      0x00000002
#define ALTERA_JTAGUART_CONTROL_RI_MSK      0x00000100
#define ALTERA_JTAGUART_CONTROL_RI_OFF      8
#define ALTERA_JTAGUART_CONTROL_WI_MSK      0x00000200
#define ALTERA_JTAGUART_CONTROL_AC_MSK      0x00000400
#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK  0xFFFF0000
#define ALTERA_JTAGUART_CONTROL_WSPACE_OFF  16

/*
 * Local per-uart structure.
 */
struct altera_jtaguart {
    struct uart_port port;
    unsigned int sigs;  /* Local copy of line sigs */
    unsigned long imr;  /* Local IMR mirror */
};

static unsigned int altera_jtaguart_tx_empty(struct uart_port *port)
{
    return (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
        ALTERA_JTAGUART_CONTROL_WSPACE_MSK) ? TIOCSER_TEMT : 0;
}

static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port)
{
    return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
}

static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs)
{
}

static void altera_jtaguart_start_tx(struct uart_port *port)
{
    struct altera_jtaguart *pp =
        container_of(port, struct altera_jtaguart, port);

    pp->imr |= ALTERA_JTAGUART_CONTROL_WE_MSK;
    writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
}

static void altera_jtaguart_stop_tx(struct uart_port *port)
{
    struct altera_jtaguart *pp =
        container_of(port, struct altera_jtaguart, port);

    pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
    writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
}

static void altera_jtaguart_stop_rx(struct uart_port *port)
{
    struct altera_jtaguart *pp =
        container_of(port, struct altera_jtaguart, port);

    pp->imr &= ~ALTERA_JTAGUART_CONTROL_RE_MSK;
    writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
}

static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state)
{
}

static void altera_jtaguart_enable_ms(struct uart_port *port)
{
}

static void altera_jtaguart_set_termios(struct uart_port *port,
                    struct ktermios *termios,
                    struct ktermios *old)
{
    /* Just copy the old termios settings back */
    if (old)
        tty_termios_copy_hw(termios, old);
}

static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
{
    struct uart_port *port = &pp->port;
    unsigned char ch, flag;
    unsigned long status;

    while ((status = readl(port->membase + ALTERA_JTAGUART_DATA_REG)) &
           ALTERA_JTAGUART_DATA_RVALID_MSK) {
        ch = status & ALTERA_JTAGUART_DATA_DATA_MSK;
        flag = TTY_NORMAL;
        port->icount.rx++;

        if (uart_handle_sysrq_char(port, ch))
            continue;
        uart_insert_char(port, 0, 0, ch, flag);
    }

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

static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
{
    struct uart_port *port = &pp->port;
    struct circ_buf *xmit = &port->state->xmit;
    unsigned int pending, count;

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

    pending = uart_circ_chars_pending(xmit);
    if (pending > 0) {
        count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
                ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
            ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
        if (count > pending)
            count = pending;
        if (count > 0) {
            pending -= count;
            while (count--) {
                writel(xmit->buf[xmit->tail],
                       port->membase + ALTERA_JTAGUART_DATA_REG);
                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
                port->icount.tx++;
            }
            if (pending < WAKEUP_CHARS)
                uart_write_wakeup(port);
        }
    }

    if (pending == 0) {
        pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
        writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
    }
}

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

    isr = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
           ALTERA_JTAGUART_CONTROL_RI_OFF) & pp->imr;

    spin_lock(&port->lock);

    if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK)
        altera_jtaguart_rx_chars(pp);
    if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK)
        altera_jtaguart_tx_chars(pp);

    spin_unlock(&port->lock);

    return IRQ_RETVAL(isr);
}

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

    /* Clear mask, so no surprise interrupts. */
    writel(0, port->membase + ALTERA_JTAGUART_CONTROL_REG);
}

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

    ret = request_irq(port->irq, altera_jtaguart_interrupt, 0,
            DRV_NAME, port);
    if (ret) {
        pr_err(DRV_NAME ": unable to attach Altera JTAG 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_JTAGUART_CONTROL_RE_MSK;
    writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);

    spin_unlock_irqrestore(&port->lock, flags);

    return 0;
}

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

    spin_lock_irqsave(&port->lock, flags);

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

    spin_unlock_irqrestore(&port->lock, flags);

    free_irq(port->irq, port);
}

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

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

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

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

/*
 *  Define the basic serial functions we support.
 */
static struct uart_ops altera_jtaguart_ops = {
    .tx_empty   = altera_jtaguart_tx_empty,
    .get_mctrl  = altera_jtaguart_get_mctrl,
    .set_mctrl  = altera_jtaguart_set_mctrl,
    .start_tx   = altera_jtaguart_start_tx,
    .stop_tx    = altera_jtaguart_stop_tx,
    .stop_rx    = altera_jtaguart_stop_rx,
    .enable_ms  = altera_jtaguart_enable_ms,
    .break_ctl  = altera_jtaguart_break_ctl,
    .startup    = altera_jtaguart_startup,
    .shutdown   = altera_jtaguart_shutdown,
    .set_termios    = altera_jtaguart_set_termios,
    .type       = altera_jtaguart_type,
    .request_port   = altera_jtaguart_request_port,
    .release_port   = altera_jtaguart_release_port,
    .config_port    = altera_jtaguart_config_port,
    .verify_port    = altera_jtaguart_verify_port,
};

#define ALTERA_JTAGUART_MAXPORTS 1
static struct altera_jtaguart altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS];

#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)

#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
static void altera_jtaguart_console_putc(struct console *co, const char c)
{
    struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
    unsigned long status;
    unsigned long flags;

    spin_lock_irqsave(&port->lock, flags);
    while (((status = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG)) &
        ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
        if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
            spin_unlock_irqrestore(&port->lock, flags);
            return; /* no connection activity */
        }
        spin_unlock_irqrestore(&port->lock, flags);
        cpu_relax();
        spin_lock_irqsave(&port->lock, flags);
    }
    writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
    spin_unlock_irqrestore(&port->lock, flags);
}
#else
static void altera_jtaguart_console_putc(struct console *co, const char c)
{
    struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
    unsigned long flags;

    spin_lock_irqsave(&port->lock, flags);
    while ((readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
        ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
        spin_unlock_irqrestore(&port->lock, flags);
        cpu_relax();
        spin_lock_irqsave(&port->lock, flags);
    }
    writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
    spin_unlock_irqrestore(&port->lock, flags);
}
#endif

static void altera_jtaguart_console_write(struct console *co, const char *s,
                      unsigned int count)
{
    for (; count; count--, s++) {
        altera_jtaguart_console_putc(co, *s);
        if (*s == '\n')
            altera_jtaguart_console_putc(co, '\r');
    }
}

static int __init altera_jtaguart_console_setup(struct console *co,
                        char *options)
{
    struct uart_port *port;

    if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS)
        return -EINVAL;
    port = &altera_jtaguart_ports[co->index].port;
    if (port->membase == NULL)
        return -ENODEV;
    return 0;
}

static struct uart_driver altera_jtaguart_driver;

static struct console altera_jtaguart_console = {
    .name   = "ttyJ",
    .write  = altera_jtaguart_console_write,
    .device = uart_console_device,
    .setup  = altera_jtaguart_console_setup,
    .flags  = CON_PRINTBUFFER,
    .index  = -1,
    .data   = &altera_jtaguart_driver,
};

static int __init altera_jtaguart_console_init(void)
{
    register_console(&altera_jtaguart_console);
    return 0;
}

console_initcall(altera_jtaguart_console_init);

#define ALTERA_JTAGUART_CONSOLE (&altera_jtaguart_console)

#else

#define ALTERA_JTAGUART_CONSOLE NULL

#endif /* CONFIG_ALTERA_JTAGUART_CONSOLE */

static struct uart_driver altera_jtaguart_driver = {
    .owner      = THIS_MODULE,
    .driver_name    = "altera_jtaguart",
    .dev_name   = "ttyJ",
    .major      = ALTERA_JTAGUART_MAJOR,
    .minor      = ALTERA_JTAGUART_MINOR,
    .nr     = ALTERA_JTAGUART_MAXPORTS,
    .cons       = ALTERA_JTAGUART_CONSOLE,
};

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

    /* -1 emphasizes that the platform must have one port, no .N suffix */
    if (i == -1)
        i = 0;

    if (i >= ALTERA_JTAGUART_MAXPORTS)
        return -EINVAL;

    port = &altera_jtaguart_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 -ENODEV;

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

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

    port->line = i;
    port->type = PORT_ALTERA_JTAGUART;
    port->iotype = SERIAL_IO_MEM;
    port->ops = &altera_jtaguart_ops;
    port->flags = UPF_BOOT_AUTOCONF;

    uart_add_one_port(&altera_jtaguart_driver, port);

    return 0;
}

static int __devexit altera_jtaguart_remove(struct platform_device *pdev)
{
    struct uart_port *port;
    int i = pdev->id;

    if (i == -1)
        i = 0;

    port = &altera_jtaguart_ports[i].port;
    uart_remove_one_port(&altera_jtaguart_driver, port);

    return 0;
}

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

static struct platform_driver altera_jtaguart_platform_driver = {
    .probe  = altera_jtaguart_probe,
    .remove = __devexit_p(altera_jtaguart_remove),
    .driver = {
        .name       = DRV_NAME,
        .owner      = THIS_MODULE,
        .of_match_table = of_match_ptr(altera_jtaguart_match),
    },
};

static int __init altera_jtaguart_init(void)
{
    int rc;

    rc = uart_register_driver(&altera_jtaguart_driver);
    if (rc)
        return rc;
    rc = platform_driver_register(&altera_jtaguart_platform_driver);
    if (rc) {
        uart_unregister_driver(&altera_jtaguart_driver);
        return rc;
    }
    return 0;
}

static void __exit altera_jtaguart_exit(void)
{
    platform_driver_unregister(&altera_jtaguart_platform_driver);
    uart_unregister_driver(&altera_jtaguart_driver);
}

module_init(altera_jtaguart_init);
module_exit(altera_jtaguart_exit);

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