serial_ks8695.c

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/*
 *  Driver for KS8695 serial ports
 *
 *  Based on drivers/serial/serial_amba.c, by Kam Lee.
 *
 *  Copyright 2002-2005 Micrel Inc.
 *
 * 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/module.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/device.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/mach/irq.h>

#include <mach/regs-uart.h>
#include <mach/regs-irq.h>

#if defined(CONFIG_SERIAL_KS8695_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/serial_core.h>


#define SERIAL_KS8695_MAJOR 204
#define SERIAL_KS8695_MINOR 16
#define SERIAL_KS8695_DEVNAME   "ttyAM"

#define SERIAL_KS8695_NR    1

/*
 * Access macros for the KS8695 UART
 */
#define UART_GET_CHAR(p)    (__raw_readl((p)->membase + KS8695_URRB) & 0xFF)
#define UART_PUT_CHAR(p, c) __raw_writel((c), (p)->membase + KS8695_URTH)
#define UART_GET_FCR(p)     __raw_readl((p)->membase + KS8695_URFC)
#define UART_PUT_FCR(p, c)  __raw_writel((c), (p)->membase + KS8695_URFC)
#define UART_GET_MSR(p)     __raw_readl((p)->membase + KS8695_URMS)
#define UART_GET_LSR(p)     __raw_readl((p)->membase + KS8695_URLS)
#define UART_GET_LCR(p)     __raw_readl((p)->membase + KS8695_URLC)
#define UART_PUT_LCR(p, c)  __raw_writel((c), (p)->membase + KS8695_URLC)
#define UART_GET_MCR(p)     __raw_readl((p)->membase + KS8695_URMC)
#define UART_PUT_MCR(p, c)  __raw_writel((c), (p)->membase + KS8695_URMC)
#define UART_GET_BRDR(p)    __raw_readl((p)->membase + KS8695_URBD)
#define UART_PUT_BRDR(p, c) __raw_writel((c), (p)->membase + KS8695_URBD)

#define KS8695_CLR_TX_INT() __raw_writel(1 << KS8695_IRQ_UART_TX, KS8695_IRQ_VA + KS8695_INTST)

#define UART_DUMMY_LSR_RX   0x100
#define UART_PORT_SIZE      (KS8695_USR - KS8695_URRB + 4)

static inline int tx_enabled(struct uart_port *port)
{
    return port->unused[0] & 1;
}

static inline int rx_enabled(struct uart_port *port)
{
    return port->unused[0] & 2;
}

static inline int ms_enabled(struct uart_port *port)
{
    return port->unused[0] & 4;
}

static inline void ms_enable(struct uart_port *port, int enabled)
{
    if(enabled)
        port->unused[0] |= 4;
    else
        port->unused[0] &= ~4;
}

static inline void rx_enable(struct uart_port *port, int enabled)
{
    if(enabled)
        port->unused[0] |= 2;
    else
        port->unused[0] &= ~2;
}

static inline void tx_enable(struct uart_port *port, int enabled)
{
    if(enabled)
        port->unused[0] |= 1;
    else
        port->unused[0] &= ~1;
}


#ifdef SUPPORT_SYSRQ
static struct console ks8695_console;
#endif

static void ks8695uart_stop_tx(struct uart_port *port)
{
    if (tx_enabled(port)) {
        /* use disable_irq_nosync() and not disable_irq() to avoid self
         * imposed deadlock by not waiting for irq handler to end,
         * since this ks8695uart_stop_tx() is called from interrupt context.
         */
        disable_irq_nosync(KS8695_IRQ_UART_TX);
        tx_enable(port, 0);
    }
}

static void ks8695uart_start_tx(struct uart_port *port)
{
    if (!tx_enabled(port)) {
        enable_irq(KS8695_IRQ_UART_TX);
        tx_enable(port, 1);
    }
}

static void ks8695uart_stop_rx(struct uart_port *port)
{
    if (rx_enabled(port)) {
        disable_irq(KS8695_IRQ_UART_RX);
        rx_enable(port, 0);
    }
}

static void ks8695uart_enable_ms(struct uart_port *port)
{
    if (!ms_enabled(port)) {
        enable_irq(KS8695_IRQ_UART_MODEM_STATUS);
        ms_enable(port,1);
    }
}

static void ks8695uart_disable_ms(struct uart_port *port)
{
    if (ms_enabled(port)) {
        disable_irq(KS8695_IRQ_UART_MODEM_STATUS);
        ms_enable(port,0);
    }
}

static irqreturn_t ks8695uart_rx_chars(int irq, void *dev_id)
{
    struct uart_port *port = dev_id;
    struct tty_struct *tty = port->state->port.tty;
    unsigned int status, ch, lsr, flg, max_count = 256;

    status = UART_GET_LSR(port);        /* clears pending LSR interrupts */
    while ((status & URLS_URDR) && max_count--) {
        ch = UART_GET_CHAR(port);
        flg = TTY_NORMAL;

        port->icount.rx++;

        /*
         * Note that the error handling code is
         * out of the main execution path
         */
        lsr = UART_GET_LSR(port) | UART_DUMMY_LSR_RX;
        if (unlikely(lsr & (URLS_URBI | URLS_URPE | URLS_URFE | URLS_URROE))) {
            if (lsr & URLS_URBI) {
                lsr &= ~(URLS_URFE | URLS_URPE);
                port->icount.brk++;
                if (uart_handle_break(port))
                    goto ignore_char;
            }
            if (lsr & URLS_URPE)
                port->icount.parity++;
            if (lsr & URLS_URFE)
                port->icount.frame++;
            if (lsr & URLS_URROE)
                port->icount.overrun++;

            lsr &= port->read_status_mask;

            if (lsr & URLS_URBI)
                flg = TTY_BREAK;
            else if (lsr & URLS_URPE)
                flg = TTY_PARITY;
            else if (lsr & URLS_URFE)
                flg = TTY_FRAME;
        }

        if (uart_handle_sysrq_char(port, ch))
            goto ignore_char;

        uart_insert_char(port, lsr, URLS_URROE, ch, flg);

ignore_char:
        status = UART_GET_LSR(port);
    }
    tty_flip_buffer_push(tty);

    return IRQ_HANDLED;
}


static irqreturn_t ks8695uart_tx_chars(int irq, void *dev_id)
{
    struct uart_port *port = dev_id;
    struct circ_buf *xmit = &port->state->xmit;
    unsigned int count;

    if (port->x_char) {
        KS8695_CLR_TX_INT();
        UART_PUT_CHAR(port, port->x_char);
        port->icount.tx++;
        port->x_char = 0;
        return IRQ_HANDLED;
    }

    if (uart_tx_stopped(port) || uart_circ_empty(xmit)) {
        ks8695uart_stop_tx(port);
        return IRQ_HANDLED;
    }

    count = 16; /* fifo size */
    while (!uart_circ_empty(xmit) && (count-- > 0)) {
        KS8695_CLR_TX_INT();
        UART_PUT_CHAR(port, xmit->buf[xmit->tail]);

        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))
        ks8695uart_stop_tx(port);

    return IRQ_HANDLED;
}

static irqreturn_t ks8695uart_modem_status(int irq, void *dev_id)
{
    struct uart_port *port = dev_id;
    unsigned int status;

    /*
     * clear modem interrupt by reading MSR
     */
    status = UART_GET_MSR(port);

    if (status & URMS_URDDCD)
        uart_handle_dcd_change(port, status & URMS_URDDCD);

    if (status & URMS_URDDST)
        port->icount.dsr++;

    if (status & URMS_URDCTS)
        uart_handle_cts_change(port, status & URMS_URDCTS);

    if (status & URMS_URTERI)
        port->icount.rng++;

    wake_up_interruptible(&port->state->port.delta_msr_wait);

    return IRQ_HANDLED;
}

static unsigned int ks8695uart_tx_empty(struct uart_port *port)
{
    return (UART_GET_LSR(port) & URLS_URTE) ? TIOCSER_TEMT : 0;
}

static unsigned int ks8695uart_get_mctrl(struct uart_port *port)
{
    unsigned int result = 0;
    unsigned int status;

    status = UART_GET_MSR(port);
    if (status & URMS_URDCD)
        result |= TIOCM_CAR;
    if (status & URMS_URDSR)
        result |= TIOCM_DSR;
    if (status & URMS_URCTS)
        result |= TIOCM_CTS;
    if (status & URMS_URRI)
        result |= TIOCM_RI;

    return result;
}

static void ks8695uart_set_mctrl(struct uart_port *port, u_int mctrl)
{
    unsigned int mcr;

    mcr = UART_GET_MCR(port);
    if (mctrl & TIOCM_RTS)
        mcr |= URMC_URRTS;
    else
        mcr &= ~URMC_URRTS;

    if (mctrl & TIOCM_DTR)
        mcr |= URMC_URDTR;
    else
        mcr &= ~URMC_URDTR;

    UART_PUT_MCR(port, mcr);
}

static void ks8695uart_break_ctl(struct uart_port *port, int break_state)
{
    unsigned int lcr;

    lcr = UART_GET_LCR(port);

    if (break_state == -1)
        lcr |= URLC_URSBC;
    else
        lcr &= ~URLC_URSBC;

    UART_PUT_LCR(port, lcr);
}

static int ks8695uart_startup(struct uart_port *port)
{
    int retval;

    set_irq_flags(KS8695_IRQ_UART_TX, IRQF_VALID | IRQF_NOAUTOEN);
    tx_enable(port, 0);
    rx_enable(port, 1);
    ms_enable(port, 1);

    /*
     * Allocate the IRQ
     */
    retval = request_irq(KS8695_IRQ_UART_TX, ks8695uart_tx_chars, 0, "UART TX", port);
    if (retval)
        goto err_tx;

    retval = request_irq(KS8695_IRQ_UART_RX, ks8695uart_rx_chars, 0, "UART RX", port);
    if (retval)
        goto err_rx;

    retval = request_irq(KS8695_IRQ_UART_LINE_STATUS, ks8695uart_rx_chars, 0, "UART LineStatus", port);
    if (retval)
        goto err_ls;

    retval = request_irq(KS8695_IRQ_UART_MODEM_STATUS, ks8695uart_modem_status, 0, "UART ModemStatus", port);
    if (retval)
        goto err_ms;

    return 0;

err_ms:
    free_irq(KS8695_IRQ_UART_LINE_STATUS, port);
err_ls:
    free_irq(KS8695_IRQ_UART_RX, port);
err_rx:
    free_irq(KS8695_IRQ_UART_TX, port);
err_tx:
    return retval;
}

static void ks8695uart_shutdown(struct uart_port *port)
{
    /*
     * Free the interrupt
     */
    free_irq(KS8695_IRQ_UART_RX, port);
    free_irq(KS8695_IRQ_UART_TX, port);
    free_irq(KS8695_IRQ_UART_MODEM_STATUS, port);
    free_irq(KS8695_IRQ_UART_LINE_STATUS, port);

    /* disable break condition and fifos */
    UART_PUT_LCR(port, UART_GET_LCR(port) & ~URLC_URSBC);
    UART_PUT_FCR(port, UART_GET_FCR(port) & ~URFC_URFE);
}

static void ks8695uart_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old)
{
    unsigned int lcr, fcr = 0;
    unsigned long flags;
    unsigned int baud, quot;

    /*
     * Ask the core to calculate the divisor for us.
     */
    baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
    quot = uart_get_divisor(port, baud);

    switch (termios->c_cflag & CSIZE) {
    case CS5:
        lcr = URCL_5;
        break;
    case CS6:
        lcr = URCL_6;
        break;
    case CS7:
        lcr = URCL_7;
        break;
    default:
        lcr = URCL_8;
        break;
    }

    /* stop bits */
    if (termios->c_cflag & CSTOPB)
        lcr |= URLC_URSB;

    /* parity */
    if (termios->c_cflag & PARENB) {
        if (termios->c_cflag & CMSPAR) {    /* Mark or Space parity */
            if (termios->c_cflag & PARODD)
                lcr |= URPE_MARK;
            else
                lcr |= URPE_SPACE;
        }
        else if (termios->c_cflag & PARODD)
            lcr |= URPE_ODD;
        else
            lcr |= URPE_EVEN;
    }

    if (port->fifosize > 1)
        fcr = URFC_URFRT_8 | URFC_URTFR | URFC_URRFR | URFC_URFE;

    spin_lock_irqsave(&port->lock, flags);

    /*
     * Update the per-port timeout.
     */
    uart_update_timeout(port, termios->c_cflag, baud);

    port->read_status_mask = URLS_URROE;
    if (termios->c_iflag & INPCK)
        port->read_status_mask |= (URLS_URFE | URLS_URPE);
    if (termios->c_iflag & (BRKINT | PARMRK))
        port->read_status_mask |= URLS_URBI;

    /*
     * Characters to ignore
     */
    port->ignore_status_mask = 0;
    if (termios->c_iflag & IGNPAR)
        port->ignore_status_mask |= (URLS_URFE | URLS_URPE);
    if (termios->c_iflag & IGNBRK) {
        port->ignore_status_mask |= URLS_URBI;
        /*
         * If we're ignoring parity and break indicators,
         * ignore overruns too (for real raw support).
         */
        if (termios->c_iflag & IGNPAR)
            port->ignore_status_mask |= URLS_URROE;
    }

    /*
     * Ignore all characters if CREAD is not set.
     */
    if ((termios->c_cflag & CREAD) == 0)
        port->ignore_status_mask |= UART_DUMMY_LSR_RX;

    /* first, disable everything */
    if (UART_ENABLE_MS(port, termios->c_cflag))
        ks8695uart_enable_ms(port);
    else
        ks8695uart_disable_ms(port);

    /* Set baud rate */
    UART_PUT_BRDR(port, quot);

    UART_PUT_LCR(port, lcr);
    UART_PUT_FCR(port, fcr);

    spin_unlock_irqrestore(&port->lock, flags);
}

static const char *ks8695uart_type(struct uart_port *port)
{
    return port->type == PORT_KS8695 ? "KS8695" : NULL;
}

/*
 * Release the memory region(s) being used by 'port'
 */
static void ks8695uart_release_port(struct uart_port *port)
{
    release_mem_region(port->mapbase, UART_PORT_SIZE);
}

/*
 * Request the memory region(s) being used by 'port'
 */
static int ks8695uart_request_port(struct uart_port *port)
{
    return request_mem_region(port->mapbase, UART_PORT_SIZE,
            "serial_ks8695") != NULL ? 0 : -EBUSY;
}

/*
 * Configure/autoconfigure the port.
 */
static void ks8695uart_config_port(struct uart_port *port, int flags)
{
    if (flags & UART_CONFIG_TYPE) {
        port->type = PORT_KS8695;
        ks8695uart_request_port(port);
    }
}

/*
 * verify the new serial_struct (for TIOCSSERIAL).
 */
static int ks8695uart_verify_port(struct uart_port *port, struct serial_struct *ser)
{
    int ret = 0;

    if (ser->type != PORT_UNKNOWN && ser->type != PORT_KS8695)
        ret = -EINVAL;
    if (ser->irq != port->irq)
        ret = -EINVAL;
    if (ser->baud_base < 9600)
        ret = -EINVAL;
    return ret;
}

static struct uart_ops ks8695uart_pops = {
    .tx_empty   = ks8695uart_tx_empty,
    .set_mctrl  = ks8695uart_set_mctrl,
    .get_mctrl  = ks8695uart_get_mctrl,
    .stop_tx    = ks8695uart_stop_tx,
    .start_tx   = ks8695uart_start_tx,
    .stop_rx    = ks8695uart_stop_rx,
    .enable_ms  = ks8695uart_enable_ms,
    .break_ctl  = ks8695uart_break_ctl,
    .startup    = ks8695uart_startup,
    .shutdown   = ks8695uart_shutdown,
    .set_termios    = ks8695uart_set_termios,
    .type       = ks8695uart_type,
    .release_port   = ks8695uart_release_port,
    .request_port   = ks8695uart_request_port,
    .config_port    = ks8695uart_config_port,
    .verify_port    = ks8695uart_verify_port,
};

static struct uart_port ks8695uart_ports[SERIAL_KS8695_NR] = {
    {
        .membase    = KS8695_UART_VA,
        .mapbase    = KS8695_UART_PA,
        .iotype     = SERIAL_IO_MEM,
        .irq        = KS8695_IRQ_UART_TX,
        .uartclk    = KS8695_CLOCK_RATE * 16,
        .fifosize   = 16,
        .ops        = &ks8695uart_pops,
        .flags      = ASYNC_BOOT_AUTOCONF,
        .line       = 0,
    }
};

#ifdef CONFIG_SERIAL_KS8695_CONSOLE
static void ks8695_console_putchar(struct uart_port *port, int ch)
{
    while (!(UART_GET_LSR(port) & URLS_URTHRE))
        barrier();

    UART_PUT_CHAR(port, ch);
}

static void ks8695_console_write(struct console *co, const char *s, u_int count)
{
    struct uart_port *port = ks8695uart_ports + co->index;

    uart_console_write(port, s, count, ks8695_console_putchar);
}

static void __init ks8695_console_get_options(struct uart_port *port, int *baud, int *parity, int *bits)
{
    unsigned int lcr;

    lcr = UART_GET_LCR(port);

    switch (lcr & URLC_PARITY) {
        case URPE_ODD:
            *parity = 'o';
            break;
        case URPE_EVEN:
            *parity = 'e';
            break;
        default:
            *parity = 'n';
    }

    switch (lcr & URLC_URCL) {
        case URCL_5:
            *bits = 5;
            break;
        case URCL_6:
            *bits = 6;
            break;
        case URCL_7:
            *bits = 7;
            break;
        default:
            *bits = 8;
    }

    *baud = port->uartclk / (UART_GET_BRDR(port) & 0x0FFF);
    *baud /= 16;
    *baud &= 0xFFFFFFF0;
}

static int __init ks8695_console_setup(struct console *co, char *options)
{
    struct uart_port *port;
    int baud = 115200;
    int bits = 8;
    int parity = 'n';
    int flow = 'n';

    /*
     * Check whether an invalid uart number has been specified, and
     * if so, search for the first available port that does have
     * console support.
     */
    port = uart_get_console(ks8695uart_ports, SERIAL_KS8695_NR, co);

    if (options)
        uart_parse_options(options, &baud, &parity, &bits, &flow);
    else
        ks8695_console_get_options(port, &baud, &parity, &bits);

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

static struct uart_driver ks8695_reg;

static struct console ks8695_console = {
    .name       = SERIAL_KS8695_DEVNAME,
    .write      = ks8695_console_write,
    .device     = uart_console_device,
    .setup      = ks8695_console_setup,
    .flags      = CON_PRINTBUFFER,
    .index      = -1,
    .data       = &ks8695_reg,
};

static int __init ks8695_console_init(void)
{
    add_preferred_console(SERIAL_KS8695_DEVNAME, 0, NULL);
    register_console(&ks8695_console);
    return 0;
}

console_initcall(ks8695_console_init);

#define KS8695_CONSOLE  &ks8695_console
#else
#define KS8695_CONSOLE  NULL
#endif

static struct uart_driver ks8695_reg = {
    .owner          = THIS_MODULE,
    .driver_name        = "serial_ks8695",
    .dev_name       = SERIAL_KS8695_DEVNAME,
    .major          = SERIAL_KS8695_MAJOR,
    .minor          = SERIAL_KS8695_MINOR,
    .nr         = SERIAL_KS8695_NR,
    .cons           = KS8695_CONSOLE,
};

static int __init ks8695uart_init(void)
{
    int i, ret;

    printk(KERN_INFO "Serial: Micrel KS8695 UART driver\n");

    ret = uart_register_driver(&ks8695_reg);
    if (ret)
        return ret;

    for (i = 0; i < SERIAL_KS8695_NR; i++)
        uart_add_one_port(&ks8695_reg, &ks8695uart_ports[0]);

    return 0;
}

static void __exit ks8695uart_exit(void)
{
    int i;

    for (i = 0; i < SERIAL_KS8695_NR; i++)
        uart_remove_one_port(&ks8695_reg, &ks8695uart_ports[0]);
    uart_unregister_driver(&ks8695_reg);
}

module_init(ks8695uart_init);
module_exit(ks8695uart_exit);

MODULE_DESCRIPTION("KS8695 serial port driver");
MODULE_AUTHOR("Micrel Inc.");
MODULE_LICENSE("GPL");