simserial.c

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/*
 * Simulated Serial Driver (fake serial)
 *
 * This driver is mostly used for bringup purposes and will go away.
 * It has a strong dependency on the system console. All outputs
 * are rerouted to the same facility as the one used by printk which, in our
 * case means sys_sim.c console (goes via the simulator).
 *
 * Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co
 *  Stephane Eranian <[email protected]>
 *  David Mosberger-Tang <[email protected]>
 */

#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/capability.h>
#include <linux/circ_buf.h>
#include <linux/console.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/serial.h>
#include <linux/sysrq.h>
#include <linux/uaccess.h>

#include <asm/hpsim.h>

#include "hpsim_ssc.h"

#undef SIMSERIAL_DEBUG  /* define this to get some debug information */

#define KEYBOARD_INTR   3   /* must match with simulator! */

#define NR_PORTS    1   /* only one port for now */

struct serial_state {
    struct tty_port port;
    struct circ_buf xmit;
    int irq;
    int x_char;
};

static struct serial_state rs_table[NR_PORTS];

struct tty_driver *hp_simserial_driver;

static struct console *console;

static void receive_chars(struct tty_struct *tty)
{
    unsigned char ch;
    static unsigned char seen_esc = 0;

    while ( (ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR)) ) {
        if (ch == 27 && seen_esc == 0) {
            seen_esc = 1;
            continue;
        } else if (seen_esc == 1 && ch == 'O') {
            seen_esc = 2;
            continue;
        } else if (seen_esc == 2) {
            if (ch == 'P') /* F1 */
                show_state();
#ifdef CONFIG_MAGIC_SYSRQ
            if (ch == 'S') { /* F4 */
                do {
                    ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR);
                } while (!ch);
                handle_sysrq(ch);
            }
#endif
            seen_esc = 0;
            continue;
        }
        seen_esc = 0;

        if (tty_insert_flip_char(tty, ch, TTY_NORMAL) == 0)
            break;
    }
    tty_flip_buffer_push(tty);
}

/*
 * This is the serial driver's interrupt routine for a single port
 */
static irqreturn_t rs_interrupt_single(int irq, void *dev_id)
{
    struct serial_state *info = dev_id;
    struct tty_struct *tty = tty_port_tty_get(&info->port);

    if (!tty) {
        printk(KERN_INFO "%s: tty=0 problem\n", __func__);
        return IRQ_NONE;
    }
    /*
     * pretty simple in our case, because we only get interrupts
     * on inbound traffic
     */
    receive_chars(tty);
    tty_kref_put(tty);
    return IRQ_HANDLED;
}

/*
 * -------------------------------------------------------------------
 * Here ends the serial interrupt routines.
 * -------------------------------------------------------------------
 */

static int rs_put_char(struct tty_struct *tty, unsigned char ch)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;

    if (!info->xmit.buf)
        return 0;

    local_irq_save(flags);
    if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) == 0) {
        local_irq_restore(flags);
        return 0;
    }
    info->xmit.buf[info->xmit.head] = ch;
    info->xmit.head = (info->xmit.head + 1) & (SERIAL_XMIT_SIZE-1);
    local_irq_restore(flags);
    return 1;
}

static void transmit_chars(struct tty_struct *tty, struct serial_state *info,
        int *intr_done)
{
    int count;
    unsigned long flags;

    local_irq_save(flags);

    if (info->x_char) {
        char c = info->x_char;

        console->write(console, &c, 1);

        info->x_char = 0;

        goto out;
    }

    if (info->xmit.head == info->xmit.tail || tty->stopped ||
            tty->hw_stopped) {
#ifdef SIMSERIAL_DEBUG
        printk("transmit_chars: head=%d, tail=%d, stopped=%d\n",
               info->xmit.head, info->xmit.tail, tty->stopped);
#endif
        goto out;
    }
    /*
     * We removed the loop and try to do it in to chunks. We need
     * 2 operations maximum because it's a ring buffer.
     *
     * First from current to tail if possible.
     * Then from the beginning of the buffer until necessary
     */

    count = min(CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE),
            SERIAL_XMIT_SIZE - info->xmit.tail);
    console->write(console, info->xmit.buf+info->xmit.tail, count);

    info->xmit.tail = (info->xmit.tail+count) & (SERIAL_XMIT_SIZE-1);

    /*
     * We have more at the beginning of the buffer
     */
    count = CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
    if (count) {
        console->write(console, info->xmit.buf, count);
        info->xmit.tail += count;
    }
out:
    local_irq_restore(flags);
}

static void rs_flush_chars(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;

    if (info->xmit.head == info->xmit.tail || tty->stopped ||
            tty->hw_stopped || !info->xmit.buf)
        return;

    transmit_chars(tty, info, NULL);
}

static int rs_write(struct tty_struct * tty,
            const unsigned char *buf, int count)
{
    struct serial_state *info = tty->driver_data;
    int c, ret = 0;
    unsigned long flags;

    if (!info->xmit.buf)
        return 0;

    local_irq_save(flags);
    while (1) {
        c = CIRC_SPACE_TO_END(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
        if (count < c)
            c = count;
        if (c <= 0) {
            break;
        }
        memcpy(info->xmit.buf + info->xmit.head, buf, c);
        info->xmit.head = ((info->xmit.head + c) &
                   (SERIAL_XMIT_SIZE-1));
        buf += c;
        count -= c;
        ret += c;
    }
    local_irq_restore(flags);
    /*
     * Hey, we transmit directly from here in our case
     */
    if (CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) &&
            !tty->stopped && !tty->hw_stopped)
        transmit_chars(tty, info, NULL);

    return ret;
}

static int rs_write_room(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;

    return CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
}

static int rs_chars_in_buffer(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;

    return CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
}

static void rs_flush_buffer(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;

    local_irq_save(flags);
    info->xmit.head = info->xmit.tail = 0;
    local_irq_restore(flags);

    tty_wakeup(tty);
}

/*
 * This function is used to send a high-priority XON/XOFF character to
 * the device
 */
static void rs_send_xchar(struct tty_struct *tty, char ch)
{
    struct serial_state *info = tty->driver_data;

    info->x_char = ch;
    if (ch) {
        /*
         * I guess we could call console->write() directly but
         * let's do that for now.
         */
        transmit_chars(tty, info, NULL);
    }
}

/*
 * ------------------------------------------------------------
 * rs_throttle()
 *
 * This routine is called by the upper-layer tty layer to signal that
 * incoming characters should be throttled.
 * ------------------------------------------------------------
 */
static void rs_throttle(struct tty_struct * tty)
{
    if (I_IXOFF(tty))
        rs_send_xchar(tty, STOP_CHAR(tty));

    printk(KERN_INFO "simrs_throttle called\n");
}

static void rs_unthrottle(struct tty_struct * tty)
{
    struct serial_state *info = tty->driver_data;

    if (I_IXOFF(tty)) {
        if (info->x_char)
            info->x_char = 0;
        else
            rs_send_xchar(tty, START_CHAR(tty));
    }
    printk(KERN_INFO "simrs_unthrottle called\n");
}

static int rs_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
{
    if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
        (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
        (cmd != TIOCMIWAIT)) {
        if (tty->flags & (1 << TTY_IO_ERROR))
            return -EIO;
    }

    switch (cmd) {
    case TIOCGSERIAL:
    case TIOCSSERIAL:
    case TIOCSERGSTRUCT:
    case TIOCMIWAIT:
        return 0;
    case TIOCSERCONFIG:
    case TIOCSERGETLSR: /* Get line status register */
        return -EINVAL;
    case TIOCSERGWILD:
    case TIOCSERSWILD:
        /* "setserial -W" is called in Debian boot */
        printk (KERN_INFO "TIOCSER?WILD ioctl obsolete, ignored.\n");
        return 0;
    }
    return -ENOIOCTLCMD;
}

#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

static void rs_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
{
    /* Handle turning off CRTSCTS */
    if ((old_termios->c_cflag & CRTSCTS) &&
        !(tty->termios.c_cflag & CRTSCTS)) {
        tty->hw_stopped = 0;
    }
}
/*
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 */
static void shutdown(struct tty_port *port)
{
    struct serial_state *info = container_of(port, struct serial_state,
            port);
    unsigned long flags;

    local_irq_save(flags);
    if (info->irq)
        free_irq(info->irq, info);

    if (info->xmit.buf) {
        free_page((unsigned long) info->xmit.buf);
        info->xmit.buf = NULL;
    }
    local_irq_restore(flags);
}

static void rs_close(struct tty_struct *tty, struct file * filp)
{
    struct serial_state *info = tty->driver_data;

    tty_port_close(&info->port, tty, filp);
}

static void rs_hangup(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;

    rs_flush_buffer(tty);
    tty_port_hangup(&info->port);
}

static int activate(struct tty_port *port, struct tty_struct *tty)
{
    struct serial_state *state = container_of(port, struct serial_state,
            port);
    unsigned long flags, page;
    int retval = 0;

    page = get_zeroed_page(GFP_KERNEL);
    if (!page)
        return -ENOMEM;

    local_irq_save(flags);

    if (state->xmit.buf)
        free_page(page);
    else
        state->xmit.buf = (unsigned char *) page;

    if (state->irq) {
        retval = request_irq(state->irq, rs_interrupt_single, 0,
                "simserial", state);
        if (retval)
            goto errout;
    }

    state->xmit.head = state->xmit.tail = 0;

    /*
     * Set up the tty->alt_speed kludge
     */
    if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
        tty->alt_speed = 57600;
    if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
        tty->alt_speed = 115200;
    if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
        tty->alt_speed = 230400;
    if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
        tty->alt_speed = 460800;

errout:
    local_irq_restore(flags);
    return retval;
}


/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port, linking in its async structure into
 * the IRQ chain.   It also performs the serial-specific
 * initialization for the tty structure.
 */
static int rs_open(struct tty_struct *tty, struct file * filp)
{
    struct serial_state *info = rs_table + tty->index;
    struct tty_port *port = &info->port;

    tty->driver_data = info;
    tty->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

    /*
     * figure out which console to use (should be one already)
     */
    console = console_drivers;
    while (console) {
        if ((console->flags & CON_ENABLED) && console->write) break;
        console = console->next;
    }

    return tty_port_open(port, tty, filp);
}

/*
 * /proc fs routines....
 */

static int rs_proc_show(struct seq_file *m, void *v)
{
    int i;

    seq_printf(m, "simserinfo:1.0\n");
    for (i = 0; i < NR_PORTS; i++)
        seq_printf(m, "%d: uart:16550 port:3F8 irq:%d\n",
               i, rs_table[i].irq);
    return 0;
}

static int rs_proc_open(struct inode *inode, struct file *file)
{
    return single_open(file, rs_proc_show, NULL);
}

static const struct file_operations rs_proc_fops = {
    .owner      = THIS_MODULE,
    .open       = rs_proc_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
};

static const struct tty_operations hp_ops = {
    .open = rs_open,
    .close = rs_close,
    .write = rs_write,
    .put_char = rs_put_char,
    .flush_chars = rs_flush_chars,
    .write_room = rs_write_room,
    .chars_in_buffer = rs_chars_in_buffer,
    .flush_buffer = rs_flush_buffer,
    .ioctl = rs_ioctl,
    .throttle = rs_throttle,
    .unthrottle = rs_unthrottle,
    .send_xchar = rs_send_xchar,
    .set_termios = rs_set_termios,
    .hangup = rs_hangup,
    .proc_fops = &rs_proc_fops,
};

static const struct tty_port_operations hp_port_ops = {
    .activate = activate,
    .shutdown = shutdown,
};

static int __init simrs_init(void)
{
    struct serial_state *state;
    int retval;

    if (!ia64_platform_is("hpsim"))
        return -ENODEV;

    hp_simserial_driver = alloc_tty_driver(NR_PORTS);
    if (!hp_simserial_driver)
        return -ENOMEM;

    printk(KERN_INFO "SimSerial driver with no serial options enabled\n");

    /* Initialize the tty_driver structure */

    hp_simserial_driver->driver_name = "simserial";
    hp_simserial_driver->name = "ttyS";
    hp_simserial_driver->major = TTY_MAJOR;
    hp_simserial_driver->minor_start = 64;
    hp_simserial_driver->type = TTY_DRIVER_TYPE_SERIAL;
    hp_simserial_driver->subtype = SERIAL_TYPE_NORMAL;
    hp_simserial_driver->init_termios = tty_std_termios;
    hp_simserial_driver->init_termios.c_cflag =
        B9600 | CS8 | CREAD | HUPCL | CLOCAL;
    hp_simserial_driver->flags = TTY_DRIVER_REAL_RAW;
    tty_set_operations(hp_simserial_driver, &hp_ops);

    state = rs_table;
    tty_port_init(&state->port);
    state->port.ops = &hp_port_ops;
    state->port.close_delay = 0; /* XXX really 0? */

    retval = hpsim_get_irq(KEYBOARD_INTR);
    if (retval < 0) {
        printk(KERN_ERR "%s: out of interrupt vectors!\n",
                __func__);
        goto err_free_tty;
    }

    state->irq = retval;

    /* the port is imaginary */
    printk(KERN_INFO "ttyS0 at 0x03f8 (irq = %d) is a 16550\n", state->irq);

    tty_port_link_device(&state->port, hp_simserial_driver, 0);
    retval = tty_register_driver(hp_simserial_driver);
    if (retval) {
        printk(KERN_ERR "Couldn't register simserial driver\n");
        goto err_free_tty;
    }

    return 0;
err_free_tty:
    put_tty_driver(hp_simserial_driver);
    return retval;
}

#ifndef MODULE
__initcall(simrs_init);
#endif