generic.c

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/*
 * USB Serial Converter Generic functions
 *
 * Copyright (C) 2010 - 2011 Johan Hovold ([email protected])
 * Copyright (C) 1999 - 2002 Greg Kroah-Hartman ([email protected])
 *
 *  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.
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/sysrq.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/uaccess.h>
#include <linux/kfifo.h>
#include <linux/serial.h>

#ifdef CONFIG_USB_SERIAL_GENERIC

static __u16 vendor  = 0x05f9;
static __u16 product = 0xffff;

module_param(vendor, ushort, 0);
MODULE_PARM_DESC(vendor, "User specified USB idVendor");

module_param(product, ushort, 0);
MODULE_PARM_DESC(product, "User specified USB idProduct");

static struct usb_device_id generic_device_ids[2]; /* Initially all zeroes. */

/* All of the device info needed for the Generic Serial Converter */
struct usb_serial_driver usb_serial_generic_device = {
    .driver = {
        .owner =    THIS_MODULE,
        .name =     "generic",
    },
    .id_table =     generic_device_ids,
    .num_ports =        1,
    .disconnect =       usb_serial_generic_disconnect,
    .release =      usb_serial_generic_release,
    .throttle =     usb_serial_generic_throttle,
    .unthrottle =       usb_serial_generic_unthrottle,
    .resume =       usb_serial_generic_resume,
};

static struct usb_serial_driver * const serial_drivers[] = {
    &usb_serial_generic_device, NULL
};

#endif

int usb_serial_generic_register(void)
{
    int retval = 0;

#ifdef CONFIG_USB_SERIAL_GENERIC
    generic_device_ids[0].idVendor = vendor;
    generic_device_ids[0].idProduct = product;
    generic_device_ids[0].match_flags =
        USB_DEVICE_ID_MATCH_VENDOR | USB_DEVICE_ID_MATCH_PRODUCT;

    /* register our generic driver with ourselves */
    retval = usb_serial_register_drivers(serial_drivers,
            "usbserial_generic", generic_device_ids);
#endif
    return retval;
}

void usb_serial_generic_deregister(void)
{
#ifdef CONFIG_USB_SERIAL_GENERIC
    /* remove our generic driver */
    usb_serial_deregister_drivers(serial_drivers);
#endif
}

int usb_serial_generic_open(struct tty_struct *tty, struct usb_serial_port *port)
{
    int result = 0;
    unsigned long flags;

    /* clear the throttle flags */
    spin_lock_irqsave(&port->lock, flags);
    port->throttled = 0;
    port->throttle_req = 0;
    spin_unlock_irqrestore(&port->lock, flags);

    /* if we have a bulk endpoint, start reading from it */
    if (port->bulk_in_size)
        result = usb_serial_generic_submit_read_urbs(port, GFP_KERNEL);

    return result;
}
EXPORT_SYMBOL_GPL(usb_serial_generic_open);

static void generic_cleanup(struct usb_serial_port *port)
{
    struct usb_serial *serial = port->serial;
    unsigned long flags;
    int i;

    if (serial->dev) {
        /* shutdown any bulk transfers that might be going on */
        if (port->bulk_out_size) {
            for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
                usb_kill_urb(port->write_urbs[i]);

            spin_lock_irqsave(&port->lock, flags);
            kfifo_reset_out(&port->write_fifo);
            spin_unlock_irqrestore(&port->lock, flags);
        }
        if (port->bulk_in_size) {
            for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i)
                usb_kill_urb(port->read_urbs[i]);
        }
    }
}

void usb_serial_generic_close(struct usb_serial_port *port)
{
    generic_cleanup(port);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_close);

int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port,
                        void *dest, size_t size)
{
    return kfifo_out_locked(&port->write_fifo, dest, size, &port->lock);
}

static int usb_serial_generic_write_start(struct usb_serial_port *port)
{
    struct urb *urb;
    int count, result;
    unsigned long flags;
    int i;

    if (test_and_set_bit_lock(USB_SERIAL_WRITE_BUSY, &port->flags))
        return 0;
retry:
    spin_lock_irqsave(&port->lock, flags);
    if (!port->write_urbs_free || !kfifo_len(&port->write_fifo)) {
        clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
        spin_unlock_irqrestore(&port->lock, flags);
        return 0;
    }
    i = (int)find_first_bit(&port->write_urbs_free,
                        ARRAY_SIZE(port->write_urbs));
    spin_unlock_irqrestore(&port->lock, flags);

    urb = port->write_urbs[i];
    count = port->serial->type->prepare_write_buffer(port,
                        urb->transfer_buffer,
                        port->bulk_out_size);
    urb->transfer_buffer_length = count;
    usb_serial_debug_data(&port->dev, __func__, count, urb->transfer_buffer);
    spin_lock_irqsave(&port->lock, flags);
    port->tx_bytes += count;
    spin_unlock_irqrestore(&port->lock, flags);

    clear_bit(i, &port->write_urbs_free);
    result = usb_submit_urb(urb, GFP_ATOMIC);
    if (result) {
        dev_err_console(port, "%s - error submitting urb: %d\n",
                        __func__, result);
        set_bit(i, &port->write_urbs_free);
        spin_lock_irqsave(&port->lock, flags);
        port->tx_bytes -= count;
        spin_unlock_irqrestore(&port->lock, flags);

        clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
        return result;
    }

    /* Try sending off another urb, unless in irq context (in which case
     * there will be no free urb). */
    if (!in_irq())
        goto retry;

    clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);

    return 0;
}

int usb_serial_generic_write(struct tty_struct *tty,
    struct usb_serial_port *port, const unsigned char *buf, int count)
{
    int result;

    /* only do something if we have a bulk out endpoint */
    if (!port->bulk_out_size)
        return -ENODEV;

    if (!count)
        return 0;

    count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);
    result = usb_serial_generic_write_start(port);
    if (result)
        return result;

    return count;
}
EXPORT_SYMBOL_GPL(usb_serial_generic_write);

int usb_serial_generic_write_room(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    unsigned long flags;
    int room;

    if (!port->bulk_out_size)
        return 0;

    spin_lock_irqsave(&port->lock, flags);
    room = kfifo_avail(&port->write_fifo);
    spin_unlock_irqrestore(&port->lock, flags);

    dev_dbg(&port->dev, "%s - returns %d\n", __func__, room);
    return room;
}

int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    unsigned long flags;
    int chars;

    if (!port->bulk_out_size)
        return 0;

    spin_lock_irqsave(&port->lock, flags);
    chars = kfifo_len(&port->write_fifo) + port->tx_bytes;
    spin_unlock_irqrestore(&port->lock, flags);

    dev_dbg(&port->dev, "%s - returns %d\n", __func__, chars);
    return chars;
}

static int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
                        int index, gfp_t mem_flags)
{
    int res;

    if (!test_and_clear_bit(index, &port->read_urbs_free))
        return 0;

    dev_dbg(&port->dev, "%s - port %d, urb %d\n", __func__,
        port->number, index);

    res = usb_submit_urb(port->read_urbs[index], mem_flags);
    if (res) {
        if (res != -EPERM) {
            dev_err(&port->dev,
                    "%s - usb_submit_urb failed: %d\n",
                    __func__, res);
        }
        set_bit(index, &port->read_urbs_free);
        return res;
    }

    return 0;
}

int usb_serial_generic_submit_read_urbs(struct usb_serial_port *port,
                    gfp_t mem_flags)
{
    int res;
    int i;

    for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) {
        res = usb_serial_generic_submit_read_urb(port, i, mem_flags);
        if (res)
            goto err;
    }

    return 0;
err:
    for (; i >= 0; --i)
        usb_kill_urb(port->read_urbs[i]);

    return res;
}
EXPORT_SYMBOL_GPL(usb_serial_generic_submit_read_urbs);

void usb_serial_generic_process_read_urb(struct urb *urb)
{
    struct usb_serial_port *port = urb->context;
    struct tty_struct *tty;
    char *ch = (char *)urb->transfer_buffer;
    int i;

    if (!urb->actual_length)
        return;

    tty = tty_port_tty_get(&port->port);
    if (!tty)
        return;

    /* The per character mucking around with sysrq path it too slow for
       stuff like 3G modems, so shortcircuit it in the 99.9999999% of cases
       where the USB serial is not a console anyway */
    if (!port->port.console || !port->sysrq)
        tty_insert_flip_string(tty, ch, urb->actual_length);
    else {
        for (i = 0; i < urb->actual_length; i++, ch++) {
            if (!usb_serial_handle_sysrq_char(port, *ch))
                tty_insert_flip_char(tty, *ch, TTY_NORMAL);
        }
    }
    tty_flip_buffer_push(tty);
    tty_kref_put(tty);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_process_read_urb);

void usb_serial_generic_read_bulk_callback(struct urb *urb)
{
    struct usb_serial_port *port = urb->context;
    unsigned char *data = urb->transfer_buffer;
    unsigned long flags;
    int i;

    for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) {
        if (urb == port->read_urbs[i])
            break;
    }
    set_bit(i, &port->read_urbs_free);

    dev_dbg(&port->dev, "%s - port %d, urb %d, len %d\n",
        __func__, port->number, i, urb->actual_length);

    if (urb->status) {
        dev_dbg(&port->dev, "%s - non-zero urb status: %d\n",
            __func__, urb->status);
        return;
    }

    usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
    port->serial->type->process_read_urb(urb);

    /* Throttle the device if requested by tty */
    spin_lock_irqsave(&port->lock, flags);
    port->throttled = port->throttle_req;
    if (!port->throttled) {
        spin_unlock_irqrestore(&port->lock, flags);
        usb_serial_generic_submit_read_urb(port, i, GFP_ATOMIC);
    } else
        spin_unlock_irqrestore(&port->lock, flags);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_read_bulk_callback);

void usb_serial_generic_write_bulk_callback(struct urb *urb)
{
    unsigned long flags;
    struct usb_serial_port *port = urb->context;
    int status = urb->status;
    int i;

    for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
        if (port->write_urbs[i] == urb)
            break;

    spin_lock_irqsave(&port->lock, flags);
    port->tx_bytes -= urb->transfer_buffer_length;
    set_bit(i, &port->write_urbs_free);
    spin_unlock_irqrestore(&port->lock, flags);

    if (status) {
        dev_dbg(&port->dev, "%s - non-zero urb status: %d\n",
            __func__, status);

        spin_lock_irqsave(&port->lock, flags);
        kfifo_reset_out(&port->write_fifo);
        spin_unlock_irqrestore(&port->lock, flags);
    } else {
        usb_serial_generic_write_start(port);
    }

    usb_serial_port_softint(port);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_write_bulk_callback);

void usb_serial_generic_throttle(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    unsigned long flags;

    /* Set the throttle request flag. It will be picked up
     * by usb_serial_generic_read_bulk_callback(). */
    spin_lock_irqsave(&port->lock, flags);
    port->throttle_req = 1;
    spin_unlock_irqrestore(&port->lock, flags);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_throttle);

void usb_serial_generic_unthrottle(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    int was_throttled;

    /* Clear the throttle flags */
    spin_lock_irq(&port->lock);
    was_throttled = port->throttled;
    port->throttled = port->throttle_req = 0;
    spin_unlock_irq(&port->lock);

    if (was_throttled)
        usb_serial_generic_submit_read_urbs(port, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_unthrottle);

#ifdef CONFIG_MAGIC_SYSRQ
int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch)
{
    if (port->sysrq && port->port.console) {
        if (ch && time_before(jiffies, port->sysrq)) {
            handle_sysrq(ch);
            port->sysrq = 0;
            return 1;
        }
        port->sysrq = 0;
    }
    return 0;
}
#else
int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch)
{
    return 0;
}
#endif
EXPORT_SYMBOL_GPL(usb_serial_handle_sysrq_char);

int usb_serial_handle_break(struct usb_serial_port *port)
{
    if (!port->sysrq) {
        port->sysrq = jiffies + HZ*5;
        return 1;
    }
    port->sysrq = 0;
    return 0;
}
EXPORT_SYMBOL_GPL(usb_serial_handle_break);

void usb_serial_handle_dcd_change(struct usb_serial_port *usb_port,
                struct tty_struct *tty, unsigned int status)
{
    struct tty_port *port = &usb_port->port;

    dev_dbg(&usb_port->dev, "%s - port %d, status %d\n", __func__,
        usb_port->number, status);

    if (status)
        wake_up_interruptible(&port->open_wait);
    else if (tty && !C_CLOCAL(tty))
        tty_hangup(tty);
}
EXPORT_SYMBOL_GPL(usb_serial_handle_dcd_change);

int usb_serial_generic_resume(struct usb_serial *serial)
{
    struct usb_serial_port *port;
    int i, c = 0, r;

    for (i = 0; i < serial->num_ports; i++) {
        port = serial->port[i];
        if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags))
            continue;

        if (port->bulk_in_size) {
            r = usb_serial_generic_submit_read_urbs(port,
                                GFP_NOIO);
            if (r < 0)
                c++;
        }

        if (port->bulk_out_size) {
            r = usb_serial_generic_write_start(port);
            if (r < 0)
                c++;
        }
    }

    return c ? -EIO : 0;
}
EXPORT_SYMBOL_GPL(usb_serial_generic_resume);

void usb_serial_generic_disconnect(struct usb_serial *serial)
{
    int i;

    /* stop reads and writes on all ports */
    for (i = 0; i < serial->num_ports; ++i)
        generic_cleanup(serial->port[i]);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_disconnect);

void usb_serial_generic_release(struct usb_serial *serial)
{
}