// SPDX-License-Identifier: GPL-2.0
/*
 * USB Serial Converter driver
 *
 * Copyright (C) 2009 - 2013 Johan Hovold (jhovold@gmail.com)
 * Copyright (C) 1999 - 2012 Greg Kroah-Hartman (greg@kroah.com)
 * Copyright (C) 2000 Peter Berger (pberger@brimson.com)
 * Copyright (C) 2000 Al Borchers (borchers@steinerpoint.com)
 *
 * This driver was originally based on the ACM driver by Armin Fuerst (which was
 * based on a driver by Brad Keryan)
 *
 * See Documentation/usb/usb-serial.rst for more information on using this
 * driver
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/uaccess.h>
#include <linux/serial.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/kfifo.h>
#include <linux/idr.h>

#define DRIVER_AUTHOR "Greg Kroah-Hartman <gregkh@linuxfoundation.org>"
#define DRIVER_DESC "USB Serial Driver core"

#define USB_SERIAL_TTY_MAJOR    188
#define USB_SERIAL_TTY_MINORS   512     /* should be enough for a while */

/* There is no MODULE_DEVICE_TABLE for usbserial.c.  Instead
   the MODULE_DEVICE_TABLE declarations in each serial driver
   cause the "hotplug" program to pull in whatever module is necessary
   via modprobe, and modprobe will load usbserial because the serial
   drivers depend on it.
*/

static DEFINE_IDR(serial_minors);
static DEFINE_MUTEX(table_lock);
static LIST_HEAD(usb_serial_driver_list);

/*
 * Look up the serial port structure.  If it is found and it hasn't been
 * disconnected, return with the parent usb_serial structure's disc_mutex held
 * and its refcount incremented.  Otherwise return NULL.
 */
struct usb_serial_port *usb_serial_port_get_by_minor(unsigned minor)
{
        struct usb_serial *serial;
        struct usb_serial_port *port;

        mutex_lock(&table_lock);
        port = idr_find(&serial_minors, minor);
        if (!port)
                goto exit;

        serial = port->serial;
        mutex_lock(&serial->disc_mutex);
        if (serial->disconnected) {
                mutex_unlock(&serial->disc_mutex);
                port = NULL;
        } else {
                kref_get(&serial->kref);
        }
exit:
        mutex_unlock(&table_lock);
        return port;
}

static int allocate_minors(struct usb_serial *serial, int num_ports)
{
        struct usb_serial_port *port;
        unsigned int i, j;
        int minor;

        dev_dbg(&serial->interface->dev, "%s %d\n", __func__, num_ports);

        mutex_lock(&table_lock);
        for (i = 0; i < num_ports; ++i) {
                port = serial->port[i];
                minor = idr_alloc(&serial_minors, port, 0,
                                        USB_SERIAL_TTY_MINORS, GFP_KERNEL);
                if (minor < 0)
                        goto error;
                port->minor = minor;
                port->port_number = i;
        }
        serial->minors_reserved = 1;
        mutex_unlock(&table_lock);
        return 0;
error:
        /* unwind the already allocated minors */
        for (j = 0; j < i; ++j)
                idr_remove(&serial_minors, serial->port[j]->minor);
        mutex_unlock(&table_lock);
        return minor;
}

static void release_minors(struct usb_serial *serial)
{
        int i;

        mutex_lock(&table_lock);
        for (i = 0; i < serial->num_ports; ++i)
                idr_remove(&serial_minors, serial->port[i]->minor);
        mutex_unlock(&table_lock);
        serial->minors_reserved = 0;
}

int usb_serial_claim_interface(struct usb_serial *serial, struct usb_interface *intf)
{
        struct usb_driver *driver = serial->type->usb_driver;
        int ret;

        if (serial->sibling)
                return -EBUSY;

        ret = usb_driver_claim_interface(driver, intf, serial);
        if (ret) {
                dev_err(&serial->interface->dev,
                                "failed to claim sibling interface: %d\n", ret);
                return ret;
        }

        serial->sibling = intf;

        return 0;
}
EXPORT_SYMBOL_GPL(usb_serial_claim_interface);

static void release_sibling(struct usb_serial *serial, struct usb_interface *intf)
{
        struct usb_driver *driver = serial->type->usb_driver;
        struct usb_interface *sibling;

        if (!serial->sibling)
                return;

        if (intf == serial->sibling)
                sibling = serial->interface;
        else
                sibling = serial->sibling;

        usb_set_intfdata(sibling, NULL);
        usb_driver_release_interface(driver, sibling);
}

static void destroy_serial(struct kref *kref)
{
        struct usb_serial *serial;
        struct usb_serial_port *port;
        int i;

        serial = to_usb_serial(kref);

        /* return the minor range that this device had */
        if (serial->minors_reserved)
                release_minors(serial);

        if (serial->attached && serial->type->release)
                serial->type->release(serial);

        /* Now that nothing is using the ports, they can be freed */
        for (i = 0; i < serial->num_port_pointers; ++i) {
                port = serial->port[i];
                if (port) {
                        port->serial = NULL;
                        put_device(&port->dev);
                }
        }

        usb_put_intf(serial->interface);
        usb_put_dev(serial->dev);
        kfree(serial);
}

void usb_serial_put(struct usb_serial *serial)
{
        kref_put(&serial->kref, destroy_serial);
}

/*****************************************************************************
 * Driver tty interface functions
 *****************************************************************************/

/**
 * serial_install - install tty
 * @driver: the driver (USB in our case)
 * @tty: the tty being created
 *
 * Initialise the termios structure for this tty.  We use the default
 * USB serial settings but permit them to be overridden by
 * serial->type->init_termios on first open.
 *
 * This is the first place a new tty gets used.  Hence this is where we
 * acquire references to the usb_serial structure and the driver module,
 * where we store a pointer to the port.  All these actions are reversed
 * in serial_cleanup().
 */
static int serial_install(struct tty_driver *driver, struct tty_struct *tty)
{
        int idx = tty->index;
        struct usb_serial *serial;
        struct usb_serial_port *port;
        bool init_termios;
        int retval = -ENODEV;

        port = usb_serial_port_get_by_minor(idx);
        if (!port)
                return retval;

        serial = port->serial;
        if (!try_module_get(serial->type->driver.owner))
                goto err_put_serial;

        init_termios = (driver->termios[idx] == NULL);

        retval = tty_standard_install(driver, tty);
        if (retval)
                goto err_put_module;

        mutex_unlock(&serial->disc_mutex);

        /* allow the driver to update the initial settings */
        if (init_termios && serial->type->init_termios)
                serial->type->init_termios(tty);

        tty->driver_data = port;

        return retval;

err_put_module:
        module_put(serial->type->driver.owner);
err_put_serial:
        usb_serial_put(serial);
        mutex_unlock(&serial->disc_mutex);
        return retval;
}

static int serial_port_activate(struct tty_port *tport, struct tty_struct *tty)
{
        struct usb_serial_port *port =
                container_of(tport, struct usb_serial_port, port);
        struct usb_serial *serial = port->serial;
        int retval;

        mutex_lock(&serial->disc_mutex);
        if (serial->disconnected) {
                retval = -ENODEV;
                goto out_unlock;
        }

        retval = usb_autopm_get_interface(serial->interface);
        if (retval)
                goto out_unlock;

        retval = port->serial->type->open(tty, port);
        if (retval)
                usb_autopm_put_interface(serial->interface);
out_unlock:
        mutex_unlock(&serial->disc_mutex);

        if (retval < 0)
                retval = usb_translate_errors(retval);

        return retval;
}

static int serial_open(struct tty_struct *tty, struct file *filp)
{
        struct usb_serial_port *port = tty->driver_data;

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

        return tty_port_open(&port->port, tty, filp);
}

/**
 * serial_port_shutdown - shut down hardware
 * @tport: tty port to shut down
 *
 * Shut down a USB serial port. Serialized against activate by the
 * tport mutex and kept to matching open/close pairs
 * of calls by the initialized flag.
 *
 * Not called if tty is console.
 */
static void serial_port_shutdown(struct tty_port *tport)
{
        struct usb_serial_port *port =
                container_of(tport, struct usb_serial_port, port);
        struct usb_serial_driver *drv = port->serial->type;

        if (drv->close)
                drv->close(port);

        usb_autopm_put_interface(port->serial->interface);
}

static void serial_hangup(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;

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

        tty_port_hangup(&port->port);
}

static void serial_close(struct tty_struct *tty, struct file *filp)
{
        struct usb_serial_port *port = tty->driver_data;

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

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

/**
 * serial_cleanup - free resources post close/hangup
 * @tty: tty to clean up
 *
 * Do the resource freeing and refcount dropping for the port.
 * Avoid freeing the console.
 *
 * Called asynchronously after the last tty kref is dropped.
 */
static void serial_cleanup(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_serial *serial;
        struct module *owner;

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

        /* The console is magical.  Do not hang up the console hardware
         * or there will be tears.
         */
        if (port->port.console)
                return;

        tty->driver_data = NULL;

        serial = port->serial;
        owner = serial->type->driver.owner;

        usb_serial_put(serial);
        module_put(owner);
}

static int serial_write(struct tty_struct *tty, const unsigned char *buf,
                                                                int count)
{
        struct usb_serial_port *port = tty->driver_data;
        int retval = -ENODEV;

        if (port->serial->dev->state == USB_STATE_NOTATTACHED)
                goto exit;

        dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);

        retval = port->serial->type->write(tty, port, buf, count);
        if (retval < 0)
                retval = usb_translate_errors(retval);
exit:
        return retval;
}

static unsigned int serial_write_room(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;

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

        return port->serial->type->write_room(tty);
}

static unsigned int serial_chars_in_buffer(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_serial *serial = port->serial;

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

        if (serial->disconnected)
                return 0;

        return serial->type->chars_in_buffer(tty);
}

static void serial_wait_until_sent(struct tty_struct *tty, int timeout)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_serial *serial = port->serial;

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

        if (!port->serial->type->wait_until_sent)
                return;

        mutex_lock(&serial->disc_mutex);
        if (!serial->disconnected)
                port->serial->type->wait_until_sent(tty, timeout);
        mutex_unlock(&serial->disc_mutex);
}

static void serial_throttle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;

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

        if (port->serial->type->throttle)
                port->serial->type->throttle(tty);
}

static void serial_unthrottle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;

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

        if (port->serial->type->unthrottle)
                port->serial->type->unthrottle(tty);
}

static int serial_get_serial(struct tty_struct *tty, struct serial_struct *ss)
{
        struct usb_serial_port *port = tty->driver_data;
        struct tty_port *tport = &port->port;
        unsigned int close_delay, closing_wait;

        mutex_lock(&tport->mutex);

        close_delay = jiffies_to_msecs(tport->close_delay) / 10;
        closing_wait = tport->closing_wait;
        if (closing_wait != ASYNC_CLOSING_WAIT_NONE)
                closing_wait = jiffies_to_msecs(closing_wait) / 10;

        ss->line = port->minor;
        ss->close_delay = close_delay;
        ss->closing_wait = closing_wait;

        if (port->serial->type->get_serial)
                port->serial->type->get_serial(tty, ss);

        mutex_unlock(&tport->mutex);

        return 0;
}

static int serial_set_serial(struct tty_struct *tty, struct serial_struct *ss)
{
        struct usb_serial_port *port = tty->driver_data;
        struct tty_port *tport = &port->port;
        unsigned int close_delay, closing_wait;
        int ret = 0;

        close_delay = msecs_to_jiffies(ss->close_delay * 10);
        closing_wait = ss->closing_wait;
        if (closing_wait != ASYNC_CLOSING_WAIT_NONE)
                closing_wait = msecs_to_jiffies(closing_wait * 10);

        mutex_lock(&tport->mutex);

        if (!capable(CAP_SYS_ADMIN)) {
                if (close_delay != tport->close_delay ||
                                closing_wait != tport->closing_wait) {
                        ret = -EPERM;
                        goto out_unlock;
                }
        }

        if (port->serial->type->set_serial) {
                ret = port->serial->type->set_serial(tty, ss);
                if (ret)
                        goto out_unlock;
        }

        tport->close_delay = close_delay;
        tport->closing_wait = closing_wait;
out_unlock:
        mutex_unlock(&tport->mutex);

        return ret;
}

static int serial_ioctl(struct tty_struct *tty,
                                        unsigned int cmd, unsigned long arg)
{
        struct usb_serial_port *port = tty->driver_data;
        int retval = -ENOIOCTLCMD;

        dev_dbg(&port->dev, "%s - cmd 0x%04x\n", __func__, cmd);

        switch (cmd) {
        case TIOCMIWAIT:
                if (port->serial->type->tiocmiwait)
                        retval = port->serial->type->tiocmiwait(tty, arg);
                break;
        default:
                if (port->serial->type->ioctl)
                        retval = port->serial->type->ioctl(tty, cmd, arg);
        }

        return retval;
}

static void serial_set_termios(struct tty_struct *tty, struct ktermios *old)
{
        struct usb_serial_port *port = tty->driver_data;

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

        if (port->serial->type->set_termios)
                port->serial->type->set_termios(tty, port, old);
        else
                tty_termios_copy_hw(&tty->termios, old);
}

static int serial_break(struct tty_struct *tty, int break_state)
{
        struct usb_serial_port *port = tty->driver_data;

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

        if (port->serial->type->break_ctl)
                port->serial->type->break_ctl(tty, break_state);

        return 0;
}

static int serial_proc_show(struct seq_file *m, void *v)
{
        struct usb_serial *serial;
        struct usb_serial_port *port;
        int i;
        char tmp[40];

        seq_puts(m, "usbserinfo:1.0 driver:2.0\n");
        for (i = 0; i < USB_SERIAL_TTY_MINORS; ++i) {
                port = usb_serial_port_get_by_minor(i);
                if (port == NULL)
                        continue;
                serial = port->serial;

                seq_printf(m, "%d:", i);
                if (serial->type->driver.owner)
                        seq_printf(m, " module:%s",
                                module_name(serial->type->driver.owner));
                seq_printf(m, " name:\"%s\"",
                                serial->type->description);
                seq_printf(m, " vendor:%04x product:%04x",
                        le16_to_cpu(serial->dev->descriptor.idVendor),
                        le16_to_cpu(serial->dev->descriptor.idProduct));
                seq_printf(m, " num_ports:%d", serial->num_ports);
                seq_printf(m, " port:%d", port->port_number);
                usb_make_path(serial->dev, tmp, sizeof(tmp));
                seq_printf(m, " path:%s", tmp);

                seq_putc(m, '\n');
                usb_serial_put(serial);
                mutex_unlock(&serial->disc_mutex);
        }
        return 0;
}

static int serial_tiocmget(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;

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

        if (port->serial->type->tiocmget)
                return port->serial->type->tiocmget(tty);
        return -ENOTTY;
}

static int serial_tiocmset(struct tty_struct *tty,
                            unsigned int set, unsigned int clear)
{
        struct usb_serial_port *port = tty->driver_data;

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

        if (port->serial->type->tiocmset)
                return port->serial->type->tiocmset(tty, set, clear);
        return -ENOTTY;
}

static int serial_get_icount(struct tty_struct *tty,
                                struct serial_icounter_struct *icount)
{
        struct usb_serial_port *port = tty->driver_data;

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

        if (port->serial->type->get_icount)
                return port->serial->type->get_icount(tty, icount);
        return -ENOTTY;
}

/*
 * We would be calling tty_wakeup here, but unfortunately some line
 * disciplines have an annoying habit of calling tty->write from
 * the write wakeup callback (e.g. n_hdlc.c).
 */
void usb_serial_port_softint(struct usb_serial_port *port)
{
        schedule_work(&port->work);
}
EXPORT_SYMBOL_GPL(usb_serial_port_softint);

static void usb_serial_port_work(struct work_struct *work)
{
        struct usb_serial_port *port =
                container_of(work, struct usb_serial_port, work);

        tty_port_tty_wakeup(&port->port);
}

static void usb_serial_port_poison_urbs(struct usb_serial_port *port)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i)
                usb_poison_urb(port->read_urbs[i]);
        for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
                usb_poison_urb(port->write_urbs[i]);

        usb_poison_urb(port->interrupt_in_urb);
        usb_poison_urb(port->interrupt_out_urb);
}

static void usb_serial_port_unpoison_urbs(struct usb_serial_port *port)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i)
                usb_unpoison_urb(port->read_urbs[i]);
        for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
                usb_unpoison_urb(port->write_urbs[i]);

        usb_unpoison_urb(port->interrupt_in_urb);
        usb_unpoison_urb(port->interrupt_out_urb);
}

static void usb_serial_port_release(struct device *dev)
{
        struct usb_serial_port *port = to_usb_serial_port(dev);
        int i;

        dev_dbg(dev, "%s\n", __func__);

        usb_free_urb(port->interrupt_in_urb);
        usb_free_urb(port->interrupt_out_urb);
        for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) {
                usb_free_urb(port->read_urbs[i]);
                kfree(port->bulk_in_buffers[i]);
        }
        for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) {
                usb_free_urb(port->write_urbs[i]);
                kfree(port->bulk_out_buffers[i]);
        }
        kfifo_free(&port->write_fifo);
        kfree(port->interrupt_in_buffer);
        kfree(port->interrupt_out_buffer);
        tty_port_destroy(&port->port);
        kfree(port);
}

static struct usb_serial *create_serial(struct usb_device *dev,
                                        struct usb_interface *interface,
                                        struct usb_serial_driver *driver)
{
        struct usb_serial *serial;

        serial = kzalloc(sizeof(*serial), GFP_KERNEL);
        if (!serial)
                return NULL;
        serial->dev = usb_get_dev(dev);
        serial->type = driver;
        serial->interface = usb_get_intf(interface);
        kref_init(&serial->kref);
        mutex_init(&serial->disc_mutex);
        serial->minors_reserved = 0;

        return serial;
}

static const struct usb_device_id *match_dynamic_id(struct usb_interface *intf,
                                            struct usb_serial_driver *drv)
{
        struct usb_dynid *dynid;

        spin_lock(&drv->dynids.lock);
        list_for_each_entry(dynid, &drv->dynids.list, node) {
                if (usb_match_one_id(intf, &dynid->id)) {
                        spin_unlock(&drv->dynids.lock);
                        return &dynid->id;
                }
        }
        spin_unlock(&drv->dynids.lock);
        return NULL;
}

static const struct usb_device_id *get_iface_id(struct usb_serial_driver *drv,
                                                struct usb_interface *intf)
{
        const struct usb_device_id *id;

        id = usb_match_id(intf, drv->id_table);
        if (id) {
                dev_dbg(&intf->dev, "static descriptor matches\n");
                goto exit;
        }
        id = match_dynamic_id(intf, drv);
        if (id)
                dev_dbg(&intf->dev, "dynamic descriptor matches\n");
exit:
        return id;
}

/* Caller must hold table_lock */
static struct usb_serial_driver *search_serial_device(
                                        struct usb_interface *iface)
{
        const struct usb_device_id *id = NULL;
        struct usb_serial_driver *drv;
        struct usb_driver *driver = to_usb_driver(iface->dev.driver);

        /* Check if the usb id matches a known device */
        list_for_each_entry(drv, &usb_serial_driver_list, driver_list) {
                if (drv->usb_driver == driver)
                        id = get_iface_id(drv, iface);
                if (id)
                        return drv;
        }

        return NULL;
}

static int serial_port_carrier_raised(struct tty_port *port)
{
        struct usb_serial_port *p = container_of(port, struct usb_serial_port, port);
        struct usb_serial_driver *drv = p->serial->type;

        if (drv->carrier_raised)
                return drv->carrier_raised(p);
        /* No carrier control - don't block */
        return 1;
}

static void serial_port_dtr_rts(struct tty_port *port, int on)
{
        struct usb_serial_port *p = container_of(port, struct usb_serial_port, port);
        struct usb_serial_driver *drv = p->serial->type;

        if (drv->dtr_rts)
                drv->dtr_rts(p, on);
}

static ssize_t port_number_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct usb_serial_port *port = to_usb_serial_port(dev);

        return sprintf(buf, "%u\n", port->port_number);
}
static DEVICE_ATTR_RO(port_number);

static struct attribute *usb_serial_port_attrs[] = {
        &dev_attr_port_number.attr,
        NULL
};
ATTRIBUTE_GROUPS(usb_serial_port);

static const struct tty_port_operations serial_port_ops = {
        .carrier_raised         = serial_port_carrier_raised,
        .dtr_rts                = serial_port_dtr_rts,
        .activate               = serial_port_activate,
        .shutdown               = serial_port_shutdown,
};

static void store_endpoint(struct usb_serial *serial,
                                        struct usb_serial_endpoints *epds,
                                        struct usb_endpoint_descriptor *epd)
{
        struct device *dev = &serial->interface->dev;
        u8 addr = epd->bEndpointAddress;

        if (usb_endpoint_is_bulk_in(epd)) {
                if (epds->num_bulk_in == ARRAY_SIZE(epds->bulk_in))
                        return;
                dev_dbg(dev, "found bulk in endpoint %02x\n", addr);
                epds->bulk_in[epds->num_bulk_in++] = epd;
        } else if (usb_endpoint_is_bulk_out(epd)) {
                if (epds->num_bulk_out == ARRAY_SIZE(epds->bulk_out))
                        return;
                dev_dbg(dev, "found bulk out endpoint %02x\n", addr);
                epds->bulk_out[epds->num_bulk_out++] = epd;
        } else if (usb_endpoint_is_int_in(epd)) {
                if (epds->num_interrupt_in == ARRAY_SIZE(epds->interrupt_in))
                        return;
                dev_dbg(dev, "found interrupt in endpoint %02x\n", addr);
                epds->interrupt_in[epds->num_interrupt_in++] = epd;
        } else if (usb_endpoint_is_int_out(epd)) {
                if (epds->num_interrupt_out == ARRAY_SIZE(epds->interrupt_out))
                        return;
                dev_dbg(dev, "found interrupt out endpoint %02x\n", addr);
                epds->interrupt_out[epds->num_interrupt_out++] = epd;
        }
}

static void find_endpoints(struct usb_serial *serial,
                                        struct usb_serial_endpoints *epds,
                                        struct usb_interface *intf)
{
        struct usb_host_interface *iface_desc;
        struct usb_endpoint_descriptor *epd;
        unsigned int i;

        iface_desc = intf->cur_altsetting;
        for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
                epd = &iface_desc->endpoint[i].desc;
                store_endpoint(serial, epds, epd);
        }
}

static int setup_port_bulk_in(struct usb_serial_port *port,
                                        struct usb_endpoint_descriptor *epd)
{
        struct usb_serial_driver *type = port->serial->type;
        struct usb_device *udev = port->serial->dev;
        int buffer_size;
        int i;

        buffer_size = max_t(int, type->bulk_in_size, usb_endpoint_maxp(epd));
        port->bulk_in_size = buffer_size;
        port->bulk_in_endpointAddress = epd->bEndpointAddress;

        for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) {
                set_bit(i, &port->read_urbs_free);
                port->read_urbs[i] = usb_alloc_urb(0, GFP_KERNEL);
                if (!port->read_urbs[i])
                        return -ENOMEM;
                port->bulk_in_buffers[i] = kmalloc(buffer_size, GFP_KERNEL);
                if (!port->bulk_in_buffers[i])
                        return -ENOMEM;
                usb_fill_bulk_urb(port->read_urbs[i], udev,
                                usb_rcvbulkpipe(udev, epd->bEndpointAddress),
                                port->bulk_in_buffers[i], buffer_size,
                                type->read_bulk_callback, port);
        }

        port->read_urb = port->read_urbs[0];
        port->bulk_in_buffer = port->bulk_in_buffers[0];

        return 0;
}

static int setup_port_bulk_out(struct usb_serial_port *port,
                                        struct usb_endpoint_descriptor *epd)
{
        struct usb_serial_driver *type = port->serial->type;
        struct usb_device *udev = port->serial->dev;
        int buffer_size;
        int i;

        if (kfifo_alloc(&port->write_fifo, PAGE_SIZE, GFP_KERNEL))
                return -ENOMEM;
        if (type->bulk_out_size)
                buffer_size = type->bulk_out_size;
        else
                buffer_size = usb_endpoint_maxp(epd);
        port->bulk_out_size = buffer_size;
        port->bulk_out_endpointAddress = epd->bEndpointAddress;

        for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) {
                set_bit(i, &port->write_urbs_free);
                port->write_urbs[i] = usb_alloc_urb(0, GFP_KERNEL);
                if (!port->write_urbs[i])
                        return -ENOMEM;
                port->bulk_out_buffers[i] = kmalloc(buffer_size, GFP_KERNEL);
                if (!port->bulk_out_buffers[i])
                        return -ENOMEM;
                usb_fill_bulk_urb(port->write_urbs[i], udev,
                                usb_sndbulkpipe(udev, epd->bEndpointAddress),
                                port->bulk_out_buffers[i], buffer_size,
                                type->write_bulk_callback, port);
        }

        port->write_urb = port->write_urbs[0];
        port->bulk_out_buffer = port->bulk_out_buffers[0];

        return 0;
}

static int setup_port_interrupt_in(struct usb_serial_port *port,
                                        struct usb_endpoint_descriptor *epd)
{
        struct usb_serial_driver *type = port->serial->type;
        struct usb_device *udev = port->serial->dev;
        int buffer_size;

        port->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!port->interrupt_in_urb)
                return -ENOMEM;
        buffer_size = usb_endpoint_maxp(epd);
        port->interrupt_in_endpointAddress = epd->bEndpointAddress;
        port->interrupt_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
        if (!port->interrupt_in_buffer)
                return -ENOMEM;
        usb_fill_int_urb(port->interrupt_in_urb, udev,
                        usb_rcvintpipe(udev, epd->bEndpointAddress),
                        port->interrupt_in_buffer, buffer_size,
                        type->read_int_callback, port,
                        epd->bInterval);

        return 0;
}

static int setup_port_interrupt_out(struct usb_serial_port *port,
                                        struct usb_endpoint_descriptor *epd)
{
        struct usb_serial_driver *type = port->serial->type;
        struct usb_device *udev = port->serial->dev;
        int buffer_size;

        port->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!port->interrupt_out_urb)
                return -ENOMEM;
        buffer_size = usb_endpoint_maxp(epd);
        port->interrupt_out_size = buffer_size;
        port->interrupt_out_endpointAddress = epd->bEndpointAddress;
        port->interrupt_out_buffer = kmalloc(buffer_size, GFP_KERNEL);
        if (!port->interrupt_out_buffer)
                return -ENOMEM;
        usb_fill_int_urb(port->interrupt_out_urb, udev,
                        usb_sndintpipe(udev, epd->bEndpointAddress),
                        port->interrupt_out_buffer, buffer_size,
                        type->write_int_callback, port,
                        epd->bInterval);

        return 0;
}

static int usb_serial_probe(struct usb_interface *interface,
                               const struct usb_device_id *id)
{
        struct device *ddev = &interface->dev;
        struct usb_device *dev = interface_to_usbdev(interface);
        struct usb_serial *serial = NULL;
        struct usb_serial_port *port;
        struct usb_serial_endpoints *epds;
        struct usb_serial_driver *type = NULL;
        int retval;
        int i;
        int num_ports = 0;
        unsigned char max_endpoints;

        mutex_lock(&table_lock);
        type = search_serial_device(interface);
        if (!type) {
                mutex_unlock(&table_lock);
                dev_dbg(ddev, "none matched\n");
                return -ENODEV;
        }

        if (!try_module_get(type->driver.owner)) {
                mutex_unlock(&table_lock);
                dev_err(ddev, "module get failed, exiting\n");
                return -EIO;
        }
        mutex_unlock(&table_lock);

        serial = create_serial(dev, interface, type);
        if (!serial) {
                retval = -ENOMEM;
                goto err_put_module;
        }

        /* if this device type has a probe function, call it */
        if (type->probe) {
                const struct usb_device_id *id;

                id = get_iface_id(type, interface);

                retval = type->probe(serial, id);

                if (retval) {
                        dev_dbg(ddev, "sub driver rejected device\n");
                        goto err_release_sibling;
                }
        }

        /* descriptor matches, let's find the endpoints needed */
        epds = kzalloc(sizeof(*epds), GFP_KERNEL);
        if (!epds) {
                retval = -ENOMEM;
                goto err_release_sibling;
        }

        find_endpoints(serial, epds, interface);
        if (serial->sibling)
                find_endpoints(serial, epds, serial->sibling);

        if (epds->num_bulk_in < type->num_bulk_in ||
                        epds->num_bulk_out < type->num_bulk_out ||
                        epds->num_interrupt_in < type->num_interrupt_in ||
                        epds->num_interrupt_out < type->num_interrupt_out) {
                dev_err(ddev, "required endpoints missing\n");
                retval = -ENODEV;
                goto err_free_epds;
        }

        if (type->calc_num_ports) {
                retval = type->calc_num_ports(serial, epds);
                if (retval < 0)
                        goto err_free_epds;
                num_ports = retval;
        }

        if (!num_ports)
                num_ports = type->num_ports;

        if (num_ports > MAX_NUM_PORTS) {
                dev_warn(ddev, "too many ports requested: %d\n", num_ports);
                num_ports = MAX_NUM_PORTS;
        }

        serial->num_ports = (unsigned char)num_ports;
        serial->num_bulk_in = epds->num_bulk_in;
        serial->num_bulk_out = epds->num_bulk_out;
        serial->num_interrupt_in = epds->num_interrupt_in;
        serial->num_interrupt_out = epds->num_interrupt_out;

        /* found all that we need */
        dev_info(ddev, "%s converter detected\n", type->description);

        /* create our ports, we need as many as the max endpoints */
        /* we don't use num_ports here because some devices have more
           endpoint pairs than ports */
        max_endpoints = max(epds->num_bulk_in, epds->num_bulk_out);
        max_endpoints = max(max_endpoints, epds->num_interrupt_in);
        max_endpoints = max(max_endpoints, epds->num_interrupt_out);
        max_endpoints = max(max_endpoints, serial->num_ports);
        serial->num_port_pointers = max_endpoints;

        dev_dbg(ddev, "setting up %d port structure(s)\n", max_endpoints);
        for (i = 0; i < max_endpoints; ++i) {
                port = kzalloc(sizeof(struct usb_serial_port), GFP_KERNEL);
                if (!port) {
                        retval = -ENOMEM;
                        goto err_free_epds;
                }
                tty_port_init(&port->port);
                port->port.ops = &serial_port_ops;
                port->serial = serial;
                spin_lock_init(&port->lock);
                /* Keep this for private driver use for the moment but
                   should probably go away */
                INIT_WORK(&port->work, usb_serial_port_work);
                serial->port[i] = port;
                port->dev.parent = &interface->dev;
                port->dev.driver = NULL;
                port->dev.bus = &usb_serial_bus_type;
                port->dev.release = &usb_serial_port_release;
                port->dev.groups = usb_serial_port_groups;
                device_initialize(&port->dev);
        }

        /* set up the endpoint information */
        for (i = 0; i < epds->num_bulk_in; ++i) {
                retval = setup_port_bulk_in(serial->port[i], epds->bulk_in[i]);
                if (retval)
                        goto err_free_epds;
        }

        for (i = 0; i < epds->num_bulk_out; ++i) {
                retval = setup_port_bulk_out(serial->port[i],
                                epds->bulk_out[i]);
                if (retval)
                        goto err_free_epds;
        }

        if (serial->type->read_int_callback) {
                for (i = 0; i < epds->num_interrupt_in; ++i) {
                        retval = setup_port_interrupt_in(serial->port[i],
                                        epds->interrupt_in[i]);
                        if (retval)
                                goto err_free_epds;
                }
        } else if (epds->num_interrupt_in) {
                dev_dbg(ddev, "The device claims to support interrupt in transfers, but read_int_callback is not defined\n");
        }

        if (serial->type->write_int_callback) {
                for (i = 0; i < epds->num_interrupt_out; ++i) {
                        retval = setup_port_interrupt_out(serial->port[i],
                                        epds->interrupt_out[i]);
                        if (retval)
                                goto err_free_epds;
                }
        } else if (epds->num_interrupt_out) {
                dev_dbg(ddev, "The device claims to support interrupt out transfers, but write_int_callback is not defined\n");
        }

        usb_set_intfdata(interface, serial);

        /* if this device type has an attach function, call it */
        if (type->attach) {
                retval = type->attach(serial);
                if (retval < 0)
                        goto err_free_epds;
                serial->attached = 1;
                if (retval > 0) {
                        /* quietly accept this device, but don't bind to a
                           serial port as it's about to disappear */
                        serial->num_ports = 0;
                        goto exit;
                }
        } else {
                serial->attached = 1;
        }

        retval = allocate_minors(serial, num_ports);
        if (retval) {
                dev_err(ddev, "No more free serial minor numbers\n");
                goto err_free_epds;
        }

        /* register all of the individual ports with the driver core */
        for (i = 0; i < num_ports; ++i) {
                port = serial->port[i];
                dev_set_name(&port->dev, "ttyUSB%d", port->minor);
                dev_dbg(ddev, "registering %s\n", dev_name(&port->dev));
                device_enable_async_suspend(&port->dev);

                retval = device_add(&port->dev);
                if (retval)
                        dev_err(ddev, "Error registering port device, continuing\n");
        }

        if (num_ports > 0)
                usb_serial_console_init(serial->port[0]->minor);
exit:
        kfree(epds);
        module_put(type->driver.owner);
        return 0;

err_free_epds:
        kfree(epds);
err_release_sibling:
        release_sibling(serial, interface);
        usb_serial_put(serial);
err_put_module:
        module_put(type->driver.owner);

        return retval;
}

static void usb_serial_disconnect(struct usb_interface *interface)
{
        int i;
        struct usb_serial *serial = usb_get_intfdata(interface);
        struct device *dev = &interface->dev;
        struct usb_serial_port *port;
        struct tty_struct *tty;

        /* sibling interface is cleaning up */
        if (!serial)
                return;

        usb_serial_console_disconnect(serial);

        mutex_lock(&serial->disc_mutex);
        /* must set a flag, to signal subdrivers */
        serial->disconnected = 1;
        mutex_unlock(&serial->disc_mutex);

        for (i = 0; i < serial->num_ports; ++i) {
                port = serial->port[i];
                tty = tty_port_tty_get(&port->port);
                if (tty) {
                        tty_vhangup(tty);
                        tty_kref_put(tty);
                }
                usb_serial_port_poison_urbs(port);
                wake_up_interruptible(&port->port.delta_msr_wait);
                cancel_work_sync(&port->work);
                if (device_is_registered(&port->dev))
                        device_del(&port->dev);
        }
        if (serial->type->disconnect)
                serial->type->disconnect(serial);

        release_sibling(serial, interface);

        /* let the last holder of this object cause it to be cleaned up */
        usb_serial_put(serial);
        dev_info(dev, "device disconnected\n");
}

int usb_serial_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct usb_serial *serial = usb_get_intfdata(intf);
        int i, r;

        /* suspend when called for first sibling interface */
        if (serial->suspend_count++)
                return 0;

        /*
         * serial->type->suspend() MUST return 0 in system sleep context,
         * otherwise, the resume callback has to recover device from
         * previous suspend failure.
         */
        if (serial->type->suspend) {
                r = serial->type->suspend(serial, message);
                if (r < 0) {
                        serial->suspend_count--;
                        return r;
                }
        }

        for (i = 0; i < serial->num_ports; ++i)
                usb_serial_port_poison_urbs(serial->port[i]);

        return 0;
}
EXPORT_SYMBOL(usb_serial_suspend);

static void usb_serial_unpoison_port_urbs(struct usb_serial *serial)
{
        int i;

        for (i = 0; i < serial->num_ports; ++i)
                usb_serial_port_unpoison_urbs(serial->port[i]);
}

int usb_serial_resume(struct usb_interface *intf)
{
        struct usb_serial *serial = usb_get_intfdata(intf);
        int rv;

        /* resume when called for last sibling interface */
        if (--serial->suspend_count)
                return 0;

        usb_serial_unpoison_port_urbs(serial);

        if (serial->type->resume)
                rv = serial->type->resume(serial);
        else
                rv = usb_serial_generic_resume(serial);

        return rv;
}
EXPORT_SYMBOL(usb_serial_resume);

static int usb_serial_reset_resume(struct usb_interface *intf)
{
        struct usb_serial *serial = usb_get_intfdata(intf);
        int rv;

        /* resume when called for last sibling interface */
        if (--serial->suspend_count)
                return 0;

        usb_serial_unpoison_port_urbs(serial);

        if (serial->type->reset_resume) {
                rv = serial->type->reset_resume(serial);
        } else {
                rv = -EOPNOTSUPP;
                intf->needs_binding = 1;
        }

        return rv;
}

static const struct tty_operations serial_ops = {
        .open =                 serial_open,
        .close =                serial_close,
        .write =                serial_write,
        .hangup =               serial_hangup,
        .write_room =           serial_write_room,
        .ioctl =                serial_ioctl,
        .set_termios =          serial_set_termios,
        .throttle =             serial_throttle,
        .unthrottle =           serial_unthrottle,
        .break_ctl =            serial_break,
        .chars_in_buffer =      serial_chars_in_buffer,
        .wait_until_sent =      serial_wait_until_sent,
        .tiocmget =             serial_tiocmget,
        .tiocmset =             serial_tiocmset,
        .get_icount =           serial_get_icount,
        .set_serial =           serial_set_serial,
        .get_serial =           serial_get_serial,
        .cleanup =              serial_cleanup,
        .install =              serial_install,
        .proc_show =            serial_proc_show,
};


struct tty_driver *usb_serial_tty_driver;

static int __init usb_serial_init(void)
{
        int result;

        usb_serial_tty_driver = tty_alloc_driver(USB_SERIAL_TTY_MINORS,
                        TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV);
        if (IS_ERR(usb_serial_tty_driver))
                return PTR_ERR(usb_serial_tty_driver);

        /* Initialize our global data */
        result = bus_register(&usb_serial_bus_type);
        if (result) {
                pr_err("%s - registering bus driver failed\n", __func__);
                goto err_put_driver;
        }

        usb_serial_tty_driver->driver_name = "usbserial";
        usb_serial_tty_driver->name = "ttyUSB";
        usb_serial_tty_driver->major = USB_SERIAL_TTY_MAJOR;
        usb_serial_tty_driver->minor_start = 0;
        usb_serial_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
        usb_serial_tty_driver->subtype = SERIAL_TYPE_NORMAL;
        usb_serial_tty_driver->init_termios = tty_std_termios;
        usb_serial_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD
                                                        | HUPCL | CLOCAL;
        usb_serial_tty_driver->init_termios.c_ispeed = 9600;
        usb_serial_tty_driver->init_termios.c_ospeed = 9600;
        tty_set_operations(usb_serial_tty_driver, &serial_ops);
        result = tty_register_driver(usb_serial_tty_driver);
        if (result) {
                pr_err("%s - tty_register_driver failed\n", __func__);
                goto err_unregister_bus;
        }

        /* register the generic driver, if we should */
        result = usb_serial_generic_register();
        if (result < 0) {
                pr_err("%s - registering generic driver failed\n", __func__);
                goto err_unregister_driver;
        }

        return result;

err_unregister_driver:
        tty_unregister_driver(usb_serial_tty_driver);
err_unregister_bus:
        bus_unregister(&usb_serial_bus_type);
err_put_driver:
        pr_err("%s - returning with error %d\n", __func__, result);
        tty_driver_kref_put(usb_serial_tty_driver);
        return result;
}


static void __exit usb_serial_exit(void)
{
        usb_serial_console_exit();

        usb_serial_generic_deregister();

        tty_unregister_driver(usb_serial_tty_driver);
        tty_driver_kref_put(usb_serial_tty_driver);
        bus_unregister(&usb_serial_bus_type);
        idr_destroy(&serial_minors);
}


module_init(usb_serial_init);
module_exit(usb_serial_exit);

#define set_to_generic_if_null(type, function)                          \
        do {                                                            \
                if (!type->function) {                                  \
                        type->function = usb_serial_generic_##function; \
                        pr_debug("%s: using generic " #function "\n",   \
                                                type->driver.name);     \
                }                                                       \
        } while (0)

static void usb_serial_operations_init(struct usb_serial_driver *device)
{
        set_to_generic_if_null(device, open);
        set_to_generic_if_null(device, write);
        set_to_generic_if_null(device, close);
        set_to_generic_if_null(device, write_room);
        set_to_generic_if_null(device, chars_in_buffer);
        if (device->tx_empty)
                set_to_generic_if_null(device, wait_until_sent);
        set_to_generic_if_null(device, read_bulk_callback);
        set_to_generic_if_null(device, write_bulk_callback);
        set_to_generic_if_null(device, process_read_urb);
        set_to_generic_if_null(device, prepare_write_buffer);
}

static int usb_serial_register(struct usb_serial_driver *driver)
{
        int retval;

        if (usb_disabled())
                return -ENODEV;

        if (!driver->description)
                driver->description = driver->driver.name;
        if (!driver->usb_driver) {
                WARN(1, "Serial driver %s has no usb_driver\n",
                                driver->description);
                return -EINVAL;
        }

        /* Prevent individual ports from being unbound. */
        driver->driver.suppress_bind_attrs = true;

        usb_serial_operations_init(driver);

        /* Add this device to our list of devices */
        mutex_lock(&table_lock);
        list_add(&driver->driver_list, &usb_serial_driver_list);

        retval = usb_serial_bus_register(driver);
        if (retval) {
                pr_err("problem %d when registering driver %s\n", retval, driver->description);
                list_del(&driver->driver_list);
        } else {
                pr_info("USB Serial support registered for %s\n", driver->description);
        }
        mutex_unlock(&table_lock);
        return retval;
}

static void usb_serial_deregister(struct usb_serial_driver *device)
{
        pr_info("USB Serial deregistering driver %s\n", device->description);

        mutex_lock(&table_lock);
        list_del(&device->driver_list);
        mutex_unlock(&table_lock);

        usb_serial_bus_deregister(device);
}

/**
 * usb_serial_register_drivers - register drivers for a usb-serial module
 * @serial_drivers: NULL-terminated array of pointers to drivers to be registered
 * @name: name of the usb_driver for this set of @serial_drivers
 * @id_table: list of all devices this @serial_drivers set binds to
 *
 * Registers all the drivers in the @serial_drivers array, and dynamically
 * creates a struct usb_driver with the name @name and id_table of @id_table.
 */
int usb_serial_register_drivers(struct usb_serial_driver *const serial_drivers[],
                                const char *name,
                                const struct usb_device_id *id_table)
{
        int rc;
        struct usb_driver *udriver;
        struct usb_serial_driver * const *sd;

        /*
         * udriver must be registered before any of the serial drivers,
         * because the store_new_id() routine for the serial drivers (in
         * bus.c) probes udriver.
         *
         * Performance hack: We don't want udriver to be probed until
         * the serial drivers are registered, because the probe would
         * simply fail for lack of a matching serial driver.
         * So we leave udriver's id_table set to NULL until we are all set.
         *
         * Suspend/resume support is implemented in the usb-serial core,
         * so fill in the PM-related fields in udriver.
         */
        udriver = kzalloc(sizeof(*udriver), GFP_KERNEL);
        if (!udriver)
                return -ENOMEM;

        udriver->name = name;
        udriver->no_dynamic_id = 1;
        udriver->supports_autosuspend = 1;
        udriver->suspend = usb_serial_suspend;
        udriver->resume = usb_serial_resume;
        udriver->probe = usb_serial_probe;
        udriver->disconnect = usb_serial_disconnect;

        /* we only set the reset_resume field if the serial_driver has one */
        for (sd = serial_drivers; *sd; ++sd) {
                if ((*sd)->reset_resume) {
                        udriver->reset_resume = usb_serial_reset_resume;
                        break;
                }
        }

        rc = usb_register(udriver);
        if (rc)
                goto err_free_driver;

        for (sd = serial_drivers; *sd; ++sd) {
                (*sd)->usb_driver = udriver;
                rc = usb_serial_register(*sd);
                if (rc)
                        goto err_deregister_drivers;
        }

        /* Now set udriver's id_table and look for matches */
        udriver->id_table = id_table;
        rc = driver_attach(&udriver->drvwrap.driver);
        return 0;

err_deregister_drivers:
        while (sd-- > serial_drivers)
                usb_serial_deregister(*sd);
        usb_deregister(udriver);
err_free_driver:
        kfree(udriver);
        return rc;
}
EXPORT_SYMBOL_GPL(usb_serial_register_drivers);

/**
 * usb_serial_deregister_drivers - deregister drivers for a usb-serial module
 * @serial_drivers: NULL-terminated array of pointers to drivers to be deregistered
 *
 * Deregisters all the drivers in the @serial_drivers array and deregisters and
 * frees the struct usb_driver that was created by the call to
 * usb_serial_register_drivers().
 */
void usb_serial_deregister_drivers(struct usb_serial_driver *const serial_drivers[])
{
        struct usb_driver *udriver = (*serial_drivers)->usb_driver;

        for (; *serial_drivers; ++serial_drivers)
                usb_serial_deregister(*serial_drivers);
        usb_deregister(udriver);
        kfree(udriver);
}
EXPORT_SYMBOL_GPL(usb_serial_deregister_drivers);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL v2");