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cdc-acm.c

/*
 * cdc-acm.c
 *
 * Copyright (c) 1999 Armin Fuerst  <fuerst@in.tum.de>
 * Copyright (c) 1999 Pavel Machek  <pavel@suse.cz>
 * Copyright (c) 1999 Johannes Erdfelt    <johannes@erdfelt.com>
 * Copyright (c) 2000 Vojtech Pavlik      <vojtech@suse.cz>
 * Copyright (c) 2004 Oliver Neukum <oliver@neukum.name>
 * Copyright (c) 2005 David Kubicek <dave@awk.cz>
 *
 * USB Abstract Control Model driver for USB modems and ISDN adapters
 *
 * Sponsored by SuSE
 *
 * ChangeLog:
 *    v0.9  - thorough cleaning, URBification, almost a rewrite
 *    v0.10 - some more cleanups
 *    v0.11 - fixed flow control, read error doesn't stop reads
 *    v0.12 - added TIOCM ioctls, added break handling, made struct acm kmalloced
 *    v0.13 - added termios, added hangup
 *    v0.14 - sized down struct acm
 *    v0.15 - fixed flow control again - characters could be lost
 *    v0.16 - added code for modems with swapped data and control interfaces
 *    v0.17 - added new style probing
 *    v0.18 - fixed new style probing for devices with more configurations
 *    v0.19 - fixed CLOCAL handling (thanks to Richard Shih-Ping Chan)
 *    v0.20 - switched to probing on interface (rather than device) class
 *    v0.21 - revert to probing on device for devices with multiple configs
 *    v0.22 - probe only the control interface. if usbcore doesn't choose the
 *          config we want, sysadmin changes bConfigurationValue in sysfs.
 *    v0.23 - use softirq for rx processing, as needed by tty layer
 *    v0.24 - change probe method to evaluate CDC union descriptor
 *    v0.25 - downstream tasks paralelized to maximize throughput
 */

/*
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#undef DEBUG

#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/mutex.h>
#include <asm/uaccess.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
#include <linux/list.h>

#include "cdc-acm.h"

/*
 * Version Information
 */
#define DRIVER_VERSION "v0.25"
#define DRIVER_AUTHOR "Armin Fuerst, Pavel Machek, Johannes Erdfelt, Vojtech Pavlik, David Kubicek"
#define DRIVER_DESC "USB Abstract Control Model driver for USB modems and ISDN adapters"

static struct usb_driver acm_driver;
static struct tty_driver *acm_tty_driver;
static struct acm *acm_table[ACM_TTY_MINORS];

static DEFINE_MUTEX(open_mutex);

#define ACM_READY(acm)  (acm && acm->dev && acm->used)

/*
 * Functions for ACM control messages.
 */

static int acm_ctrl_msg(struct acm *acm, int request, int value, void *buf, int len)
{
      int retval = usb_control_msg(acm->dev, usb_sndctrlpipe(acm->dev, 0),
            request, USB_RT_ACM, value,
            acm->control->altsetting[0].desc.bInterfaceNumber,
            buf, len, 5000);
      dbg("acm_control_msg: rq: 0x%02x val: %#x len: %#x result: %d", request, value, len, retval);
      return retval < 0 ? retval : 0;
}

/* devices aren't required to support these requests.
 * the cdc acm descriptor tells whether they do...
 */
#define acm_set_control(acm, control) \
      acm_ctrl_msg(acm, USB_CDC_REQ_SET_CONTROL_LINE_STATE, control, NULL, 0)
#define acm_set_line(acm, line) \
      acm_ctrl_msg(acm, USB_CDC_REQ_SET_LINE_CODING, 0, line, sizeof *(line))
#define acm_send_break(acm, ms) \
      acm_ctrl_msg(acm, USB_CDC_REQ_SEND_BREAK, ms, NULL, 0)

/*
 * Write buffer management.
 * All of these assume proper locks taken by the caller.
 */

static int acm_wb_alloc(struct acm *acm)
{
      int i, wbn;
      struct acm_wb *wb;

      wbn = acm->write_current;
      i = 0;
      for (;;) {
            wb = &acm->wb[wbn];
            if (!wb->use) {
                  wb->use = 1;
                  return wbn;
            }
            wbn = (wbn + 1) % ACM_NW;
            if (++i >= ACM_NW)
                  return -1;
      }
}

static void acm_wb_free(struct acm *acm, int wbn)
{
      acm->wb[wbn].use = 0;
}

static int acm_wb_is_avail(struct acm *acm)
{
      int i, n;

      n = ACM_NW;
      for (i = 0; i < ACM_NW; i++) {
            n -= acm->wb[i].use;
      }
      return n;
}

static inline int acm_wb_is_used(struct acm *acm, int wbn)
{
      return acm->wb[wbn].use;
}

/*
 * Finish write.
 */
static void acm_write_done(struct acm *acm)
{
      unsigned long flags;
      int wbn;

      spin_lock_irqsave(&acm->write_lock, flags);
      acm->write_ready = 1;
      wbn = acm->write_current;
      acm_wb_free(acm, wbn);
      acm->write_current = (wbn + 1) % ACM_NW;
      spin_unlock_irqrestore(&acm->write_lock, flags);
}

/*
 * Poke write.
 */
static int acm_write_start(struct acm *acm)
{
      unsigned long flags;
      int wbn;
      struct acm_wb *wb;
      int rc;

      spin_lock_irqsave(&acm->write_lock, flags);
      if (!acm->dev) {
            spin_unlock_irqrestore(&acm->write_lock, flags);
            return -ENODEV;
      }

      if (!acm->write_ready) {
            spin_unlock_irqrestore(&acm->write_lock, flags);
            return 0;   /* A white lie */
      }

      wbn = acm->write_current;
      if (!acm_wb_is_used(acm, wbn)) {
            spin_unlock_irqrestore(&acm->write_lock, flags);
            return 0;
      }
      wb = &acm->wb[wbn];

      acm->write_ready = 0;
      spin_unlock_irqrestore(&acm->write_lock, flags);

      acm->writeurb->transfer_buffer = wb->buf;
      acm->writeurb->transfer_dma = wb->dmah;
      acm->writeurb->transfer_buffer_length = wb->len;
      acm->writeurb->dev = acm->dev;

      if ((rc = usb_submit_urb(acm->writeurb, GFP_ATOMIC)) < 0) {
            dbg("usb_submit_urb(write bulk) failed: %d", rc);
            acm_write_done(acm);
      }
      return rc;
}
/*
 * attributes exported through sysfs
 */
static ssize_t show_caps
(struct device *dev, struct device_attribute *attr, char *buf)
{
      struct usb_interface *intf = to_usb_interface(dev);
      struct acm *acm = usb_get_intfdata(intf);

      return sprintf(buf, "%d", acm->ctrl_caps);
}
static DEVICE_ATTR(bmCapabilities, S_IRUGO, show_caps, NULL);

static ssize_t show_country_codes
(struct device *dev, struct device_attribute *attr, char *buf)
{
      struct usb_interface *intf = to_usb_interface(dev);
      struct acm *acm = usb_get_intfdata(intf);

      memcpy(buf, acm->country_codes, acm->country_code_size);
      return acm->country_code_size;
}

static DEVICE_ATTR(wCountryCodes, S_IRUGO, show_country_codes, NULL);

static ssize_t show_country_rel_date
(struct device *dev, struct device_attribute *attr, char *buf)
{
      struct usb_interface *intf = to_usb_interface(dev);
      struct acm *acm = usb_get_intfdata(intf);

      return sprintf(buf, "%d", acm->country_rel_date);
}

static DEVICE_ATTR(iCountryCodeRelDate, S_IRUGO, show_country_rel_date, NULL);
/*
 * Interrupt handlers for various ACM device responses
 */

/* control interface reports status changes with "interrupt" transfers */
static void acm_ctrl_irq(struct urb *urb)
{
      struct acm *acm = urb->context;
      struct usb_cdc_notification *dr = urb->transfer_buffer;
      unsigned char *data;
      int newctrl;
      int retval;
      int status = urb->status;

      switch (status) {
      case 0:
            /* success */
            break;
      case -ECONNRESET:
      case -ENOENT:
      case -ESHUTDOWN:
            /* this urb is terminated, clean up */
            dbg("%s - urb shutting down with status: %d", __FUNCTION__, status);
            return;
      default:
            dbg("%s - nonzero urb status received: %d", __FUNCTION__, status);
            goto exit;
      }

      if (!ACM_READY(acm))
            goto exit;

      data = (unsigned char *)(dr + 1);
      switch (dr->bNotificationType) {

            case USB_CDC_NOTIFY_NETWORK_CONNECTION:

                  dbg("%s network", dr->wValue ? "connected to" : "disconnected from");
                  break;

            case USB_CDC_NOTIFY_SERIAL_STATE:

                  newctrl = le16_to_cpu(get_unaligned((__le16 *) data));

                  if (acm->tty && !acm->clocal && (acm->ctrlin & ~newctrl & ACM_CTRL_DCD)) {
                        dbg("calling hangup");
                        tty_hangup(acm->tty);
                  }

                  acm->ctrlin = newctrl;

                  dbg("input control lines: dcd%c dsr%c break%c ring%c framing%c parity%c overrun%c",
                        acm->ctrlin & ACM_CTRL_DCD ? '+' : '-',   acm->ctrlin & ACM_CTRL_DSR ? '+' : '-',
                        acm->ctrlin & ACM_CTRL_BRK ? '+' : '-',   acm->ctrlin & ACM_CTRL_RI  ? '+' : '-',
                        acm->ctrlin & ACM_CTRL_FRAMING ? '+' : '-',     acm->ctrlin & ACM_CTRL_PARITY ? '+' : '-',
                        acm->ctrlin & ACM_CTRL_OVERRUN ? '+' : '-');

                  break;

            default:
                  dbg("unknown notification %d received: index %d len %d data0 %d data1 %d",
                        dr->bNotificationType, dr->wIndex,
                        dr->wLength, data[0], data[1]);
                  break;
      }
exit:
      retval = usb_submit_urb (urb, GFP_ATOMIC);
      if (retval)
            err ("%s - usb_submit_urb failed with result %d",
                 __FUNCTION__, retval);
}

/* data interface returns incoming bytes, or we got unthrottled */
static void acm_read_bulk(struct urb *urb)
{
      struct acm_rb *buf;
      struct acm_ru *rcv = urb->context;
      struct acm *acm = rcv->instance;
      int status = urb->status;

      dbg("Entering acm_read_bulk with status %d", status);

      if (!ACM_READY(acm))
            return;

      if (status)
            dev_dbg(&acm->data->dev, "bulk rx status %d\n", status);

      buf = rcv->buffer;
      buf->size = urb->actual_length;

      if (likely(status == 0)) {
            spin_lock(&acm->read_lock);
            list_add_tail(&rcv->list, &acm->spare_read_urbs);
            list_add_tail(&buf->list, &acm->filled_read_bufs);
            spin_unlock(&acm->read_lock);
      } else {
            /* we drop the buffer due to an error */
            spin_lock(&acm->read_lock);
            list_add_tail(&rcv->list, &acm->spare_read_urbs);
            list_add(&buf->list, &acm->spare_read_bufs);
            spin_unlock(&acm->read_lock);
            /* nevertheless the tasklet must be kicked unconditionally
            so the queue cannot dry up */
      }
      tasklet_schedule(&acm->urb_task);
}

static void acm_rx_tasklet(unsigned long _acm)
{
      struct acm *acm = (void *)_acm;
      struct acm_rb *buf;
      struct tty_struct *tty = acm->tty;
      struct acm_ru *rcv;
      unsigned long flags;
      unsigned char throttled;
      dbg("Entering acm_rx_tasklet");

      if (!ACM_READY(acm))
            return;

      spin_lock_irqsave(&acm->throttle_lock, flags);
      throttled = acm->throttle;
      spin_unlock_irqrestore(&acm->throttle_lock, flags);
      if (throttled)
            return;

next_buffer:
      spin_lock_irqsave(&acm->read_lock, flags);
      if (list_empty(&acm->filled_read_bufs)) {
            spin_unlock_irqrestore(&acm->read_lock, flags);
            goto urbs;
      }
      buf = list_entry(acm->filled_read_bufs.next,
                   struct acm_rb, list);
      list_del(&buf->list);
      spin_unlock_irqrestore(&acm->read_lock, flags);

      dbg("acm_rx_tasklet: procesing buf 0x%p, size = %d", buf, buf->size);

      tty_buffer_request_room(tty, buf->size);
      spin_lock_irqsave(&acm->throttle_lock, flags);
      throttled = acm->throttle;
      spin_unlock_irqrestore(&acm->throttle_lock, flags);
      if (!throttled)
            tty_insert_flip_string(tty, buf->base, buf->size);
      tty_flip_buffer_push(tty);

      if (throttled) {
            dbg("Throttling noticed");
            spin_lock_irqsave(&acm->read_lock, flags);
            list_add(&buf->list, &acm->filled_read_bufs);
            spin_unlock_irqrestore(&acm->read_lock, flags);
            return;
      }

      spin_lock_irqsave(&acm->read_lock, flags);
      list_add(&buf->list, &acm->spare_read_bufs);
      spin_unlock_irqrestore(&acm->read_lock, flags);
      goto next_buffer;

urbs:
      while (!list_empty(&acm->spare_read_bufs)) {
            spin_lock_irqsave(&acm->read_lock, flags);
            if (list_empty(&acm->spare_read_urbs)) {
                  spin_unlock_irqrestore(&acm->read_lock, flags);
                  return;
            }
            rcv = list_entry(acm->spare_read_urbs.next,
                         struct acm_ru, list);
            list_del(&rcv->list);
            spin_unlock_irqrestore(&acm->read_lock, flags);

            buf = list_entry(acm->spare_read_bufs.next,
                         struct acm_rb, list);
            list_del(&buf->list);

            rcv->buffer = buf;

            usb_fill_bulk_urb(rcv->urb, acm->dev,
                          acm->rx_endpoint,
                          buf->base,
                          acm->readsize,
                          acm_read_bulk, rcv);
            rcv->urb->transfer_dma = buf->dma;
            rcv->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

            dbg("acm_rx_tasklet: sending urb 0x%p, rcv 0x%p, buf 0x%p", rcv->urb, rcv, buf);

            /* This shouldn't kill the driver as unsuccessful URBs are returned to the
               free-urbs-pool and resubmited ASAP */
            if (usb_submit_urb(rcv->urb, GFP_ATOMIC) < 0) {
                  list_add(&buf->list, &acm->spare_read_bufs);
                  spin_lock_irqsave(&acm->read_lock, flags);
                  list_add(&rcv->list, &acm->spare_read_urbs);
                  spin_unlock_irqrestore(&acm->read_lock, flags);
                  return;
            }
      }
}

/* data interface wrote those outgoing bytes */
static void acm_write_bulk(struct urb *urb)
{
      struct acm *acm = (struct acm *)urb->context;

      dbg("Entering acm_write_bulk with status %d", urb->status);

      acm_write_done(acm);
      acm_write_start(acm);
      if (ACM_READY(acm))
            schedule_work(&acm->work);
}

static void acm_softint(struct work_struct *work)
{
      struct acm *acm = container_of(work, struct acm, work);
      dbg("Entering acm_softint.");
      
      if (!ACM_READY(acm))
            return;
      tty_wakeup(acm->tty);
}

/*
 * TTY handlers
 */

static int acm_tty_open(struct tty_struct *tty, struct file *filp)
{
      struct acm *acm;
      int rv = -EINVAL;
      int i;
      dbg("Entering acm_tty_open.");

      mutex_lock(&open_mutex);

      acm = acm_table[tty->index];
      if (!acm || !acm->dev)
            goto err_out;
      else
            rv = 0;

      tty->driver_data = acm;
      acm->tty = tty;

      /* force low_latency on so that our tty_push actually forces the data through,
         otherwise it is scheduled, and with high data rates data can get lost. */
      tty->low_latency = 1;

      if (acm->used++) {
            goto done;
        }

      acm->ctrlurb->dev = acm->dev;
      if (usb_submit_urb(acm->ctrlurb, GFP_KERNEL)) {
            dbg("usb_submit_urb(ctrl irq) failed");
            goto bail_out;
      }

      if (0 > acm_set_control(acm, acm->ctrlout = ACM_CTRL_DTR | ACM_CTRL_RTS) &&
          (acm->ctrl_caps & USB_CDC_CAP_LINE))
            goto full_bailout;

      INIT_LIST_HEAD(&acm->spare_read_urbs);
      INIT_LIST_HEAD(&acm->spare_read_bufs);
      INIT_LIST_HEAD(&acm->filled_read_bufs);
      for (i = 0; i < acm->rx_buflimit; i++) {
            list_add(&(acm->ru[i].list), &acm->spare_read_urbs);
      }
      for (i = 0; i < acm->rx_buflimit; i++) {
            list_add(&(acm->rb[i].list), &acm->spare_read_bufs);
      }

      acm->throttle = 0;

      tasklet_schedule(&acm->urb_task);

done:
err_out:
      mutex_unlock(&open_mutex);
      return rv;

full_bailout:
      usb_kill_urb(acm->ctrlurb);
bail_out:
      acm->used--;
      mutex_unlock(&open_mutex);
      return -EIO;
}

static void acm_tty_unregister(struct acm *acm)
{
      int i,nr;

      nr = acm->rx_buflimit;
      tty_unregister_device(acm_tty_driver, acm->minor);
      usb_put_intf(acm->control);
      acm_table[acm->minor] = NULL;
      usb_free_urb(acm->ctrlurb);
      usb_free_urb(acm->writeurb);
      for (i = 0; i < nr; i++)
            usb_free_urb(acm->ru[i].urb);
      kfree(acm->country_codes);
      kfree(acm);
}

static void acm_tty_close(struct tty_struct *tty, struct file *filp)
{
      struct acm *acm = tty->driver_data;
      int i,nr;

      if (!acm || !acm->used)
            return;

      nr = acm->rx_buflimit;
      mutex_lock(&open_mutex);
      if (!--acm->used) {
            if (acm->dev) {
                  acm_set_control(acm, acm->ctrlout = 0);
                  usb_kill_urb(acm->ctrlurb);
                  usb_kill_urb(acm->writeurb);
                  for (i = 0; i < nr; i++)
                        usb_kill_urb(acm->ru[i].urb);
            } else
                  acm_tty_unregister(acm);
      }
      mutex_unlock(&open_mutex);
}

static int acm_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
      struct acm *acm = tty->driver_data;
      int stat;
      unsigned long flags;
      int wbn;
      struct acm_wb *wb;

      dbg("Entering acm_tty_write to write %d bytes,", count);

      if (!ACM_READY(acm))
            return -EINVAL;
      if (!count)
            return 0;

      spin_lock_irqsave(&acm->write_lock, flags);
      if ((wbn = acm_wb_alloc(acm)) < 0) {
            spin_unlock_irqrestore(&acm->write_lock, flags);
            acm_write_start(acm);
            return 0;
      }
      wb = &acm->wb[wbn];

      count = (count > acm->writesize) ? acm->writesize : count;
      dbg("Get %d bytes...", count);
      memcpy(wb->buf, buf, count);
      wb->len = count;
      spin_unlock_irqrestore(&acm->write_lock, flags);

      if ((stat = acm_write_start(acm)) < 0)
            return stat;
      return count;
}

static int acm_tty_write_room(struct tty_struct *tty)
{
      struct acm *acm = tty->driver_data;
      if (!ACM_READY(acm))
            return -EINVAL;
      /*
       * Do not let the line discipline to know that we have a reserve,
       * or it might get too enthusiastic.
       */
      return (acm->write_ready && acm_wb_is_avail(acm)) ? acm->writesize : 0;
}

static int acm_tty_chars_in_buffer(struct tty_struct *tty)
{
      struct acm *acm = tty->driver_data;
      if (!ACM_READY(acm))
            return -EINVAL;
      /*
       * This is inaccurate (overcounts), but it works.
       */
      return (ACM_NW - acm_wb_is_avail(acm)) * acm->writesize;
}

static void acm_tty_throttle(struct tty_struct *tty)
{
      struct acm *acm = tty->driver_data;
      if (!ACM_READY(acm))
            return;
      spin_lock_bh(&acm->throttle_lock);
      acm->throttle = 1;
      spin_unlock_bh(&acm->throttle_lock);
}

static void acm_tty_unthrottle(struct tty_struct *tty)
{
      struct acm *acm = tty->driver_data;
      if (!ACM_READY(acm))
            return;
      spin_lock_bh(&acm->throttle_lock);
      acm->throttle = 0;
      spin_unlock_bh(&acm->throttle_lock);
      tasklet_schedule(&acm->urb_task);
}

static void acm_tty_break_ctl(struct tty_struct *tty, int state)
{
      struct acm *acm = tty->driver_data;
      if (!ACM_READY(acm))
            return;
      if (acm_send_break(acm, state ? 0xffff : 0))
            dbg("send break failed");
}

static int acm_tty_tiocmget(struct tty_struct *tty, struct file *file)
{
      struct acm *acm = tty->driver_data;

      if (!ACM_READY(acm))
            return -EINVAL;

      return (acm->ctrlout & ACM_CTRL_DTR ? TIOCM_DTR : 0) |
             (acm->ctrlout & ACM_CTRL_RTS ? TIOCM_RTS : 0) |
             (acm->ctrlin  & ACM_CTRL_DSR ? TIOCM_DSR : 0) |
             (acm->ctrlin  & ACM_CTRL_RI  ? TIOCM_RI  : 0) |
             (acm->ctrlin  & ACM_CTRL_DCD ? TIOCM_CD  : 0) |
             TIOCM_CTS;
}

static int acm_tty_tiocmset(struct tty_struct *tty, struct file *file,
                      unsigned int set, unsigned int clear)
{
      struct acm *acm = tty->driver_data;
      unsigned int newctrl;

      if (!ACM_READY(acm))
            return -EINVAL;

      newctrl = acm->ctrlout;
      set = (set & TIOCM_DTR ? ACM_CTRL_DTR : 0) | (set & TIOCM_RTS ? ACM_CTRL_RTS : 0);
      clear = (clear & TIOCM_DTR ? ACM_CTRL_DTR : 0) | (clear & TIOCM_RTS ? ACM_CTRL_RTS : 0);

      newctrl = (newctrl & ~clear) | set;

      if (acm->ctrlout == newctrl)
            return 0;
      return acm_set_control(acm, acm->ctrlout = newctrl);
}

static int acm_tty_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
{
      struct acm *acm = tty->driver_data;

      if (!ACM_READY(acm))
            return -EINVAL;

      return -ENOIOCTLCMD;
}

static const __u32 acm_tty_speed[] = {
      0, 50, 75, 110, 134, 150, 200, 300, 600,
      1200, 1800, 2400, 4800, 9600, 19200, 38400,
      57600, 115200, 230400, 460800, 500000, 576000,
      921600, 1000000, 1152000, 1500000, 2000000,
      2500000, 3000000, 3500000, 4000000
};

static const __u8 acm_tty_size[] = {
      5, 6, 7, 8
};

static void acm_tty_set_termios(struct tty_struct *tty, struct ktermios *termios_old)
{
      struct acm *acm = tty->driver_data;
      struct ktermios *termios = tty->termios;
      struct usb_cdc_line_coding newline;
      int newctrl = acm->ctrlout;

      if (!ACM_READY(acm))
            return;

      newline.dwDTERate = cpu_to_le32p(acm_tty_speed +
            (termios->c_cflag & CBAUD & ~CBAUDEX) + (termios->c_cflag & CBAUDEX ? 15 : 0));
      newline.bCharFormat = termios->c_cflag & CSTOPB ? 2 : 0;
      newline.bParityType = termios->c_cflag & PARENB ?
            (termios->c_cflag & PARODD ? 1 : 2) + (termios->c_cflag & CMSPAR ? 2 : 0) : 0;
      newline.bDataBits = acm_tty_size[(termios->c_cflag & CSIZE) >> 4];

      acm->clocal = ((termios->c_cflag & CLOCAL) != 0);

      if (!newline.dwDTERate) {
            newline.dwDTERate = acm->line.dwDTERate;
            newctrl &= ~ACM_CTRL_DTR;
      } else  newctrl |=  ACM_CTRL_DTR;

      if (newctrl != acm->ctrlout)
            acm_set_control(acm, acm->ctrlout = newctrl);

      if (memcmp(&acm->line, &newline, sizeof newline)) {
            memcpy(&acm->line, &newline, sizeof newline);
            dbg("set line: %d %d %d %d", le32_to_cpu(newline.dwDTERate),
                  newline.bCharFormat, newline.bParityType,
                  newline.bDataBits);
            acm_set_line(acm, &acm->line);
      }
}

/*
 * USB probe and disconnect routines.
 */

/* Little helper: write buffers free */
static void acm_write_buffers_free(struct acm *acm)
{
      int i;
      struct acm_wb *wb;

      for (wb = &acm->wb[0], i = 0; i < ACM_NW; i++, wb++) {
            usb_buffer_free(acm->dev, acm->writesize, wb->buf, wb->dmah);
      }
}

/* Little helper: write buffers allocate */
static int acm_write_buffers_alloc(struct acm *acm)
{
      int i;
      struct acm_wb *wb;

      for (wb = &acm->wb[0], i = 0; i < ACM_NW; i++, wb++) {
            wb->buf = usb_buffer_alloc(acm->dev, acm->writesize, GFP_KERNEL,
                &wb->dmah);
            if (!wb->buf) {
                  while (i != 0) {
                        --i;
                        --wb;
                        usb_buffer_free(acm->dev, acm->writesize,
                            wb->buf, wb->dmah);
                  }
                  return -ENOMEM;
            }
      }
      return 0;
}

static int acm_probe (struct usb_interface *intf,
                  const struct usb_device_id *id)
{
      struct usb_cdc_union_desc *union_header = NULL;
      struct usb_cdc_country_functional_desc *cfd = NULL;
      char *buffer = intf->altsetting->extra;
      int buflen = intf->altsetting->extralen;
      struct usb_interface *control_interface;
      struct usb_interface *data_interface;
      struct usb_endpoint_descriptor *epctrl;
      struct usb_endpoint_descriptor *epread;
      struct usb_endpoint_descriptor *epwrite;
      struct usb_device *usb_dev = interface_to_usbdev(intf);
      struct acm *acm;
      int minor;
      int ctrlsize,readsize;
      u8 *buf;
      u8 ac_management_function = 0;
      u8 call_management_function = 0;
      int call_interface_num = -1;
      int data_interface_num;
      unsigned long quirks;
      int num_rx_buf;
      int i;

      /* normal quirks */
      quirks = (unsigned long)id->driver_info;
      num_rx_buf = (quirks == SINGLE_RX_URB) ? 1 : ACM_NR;

      /* handle quirks deadly to normal probing*/
      if (quirks == NO_UNION_NORMAL) {
            data_interface = usb_ifnum_to_if(usb_dev, 1);
            control_interface = usb_ifnum_to_if(usb_dev, 0);
            goto skip_normal_probe;
      }
      
      /* normal probing*/
      if (!buffer) {
            err("Weird descriptor references\n");
            return -EINVAL;
      }

      if (!buflen) {
            if (intf->cur_altsetting->endpoint->extralen && intf->cur_altsetting->endpoint->extra) {
                  dev_dbg(&intf->dev,"Seeking extra descriptors on endpoint\n");
                  buflen = intf->cur_altsetting->endpoint->extralen;
                  buffer = intf->cur_altsetting->endpoint->extra;
            } else {
                  err("Zero length descriptor references\n");
                  return -EINVAL;
            }
      }

      while (buflen > 0) {
            if (buffer [1] != USB_DT_CS_INTERFACE) {
                  err("skipping garbage\n");
                  goto next_desc;
            }

            switch (buffer [2]) {
                  case USB_CDC_UNION_TYPE: /* we've found it */
                        if (union_header) {
                              err("More than one union descriptor, skipping ...");
                              goto next_desc;
                        }
                        union_header = (struct usb_cdc_union_desc *)
                                          buffer;
                        break;
                  case USB_CDC_COUNTRY_TYPE: /* export through sysfs*/
                        cfd = (struct usb_cdc_country_functional_desc *)buffer;
                        break;
                  case USB_CDC_HEADER_TYPE: /* maybe check version */ 
                        break; /* for now we ignore it */ 
                  case USB_CDC_ACM_TYPE:
                        ac_management_function = buffer[3];
                        break;
                  case USB_CDC_CALL_MANAGEMENT_TYPE:
                        call_management_function = buffer[3];
                        call_interface_num = buffer[4];
                        if ((call_management_function & 3) != 3)
                              err("This device cannot do calls on its own. It is no modem.");
                        break;
                        
                  default:
                        err("Ignoring extra header, type %d, length %d", buffer[2], buffer[0]);
                        break;
                  }
next_desc:
            buflen -= buffer[0];
            buffer += buffer[0];
      }

      if (!union_header) {
            if (call_interface_num > 0) {
                  dev_dbg(&intf->dev,"No union descriptor, using call management descriptor\n");
                  data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = call_interface_num));
                  control_interface = intf;
            } else {
                  dev_dbg(&intf->dev,"No union descriptor, giving up\n");
                  return -ENODEV;
            }
      } else {
            control_interface = usb_ifnum_to_if(usb_dev, union_header->bMasterInterface0);
            data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = union_header->bSlaveInterface0));
            if (!control_interface || !data_interface) {
                  dev_dbg(&intf->dev,"no interfaces\n");
                  return -ENODEV;
            }
      }
      
      if (data_interface_num != call_interface_num)
            dev_dbg(&intf->dev,"Seperate call control interface. That is not fully supported.\n");

skip_normal_probe:

      /*workaround for switched interfaces */
      if (data_interface->cur_altsetting->desc.bInterfaceClass != CDC_DATA_INTERFACE_TYPE) {
            if (control_interface->cur_altsetting->desc.bInterfaceClass == CDC_DATA_INTERFACE_TYPE) {
                  struct usb_interface *t;
                  dev_dbg(&intf->dev,"Your device has switched interfaces.\n");

                  t = control_interface;
                  control_interface = data_interface;
                  data_interface = t;
            } else {
                  return -EINVAL;
            }
      }

      /* Accept probe requests only for the control interface */
      if (intf != control_interface)
            return -ENODEV;
      
      if (usb_interface_claimed(data_interface)) { /* valid in this context */
            dev_dbg(&intf->dev,"The data interface isn't available\n");
            return -EBUSY;
      }


      if (data_interface->cur_altsetting->desc.bNumEndpoints < 2)
            return -EINVAL;

      epctrl = &control_interface->cur_altsetting->endpoint[0].desc;
      epread = &data_interface->cur_altsetting->endpoint[0].desc;
      epwrite = &data_interface->cur_altsetting->endpoint[1].desc;


      /* workaround for switched endpoints */
      if (!usb_endpoint_dir_in(epread)) {
            /* descriptors are swapped */
            struct usb_endpoint_descriptor *t;
            dev_dbg(&intf->dev,"The data interface has switched endpoints\n");
            
            t = epread;
            epread = epwrite;
            epwrite = t;
      }
      dbg("interfaces are valid");
      for (minor = 0; minor < ACM_TTY_MINORS && acm_table[minor]; minor++);

      if (minor == ACM_TTY_MINORS) {
            err("no more free acm devices");
            return -ENODEV;
      }

      if (!(acm = kzalloc(sizeof(struct acm), GFP_KERNEL))) {
            dev_dbg(&intf->dev, "out of memory (acm kzalloc)\n");
            goto alloc_fail;
      }

      ctrlsize = le16_to_cpu(epctrl->wMaxPacketSize);
      readsize = le16_to_cpu(epread->wMaxPacketSize)* ( quirks == SINGLE_RX_URB ? 1 : 2);
      acm->writesize = le16_to_cpu(epwrite->wMaxPacketSize);
      acm->control = control_interface;
      acm->data = data_interface;
      acm->minor = minor;
      acm->dev = usb_dev;
      acm->ctrl_caps = ac_management_function;
      acm->ctrlsize = ctrlsize;
      acm->readsize = readsize;
      acm->rx_buflimit = num_rx_buf;
      acm->urb_task.func = acm_rx_tasklet;
      acm->urb_task.data = (unsigned long) acm;
      INIT_WORK(&acm->work, acm_softint);
      spin_lock_init(&acm->throttle_lock);
      spin_lock_init(&acm->write_lock);
      spin_lock_init(&acm->read_lock);
      acm->write_ready = 1;
      acm->rx_endpoint = usb_rcvbulkpipe(usb_dev, epread->bEndpointAddress);

      buf = usb_buffer_alloc(usb_dev, ctrlsize, GFP_KERNEL, &acm->ctrl_dma);
      if (!buf) {
            dev_dbg(&intf->dev, "out of memory (ctrl buffer alloc)\n");
            goto alloc_fail2;
      }
      acm->ctrl_buffer = buf;

      if (acm_write_buffers_alloc(acm) < 0) {
            dev_dbg(&intf->dev, "out of memory (write buffer alloc)\n");
            goto alloc_fail4;
      }

      acm->ctrlurb = usb_alloc_urb(0, GFP_KERNEL);
      if (!acm->ctrlurb) {
            dev_dbg(&intf->dev, "out of memory (ctrlurb kmalloc)\n");
            goto alloc_fail5;
      }
      for (i = 0; i < num_rx_buf; i++) {
            struct acm_ru *rcv = &(acm->ru[i]);

            if (!(rcv->urb = usb_alloc_urb(0, GFP_KERNEL))) {
                  dev_dbg(&intf->dev, "out of memory (read urbs usb_alloc_urb)\n");
                  goto alloc_fail7;
            }

            rcv->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
            rcv->instance = acm;
      }
      for (i = 0; i < num_rx_buf; i++) {
            struct acm_rb *buf = &(acm->rb[i]);

            if (!(buf->base = usb_buffer_alloc(acm->dev, readsize, GFP_KERNEL, &buf->dma))) {
                  dev_dbg(&intf->dev, "out of memory (read bufs usb_buffer_alloc)\n");
                  goto alloc_fail7;
            }
      }
      acm->writeurb = usb_alloc_urb(0, GFP_KERNEL);
      if (!acm->writeurb) {
            dev_dbg(&intf->dev, "out of memory (writeurb kmalloc)\n");
            goto alloc_fail7;
      }

      usb_set_intfdata (intf, acm);

      i = device_create_file(&intf->dev, &dev_attr_bmCapabilities);
      if (i < 0)
            goto alloc_fail8;

      if (cfd) { /* export the country data */
            acm->country_codes = kmalloc(cfd->bLength - 4, GFP_KERNEL);
            if (!acm->country_codes)
                  goto skip_countries;
            acm->country_code_size = cfd->bLength - 4;
            memcpy(acm->country_codes, (u8 *)&cfd->wCountyCode0, cfd->bLength - 4);
            acm->country_rel_date = cfd->iCountryCodeRelDate;

            i = device_create_file(&intf->dev, &dev_attr_wCountryCodes);
            if (i < 0) {
                  kfree(acm->country_codes);
                  goto skip_countries;
            }

            i = device_create_file(&intf->dev, &dev_attr_iCountryCodeRelDate);
            if (i < 0) {
                  kfree(acm->country_codes);
                  goto skip_countries;
            }
      }

skip_countries:
      usb_fill_int_urb(acm->ctrlurb, usb_dev, usb_rcvintpipe(usb_dev, epctrl->bEndpointAddress),
                   acm->ctrl_buffer, ctrlsize, acm_ctrl_irq, acm, epctrl->bInterval);
      acm->ctrlurb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
      acm->ctrlurb->transfer_dma = acm->ctrl_dma;

      usb_fill_bulk_urb(acm->writeurb, usb_dev, usb_sndbulkpipe(usb_dev, epwrite->bEndpointAddress),
                    NULL, acm->writesize, acm_write_bulk, acm);
      acm->writeurb->transfer_flags |= URB_NO_FSBR | URB_NO_TRANSFER_DMA_MAP;

      dev_info(&intf->dev, "ttyACM%d: USB ACM device\n", minor);

      acm_set_control(acm, acm->ctrlout);

      acm->line.dwDTERate = cpu_to_le32(9600);
      acm->line.bDataBits = 8;
      acm_set_line(acm, &acm->line);

      usb_driver_claim_interface(&acm_driver, data_interface, acm);

      usb_get_intf(control_interface);
      tty_register_device(acm_tty_driver, minor, &control_interface->dev);

      acm_table[minor] = acm;

      return 0;
alloc_fail8:
      usb_free_urb(acm->writeurb);
alloc_fail7:
      for (i = 0; i < num_rx_buf; i++)
            usb_buffer_free(usb_dev, acm->readsize, acm->rb[i].base, acm->rb[i].dma);
      for (i = 0; i < num_rx_buf; i++)
            usb_free_urb(acm->ru[i].urb);
      usb_free_urb(acm->ctrlurb);
alloc_fail5:
      acm_write_buffers_free(acm);
alloc_fail4:
      usb_buffer_free(usb_dev, ctrlsize, acm->ctrl_buffer, acm->ctrl_dma);
alloc_fail2:
      kfree(acm);
alloc_fail:
      return -ENOMEM;
}

static void acm_disconnect(struct usb_interface *intf)
{
      struct acm *acm = usb_get_intfdata(intf);
      struct usb_device *usb_dev = interface_to_usbdev(intf);
      int i;

      if (!acm || !acm->dev) {
            dbg("disconnect on nonexisting interface");
            return;
      }

      mutex_lock(&open_mutex);
      if (!usb_get_intfdata(intf)) {
            mutex_unlock(&open_mutex);
            return;
      }
      if (acm->country_codes){
            device_remove_file(&acm->control->dev,
                        &dev_attr_wCountryCodes);
            device_remove_file(&acm->control->dev,
                        &dev_attr_iCountryCodeRelDate);
      }
      device_remove_file(&acm->control->dev, &dev_attr_bmCapabilities);
      acm->dev = NULL;
      usb_set_intfdata(acm->control, NULL);
      usb_set_intfdata(acm->data, NULL);

      tasklet_disable(&acm->urb_task);

      usb_kill_urb(acm->ctrlurb);
      usb_kill_urb(acm->writeurb);
      for (i = 0; i < acm->rx_buflimit; i++)
            usb_kill_urb(acm->ru[i].urb);

      INIT_LIST_HEAD(&acm->filled_read_bufs);
      INIT_LIST_HEAD(&acm->spare_read_bufs);

      tasklet_enable(&acm->urb_task);

      flush_scheduled_work(); /* wait for acm_softint */

      acm_write_buffers_free(acm);
      usb_buffer_free(usb_dev, acm->ctrlsize, acm->ctrl_buffer, acm->ctrl_dma);
      for (i = 0; i < acm->rx_buflimit; i++)
            usb_buffer_free(usb_dev, acm->readsize, acm->rb[i].base, acm->rb[i].dma);

      usb_driver_release_interface(&acm_driver, intf == acm->control ? acm->data : intf);

      if (!acm->used) {
            acm_tty_unregister(acm);
            mutex_unlock(&open_mutex);
            return;
      }

      mutex_unlock(&open_mutex);

      if (acm->tty)
            tty_hangup(acm->tty);
}

/*
 * USB driver structure.
 */

static struct usb_device_id acm_ids[] = {
      /* quirky and broken devices */
      { USB_DEVICE(0x0870, 0x0001), /* Metricom GS Modem */
      .driver_info = NO_UNION_NORMAL, /* has no union descriptor */
      },
      { USB_DEVICE(0x0e8d, 0x0003), /* FIREFLY, MediaTek Inc; andrey.arapov@gmail.com */
      .driver_info = NO_UNION_NORMAL, /* has no union descriptor */
      },
      { USB_DEVICE(0x0482, 0x0203), /* KYOCERA AH-K3001V */
      .driver_info = NO_UNION_NORMAL, /* has no union descriptor */
      },
      { USB_DEVICE(0x079b, 0x000f), /* BT On-Air USB MODEM */
      .driver_info = NO_UNION_NORMAL, /* has no union descriptor */
      },
      { USB_DEVICE(0x0ace, 0x1608), /* ZyDAS 56K USB MODEM */
      .driver_info = SINGLE_RX_URB, /* firmware bug */
      },
      { USB_DEVICE(0x0ace, 0x1611), /* ZyDAS 56K USB MODEM - new version */
      .driver_info = SINGLE_RX_URB, /* firmware bug */
      },
      { USB_DEVICE(0x22b8, 0x7000), /* Motorola Q Phone */
      .driver_info = NO_UNION_NORMAL, /* has no union descriptor */
      },

      /* control interfaces with various AT-command sets */
      { USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM,
            USB_CDC_ACM_PROTO_AT_V25TER) },
      { USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM,
            USB_CDC_ACM_PROTO_AT_PCCA101) },
      { USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM,
            USB_CDC_ACM_PROTO_AT_PCCA101_WAKE) },
      { USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM,
            USB_CDC_ACM_PROTO_AT_GSM) },
      { USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM,
            USB_CDC_ACM_PROTO_AT_3G ) },
      { USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM,
            USB_CDC_ACM_PROTO_AT_CDMA) },

      /* NOTE:  COMM/ACM/0xff is likely MSFT RNDIS ... NOT a modem!! */
      { }
};

MODULE_DEVICE_TABLE (usb, acm_ids);

static struct usb_driver acm_driver = {
      .name =           "cdc_acm",
      .probe =    acm_probe,
      .disconnect =     acm_disconnect,
      .id_table = acm_ids,
};

/*
 * TTY driver structures.
 */

static const struct tty_operations acm_ops = {
      .open =                 acm_tty_open,
      .close =          acm_tty_close,
      .write =          acm_tty_write,
      .write_room =           acm_tty_write_room,
      .ioctl =          acm_tty_ioctl,
      .throttle =       acm_tty_throttle,
      .unthrottle =           acm_tty_unthrottle,
      .chars_in_buffer =      acm_tty_chars_in_buffer,
      .break_ctl =            acm_tty_break_ctl,
      .set_termios =          acm_tty_set_termios,
      .tiocmget =       acm_tty_tiocmget,
      .tiocmset =       acm_tty_tiocmset,
};

/*
 * Init / exit.
 */

static int __init acm_init(void)
{
      int retval;
      acm_tty_driver = alloc_tty_driver(ACM_TTY_MINORS);
      if (!acm_tty_driver)
            return -ENOMEM;
      acm_tty_driver->owner = THIS_MODULE,
      acm_tty_driver->driver_name = "acm",
      acm_tty_driver->name = "ttyACM",
      acm_tty_driver->major = ACM_TTY_MAJOR,
      acm_tty_driver->minor_start = 0,
      acm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL,
      acm_tty_driver->subtype = SERIAL_TYPE_NORMAL,
      acm_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
      acm_tty_driver->init_termios = tty_std_termios;
      acm_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
      tty_set_operations(acm_tty_driver, &acm_ops);

      retval = tty_register_driver(acm_tty_driver);
      if (retval) {
            put_tty_driver(acm_tty_driver);
            return retval;
      }

      retval = usb_register(&acm_driver);
      if (retval) {
            tty_unregister_driver(acm_tty_driver);
            put_tty_driver(acm_tty_driver);
            return retval;
      }

      info(DRIVER_VERSION ":" DRIVER_DESC);

      return 0;
}

static void __exit acm_exit(void)
{
      usb_deregister(&acm_driver);
      tty_unregister_driver(acm_tty_driver);
      put_tty_driver(acm_tty_driver);
}

module_init(acm_init);
module_exit(acm_exit);

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


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