USB: autosuspend for cdc-acm

Here we go. This patch implements suspend/resume and autosuspend
for the CDC ACM driver.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 79 insertions, 15 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 912d97aaf9bf..b0f9873ce6b7 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -496,10 +496,19 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
            otherwise it is scheduled, and with high data rates data can get lost. */
         tty->low_latency = 1;
 
+        if (usb_autopm_get_interface(acm->control)) {
+                mutex_unlock(&open_mutex);
+                return -EIO;
+        }
+
+        mutex_lock(&acm->mutex);
+        mutex_unlock(&open_mutex);
         if (acm->used++) {
+                usb_autopm_put_interface(acm->control);
                 goto done;
         }
 
+
         acm->ctrlurb->dev = acm->dev;
         if (usb_submit_urb(acm->ctrlurb, GFP_KERNEL)) {
                 dbg("usb_submit_urb(ctrl irq) failed");
@@ -526,14 +535,15 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
 
 done:
 err_out:
-        mutex_unlock(&open_mutex);
+        mutex_unlock(&acm->mutex);
         return rv;
 
 full_bailout:
         usb_kill_urb(acm->ctrlurb);
 bail_out:
+        usb_autopm_put_interface(acm->control);
         acm->used--;
-        mutex_unlock(&open_mutex);
+        mutex_unlock(&acm->mutex);
         return -EIO;
 }
 
@@ -570,6 +580,7 @@ static void acm_tty_close(struct tty_struct *tty, struct file *filp)
                         usb_kill_urb(acm->writeurb);
                         for (i = 0; i < nr; i++)
                                 usb_kill_urb(acm->ru[i].urb);
+                        usb_autopm_put_interface(acm->control);
                 } else
                         acm_tty_unregister(acm);
         }
@@ -980,6 +991,7 @@ skip_normal_probe:
         spin_lock_init(&acm->throttle_lock);
         spin_lock_init(&acm->write_lock);
         spin_lock_init(&acm->read_lock);
+        mutex_init(&acm->mutex);
         acm->write_ready = 1;
         acm->rx_endpoint = usb_rcvbulkpipe(usb_dev, epread->bEndpointAddress);
 
@@ -1096,6 +1108,25 @@ alloc_fail:
         return -ENOMEM;
 }
 
+static void stop_data_traffic(struct acm *acm)
+{
+        int i;
+
+        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);
+
+        cancel_work_sync(&acm->work);
+}
+
 static void acm_disconnect(struct usb_interface *intf)
 {
         struct acm *acm = usb_get_intfdata(intf);
@@ -1123,19 +1154,7 @@ static void acm_disconnect(struct usb_interface *intf)
         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 */
+        stop_data_traffic(acm);
 
         acm_write_buffers_free(acm);
         usb_buffer_free(usb_dev, acm->ctrlsize, acm->ctrl_buffer, acm->ctrl_dma);
@@ -1156,6 +1175,46 @@ static void acm_disconnect(struct usb_interface *intf)
                 tty_hangup(acm->tty);
 }
 
+static int acm_suspend(struct usb_interface *intf, pm_message_t message)
+{
+        struct acm *acm = usb_get_intfdata(intf);
+
+        if (acm->susp_count++)
+                return 0;
+        /*
+        we treat opened interfaces differently,
+        we must guard against open
+        */
+        mutex_lock(&acm->mutex);
+
+        if (acm->used)
+                stop_data_traffic(acm);
+
+        mutex_unlock(&acm->mutex);
+        return 0;
+}
+
+static int acm_resume(struct usb_interface *intf)
+{
+        struct acm *acm = usb_get_intfdata(intf);
+        int rv = 0;
+
+        if (--acm->susp_count)
+                return 0;
+
+        mutex_lock(&acm->mutex);
+        if (acm->used) {
+                rv = usb_submit_urb(acm->ctrlurb, GFP_NOIO);
+                if (rv < 0)
+                goto err_out;
+
+                tasklet_schedule(&acm->urb_task);
+        }
+
+err_out:
+        mutex_unlock(&acm->mutex);
+        return rv;
+}
 /*
  * USB driver structure.
  */
@@ -1208,7 +1267,10 @@ static struct usb_driver acm_driver = {
         .name =         "cdc_acm",
         .probe =        acm_probe,
         .disconnect =   acm_disconnect,
+        .suspend =      acm_suspend,
+        .resume =       acm_resume,
         .id_table =     acm_ids,
+        .supports_autosuspend = 1,
 };
 
 /*
diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index 09f7765dbf8d..8df6a57dcf9e 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -107,6 +107,7 @@ struct acm {
         int write_used;                                 /* number of non-empty write buffers */
         int write_ready;                                /* write urb is not running */
         spinlock_t write_lock;
+        struct mutex mutex;
         struct usb_cdc_line_coding line;                /* bits, stop, parity */
         struct work_struct work;                        /* work queue entry for line discipline waking up */
         struct tasklet_struct urb_task;                 /* rx processing */
@@ -120,6 +121,7 @@ struct acm {
         unsigned char throttle;                         /* throttled by tty layer */
         unsigned char clocal;                           /* termios CLOCAL */
         unsigned int ctrl_caps;                         /* control capabilities from the class specific header */
+        unsigned int susp_count;                        /* number of suspended interfaces */
 };
 
 #define CDC_DATA_INTERFACE_TYPE 0x0a