cdc-acm: add TIOCMIWAIT

This implements TIOCMIWAIT for TIOCM_DSR, TIOCM_RI and TIOCM_CD
Disconnect is handled as TIOCM_CD or an error.

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

2 files changed, 77 insertions, 12 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 3e7560f004f8..7c0051710a04 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -262,6 +262,7 @@ static void acm_ctrl_irq(struct urb *urb)
         struct usb_cdc_notification *dr = urb->transfer_buffer;
         unsigned char *data;
         int newctrl;
+        int difference;
         int retval;
         int status = urb->status;
 
@@ -302,20 +303,31 @@ static void acm_ctrl_irq(struct urb *urb)
                         tty_port_tty_hangup(&acm->port, false);
                 }
 
+                difference = acm->ctrlin ^ newctrl;
+                spin_lock(&acm->read_lock);
                 acm->ctrlin = newctrl;
+                acm->oldcount = acm->iocount;
+
+                if (difference & ACM_CTRL_DSR)
+                        acm->iocount.dsr++;
+                if (difference & ACM_CTRL_BRK)
+                        acm->iocount.brk++;
+                if (difference & ACM_CTRL_RI)
+                        acm->iocount.rng++;
+                if (difference & ACM_CTRL_DCD)
+                        acm->iocount.dcd++;
+                if (difference & ACM_CTRL_FRAMING)
+                        acm->iocount.frame++;
+                if (difference & ACM_CTRL_PARITY)
+                        acm->iocount.parity++;
+                if (difference & ACM_CTRL_OVERRUN)
+                        acm->iocount.overrun++;
+                spin_unlock(&acm->read_lock);
+
+                if (difference)
+                        wake_up_all(&acm->wioctl);
 
-                dev_dbg(&acm->control->dev,
-                        "%s - input control lines: dcd%c dsr%c break%c "
-                        "ring%c framing%c parity%c overrun%c\n",
-                        __func__,
-                        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;
+                break;
 
         default:
                 dev_dbg(&acm->control->dev,
@@ -796,6 +808,51 @@ static int set_serial_info(struct acm *acm,
         return retval;
 }
 
+static int wait_serial_change(struct acm *acm, unsigned long arg)
+{
+        int rv = 0;
+        DECLARE_WAITQUEUE(wait, current);
+        struct async_icount old, new;
+
+        if (arg & (TIOCM_DSR | TIOCM_RI | TIOCM_CD ))
+                return -EINVAL;
+        do {
+                spin_lock_irq(&acm->read_lock);
+                old = acm->oldcount;
+                new = acm->iocount;
+                acm->oldcount = new;
+                spin_unlock_irq(&acm->read_lock);
+
+                if ((arg & TIOCM_DSR) &&
+                        old.dsr != new.dsr)
+                        break;
+                if ((arg & TIOCM_CD)  &&
+                        old.dcd != new.dcd)
+                        break;
+                if ((arg & TIOCM_RI) &&
+                        old.rng != new.rng)
+                        break;
+
+                add_wait_queue(&acm->wioctl, &wait);
+                set_current_state(TASK_INTERRUPTIBLE);
+                schedule();
+                remove_wait_queue(&acm->wioctl, &wait);
+                if (acm->disconnected) {
+                        if (arg & TIOCM_CD)
+                                break;
+                        else
+                                rv = -ENODEV;
+                } else {
+                        if (signal_pending(current))
+                                rv = -ERESTARTSYS;
+                }
+        } while (!rv);
+
+        
+
+        return rv;
+}
+
 static int acm_tty_ioctl(struct tty_struct *tty,
                                         unsigned int cmd, unsigned long arg)
 {
@@ -809,6 +866,9 @@ static int acm_tty_ioctl(struct tty_struct *tty,
         case TIOCSSERIAL:
                 rv = set_serial_info(acm, (struct serial_struct __user *) arg);
                 break;
+        case TIOCMIWAIT:
+                rv = wait_serial_change(acm, arg);
+                break;
         }
 
         return rv;
@@ -1167,6 +1227,7 @@ made_compressed_probe:
         acm->readsize = readsize;
         acm->rx_buflimit = num_rx_buf;
         INIT_WORK(&acm->work, acm_softint);
+        init_waitqueue_head(&acm->wioctl);
         spin_lock_init(&acm->write_lock);
         spin_lock_init(&acm->read_lock);
         mutex_init(&acm->mutex);
@@ -1383,6 +1444,7 @@ static void acm_disconnect(struct usb_interface *intf)
                 device_remove_file(&acm->control->dev,
                                 &dev_attr_iCountryCodeRelDate);
         }
+        wake_up_all(&acm->wioctl);
         device_remove_file(&acm->control->dev, &dev_attr_bmCapabilities);
         usb_set_intfdata(acm->control, NULL);
         usb_set_intfdata(acm->data, NULL);
diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index 0f76e4af600e..e38dc785808f 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -106,6 +106,9 @@ struct acm {
         struct work_struct work;                        /* work queue entry for line discipline waking up */
         unsigned int ctrlin;                            /* input control lines (DCD, DSR, RI, break, overruns) */
         unsigned int ctrlout;                           /* output control lines (DTR, RTS) */
+        struct async_icount iocount;                    /* counters for control line changes */
+        struct async_icount oldcount;                   /* for comparison of counter */
+        wait_queue_head_t wioctl;                       /* for ioctl */
         unsigned int writesize;                         /* max packet size for the output bulk endpoint */
         unsigned int readsize,ctrlsize;                 /* buffer sizes for freeing */
         unsigned int minor;                             /* acm minor number */