usb gadget: issue notifications from ACM function

Update the CDC-ACM gadget code to support the peripheral-to-host
notifications when the tty is opened or closed, or issues a BREAK.
The serial framework code calls new generic hooks; right now only
CDC-ACM uses those hooks.  This resolves several REVISIT comments
in the code.  (Based on a patch from Felipe Balbi.)

Note that this doesn't expose USB_CDC_CAP_BRK to the host, since
this code still rejects USB_CDC_REQ_SEND_BREAK control requests
for host-to-peripheral BREAK signaling (received via /dev/ttyGS*).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 42 insertions, 14 deletions

diff --git a/drivers/usb/gadget/u_serial.c b/drivers/usb/gadget/u_serial.c
index 6641efa55639..53d59287f2bc 100644
--- a/drivers/usb/gadget/u_serial.c
+++ b/drivers/usb/gadget/u_serial.c
@@ -60,7 +60,8 @@
  * tty_struct links to the tty/filesystem framework
  *
  * gserial <---> gs_port ... links will be null when the USB link is
- * inactive; managed by gserial_{connect,disconnect}().
+ * inactive; managed by gserial_{connect,disconnect}().  each gserial
+ * instance can wrap its own USB control protocol.
  *      gserial->ioport == usb_ep->driver_data ... gs_port
  *      gs_port->port_usb ... gserial
  *
@@ -181,7 +182,7 @@ static void gs_buf_clear(struct gs_buf *gb)
 /*
  * gs_buf_data_avail
  *
- * Return the number of bytes of data available in the circular
+ * Return the number of bytes of data written into the circular
  * buffer.
  */
 static unsigned gs_buf_data_avail(struct gs_buf *gb)
@@ -282,7 +283,7 @@ gs_buf_get(struct gs_buf *gb, char *buf, unsigned count)
  * Allocate a usb_request and its buffer.  Returns a pointer to the
  * usb_request or NULL if there is an error.
  */
-static struct usb_request *
+struct usb_request *
 gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
 {
         struct usb_request *req;
@@ -306,7 +307,7 @@ gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
  *
  * Free a usb_request and its buffer.
  */
-static void gs_free_req(struct usb_ep *ep, struct usb_request *req)
+void gs_free_req(struct usb_ep *ep, struct usb_request *req)
 {
         kfree(req->buf);
         usb_ep_free_request(ep, req);
@@ -788,10 +789,13 @@ static int gs_open(struct tty_struct *tty, struct file *file)
 
         /* if connected, start the I/O stream */
         if (port->port_usb) {
+                struct gserial  *gser = port->port_usb;
+
                 pr_debug("gs_open: start ttyGS%d\n", port->port_num);
                 gs_start_io(port);
 
-                /* REVISIT for ACM, issue "network connected" event */
+                if (gser->connect)
+                        gser->connect(gser);
         }
 
         pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
@@ -818,6 +822,7 @@ static int gs_writes_finished(struct gs_port *p)
 static void gs_close(struct tty_struct *tty, struct file *file)
 {
         struct gs_port *port = tty->driver_data;
+        struct gserial  *gser;
 
         spin_lock_irq(&port->port_lock);
 
@@ -837,26 +842,27 @@ static void gs_close(struct tty_struct *tty, struct file *file)
         port->openclose = true;
         port->open_count = 0;
 
-        if (port->port_usb)
-                /* REVISIT for ACM, issue "network disconnected" event */;
+        gser = port->port_usb;
+        if (gser && gser->disconnect)
+                gser->disconnect(gser);
 
         /* wait for circular write buffer to drain, disconnect, or at
          * most GS_CLOSE_TIMEOUT seconds; then discard the rest
          */
-        if (gs_buf_data_avail(&port->port_write_buf) > 0
-                        && port->port_usb) {
+        if (gs_buf_data_avail(&port->port_write_buf) > 0 && gser) {
                 spin_unlock_irq(&port->port_lock);
                 wait_event_interruptible_timeout(port->drain_wait,
                                         gs_writes_finished(port),
                                         GS_CLOSE_TIMEOUT * HZ);
                 spin_lock_irq(&port->port_lock);
+                gser = port->port_usb;
         }
 
         /* Iff we're disconnected, there can be no I/O in flight so it's
          * ok to free the circular buffer; else just scrub it.  And don't
          * let the push tasklet fire again until we're re-opened.
          */
-        if (port->port_usb == NULL)
+        if (gser == NULL)
                 gs_buf_free(&port->port_write_buf);
         else
                 gs_buf_clear(&port->port_write_buf);
@@ -974,6 +980,24 @@ static void gs_unthrottle(struct tty_struct *tty)
         spin_unlock_irqrestore(&port->port_lock, flags);
 }
 
+static int gs_break_ctl(struct tty_struct *tty, int duration)
+{
+        struct gs_port  *port = tty->driver_data;
+        int             status = 0;
+        struct gserial  *gser;
+
+        pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
+                        port->port_num, duration);
+
+        spin_lock_irq(&port->port_lock);
+        gser = port->port_usb;
+        if (gser && gser->send_break)
+                status = gser->send_break(gser, duration);
+        spin_unlock_irq(&port->port_lock);
+
+        return status;
+}
+
 static const struct tty_operations gs_tty_ops = {
         .open =                 gs_open,
         .close =                gs_close,
@@ -983,6 +1007,7 @@ static const struct tty_operations gs_tty_ops = {
         .write_room =           gs_write_room,
         .chars_in_buffer =      gs_chars_in_buffer,
         .unthrottle =           gs_unthrottle,
+        .break_ctl =            gs_break_ctl,
 };
 
 /*-------------------------------------------------------------------------*/
@@ -1230,14 +1255,17 @@ int gserial_connect(struct gserial *gser, u8 port_num)
 
         /* REVISIT if waiting on "carrier detect", signal. */
 
-        /* REVISIT for ACM, issue "network connection" status notification:
-         * connected if open_count, else disconnected.
+        /* if it's already open, start I/O ... and notify the serial
+         * protocol about open/close status (connect/disconnect).
          */
-
-        /* if it's already open, start I/O */
         if (port->open_count) {
                 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
                 gs_start_io(port);
+                if (gser->connect)
+                        gser->connect(gser);
+        } else {
+                if (gser->disconnect)
+                        gser->disconnect(gser);
         }
 
         spin_unlock_irqrestore(&port->port_lock, flags);