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, 10 insertions, 2 deletions

diff --git a/drivers/usb/gadget/u_serial.h b/drivers/usb/gadget/u_serial.h
index 7b561138f90e..af3910d01aea 100644
--- a/drivers/usb/gadget/u_serial.h
+++ b/drivers/usb/gadget/u_serial.h
@@ -23,8 +23,7 @@
  * style I/O using the USB peripheral endpoints listed here, including
  * hookups to sysfs and /dev for each logical "tty" device.
  *
- * REVISIT need TTY --> USB event flow too, so ACM can report open/close
- * as carrier detect events.  Model after ECM.  There's more ACM state too.
+ * REVISIT at least ACM could support tiocmget() if needed.
  *
  * REVISIT someday, allow multiplexing several TTYs over these endpoints.
  */
@@ -41,8 +40,17 @@ struct gserial {
 
         /* REVISIT avoid this CDC-ACM support harder ... */
         struct usb_cdc_line_coding port_line_coding;    /* 9600-8-N-1 etc */
+
+        /* notification callbacks */
+        void (*connect)(struct gserial *p);
+        void (*disconnect)(struct gserial *p);
+        int (*send_break)(struct gserial *p, int duration);
 };
 
+/* utilities to allocate/free request and buffer */
+struct usb_request *gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t flags);
+void gs_free_req(struct usb_ep *, struct usb_request *req);
+
 /* port setup/teardown is handled by gadget driver */
 int gserial_setup(struct usb_gadget *g, unsigned n_ports);
 void gserial_cleanup(void);