USB: serial: usb_debug,usb_generic_serial: implement sysrq and serial break

The usb_debug driver was modified to implement serial break handling
by using a "magic" data packet comprised of the sequence:

       0x00 0xff 0x01 0xfe   0x00 0xfe 0x01 0xff

When the tty layer requests a serial break the usb_debug driver sends
the magic packet.  On the receiving side the magic packet is thrown
away or a sysrq is activated depending on what kernel .config options
have been set.

The generic serial driver was modified as well as the usb serial
headers to generically implement sysrq processing in the same way the
non usb uart based drivers implement the sysrq handling.  This will
allow other usb serial devices to implement sysrq handling as desired.

The new usb serial functions are named similarly and implemented
similarly to the uart functions as follows:

usb_serial_handle_break <-> uart_handle_break
usb_serial_handle_sysrq_char <-> uart_handle_sysrq_char

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index e2938fd179e2..e29ebcf3287b 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -15,6 +15,7 @@
 
 #include <linux/kref.h>
 #include <linux/mutex.h>
+#include <linux/sysrq.h>
 
 #define SERIAL_TTY_MAJOR        188     /* Nice legal number now */
 #define SERIAL_TTY_MINORS       254     /* loads of devices :) */
@@ -99,6 +100,7 @@ struct usb_serial_port {
         char                    throttled;
         char                    throttle_req;
         char                    console;
+        unsigned long           sysrq; /* sysrq timeout */
         struct device           dev;
 };
 #define to_usb_serial_port(d) container_of(d, struct usb_serial_port, dev)
@@ -301,6 +303,12 @@ extern void usb_serial_generic_unthrottle(struct tty_struct *tty);
 extern void usb_serial_generic_shutdown(struct usb_serial *serial);
 extern int usb_serial_generic_register(int debug);
 extern void usb_serial_generic_deregister(void);
+extern void usb_serial_generic_resubmit_read_urb(struct usb_serial_port *port,
+                                                 gfp_t mem_flags);
+extern int usb_serial_handle_sysrq_char(struct usb_serial_port *port,
+                                        unsigned int ch);
+extern int usb_serial_handle_break(struct usb_serial_port *port);
+
 
 extern int usb_serial_bus_register(struct usb_serial_driver *device);
 extern void usb_serial_bus_deregister(struct usb_serial_driver *device);