USB: serial: add generic TIOCMIWAIT implementation
Add generic TIOCMIWAIT implementation which correctly handles hangup,
USB-device disconnect, does not rely on the deprecated sleep_on
functions and hence does not suffer from the races currently affecting
several usb-serial drivers.
This makes it much easier to add TIOCMIWAIT support to subdrivers as the
tricky details related to hangup and disconnect (e.g. atomicity, that
the private port data may have been freed when woken up, and waking up
processes at disconnect) have been handled once and for all.
To add support to a subdriver, simply set the tiocmiwait-port-operation
field, update the port icount fields and wake up any process sleeping on
the tty-port modem-status-change wait queue on changes.
Note that the tty-port initialised flag can be used to detect
disconnected as the port will be hung up as part of disconnect (and
cannot be reactivated due to the disconnected flag). However, as the
tty-port implementation currently wakes up processes before calling port
shutdown, the tty-hupping flag must also be checked to detect hangup for
now.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 9c8b53f..47c8d2c 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/serial.h>
#include <linux/sysrq.h>
#include <linux/kfifo.h>
@@ -61,6 +62,7 @@
* @bulk_out_buffers: pointers to the bulk out buffers for this port
* @write_urbs: pointers to the bulk out urbs for this port
* @write_urbs_free: status bitmap the for bulk out urbs
+ * @icount: interrupt counters
* @tx_bytes: number of bytes currently in host stack queues
* @bulk_out_endpointAddress: endpoint address for the bulk out pipe for this
* port.
@@ -109,6 +111,7 @@
unsigned long write_urbs_free;
__u8 bulk_out_endpointAddress;
+ struct async_icount icount;
int tx_bytes;
unsigned long flags;
@@ -330,6 +333,8 @@
extern void usb_serial_generic_write_bulk_callback(struct urb *urb);
extern void usb_serial_generic_throttle(struct tty_struct *tty);
extern void usb_serial_generic_unthrottle(struct tty_struct *tty);
+extern int usb_serial_generic_tiocmiwait(struct tty_struct *tty,
+ unsigned long arg);
extern int usb_serial_generic_register(void);
extern void usb_serial_generic_deregister(void);
extern int usb_serial_generic_submit_read_urbs(struct usb_serial_port *port,