diff options
| -rw-r--r-- | drivers/usb/serial/generic.c | 102 | ||||
| -rw-r--r-- | include/linux/usb/serial.h | 6 |
2 files changed, 90 insertions, 18 deletions
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c index 601e0648dec6..53baeec8f265 100644 --- a/drivers/usb/serial/generic.c +++ b/drivers/usb/serial/generic.c @@ -66,6 +66,8 @@ struct usb_serial_driver usb_serial_generic_device = { .num_bulk_out = NUM_DONT_CARE, .num_ports = 1, .shutdown = usb_serial_generic_shutdown, + .throttle = usb_serial_generic_throttle, + .unthrottle = usb_serial_generic_unthrottle, }; static int generic_probe(struct usb_interface *interface, @@ -115,6 +117,7 @@ int usb_serial_generic_open (struct usb_serial_port *port, struct file *filp) { struct usb_serial *serial = port->serial; int result = 0; + unsigned long flags; dbg("%s - port %d", __FUNCTION__, port->number); @@ -124,7 +127,13 @@ int usb_serial_generic_open (struct usb_serial_port *port, struct file *filp) if (port->tty) port->tty->low_latency = 1; - /* if we have a bulk interrupt, start reading from it */ + /* clear the throttle flags */ + spin_lock_irqsave(&port->lock, flags); + port->throttled = 0; + port->throttle_req = 0; + spin_unlock_irqrestore(&port->lock, flags); + + /* if we have a bulk endpoint, start reading from it */ if (serial->num_bulk_in) { /* Start reading from the device */ usb_fill_bulk_urb (port->read_urb, serial->dev, @@ -253,31 +262,22 @@ int usb_serial_generic_chars_in_buffer (struct usb_serial_port *port) return (chars); } -void usb_serial_generic_read_bulk_callback (struct urb *urb) +/* Push data to tty layer and resubmit the bulk read URB */ +static void flush_and_resubmit_read_urb (struct usb_serial_port *port) { - struct usb_serial_port *port = (struct usb_serial_port *)urb->context; struct usb_serial *serial = port->serial; - struct tty_struct *tty; - unsigned char *data = urb->transfer_buffer; + struct urb *urb = port->read_urb; + struct tty_struct *tty = port->tty; int result; - dbg("%s - port %d", __FUNCTION__, port->number); - - if (urb->status) { - dbg("%s - nonzero read bulk status received: %d", __FUNCTION__, urb->status); - return; - } - - usb_serial_debug_data(debug, &port->dev, __FUNCTION__, urb->actual_length, data); - - tty = port->tty; + /* Push data to tty */ if (tty && urb->actual_length) { tty_buffer_request_room(tty, urb->actual_length); - tty_insert_flip_string(tty, data, urb->actual_length); - tty_flip_buffer_push(tty); + tty_insert_flip_string(tty, urb->transfer_buffer, urb->actual_length); + tty_flip_buffer_push(tty); /* is this allowed from an URB callback ? */ } - /* Continue trying to always read */ + /* Continue reading from device */ usb_fill_bulk_urb (port->read_urb, serial->dev, usb_rcvbulkpipe (serial->dev, port->bulk_in_endpointAddress), @@ -290,6 +290,40 @@ void usb_serial_generic_read_bulk_callback (struct urb *urb) if (result) dev_err(&port->dev, "%s - failed resubmitting read urb, error %d\n", __FUNCTION__, result); } + +void usb_serial_generic_read_bulk_callback (struct urb *urb) +{ + struct usb_serial_port *port = (struct usb_serial_port *)urb->context; + unsigned char *data = urb->transfer_buffer; + int is_throttled; + unsigned long flags; + + dbg("%s - port %d", __FUNCTION__, port->number); + + if (urb->status) { + dbg("%s - nonzero read bulk status received: %d", __FUNCTION__, urb->status); + return; + } + + usb_serial_debug_data(debug, &port->dev, __FUNCTION__, urb->actual_length, data); + + /* Throttle the device if requested by tty */ + if (urb->actual_length) { + spin_lock_irqsave(&port->lock, flags); + is_throttled = port->throttled = port->throttle_req; + spin_unlock_irqrestore(&port->lock, flags); + if (is_throttled) { + /* Let the received data linger in the read URB; + * usb_serial_generic_unthrottle() will pick it + * up later. */ + dbg("%s - throttling device", __FUNCTION__); + return; + } + } + + /* Handle data and continue reading from device */ + flush_and_resubmit_read_urb(port); +} EXPORT_SYMBOL_GPL(usb_serial_generic_read_bulk_callback); void usb_serial_generic_write_bulk_callback (struct urb *urb) @@ -308,6 +342,38 @@ void usb_serial_generic_write_bulk_callback (struct urb *urb) } EXPORT_SYMBOL_GPL(usb_serial_generic_write_bulk_callback); +void usb_serial_generic_throttle (struct usb_serial_port *port) +{ + unsigned long flags; + + dbg("%s - port %d", __FUNCTION__, port->number); + + /* Set the throttle request flag. It will be picked up + * by usb_serial_generic_read_bulk_callback(). */ + spin_lock_irqsave(&port->lock, flags); + port->throttle_req = 1; + spin_unlock_irqrestore(&port->lock, flags); +} + +void usb_serial_generic_unthrottle (struct usb_serial_port *port) +{ + int was_throttled; + unsigned long flags; + + dbg("%s - port %d", __FUNCTION__, port->number); + + /* Clear the throttle flags */ + spin_lock_irqsave(&port->lock, flags); + was_throttled = port->throttled; + port->throttled = port->throttle_req = 0; + spin_unlock_irqrestore(&port->lock, flags); + + if (was_throttled) { + /* Handle pending data and resume reading from device */ + flush_and_resubmit_read_urb(port); + } +} + void usb_serial_generic_shutdown (struct usb_serial *serial) { int i; diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h index 33dcd8576696..32acbae28d24 100644 --- a/include/linux/usb/serial.h +++ b/include/linux/usb/serial.h @@ -54,6 +54,8 @@ * @write_wait: a wait_queue_head_t used by the port. * @work: work queue entry for the line discipline waking up. * @open_count: number of times this port has been opened. + * @throttled: nonzero if the read urb is inactive to throttle the device + * @throttle_req: nonzero if the tty wants to throttle us * * This structure is used by the usb-serial core and drivers for the specific * ports of a device. @@ -88,6 +90,8 @@ struct usb_serial_port { wait_queue_head_t write_wait; struct work_struct work; int open_count; + char throttled; + char throttle_req; struct device dev; }; #define to_usb_serial_port(d) container_of(d, struct usb_serial_port, dev) @@ -269,6 +273,8 @@ extern int usb_serial_generic_write_room (struct usb_serial_port *port); extern int usb_serial_generic_chars_in_buffer (struct usb_serial_port *port); extern void usb_serial_generic_read_bulk_callback (struct urb *urb); extern void usb_serial_generic_write_bulk_callback (struct urb *urb); +extern void usb_serial_generic_throttle (struct usb_serial_port *port); +extern void usb_serial_generic_unthrottle (struct usb_serial_port *port); 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); |
