USB: RTS/CTS handshaking support, DTR fixes for MCT U232 serial adapter
Improvements and fixes to the MCT U232 USB/serial interface driver.
Implement RTS/CTS hardware flow control. Implement HUPCL. Bring
handling of DTR and RTS into conformance with other Linux serial
port drivers - assert both signals when opening device, even if
"crtscts" is not currently selected.
Signed-off-by: Dave Platt <dplatt@radagast.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/serial/mct_u232.h b/drivers/usb/serial/mct_u232.h
index 73dd0d9..a61bac8 100644
--- a/drivers/usb/serial/mct_u232.h
+++ b/drivers/usb/serial/mct_u232.h
@@ -63,14 +63,15 @@
#define MCT_U232_SET_UNKNOWN1_REQUEST 11 /* Unknown functionality */
#define MCT_U232_SET_UNKNOWN1_SIZE 1
-/* This USB device request code is not well understood. It is transmitted by
- the MCT-supplied Windows driver whenever the baud rate changes.
+/* This USB device request code appears to control whether CTS is required
+ during transmission.
- Without this USB device request, the USB/RS-232 adapter will not write to
- RS-232 devices which do not assert the 'CTS' signal.
+ Sending a zero byte allows data transmission to a device which is not
+ asserting CTS. Sending a '1' byte will cause transmission to be deferred
+ until the device asserts CTS.
*/
-#define MCT_U232_SET_UNKNOWN2_REQUEST 12 /* Unknown functionality */
-#define MCT_U232_SET_UNKNOWN2_SIZE 1
+#define MCT_U232_SET_CTS_REQUEST 12
+#define MCT_U232_SET_CTS_SIZE 1
/*
* Baud rate (divisor)
@@ -439,7 +440,7 @@
* which says "U232-P9" ;-)
*
* The circuit board inside the adaptor contains a Philips PDIUSBD12
- * USB endpoint chip and a Phillips P87C52UBAA microcontroller with
+ * USB endpoint chip and a Philips P87C52UBAA microcontroller with
* embedded UART. Exhaustive documentation for these is available at:
*
* http://www.semiconductors.philips.com/pip/p87c52ubaa