[SERIAL] Update serial driver documentation
Improve serial driver documentation:
- Remove CVS id.
- Update pointer to reference driver documentation.
- Add comments about new uart_write_console function.
- Add TIOCM_LOOP modem control bit description.
- Add commentry about enable_ms method being called multiple times.
- Add commentry about startup/shutdown method calling.
- Mention that dereferencing port->info after shutdown is invalid.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index 42ef997..df82116 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -3,14 +3,11 @@
--------------------
- $Id: driver,v 1.10 2002/07/22 15:27:30 rmk Exp $
-
-
This document is meant as a brief overview of some aspects of the new serial
driver. It is not complete, any questions you have should be directed to
<rmk@arm.linux.org.uk>
-The reference implementation is contained within serial_amba.c.
+The reference implementation is contained within amba_pl011.c.
@@ -31,6 +28,11 @@
the correct port structure (via uart_get_console) and decoding command line
arguments (uart_parse_options).
+There is also a helper function (uart_write_console) which performs a
+character by character write, translating newlines to CRLF sequences.
+Driver writers are recommended to use this function rather than implementing
+their own version.
+
Locking
-------
@@ -86,6 +88,7 @@
- TIOCM_DTR DTR signal.
- TIOCM_OUT1 OUT1 signal.
- TIOCM_OUT2 OUT2 signal.
+ - TIOCM_LOOP Set the port into loopback mode.
If the appropriate bit is set, the signal should be driven
active. If the bit is clear, the signal should be driven
inactive.
@@ -141,6 +144,10 @@
enable_ms(port)
Enable the modem status interrupts.
+ This method may be called multiple times. Modem status
+ interrupts should be disabled when the shutdown method is
+ called.
+
Locking: port->lock taken.
Interrupts: locally disabled.
This call must not sleep
@@ -160,6 +167,8 @@
state. Enable the port for reception. It should not activate
RTS nor DTR; this will be done via a separate call to set_mctrl.
+ This method will only be called when the port is initially opened.
+
Locking: port_sem taken.
Interrupts: globally disabled.
@@ -169,6 +178,11 @@
RTS nor DTR; this will have already been done via a separate
call to set_mctrl.
+ Drivers must not access port->info once this call has completed.
+
+ This method will only be called when there are no more users of
+ this port.
+
Locking: port_sem taken.
Interrupts: caller dependent.