[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>

1 files changed, 18 insertions, 4 deletions

diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index 42ef9970bc86..df82116a9f26 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 serial core provides a few helper functions.  This includes identifing
 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 @@ hardware.
                 - 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 @@ hardware.
   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 @@ hardware.
         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 @@ hardware.
         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.