path: root/Documentation/serial
diff options
authorRussell King <rmk@dyn-67.arm.linux.org.uk>2005-10-31 11:53:19 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2005-10-31 11:53:19 +0000
commit6a8f8d72bd2fe9964ee10c0f58b14d6370e49769 (patch)
tree547b037f60f4889a8702b4c4187739366b66c777 /Documentation/serial
parent0cf669d5c5d08eb827df9867429df21cf030eba6 (diff)
[SERIAL] Update serial_core documentation
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'Documentation/serial')
1 files changed, 57 insertions, 9 deletions
diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index 87856d3cfb6..42ef9970bc8 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -116,12 +116,15 @@ hardware.
line becoming inactive or the tty layer indicating we want
to stop transmission due to an XOFF character.
+ The driver should stop transmitting characters as soon as
+ possible.
Locking: port->lock taken.
Interrupts: locally disabled.
This call must not sleep
- start transmitting characters.
+ Start transmitting characters.
Locking: port->lock taken.
Interrupts: locally disabled.
@@ -281,26 +284,31 @@ hardware.
Other functions
Update the FIFO drain timeout, port->timeout, according to the
- number of bits, parity, stop bits and quotient.
+ number of bits, parity, stop bits and baud rate.
Locking: caller is expected to take port->lock
Interrupts: n/a
Return the numeric baud rate for the specified termios, taking
account of the special 38400 baud "kludge". The B0 baud rate
is mapped to 9600 baud.
+ If the baud rate is not within min..max, then if old is non-NULL,
+ the original baud rate will be tried. If that exceeds the
+ min..max constraint, 9600 baud will be returned. termios will
+ be updated to the baud rate in use.
+ Note: min..max must always allow 9600 baud to be selected.
Locking: caller dependent.
Interrupts: n/a
- Return the divsor (baud_base / baud) for the selected baud rate
- specified by termios. If the baud rate is out of range, try
- the original baud rate specified by oldtermios (if non-NULL).
- If that fails, try 9600 baud.
+ Return the divsor (baud_base / baud) for the specified baud
+ rate, appropriately rounded.
If 38400 baud and custom divisor is selected, return the
custom divisor instead.
@@ -308,6 +316,46 @@ uart_get_divisor(port,termios,oldtermios)
Locking: caller dependent.
Interrupts: n/a
+ This utility function can be used to determine whether two
+ uart_port structures describe the same port.
+ Locking: n/a
+ Interrupts: n/a
+ A driver is expected to call this function when the number of
+ characters in the transmit buffer have dropped below a threshold.
+ Locking: port->lock should be held.
+ Interrupts: n/a
+ Register a uart driver with the core driver. We in turn register
+ with the tty layer, and initialise the core driver per-port state.
+ drv->port should be NULL, and the per-port structures should be
+ registered using uart_add_one_port after this call has succeeded.
+ Locking: none
+ Interrupts: enabled
+ Remove all references to a driver from the core driver. The low
+ level driver must have removed all its ports via the
+ uart_remove_one_port() if it registered them with uart_add_one_port().
+ Locking: none
+ Interrupts: enabled
Other notes