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