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serial: Add common rs485 device tree parsing function

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Several drivers have the same device tree parsing code. Create
a common helper function for it.

This patch bases on work done by Sascha Hauer.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Uwe Kleine-König 2017-09-13 10:18:27 +02:00 committed by Greg Kroah-Hartman
parent c45e2d2547
commit ef838a81dd
2 changed files with 41 additions and 0 deletions
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36
drivers/tty/serial/serial_core.c
View File

@ -3026,5 +3026,41 @@ EXPORT_SYMBOL(uart_resume_port);
EXPORT_SYMBOL(uart_add_one_port);
EXPORT_SYMBOL(uart_remove_one_port);
/**
* of_get_rs485_mode() - Implement parsing rs485 properties
* @np: uart node
* @rs485conf: output parameter
*
* This function implements the device tree binding described in
* Documentation/devicetree/bindings/serial/rs485.txt.
*/
void of_get_rs485_mode(struct device_node *np, struct serial_rs485 *rs485conf)
{
u32 rs485_delay[2];
int ret;
ret = of_property_read_u32_array(np, "rs485-rts-delay", rs485_delay, 2);
if (!ret) {
rs485conf->delay_rts_before_send = rs485_delay[0];
rs485conf->delay_rts_after_send = rs485_delay[1];
} else {
rs485conf->delay_rts_before_send = 0;
rs485conf->delay_rts_after_send = 0;
}
/*
* clear full-duplex and enabled flags to get to a defined state with
* the two following properties.
*/
rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED);
if (of_property_read_bool(np, "rs485-rx-during-tx"))
rs485conf->flags |= SER_RS485_RX_DURING_TX;
if (of_property_read_bool(np, "linux,rs485-enabled-at-boot-time"))
rs485conf->flags |= SER_RS485_ENABLED;
}
EXPORT_SYMBOL_GPL(of_get_rs485_mode);
MODULE_DESCRIPTION("Serial driver core");
MODULE_LICENSE("GPL");

5
include/linux/serial_core.h
View File

@ -501,4 +501,9 @@ static inline int uart_handle_break(struct uart_port *port)
(cflag) & CRTSCTS || \
!((cflag) & CLOCAL))
/*
* Common device tree parsing helpers
*/
void of_get_rs485_mode(struct device_node *np, struct serial_rs485 *rs485conf);
#endif /* LINUX_SERIAL_CORE_H */