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serial: 8250: Support rs485 devicetree properties

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Retrieve rs485 devicetree properties on registration of 8250 ports in
case they are attached to an rs485 transceiver.

If the property "linux,rs485-enabled-at-boot-time" is present, invoke
the ->rs485_config() callback to immediately deassert RTS, thereby
ceasing control of the bus.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Giulio Benetti <giulio.benetti@micronovasrl.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/5908ea89b7f9da54872d6634b606d83db032297a.1582895077.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lukas Wunner 2020-02-28 14:31:02 +01:00 committed by Greg Kroah-Hartman
parent f45709df77
commit fe7f0fa43c
2 changed files with 6 additions and 1 deletions
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4
drivers/tty/serial/8250/8250_core.c
View File

@ -1013,8 +1013,10 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
if (uart->port.fifosize && !uart->tx_loadsz)
uart->tx_loadsz = uart->port.fifosize;
if (up->port.dev)
if (up->port.dev) {
uart->port.dev = up->port.dev;
uart_get_rs485_mode(uart->port.dev, &uart->port.rs485);
}
if (up->port.flags & UPF_FIXED_TYPE)
uart->port.type = up->port.type;

3
drivers/tty/serial/8250/8250_port.c
View File

@ -2989,6 +2989,9 @@ static void serial8250_config_port(struct uart_port *port, int flags)
if (flags & UART_CONFIG_TYPE)
autoconfig(up);
if (port->rs485.flags & SER_RS485_ENABLED)
port->rs485_config(port, &port->rs485);
/* if access method is AU, it is a 16550 with a quirk */
if (port->type == PORT_16550A && port->iotype == UPIO_AU)
up->bugs |= UART_BUG_NOMSR;