Commit e2752ae3 authored by Lukas Wunner's avatar Lukas Wunner Committed by Greg Kroah-Hartman
Browse files

serial: omap: Disallow RS-485 if rts-gpio is not specified 



The serial-omap driver requires an rts-gpio for RS-485 to work.
Historically it has allowed enabling RS-485 even if no rts-gpio was
specified in the device tree.

That doesn't make any sense, so disable RS-485 on probe if rts-gpio is
missing and disallow user space from enabling it.

Three NULL pointer checks for up->rts_gpiod can be dropped as a result,
simplifying the driver slightly.

Cc: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/f191dcca0d8ea03598c463fc0d3fba8941ff2275.1662888075.git.lukas@wunner.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ed9f4bb3

drivers/tty/serial/omap-serial.c

+13 −14
Original line number Diff line number Diff line
@@ -300,8 +300,7 @@ static void serial_omap_stop_tx(struct uart_port *port) 
			serial_out(up, UART_OMAP_SCR, up->scr);

			res = (port->rs485.flags & SER_RS485_RTS_AFTER_SEND) ?

				1 : 0;

			if (up->rts_gpiod &&

			    gpiod_get_value(up->rts_gpiod) != res) {

			if (gpiod_get_value(up->rts_gpiod) != res) {

				if (port->rs485.delay_rts_after_send > 0)

					mdelay(

					port->rs485.delay_rts_after_send);
@@ -397,7 +396,7 @@ static void serial_omap_start_tx(struct uart_port *port) 


		/* if rts not already enabled */

		res = (port->rs485.flags & SER_RS485_RTS_ON_SEND) ? 1 : 0;

		if (up->rts_gpiod && gpiod_get_value(up->rts_gpiod) != res) {

		if (gpiod_get_value(up->rts_gpiod) != res) {

			gpiod_set_value(up->rts_gpiod, res);

			if (port->rs485.delay_rts_before_send > 0)

				mdelay(port->rs485.delay_rts_before_send);
@@ -1336,13 +1335,11 @@ serial_omap_config_rs485(struct uart_port *port, struct ktermios *termios, 
	up->ier = 0;

	serial_out(up, UART_IER, 0);



	if (up->rts_gpiod) {

	/* enable / disable rts */

	val = (rs485->flags & SER_RS485_ENABLED) ?

	      SER_RS485_RTS_AFTER_SEND : SER_RS485_RTS_ON_SEND;

	val = (rs485->flags & val) ? 1 : 0;

	gpiod_set_value(up->rts_gpiod, val);

	}



	/* Enable interrupts */

	up->ier = mode;
@@ -1547,11 +1544,13 @@ static int serial_omap_probe_rs485(struct uart_omap_port *up, 
		ret = PTR_ERR(up->rts_gpiod);

	        if (ret == -EPROBE_DEFER)

			return ret;

		/*

		 * FIXME: the code historically ignored any other error than

		 * -EPROBE_DEFER and just went on without GPIO.

		 */



		up->rts_gpiod = NULL;

		up->port.rs485_supported = (const struct serial_rs485) { };

		if (rs485conf->flags & SER_RS485_ENABLED) {

			dev_err(dev, "disabling RS-485 (rts-gpio missing in device tree)\n");

			memset(rs485conf, 0, sizeof(*rs485conf));

		}

	} else {

		gpiod_set_consumer_name(up->rts_gpiod, "omap-serial");

	}