linux-kernel - [PATCH 13/36] serial: ar933x: Fill in rs485

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Date:   Mon,  6 Jun 2022 13:04:10 +0300
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     linux-serial@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>, linux-kernel@...r.kernel.org
Cc:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 13/36] serial: ar933x: Fill in rs485_supported

Add information on supported serial_rs485 features.

In the case where RTS is lacking, RS485 cannot be enabled so provide
zero rs485_supported for that case. Perhaps it would make sense to not
provide rs485_config() at all in that case but such a change would have
userspace visible impact/change in behavior so this patch does not
attempt it.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 drivers/tty/serial/ar933x_uart.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/tty/serial/ar933x_uart.c b/drivers/tty/serial/ar933x_uart.c
index 6269dbf93546..ab2c5b2a1ce8 100644
--- a/drivers/tty/serial/ar933x_uart.c
+++ b/drivers/tty/serial/ar933x_uart.c
@@ -702,6 +702,11 @@ static struct uart_driver ar933x_uart_driver = {
 	.cons		= NULL, /* filled in runtime */
 };
 
+static const struct serial_rs485 ar933x_no_rs485 = {};
+static const struct serial_rs485 ar933x_rs485_supported = {
+	.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND,
+};
+
 static int ar933x_uart_probe(struct platform_device *pdev)
 {
 	struct ar933x_uart_port *up;
@@ -773,6 +778,7 @@ static int ar933x_uart_probe(struct platform_device *pdev)
 	port->fifosize = AR933X_UART_FIFO_SIZE;
 	port->ops = &ar933x_uart_ops;
 	port->rs485_config = ar933x_config_rs485;
+	port->rs485_supported = &ar933x_rs485_supported;
 
 	baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
 	up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);
@@ -796,6 +802,7 @@ static int ar933x_uart_probe(struct platform_device *pdev)
 	    !up->rts_gpiod) {
 		dev_err(&pdev->dev, "lacking rts-gpio, disabling RS485\n");
 		port->rs485.flags &= ~SER_RS485_ENABLED;
+		port->rs485_supported = &ar933x_no_rs485;
 	}
 
 #ifdef CONFIG_SERIAL_AR933X_CONSOLE
-- 
2.30.2