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@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/imx.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 9ce09b81ac9b..ba853bc9b4db 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2200,6 +2200,14 @@ static enum hrtimer_restart imx_trigger_stop_tx(struct hrtimer *t)
return HRTIMER_NORESTART;
}
+static const struct serial_rs485 imx_no_rs485 = {}; /* No RS485 if no RTS */
+static const struct serial_rs485 imx_rs485_supported = {
+ .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND |
+ SER_RS485_RX_DURING_TX,
+ .delay_rts_before_send = 1,
+ .delay_rts_after_send = 1,
+};
+
/* Default RX DMA buffer configuration */
#define RX_DMA_PERIODS 16
#define RX_DMA_PERIOD_LEN (PAGE_SIZE / 4)
@@ -2279,6 +2287,11 @@ static int imx_uart_probe(struct platform_device *pdev)
sport->port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE);
sport->port.ops = &imx_uart_pops;
sport->port.rs485_config = imx_uart_rs485_config;
+ /* RTS is required to control the RS485 transmitter */
+ if (sport->have_rtscts || sport->have_rtsgpio)
+ sport->port.rs485_supported = &imx_rs485_supported;
+ else
+ sport->port.rs485_supported = &imx_no_rs485;
sport->port.flags = UPF_BOOT_AUTOCONF;
timer_setup(&sport->timer, imx_uart_timeout, 0);
--
2.30.2
