If we have a "linux,rs485-enabled-at-boot-time" DT property, we should
set CTS flag as soon as possible to the active state. This will set an
RS485 transmitter to receive-enable mode. Otherwise the RS485 bus will
be blocked for entire system boot time and other bus participants will
not be able to communicate.
Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
---
drivers/serial/serial_imx.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/serial/serial_imx.c b/drivers/serial/serial_imx.c
index c0265fc2d7..fe9b15d8b5 100644
--- a/drivers/serial/serial_imx.c
+++ b/drivers/serial/serial_imx.c
@@ -60,6 +60,7 @@ struct imx_serial_priv {
void __iomem *regs;
struct clk *clk;
struct imx_serial_devtype_data *devtype;
+ bool rs485_mode;
};
static int imx_serial_reffreq(struct imx_serial_priv *priv)
@@ -107,6 +108,9 @@ static int imx_serial_init_port(struct console_device *cdev)
/* Enable FIFOs */
val = readl(regs + UCR2);
+ /* set CTS to not block RS485 bus */
+ if (priv->rs485_mode)
+ val |= UCR2_CTS;
val |= UCR2_SRST | UCR2_RXEN | UCR2_TXEN;
writel(val, regs + UCR2);
@@ -252,6 +256,10 @@ static int imx_serial_probe(struct device_d *dev)
if (of_property_read_bool(dev->device_node, "fsl,dte-mode"))
priv->dte_mode = 1;
+ if (of_property_read_bool(dev->device_node,
+ "linux,rs485-enabled-at-boot-time"))
+ priv->rs485_mode = 1;
+
imx_serial_init_port(cdev);
/* Enable UART */
--
2.28.0
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