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 <[email protected]> --- 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 _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
