The peripheral has support for inverting its input and/or output
signals. This is useful if the hardware flips polarity of the
peripheral's signal, such as swapped +/- pins on an RS-422 transceiver,
or an inverting level shifter. Add support for these control registers
via the device tree binding.
Signed-off-by: George Hilliard <ghilliard@xxxxxxxxxxxxxxx>
---
v1..v2: Remove confidentiality spam
v2..v3: Set *and* clear register, and do it before TX enable
drivers/tty/serial/imx.c | 28 +++++++++++++++++++++++-----
1 file changed, 23 insertions(+), 5 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 0c6c63166250..205627bcad66 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -195,6 +195,8 @@ struct imx_port {
unsigned int have_rtscts:1;
unsigned int have_rtsgpio:1;
unsigned int dte_mode:1;
+ unsigned int inverted_tx:1;
+ unsigned int inverted_rx:1;
struct clk *clk_ipg;
struct clk *clk_per;
const struct imx_uart_data *devdata;
@@ -1335,7 +1337,7 @@ static int imx_uart_startup(struct uart_port *port)
int retval, i;
unsigned long flags;
int dma_is_inited = 0;
- u32 ucr1, ucr2, ucr4;
+ u32 ucr1, ucr2, ucr3, ucr4;
retval = clk_prepare_enable(sport->clk_per);
if (retval)
@@ -1390,8 +1392,22 @@ static int imx_uart_startup(struct uart_port *port)
ucr4 = imx_uart_readl(sport, UCR4) & ~UCR4_OREN;
if (!sport->dma_is_enabled)
ucr4 |= UCR4_OREN;
+ if (sport->inverted_rx)
+ ucr4 |= UCR4_INVR;
+ else
+ ucr4 &= ~UCR4_INVR;
imx_uart_writel(sport, ucr4, UCR4);
+ /*
+ * configure tx polarity before enabling tx
+ */
+ ucr3 = imx_uart_readl(sport, UCR3);
+ if (sport->inverted_tx)
+ ucr3 |= UCR3_INVT;
+ else
+ ucr3 &= ~UCR3_INVT;
+ imx_uart_writel(sport, ucr3, UCR3);
+
ucr2 = imx_uart_readl(sport, UCR2) & ~UCR2_ATEN;
ucr2 |= (UCR2_RXEN | UCR2_TXEN);
if (!sport->have_rtscts)
@@ -1405,10 +1421,6 @@ static int imx_uart_startup(struct uart_port *port)
imx_uart_writel(sport, ucr2, UCR2);
if (!imx_uart_is_imx1(sport)) {
- u32 ucr3;
-
- ucr3 = imx_uart_readl(sport, UCR3);
-
ucr3 |= UCR3_DTRDEN | UCR3_RI | UCR3_DCD;
if (sport->dte_mode)
@@ -2184,6 +2196,12 @@ static int imx_uart_probe_dt(struct imx_port *sport,
if (of_get_property(np, "rts-gpios", NULL))
sport->have_rtsgpio = 1;
+ if (of_get_property(np, "fsl,inverted-tx", NULL))
+ sport->inverted_tx = 1;
+
+ if (of_get_property(np, "fsl,inverted-rx", NULL))
+ sport->inverted_rx = 1;
+
return 0;
}
#else
--
2.25.0
