* [PATCH v2 0/2] Implement support for inverted serial TX/RX on i.MX
@ 2020-02-10 19:29 George Hilliard
2020-02-10 19:29 ` [PATCH v2 1/2] dt-bindings: serial: document fsl,inverted-tx and -rx options George Hilliard
2020-02-10 19:29 ` [PATCH v2 2/2] tty: imx serial: Implement support for reversing TX and RX polarity George Hilliard
0 siblings, 2 replies; 7+ messages in thread
From: George Hilliard @ 2020-02-10 19:29 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: George Hilliard, NXP Linux Team, linux-serial, devicetree, kernel
This peripheral has dedicated control bits that flip input/output
signals before handing them off to the OS. This is useful on my
hardware because the UART is connected to an RS-422 transceiver with the
+/- pins hooked up backward. Instead of a hack flipping all the bits
before sending them, the hardware can do it for free.
Functionally unchanged from v1, but the confidentiality notice has been
removed. I also CC'd other lists that Uwe suggested.
George Hilliard (2):
dt-bindings: serial: document fsl,inverted-tx and -rx options
tty: imx serial: Implement support for reversing TX and RX polarity
.../bindings/serial/fsl-imx-uart.txt | 4 ++++
drivers/tty/serial/imx.c | 22 +++++++++++++------
2 files changed, 19 insertions(+), 7 deletions(-)
--
2.25.0
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 1/2] dt-bindings: serial: document fsl,inverted-tx and -rx options
2020-02-10 19:29 [PATCH v2 0/2] Implement support for inverted serial TX/RX on i.MX George Hilliard
@ 2020-02-10 19:29 ` George Hilliard
2020-02-10 19:29 ` [PATCH v2 2/2] tty: imx serial: Implement support for reversing TX and RX polarity George Hilliard
1 sibling, 0 replies; 7+ messages in thread
From: George Hilliard @ 2020-02-10 19:29 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: George Hilliard, NXP Linux Team, linux-serial, devicetree, kernel
Add a description for the new fsl,inverted-tx and fsl,inverted-rx
options for the i.MX UART peripheral.
Signed-off-by: George Hilliard <ghilliard@kopismobile.com>
---
v1..v2: Removed confidentiality spam
Documentation/devicetree/bindings/serial/fsl-imx-uart.txt | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt b/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt
index 35957cbf1571..c8d677f9491f 100644
--- a/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt
+++ b/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt
@@ -8,6 +8,10 @@ Required properties:
Optional properties:
- fsl,dte-mode : Indicate the uart works in DTE mode. The uart works
in DCE mode by default.
+- fsl,inverted-tx , fsl,inverted-rx : Indicate that the hardware attached
+ to the peripheral inverts the signal transmitted or received,
+ respectively, and that the peripheral should invert its output/input
+ using the INVT/INVR registers.
- rs485-rts-delay, rs485-rts-active-low, rs485-rx-during-tx,
linux,rs485-enabled-at-boot-time: see rs485.txt. Note that for RS485
you must enable either the "uart-has-rtscts" or the "rts-gpios"
--
2.25.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 2/2] tty: imx serial: Implement support for reversing TX and RX polarity
2020-02-10 19:29 [PATCH v2 0/2] Implement support for inverted serial TX/RX on i.MX George Hilliard
2020-02-10 19:29 ` [PATCH v2 1/2] dt-bindings: serial: document fsl,inverted-tx and -rx options George Hilliard
@ 2020-02-10 19:29 ` George Hilliard
2020-02-10 20:50 ` Uwe Kleine-König
1 sibling, 1 reply; 7+ messages in thread
From: George Hilliard @ 2020-02-10 19:29 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: George Hilliard, NXP Linux Team, linux-serial, devicetree, kernel
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@kopismobile.com>
---
v1..v2: removed confidentiality spam
drivers/tty/serial/imx.c | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 0c6c63166250..467e78794997 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)
@@ -1390,6 +1392,8 @@ 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;
imx_uart_writel(sport, ucr4, UCR4);
ucr2 = imx_uart_readl(sport, UCR2) & ~UCR2_ATEN;
@@ -1404,19 +1408,17 @@ static int imx_uart_startup(struct uart_port *port)
ucr2 &= ~UCR2_RTSEN;
imx_uart_writel(sport, ucr2, UCR2);
+ ucr3 = imx_uart_readl(sport, UCR3);
+ if (sport->inverted_tx)
+ ucr3 |= UCR3_INVT;
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)
/* disable broken interrupts */
ucr3 &= ~(UCR3_RI | UCR3_DCD);
-
- imx_uart_writel(sport, ucr3, UCR3);
}
+ imx_uart_writel(sport, ucr3, UCR3);
/*
* Enable modem status interrupts
@@ -2184,6 +2186,12 @@ 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
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/2] tty: imx serial: Implement support for reversing TX and RX polarity
2020-02-10 19:29 ` [PATCH v2 2/2] tty: imx serial: Implement support for reversing TX and RX polarity George Hilliard
@ 2020-02-10 20:50 ` Uwe Kleine-König
2020-02-10 23:03 ` George Hilliard
0 siblings, 1 reply; 7+ messages in thread
From: Uwe Kleine-König @ 2020-02-10 20:50 UTC (permalink / raw)
To: George Hilliard
Cc: Greg Kroah-Hartman, kernel, devicetree, NXP Linux Team, linux-serial
Hello George,
On Mon, Feb 10, 2020 at 01:29:49PM -0600, George Hilliard wrote:
> @@ -1390,6 +1392,8 @@ 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;
You fail to clear this bit if .inverted_rx is false.
> imx_uart_writel(sport, ucr4, UCR4);
>
> ucr2 = imx_uart_readl(sport, UCR2) & ~UCR2_ATEN;
> @@ -1404,19 +1408,17 @@ static int imx_uart_startup(struct uart_port *port)
> ucr2 &= ~UCR2_RTSEN;
> imx_uart_writel(sport, ucr2, UCR2);
>
> + ucr3 = imx_uart_readl(sport, UCR3);
> + if (sport->inverted_tx)
> + ucr3 |= UCR3_INVT;
ditto.
Also I think setting this bit here is a bit late because UCR2_TXEN was
already set so changing UCR3_INVT probably results in a spike?!
> if (!imx_uart_is_imx1(sport)) {
> - u32 ucr3;
> -
> - ucr3 = imx_uart_readl(sport, UCR3);
> [...]
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/2] tty: imx serial: Implement support for reversing TX and RX polarity
2020-02-10 20:50 ` Uwe Kleine-König
@ 2020-02-10 23:03 ` George Hilliard
2020-02-11 7:38 ` Uwe Kleine-König
0 siblings, 1 reply; 7+ messages in thread
From: George Hilliard @ 2020-02-10 23:03 UTC (permalink / raw)
To: Uwe Kleine-König
Cc: Greg Kroah-Hartman, kernel, devicetree, NXP Linux Team, linux-serial
On Mon, Feb 10, 2020 at 2:50 PM Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
>
> Hello George,
>
> On Mon, Feb 10, 2020 at 01:29:49PM -0600, George Hilliard wrote:
> > @@ -1390,6 +1392,8 @@ 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;
>
> You fail to clear this bit if .inverted_rx is false.
I believe this is taken care of by the SRST asserted slightly above
this - UCR* is reset by this. I see that this reset is also done in the
imx_uart_flush_buffer() implementation, but as I understand it, this
is a cleanup method that doesn't reconfigure much of the peripheral.
> > imx_uart_writel(sport, ucr4, UCR4);
> >
> > ucr2 = imx_uart_readl(sport, UCR2) & ~UCR2_ATEN;
> > @@ -1404,19 +1408,17 @@ static int imx_uart_startup(struct uart_port *port)
> > ucr2 &= ~UCR2_RTSEN;
> > imx_uart_writel(sport, ucr2, UCR2);
> >
> > + ucr3 = imx_uart_readl(sport, UCR3);
> > + if (sport->inverted_tx)
> > + ucr3 |= UCR3_INVT;
>
> Also I think setting this bit here is a bit late because UCR2_TXEN was
> already set so changing UCR3_INVT probably results in a spike?!
Good point here; this should indeed be done before TX start.
George
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/2] tty: imx serial: Implement support for reversing TX and RX polarity
2020-02-10 23:03 ` George Hilliard
@ 2020-02-11 7:38 ` Uwe Kleine-König
2020-02-11 16:18 ` George Hilliard
0 siblings, 1 reply; 7+ messages in thread
From: Uwe Kleine-König @ 2020-02-11 7:38 UTC (permalink / raw)
To: George Hilliard
Cc: Greg Kroah-Hartman, kernel, devicetree, NXP Linux Team, linux-serial
Hello George,
On Mon, Feb 10, 2020 at 05:03:14PM -0600, George Hilliard wrote:
> On Mon, Feb 10, 2020 at 2:50 PM Uwe Kleine-König
> <u.kleine-koenig@pengutronix.de> wrote:
> > On Mon, Feb 10, 2020 at 01:29:49PM -0600, George Hilliard wrote:
> > > @@ -1390,6 +1392,8 @@ 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;
> >
> > You fail to clear this bit if .inverted_rx is false.
>
> I believe this is taken care of by the SRST asserted slightly above
> this - UCR* is reset by this.
The i.MX6 manual states: Reset the transmit and receive state machines,
all FIFOs and register USR1, USR2, UBIR, UBMR, UBRC, URXD, UTXD and
UTS[6-3]. UCR* isn't mentioned here. So please at least confirm your
belief experimentally.
> I see that this reset is also done in the imx_uart_flush_buffer()
> implementation, but as I understand it, this is a cleanup method that
> doesn't reconfigure much of the peripheral.
The comment there even has the above list of registers. If the
experiment I suggested above should confirm your believe IMHO this
function needs fixing anyhow.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/2] tty: imx serial: Implement support for reversing TX and RX polarity
2020-02-11 7:38 ` Uwe Kleine-König
@ 2020-02-11 16:18 ` George Hilliard
0 siblings, 0 replies; 7+ messages in thread
From: George Hilliard @ 2020-02-11 16:18 UTC (permalink / raw)
To: Uwe Kleine-König
Cc: Greg Kroah-Hartman, kernel, devicetree, NXP Linux Team, linux-serial
On Tue, Feb 11, 2020 at 1:38 AM Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
>
> Hello George,
>
> On Mon, Feb 10, 2020 at 05:03:14PM -0600, George Hilliard wrote:
> > On Mon, Feb 10, 2020 at 2:50 PM Uwe Kleine-König
> > <u.kleine-koenig@pengutronix.de> wrote:
> > > On Mon, Feb 10, 2020 at 01:29:49PM -0600, George Hilliard wrote:
> > > > @@ -1390,6 +1392,8 @@ 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;
> > >
> > > You fail to clear this bit if .inverted_rx is false.
> >
> > I believe this is taken care of by the SRST asserted slightly above
> > this - UCR* is reset by this.
>
> The i.MX6 manual states: Reset the transmit and receive state machines,
> all FIFOs and register USR1, USR2, UBIR, UBMR, UBRC, URXD, UTXD and
> UTS[6-3]. UCR* isn't mentioned here. So please at least confirm your
> belief experimentally.
Oh, I see now - I misread "S" vs "C". You are correct; I will send v3
with both changes.
Even with experimental evidence, there's no guarantee made by NXP, so
I'll handle it.
Thanks,
George
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-02-11 16:18 UTC | newest]
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2020-02-10 19:29 ` [PATCH v2 2/2] tty: imx serial: Implement support for reversing TX and RX polarity George Hilliard
2020-02-10 20:50 ` Uwe Kleine-König
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