* [PATCH V3] serial: stm32: Add RS485 RTS GPIO control again
@ 2020-08-31 17:10 Marek Vasut
2020-09-02 8:08 ` Fabrice Gasnier
0 siblings, 1 reply; 3+ messages in thread
From: Marek Vasut @ 2020-08-31 17:10 UTC (permalink / raw)
To: linux-serial
Cc: Marek Vasut, Alexandre Torgue, Andy Shevchenko,
Manivannan Sadhasivam, Fabrice Gasnier, Greg Kroah-Hartman,
linux-stm32
While the STM32 does support RS485 drive-enable control within the
UART IP itself, some systems have the drive-enable line connected
to a pin which cannot be pinmuxed as RTS. Add support for toggling
the RTS GPIO line using the modem control GPIOs to provide at least
some sort of emulation.
Fixes: 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control")
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Cc: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-stm32@st-md-mailman.stormreply.com
---
V2: Use mctrl_gpio_set() instead of stm32_set_mctrl()
V3: - Actually toggle the RTS line before and after TX
- Undo 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control")
which was previous version of this patch ; I messed up.
---
drivers/tty/serial/stm32-usart.c | 33 ++++++++++++++++++++++++--------
1 file changed, 25 insertions(+), 8 deletions(-)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 143300a80090..23f7453441ae 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -129,13 +129,9 @@ static int stm32_config_rs485(struct uart_port *port,
if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
cr3 &= ~USART_CR3_DEP;
rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
- mctrl_gpio_set(stm32_port->gpios,
- stm32_port->port.mctrl & ~TIOCM_RTS);
} else {
cr3 |= USART_CR3_DEP;
rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
- mctrl_gpio_set(stm32_port->gpios,
- stm32_port->port.mctrl | TIOCM_RTS);
}
writel_relaxed(cr3, port->membase + ofs->cr3);
@@ -541,17 +537,42 @@ static void stm32_disable_ms(struct uart_port *port)
/* Transmit stop */
static void stm32_stop_tx(struct uart_port *port)
{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct serial_rs485 *rs485conf = &port->rs485;
+
stm32_tx_interrupt_disable(port);
+
+ if (rs485conf->flags & SER_RS485_ENABLED) {
+ if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+ mctrl_gpio_set(stm32_port->gpios,
+ stm32_port->port.mctrl & ~TIOCM_RTS);
+ } else {
+ mctrl_gpio_set(stm32_port->gpios,
+ stm32_port->port.mctrl | TIOCM_RTS);
+ }
+ }
}
/* There are probably characters waiting to be transmitted. */
static void stm32_start_tx(struct uart_port *port)
{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct serial_rs485 *rs485conf = &port->rs485;
struct circ_buf *xmit = &port->state->xmit;
if (uart_circ_empty(xmit))
return;
+ if (rs485conf->flags & SER_RS485_ENABLED) {
+ if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+ mctrl_gpio_set(stm32_port->gpios,
+ stm32_port->port.mctrl | TIOCM_RTS);
+ } else {
+ mctrl_gpio_set(stm32_port->gpios,
+ stm32_port->port.mctrl & ~TIOCM_RTS);
+ }
+ }
+
stm32_transmit_chars(port);
}
@@ -851,13 +872,9 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
cr3 &= ~USART_CR3_DEP;
rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
- mctrl_gpio_set(stm32_port->gpios,
- stm32_port->port.mctrl & ~TIOCM_RTS);
} else {
cr3 |= USART_CR3_DEP;
rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
- mctrl_gpio_set(stm32_port->gpios,
- stm32_port->port.mctrl | TIOCM_RTS);
}
} else {
--
2.28.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH V3] serial: stm32: Add RS485 RTS GPIO control again
2020-08-31 17:10 [PATCH V3] serial: stm32: Add RS485 RTS GPIO control again Marek Vasut
@ 2020-09-02 8:08 ` Fabrice Gasnier
2020-09-02 12:50 ` Marek Vasut
0 siblings, 1 reply; 3+ messages in thread
From: Fabrice Gasnier @ 2020-09-02 8:08 UTC (permalink / raw)
To: Marek Vasut, linux-serial
Cc: Alexandre Torgue, Andy Shevchenko, Manivannan Sadhasivam,
Greg Kroah-Hartman, linux-stm32, Erwan LE RAY
On 8/31/20 7:10 PM, Marek Vasut wrote:
> While the STM32 does support RS485 drive-enable control within the
> UART IP itself, some systems have the drive-enable line connected
> to a pin which cannot be pinmuxed as RTS. Add support for toggling
> the RTS GPIO line using the modem control GPIOs to provide at least
> some sort of emulation.
>
> Fixes: 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control")
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Alexandre Torgue <alexandre.torgue@st.com>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Manivannan Sadhasivam <mani@kernel.org>
> Cc: Fabrice Gasnier <fabrice.gasnier@st.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-stm32@st-md-mailman.stormreply.com
> ---
> V2: Use mctrl_gpio_set() instead of stm32_set_mctrl()
> V3: - Actually toggle the RTS line before and after TX
> - Undo 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control")
> which was previous version of this patch ; I messed up.
> ---
> drivers/tty/serial/stm32-usart.c | 33 ++++++++++++++++++++++++--------
> 1 file changed, 25 insertions(+), 8 deletions(-)
Hi Marek,
This seems sensible. I've few comments on the commit tittle and commit
message:
- tittle: this could be named as a "fix" rather than "add... again" ?
- I may have missed it... Is it a V3 ?
Could explain what is being fixed? Why moving the mctrl_gpio_* calls
away from the stm32_config_rs485()/set_termios() routines to the
start_tx/stop_tx ops improves/fixes the RS485 RTS GPIO control (what was
wrong) ?
Thanks,
Best regards,
Fabrice
>
> diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
> index 143300a80090..23f7453441ae 100644
> --- a/drivers/tty/serial/stm32-usart.c
> +++ b/drivers/tty/serial/stm32-usart.c
> @@ -129,13 +129,9 @@ static int stm32_config_rs485(struct uart_port *port,
> if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
> cr3 &= ~USART_CR3_DEP;
> rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
> - mctrl_gpio_set(stm32_port->gpios,
> - stm32_port->port.mctrl & ~TIOCM_RTS);
> } else {
> cr3 |= USART_CR3_DEP;
> rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
> - mctrl_gpio_set(stm32_port->gpios,
> - stm32_port->port.mctrl | TIOCM_RTS);
> }
>
> writel_relaxed(cr3, port->membase + ofs->cr3);
> @@ -541,17 +537,42 @@ static void stm32_disable_ms(struct uart_port *port)
> /* Transmit stop */
> static void stm32_stop_tx(struct uart_port *port)
> {
> + struct stm32_port *stm32_port = to_stm32_port(port);
> + struct serial_rs485 *rs485conf = &port->rs485;
> +
> stm32_tx_interrupt_disable(port);
> +
> + if (rs485conf->flags & SER_RS485_ENABLED) {
> + if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
> + mctrl_gpio_set(stm32_port->gpios,
> + stm32_port->port.mctrl & ~TIOCM_RTS);
> + } else {
> + mctrl_gpio_set(stm32_port->gpios,
> + stm32_port->port.mctrl | TIOCM_RTS);
> + }
> + }
> }
>
> /* There are probably characters waiting to be transmitted. */
> static void stm32_start_tx(struct uart_port *port)
> {
> + struct stm32_port *stm32_port = to_stm32_port(port);
> + struct serial_rs485 *rs485conf = &port->rs485;
> struct circ_buf *xmit = &port->state->xmit;
>
> if (uart_circ_empty(xmit))
> return;
>
> + if (rs485conf->flags & SER_RS485_ENABLED) {
> + if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
> + mctrl_gpio_set(stm32_port->gpios,
> + stm32_port->port.mctrl | TIOCM_RTS);
> + } else {
> + mctrl_gpio_set(stm32_port->gpios,
> + stm32_port->port.mctrl & ~TIOCM_RTS);
> + }
> + }
> +
> stm32_transmit_chars(port);
> }
>
> @@ -851,13 +872,9 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
> if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
> cr3 &= ~USART_CR3_DEP;
> rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
> - mctrl_gpio_set(stm32_port->gpios,
> - stm32_port->port.mctrl & ~TIOCM_RTS);
> } else {
> cr3 |= USART_CR3_DEP;
> rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
> - mctrl_gpio_set(stm32_port->gpios,
> - stm32_port->port.mctrl | TIOCM_RTS);
> }
>
> } else {
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH V3] serial: stm32: Add RS485 RTS GPIO control again
2020-09-02 8:08 ` Fabrice Gasnier
@ 2020-09-02 12:50 ` Marek Vasut
0 siblings, 0 replies; 3+ messages in thread
From: Marek Vasut @ 2020-09-02 12:50 UTC (permalink / raw)
To: Fabrice Gasnier, linux-serial
Cc: Alexandre Torgue, Andy Shevchenko, Manivannan Sadhasivam,
Greg Kroah-Hartman, linux-stm32, Erwan LE RAY
On 9/2/20 10:08 AM, Fabrice Gasnier wrote:
> On 8/31/20 7:10 PM, Marek Vasut wrote:
>> While the STM32 does support RS485 drive-enable control within the
>> UART IP itself, some systems have the drive-enable line connected
>> to a pin which cannot be pinmuxed as RTS. Add support for toggling
>> the RTS GPIO line using the modem control GPIOs to provide at least
>> some sort of emulation.
>>
>> Fixes: 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control")
>> Signed-off-by: Marek Vasut <marex@denx.de>
>> Cc: Alexandre Torgue <alexandre.torgue@st.com>
>> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
>> Cc: Manivannan Sadhasivam <mani@kernel.org>
>> Cc: Fabrice Gasnier <fabrice.gasnier@st.com>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> Cc: linux-stm32@st-md-mailman.stormreply.com
>> ---
>> V2: Use mctrl_gpio_set() instead of stm32_set_mctrl()
>> V3: - Actually toggle the RTS line before and after TX
>> - Undo 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control")
>> which was previous version of this patch ; I messed up.
>> ---
>> drivers/tty/serial/stm32-usart.c | 33 ++++++++++++++++++++++++--------
>> 1 file changed, 25 insertions(+), 8 deletions(-)
>
>
> Hi Marek,
>
> This seems sensible. I've few comments on the commit tittle and commit
> message:
> - tittle: this could be named as a "fix" rather than "add... again" ?
> - I may have missed it... Is it a V3 ?
There was a V2 which got applied before I had the chance to send a V3.
> Could explain what is being fixed? Why moving the mctrl_gpio_* calls
> away from the stm32_config_rs485()/set_termios() routines to the
> start_tx/stop_tx ops improves/fixes the RS485 RTS GPIO control (what was
> wrong) ?
Because set_termios is not called every time there is a transfer, but
the DE GPIOs must be toggled every time there is a transfer (to enable
the DE on TX and disable it right after TX).
> Thanks,
> Best regards,
> Fabrice
>
>>
>> diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
>> index 143300a80090..23f7453441ae 100644
>> --- a/drivers/tty/serial/stm32-usart.c
>> +++ b/drivers/tty/serial/stm32-usart.c
>> @@ -129,13 +129,9 @@ static int stm32_config_rs485(struct uart_port *port,
>> if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
>> cr3 &= ~USART_CR3_DEP;
>> rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
>> - mctrl_gpio_set(stm32_port->gpios,
>> - stm32_port->port.mctrl & ~TIOCM_RTS);
>> } else {
>> cr3 |= USART_CR3_DEP;
>> rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
>> - mctrl_gpio_set(stm32_port->gpios,
>> - stm32_port->port.mctrl | TIOCM_RTS);
>> }
>>
>> writel_relaxed(cr3, port->membase + ofs->cr3);
>> @@ -541,17 +537,42 @@ static void stm32_disable_ms(struct uart_port *port)
>> /* Transmit stop */
>> static void stm32_stop_tx(struct uart_port *port)
>> {
>> + struct stm32_port *stm32_port = to_stm32_port(port);
>> + struct serial_rs485 *rs485conf = &port->rs485;
>> +
>> stm32_tx_interrupt_disable(port);
>> +
>> + if (rs485conf->flags & SER_RS485_ENABLED) {
>> + if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
>> + mctrl_gpio_set(stm32_port->gpios,
>> + stm32_port->port.mctrl & ~TIOCM_RTS);
>> + } else {
>> + mctrl_gpio_set(stm32_port->gpios,
>> + stm32_port->port.mctrl | TIOCM_RTS);
>> + }
>> + }
>> }
>>
>> /* There are probably characters waiting to be transmitted. */
>> static void stm32_start_tx(struct uart_port *port)
>> {
>> + struct stm32_port *stm32_port = to_stm32_port(port);
>> + struct serial_rs485 *rs485conf = &port->rs485;
>> struct circ_buf *xmit = &port->state->xmit;
>>
>> if (uart_circ_empty(xmit))
>> return;
>>
>> + if (rs485conf->flags & SER_RS485_ENABLED) {
>> + if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
>> + mctrl_gpio_set(stm32_port->gpios,
>> + stm32_port->port.mctrl | TIOCM_RTS);
>> + } else {
>> + mctrl_gpio_set(stm32_port->gpios,
>> + stm32_port->port.mctrl & ~TIOCM_RTS);
>> + }
>> + }
>> +
>> stm32_transmit_chars(port);
>> }
>>
>> @@ -851,13 +872,9 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
>> if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
>> cr3 &= ~USART_CR3_DEP;
>> rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
>> - mctrl_gpio_set(stm32_port->gpios,
>> - stm32_port->port.mctrl & ~TIOCM_RTS);
>> } else {
>> cr3 |= USART_CR3_DEP;
>> rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
>> - mctrl_gpio_set(stm32_port->gpios,
>> - stm32_port->port.mctrl | TIOCM_RTS);
>> }
>>
>> } else {
>>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-08-31 17:10 [PATCH V3] serial: stm32: Add RS485 RTS GPIO control again Marek Vasut
2020-09-02 8:08 ` Fabrice Gasnier
2020-09-02 12:50 ` Marek Vasut
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