Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote: > From: Yegor Yefremov > > This patch permits the usage for GPIOs to control > the CTS/RTS/DTR/DSR/DCD/RI signals. > > Changed by Stefan: > Only call mctrl_gpio_init(), if the device has no ACPI companion device > to not break existing ACPI based systems. Also only use the mctrl_gpio_ > functions when "gpios" is available. > > Signed-off-by: Yegor Yefremov > Signed-off-by: Greg Kroah-Hartman Please do not add a signed-off-by from people for an old patch that was reverted. It implies that I still agree with this change :( greg k-h
Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
On 12.06.19 11:16, Andy Shevchenko wrote:
On Wed, Jun 12, 2019 at 10:13:05AM +0200, Stefan Roese wrote:
On 11.06.19 16:48, Andy Shevchenko wrote:
On Tue, Jun 11, 2019 at 04:02:54PM +0200, Stefan Roese wrote:
On 11.06.19 14:44, Andy Shevchenko wrote:
On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
{
serial_out(up, UART_MCR, value);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ if (value & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (value & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio_set(up->gpios, mctrl_gpio);
+ }
}
static inline int serial8250_in_MCR(struct uart_8250_port *up)
{
- return serial_in(up, UART_MCR);
+ int mctrl;
+
+ mctrl = serial_in(up, UART_MCR);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ /* save current MCR values */
+ if (mctrl & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (mctrl & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, _gpio);
+ if (mctrl_gpio & TIOCM_RTS)
+ mctrl |= UART_MCR_RTS;
+ else
+ mctrl &= ~UART_MCR_RTS;
+
+ if (mctrl_gpio & TIOCM_DTR)
+ mctrl |= UART_MCR_DTR;
+ else
+ mctrl &= ~UART_MCR_DTR;
+ }
+
+ return mctrl;
}
These are using OR logic with potentially volatile data. Shouldn't we mask
unused bits in UART_MCR in case of up->gpios != NULL?
Sorry, I don't see, which bits you are referring to? Could you please be
a bit more specific with the variable / macro meant (example)?
I meant that we double write values in the out() which might have some
consequences, though I hope nothing wrong with it happens.
Where is the double write to a register? Sorry, I fail to spot it.
Not to the one register. From the functional point of view the same signal is
set up twice: once per UART register, once per GPIO pins.
In the in() we read the all bits in the register.
As now I look at the implementation of mctrl_gpio_get_outputs(),
I think we rather get helpers for conversion between TIOCM and UART_MCR values,
so, they can be used in get_mctrl() / set_mctrl() and above.
Do you something like this in mind?
More likely
static inline int serial8250_MCR_to_TIOCM(int mcr)
MSR_to_TIOCM (see below) ...
{
int tiocm = 0;
if (mcr & ...)
tiocm |= ...;
...
return tiocm;
}
static inline int serial8250_TIOCM_to_MCR(int tiocm)
{
... in a similar way ...
}
While implementing such wrapper functions I noticed, that get_mctrl() /
set_mctrl() need TIOCM->MCR and MSR->TIOCM (notice MSR vs MCR here) but
serial8250_in_MCR() needs MCR->TIOCM. So there is not that much
overlay here. Additionally the wrappers would need to handle all bits
and only some of them are needed in serial8250_in/out_MCR(), so I would
need to add masking here as well.
For my taste its not really worth adding these wrappers as they won't
make things much clearer (if at all).
Thanks,
Stefan
Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
On Thu, Jun 13, 2019 at 07:32:39AM +0200, Stefan Roese wrote:
> On 12.06.19 11:16, Andy Shevchenko wrote:
> > On Wed, Jun 12, 2019 at 10:13:05AM +0200, Stefan Roese wrote:
> > > On 11.06.19 16:48, Andy Shevchenko wrote:
> > > Do you something like this in mind?
> >
> > More likely
> >
> > static inline int serial8250_MCR_to_TIOCM(int mcr)
>
> MSR_to_TIOCM (see below) ...
Yes. true.
> > {
> > int tiocm = 0;
> >
> > if (mcr & ...)
> > tiocm |= ...;
> > ...
> >
> > return tiocm;
> > }
> >
> > static inline int serial8250_TIOCM_to_MCR(int tiocm)
> > {
> > ... in a similar way ...
> > }
>
> While implementing such wrapper functions I noticed, that get_mctrl() /
> set_mctrl() need TIOCM->MCR and MSR->TIOCM (notice MSR vs MCR here) but
> serial8250_in_MCR() needs MCR->TIOCM. So there is not that much
> overlay here.
It seems not only this driver is using such conversion. It's even possible to
move it to serial level for all.
> Additionally the wrappers would need to handle all bits
> and only some of them are needed in serial8250_in/out_MCR(),
> so I would
> need to add masking here as well.
I don't see this. You will get a value for exclusive bits only. No additional
mask would be needed.
> For my taste its not really worth adding these wrappers as they won't
> make things much clearer (if at all).
Hmm.. For me it would be quite clear if something with proposed name would be
called in the code.
--
With Best Regards,
Andy Shevchenko
Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
On Wed, Jun 12, 2019 at 10:13:05AM +0200, Stefan Roese wrote:
> On 11.06.19 16:48, Andy Shevchenko wrote:
> > On Tue, Jun 11, 2019 at 04:02:54PM +0200, Stefan Roese wrote:
> > > On 11.06.19 14:44, Andy Shevchenko wrote:
> > > > On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
> >
> > > > >static inline void serial8250_out_MCR(struct uart_8250_port *up,
> > > > > int value)
> > > > >{
> > > > > serial_out(up, UART_MCR, value);
> > > > > +
> > > > > + if (up->gpios) {
> > > > > + int mctrl_gpio = 0;
> > > > > +
> > > > > + if (value & UART_MCR_RTS)
> > > > > + mctrl_gpio |= TIOCM_RTS;
> > > > > + if (value & UART_MCR_DTR)
> > > > > + mctrl_gpio |= TIOCM_DTR;
> > > > > +
> > > > > + mctrl_gpio_set(up->gpios, mctrl_gpio);
> > > > > + }
> > > > >}
> >
> > > > >static inline int serial8250_in_MCR(struct uart_8250_port *up)
> > > > >{
> > > > > - return serial_in(up, UART_MCR);
> > > > > + int mctrl;
> > > > > +
> > > > > + mctrl = serial_in(up, UART_MCR);
> > > > > +
> > > > > + if (up->gpios) {
> > > > > + int mctrl_gpio = 0;
> > > > > +
> > > > > + /* save current MCR values */
> > > > > + if (mctrl & UART_MCR_RTS)
> > > > > + mctrl_gpio |= TIOCM_RTS;
> > > > > + if (mctrl & UART_MCR_DTR)
> > > > > + mctrl_gpio |= TIOCM_DTR;
> > > > > +
> > > > > + mctrl_gpio = mctrl_gpio_get_outputs(up->gpios,
> > > > > _gpio);
> > > > > + if (mctrl_gpio & TIOCM_RTS)
> > > > > + mctrl |= UART_MCR_RTS;
> > > > > + else
> > > > > + mctrl &= ~UART_MCR_RTS;
> > > > > +
> > > > > + if (mctrl_gpio & TIOCM_DTR)
> > > > > + mctrl |= UART_MCR_DTR;
> > > > > + else
> > > > > + mctrl &= ~UART_MCR_DTR;
> > > > > + }
> > > > > +
> > > > > + return mctrl;
> > > > >}
> > > >
> > > > These are using OR logic with potentially volatile data. Shouldn't we
> > > > mask
> > > > unused bits in UART_MCR in case of up->gpios != NULL?
> > >
> > > Sorry, I don't see, which bits you are referring to? Could you please be
> > > a bit more specific with the variable / macro meant (example)?
> >
> > I meant that we double write values in the out() which might have some
> > consequences, though I hope nothing wrong with it happens.
>
> Where is the double write to a register? Sorry, I fail to spot it.
Not to the one register. From the functional point of view the same signal is
set up twice: once per UART register, once per GPIO pins.
> > In the in() we read the all bits in the register.
> >
> > As now I look at the implementation of mctrl_gpio_get_outputs(),
> > I think we rather get helpers for conversion between TIOCM and UART_MCR
> > values,
> > so, they can be used in get_mctrl() / set_mctrl() and above.
>
> Do you something like this in mind?
More likely
static inline int serial8250_MCR_to_TIOCM(int mcr)
{
int tiocm = 0;
if (mcr & ...)
tiocm |= ...;
...
return tiocm;
}
static inline int serial8250_TIOCM_to_MCR(int tiocm)
{
... in a similar way ...
}
> Plus the use of these macros in this patch of course.
No macros, please.
--
With Best Regards,
Andy Shevchenko
Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
On 11.06.19 16:48, Andy Shevchenko wrote:
On Tue, Jun 11, 2019 at 04:02:54PM +0200, Stefan Roese wrote:
On 11.06.19 14:44, Andy Shevchenko wrote:
On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
{
serial_out(up, UART_MCR, value);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ if (value & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (value & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio_set(up->gpios, mctrl_gpio);
+ }
}
static inline int serial8250_in_MCR(struct uart_8250_port *up)
{
- return serial_in(up, UART_MCR);
+ int mctrl;
+
+ mctrl = serial_in(up, UART_MCR);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ /* save current MCR values */
+ if (mctrl & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (mctrl & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, _gpio);
+ if (mctrl_gpio & TIOCM_RTS)
+ mctrl |= UART_MCR_RTS;
+ else
+ mctrl &= ~UART_MCR_RTS;
+
+ if (mctrl_gpio & TIOCM_DTR)
+ mctrl |= UART_MCR_DTR;
+ else
+ mctrl &= ~UART_MCR_DTR;
+ }
+
+ return mctrl;
}
These are using OR logic with potentially volatile data. Shouldn't we mask
unused bits in UART_MCR in case of up->gpios != NULL?
Sorry, I don't see, which bits you are referring to? Could you please be
a bit more specific with the variable / macro meant (example)?
I meant that we double write values in the out() which might have some
consequences, though I hope nothing wrong with it happens.
Where is the double write to a register? Sorry, I fail to spot it.
In the in() we read the all bits in the register.
As now I look at the implementation of mctrl_gpio_get_outputs(),
I think we rather get helpers for conversion between TIOCM and UART_MCR values,
so, they can be used in get_mctrl() / set_mctrl() and above.
Do you something like this in mind?
diff --git a/drivers/tty/serial/8250/8250_port.c
b/drivers/tty/serial/8250/8250_port.c
index dc9354e34b60..f44561fcb941 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1954,19 +1954,12 @@ unsigned int serial8250_do_get_mctrl(struct uart_port
*port)
status = serial8250_modem_status(up);
serial8250_rpm_put(up);
- ret = 0;
-
if (up->gpios)
return mctrl_gpio_get(up->gpios, );
- if (status & UART_MSR_DCD)
- ret |= TIOCM_CAR;
- if (status & UART_MSR_RI)
- ret |= TIOCM_RNG;
- if (status & UART_MSR_DSR)
- ret |= TIOCM_DSR;
- if (status & UART_MSR_CTS)
- ret |= TIOCM_CTS;
+ ret = UART_MSR_TO_TIOCM_DCD(status) | UART_MSR_TO_TIOCM_RI(status) |
+ UART_MSR_TO_TIOCM_DSR(status) | UART_MSR_TO_TIOCM_CTS(status);
+
return ret;
}
EXPORT_SYMBOL_GPL(serial8250_do_get_mctrl);
@@ -1983,16 +1976,9 @@ void serial8250_do_set_mctrl(struct uart_port *port,
unsigned int mctrl)
struct uart_8250_port *up = up_to_u8250p(port);
unsigned char mcr = 0;
- if (mctrl & TIOCM_RTS)
- mcr |= UART_MCR_RTS;
- if (mctrl & TIOCM_DTR)
- mcr |= UART_MCR_DTR;
- if (mctrl & TIOCM_OUT1)
- mcr |= UART_MCR_OUT1;
- if (mctrl & TIOCM_OUT2)
- mcr |= UART_MCR_OUT2;
- if (mctrl & TIOCM_LOOP)
- mcr |= UART_MCR_LOOP;
+ mcr = TIOCM_TO_UART_MCR_RTS(mctrl) | TIOCM_TO_UART_MCR_DTR(mctrl) |
+ TIOCM_TO_UART_MCR_OUT1(mctrl) | TIOCM_TO_UART_MCR_OUT2(mctrl) |
+ TIOCM_TO_UART_MCR_LOOP(mctrl);
mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr;
diff --git a/include/uapi/linux/serial_reg.h b/include/uapi/linux/serial_reg.h
index be07b5470f4b..bda905a1b765 100644
--- a/include/uapi/linux/serial_reg.h
+++ b/include/uapi/linux/serial_reg.h
@@ -376,5 +376,22 @@
#define UART_ALTR_EN_TXFIFO_LW 0x01/* Enable the TX FIFO Low Watermark */
#define UART_ALTR_TX_LOW 0x41/* Tx FIFO Low Watermark */
+#define UART_MSR_TO_TIOCM_DCD(val) ((val & UART_MSR_DCD) ? TIOCM_CAR : 0)
+#define UART_MSR_TO_TIOCM_RI(val) ((val & UART_MSR_RI) ? TIOCM_RNG : 0)
+#define UART_MSR_TO_TIOCM_DSR(val) ((val & UART_MSR_DSR) ? TIOCM_DSR : 0)
+#define UART_MSR_TO_TIOCM_CTS(val) ((val & UART_MSR_CTS) ? TIOCM_CTS : 0)
+#define UART_MSR_TO_TIOCM_RTS(val) ((val & UART_MSR_RTS) ? TIOCM_RTS : 0)
+#define UART_MSR_TO_TIOCM_DTR(val) ((val & UART_MSR_DTR) ? TIOCM_DTR : 0)
+
+#define TIOCM_TO_UART_MCR_DCD(val) ((val
Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
On Tue, Jun 11, 2019 at 04:02:54PM +0200, Stefan Roese wrote:
> On 11.06.19 14:44, Andy Shevchenko wrote:
> > On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
> > > static inline void serial8250_out_MCR(struct uart_8250_port *up, int
> > > value)
> > > {
> > > serial_out(up, UART_MCR, value);
> > > +
> > > + if (up->gpios) {
> > > + int mctrl_gpio = 0;
> > > +
> > > + if (value & UART_MCR_RTS)
> > > + mctrl_gpio |= TIOCM_RTS;
> > > + if (value & UART_MCR_DTR)
> > > + mctrl_gpio |= TIOCM_DTR;
> > > +
> > > + mctrl_gpio_set(up->gpios, mctrl_gpio);
> > > + }
> > > }
> > > static inline int serial8250_in_MCR(struct uart_8250_port *up)
> > > {
> > > - return serial_in(up, UART_MCR);
> > > + int mctrl;
> > > +
> > > + mctrl = serial_in(up, UART_MCR);
> > > +
> > > + if (up->gpios) {
> > > + int mctrl_gpio = 0;
> > > +
> > > + /* save current MCR values */
> > > + if (mctrl & UART_MCR_RTS)
> > > + mctrl_gpio |= TIOCM_RTS;
> > > + if (mctrl & UART_MCR_DTR)
> > > + mctrl_gpio |= TIOCM_DTR;
> > > +
> > > + mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, _gpio);
> > > + if (mctrl_gpio & TIOCM_RTS)
> > > + mctrl |= UART_MCR_RTS;
> > > + else
> > > + mctrl &= ~UART_MCR_RTS;
> > > +
> > > + if (mctrl_gpio & TIOCM_DTR)
> > > + mctrl |= UART_MCR_DTR;
> > > + else
> > > + mctrl &= ~UART_MCR_DTR;
> > > + }
> > > +
> > > + return mctrl;
> > > }
> >
> > These are using OR logic with potentially volatile data. Shouldn't we mask
> > unused bits in UART_MCR in case of up->gpios != NULL?
>
> Sorry, I don't see, which bits you are referring to? Could you please be
> a bit more specific with the variable / macro meant (example)?
I meant that we double write values in the out() which might have some
consequences, though I hope nothing wrong with it happens.
In the in() we read the all bits in the register.
As now I look at the implementation of mctrl_gpio_get_outputs(),
I think we rather get helpers for conversion between TIOCM and UART_MCR values,
so, they can be used in get_mctrl() / set_mctrl() and above.
The logic now is understandable to me (I was confused by the conversions here
and there).
--
With Best Regards,
Andy Shevchenko
Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
On 11.06.19 14:44, Andy Shevchenko wrote:
On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
From: Yegor Yefremov
This patch permits the usage for GPIOs to control
the CTS/RTS/DTR/DSR/DCD/RI signals.
static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
{
serial_out(up, UART_MCR, value);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ if (value & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (value & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio_set(up->gpios, mctrl_gpio);
+ }
}
static inline int serial8250_in_MCR(struct uart_8250_port *up)
{
- return serial_in(up, UART_MCR);
+ int mctrl;
+
+ mctrl = serial_in(up, UART_MCR);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ /* save current MCR values */
+ if (mctrl & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (mctrl & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, _gpio);
+ if (mctrl_gpio & TIOCM_RTS)
+ mctrl |= UART_MCR_RTS;
+ else
+ mctrl &= ~UART_MCR_RTS;
+
+ if (mctrl_gpio & TIOCM_DTR)
+ mctrl |= UART_MCR_DTR;
+ else
+ mctrl &= ~UART_MCR_DTR;
+ }
+
+ return mctrl;
}
These are using OR logic with potentially volatile data. Shouldn't we mask
unused bits in UART_MCR in case of up->gpios != NULL?
Sorry, I don't see, which bits you are referring to? Could you please be
a bit more specific with the variable / macro meant (example)?
+ if (up->gpios == 0)
This is type inconsistency with this check as far as I understand.
I guess you have to do either (up->gpios == NULL), or (!up->gpios).
Ah, right. Thanks for spotting.
Thanks,
Stefan
Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
> From: Yegor Yefremov
>
> This patch permits the usage for GPIOs to control
> the CTS/RTS/DTR/DSR/DCD/RI signals.
> static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
> {
> serial_out(up, UART_MCR, value);
> +
> + if (up->gpios) {
> + int mctrl_gpio = 0;
> +
> + if (value & UART_MCR_RTS)
> + mctrl_gpio |= TIOCM_RTS;
> + if (value & UART_MCR_DTR)
> + mctrl_gpio |= TIOCM_DTR;
> +
> + mctrl_gpio_set(up->gpios, mctrl_gpio);
> + }
> }
>
> static inline int serial8250_in_MCR(struct uart_8250_port *up)
> {
> - return serial_in(up, UART_MCR);
> + int mctrl;
> +
> + mctrl = serial_in(up, UART_MCR);
> +
> + if (up->gpios) {
> + int mctrl_gpio = 0;
> +
> + /* save current MCR values */
> + if (mctrl & UART_MCR_RTS)
> + mctrl_gpio |= TIOCM_RTS;
> + if (mctrl & UART_MCR_DTR)
> + mctrl_gpio |= TIOCM_DTR;
> +
> + mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, _gpio);
> + if (mctrl_gpio & TIOCM_RTS)
> + mctrl |= UART_MCR_RTS;
> + else
> + mctrl &= ~UART_MCR_RTS;
> +
> + if (mctrl_gpio & TIOCM_DTR)
> + mctrl |= UART_MCR_DTR;
> + else
> + mctrl &= ~UART_MCR_DTR;
> + }
> +
> + return mctrl;
> }
These are using OR logic with potentially volatile data. Shouldn't we mask
unused bits in UART_MCR in case of up->gpios != NULL?
> + if (up->gpios == 0)
This is type inconsistency with this check as far as I understand.
I guess you have to do either (up->gpios == NULL), or (!up->gpios).
> ret = 0;
+ Blank line.
> + if (up->gpios)
> + return mctrl_gpio_get(up->gpios, );
--
With Best Regards,
Andy Shevchenko
[PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
From: Yegor Yefremov
This patch permits the usage for GPIOs to control
the CTS/RTS/DTR/DSR/DCD/RI signals.
Changed by Stefan:
Only call mctrl_gpio_init(), if the device has no ACPI companion device
to not break existing ACPI based systems. Also only use the mctrl_gpio_
functions when "gpios" is available.
Signed-off-by: Yegor Yefremov
Signed-off-by: Greg Kroah-Hartman
Signed-off-by: Stefan Roese
Reviewed-by: Mika Westerberg
Cc: Mika Westerberg
Cc: Andy Shevchenko
Cc: Giulio Benetti
Cc: Yegor Yefremov
Cc: Greg Kroah-Hartman
---
v5:
- Dropped a few "if (up->gpios)" checks, as the mctrl_gpio_foo() API
handles gpios == NULL (return)
- 8250_omap: Changed "IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(up->gpios, ...))"
to "up->gpios == NULL", as mctrl_gpio_to_gpiod() does not handle
gpios == NULL correctly.
v4:
- Added Mika's reviewed by tag
- Added Johan to Cc
v3:
- Only call mctrl_gpio_init(), if the device has no ACPI companion device
to not break existing ACPI based systems, as suggested by Andy
v2:
- No change
Please note that this patch was already applied before [1]. And later
reverted [2] because it introduced problems on some x86 based boards
(ACPI GPIO related). Here a detailed description of the issue at that
time:
https://lkml.org/lkml/2016/8/9/357
http://www.spinics.net/lists/linux-serial/msg23071.html
This is a re-send of the original patch that was applied at that time.
With patch 1/2 from this series this issue should be fixed now (please
note that I can't test it on such an x86 platform causing these
problems).
Andy (or Mika), perhaps it would be possible for you to test this
patch again, now with patch 1/2 of this series applied as well?
That would be really helpful.
Thanks,
Stefan
[1] 4ef03d328769 ("tty/serial/8250: use mctrl_gpio helpers")
[2] 5db4f7f80d16 ("Revert "tty/serial/8250: use mctrl_gpio helpers"")
.../devicetree/bindings/serial/8250.txt | 19 +
drivers/tty/serial/8250/8250.h| 40 ++-
drivers/tty/serial/8250/8250_core.c | 17
drivers/tty/serial/8250/8250_omap.c | 29 --
drivers/tty/serial/8250/8250_port.c | 7
drivers/tty/serial/8250/Kconfig | 1 +
include/linux/serial_8250.h | 1 +
7 files changed, 100 insertions(+), 14 deletions(-)
diff --git a/Documentation/devicetree/bindings/serial/8250.txt
b/Documentation/devicetree/bindings/serial/8250.txt
index 3cba12f855b7..20d351f268ef 100644
--- a/Documentation/devicetree/bindings/serial/8250.txt
+++ b/Documentation/devicetree/bindings/serial/8250.txt
@@ -53,6 +53,9 @@ Optional properties:
programmable TX FIFO thresholds.
- resets : phandle + reset specifier pairs
- overrun-throttle-ms : how long to pause uart rx when input overrun is
encountered.
+- {rts,cts,dtr,dsr,rng,dcd}-gpios: specify a GPIO for RTS/CTS/DTR/DSR/RI/DCD
+ line respectively. It will use specified GPIO instead of the peripheral
+ function pin for the UART feature. If unsure, don't specify this property.
Note:
* fsl,ns16550:
@@ -74,3 +77,19 @@ Example:
interrupts = <10>;
reg-shift = <2>;
};
+
+Example for OMAP UART using GPIO-based modem control signals:
+
+ uart4: serial@49042000 {
+ compatible = "ti,omap3-uart";
+ reg = <0x49042000 0x400>;
+ interrupts = <80>;
+ ti,hwmods = "uart4";
+ clock-frequency = <4800>;
+ cts-gpios = < 5 GPIO_ACTIVE_LOW>;
+ rts-gpios = < 6 GPIO_ACTIVE_LOW>;
+ dtr-gpios = < 12 GPIO_ACTIVE_LOW>;
+ dsr-gpios = < 13 GPIO_ACTIVE_LOW>;
+ dcd-gpios = < 14 GPIO_ACTIVE_LOW>;
+ rng-gpios = < 15 GPIO_ACTIVE_LOW>;
+ };
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index ebfb0bd5bef5..441aab94264b 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -11,6 +11,8 @@
#include
#include
+#include "../serial_mctrl_gpio.h"
+
struct uart_8250_dma {
int (*tx_dma)(struct uart_8250_port *p);
int (*rx_dma)(struct uart_8250_port *p);
@@ -142,11 +144,47 @@ void serial8250_em485_destroy(struct uart_8250_port *p);
static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
{
serial_out(up, UART_MCR, value);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ if (value & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (value & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio_set(up->gpios, mctrl_gpio);
+ }
}
static inline int serial8250_in_MCR(struct uart_8250_port *up)
{
- return serial_in(up, UART_MCR);
+ int mctrl;
+
+ mctrl = serial_in(up, UART_MCR);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ /* save current MCR
