Re: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x

[Boris BREZILLON <b.brezillon.dev@gmail.com>]

Le 13/03/2014 07:00, Yang, Wenyou a écrit :
> Hi JC,
>
>> -----Original Message-----
>> From: Jean-Christophe PLAGNIOL-VILLARD [mailto:plagnioj@jcrosoft.com]
>> Sent: Tuesday, March 11, 2014 7:14 PM
>> To: Yang, Wenyou
>> Cc: Jean-Christophe PLAGNIOL-VILLARD; mark.rutland@arm.com;
>> devicetree@vger.kernel.org; pawel.moll@arm.com;
>> ijc+devicetree@hellion.org.uk; linus.walleij@linaro.org; Linux Kernel
>> list; b.brezillon@overkiz.com; robh+dt@kernel.org; galak@codeaurora.org;
>> <linux-arm-kernel@lists.infradead.org> mailing list; Lin, JM
>> Subject: Re: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x
>>
>>
>> On Mar 11, 2014, at 2:54 PM, Yang, Wenyou <Wenyou.Yang@atmel.com> wrote:
>>
>>>
>>>> -----Original Message-----
>>>> From: Jean-Christophe PLAGNIOL-VILLARD [mailto:plagnioj@jcrosoft.com]
>>>> Sent: Tuesday, March 11, 2014 12:16 PM
>>>> To: Yang, Wenyou
>>>> Cc: Jean-Christophe PLAGNIOL-VILLARD; mark.rutland@arm.com;
>>>> devicetree@vger.kernel.org; pawel.moll@arm.com;
>>>> ijc+devicetree@hellion.org.uk; linus.walleij@linaro.org; Linux Kernel
>>>> list; b.brezillon@overkiz.com; robh+dt@kernel.org;
>>>> galak@codeaurora.org; <linux-arm-kernel@lists.infradead.org> mailing
>>>> list
>>>> Subject: Re: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x
>>>>
>>>>
>>>> On Mar 11, 2014, at 9:28 AM, Yang, Wenyou <Wenyou.Yang@atmel.com>
>> wrote:
>>>>> Hi JC,
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Yang, Wenyou
>>>>>> Sent: Wednesday, March 05, 2014 1:32 PM
>>>>>> To: Jean-Christophe PLAGNIOL-VILLARD
>>>>>> Cc: linus.walleij@linaro.org; b.brezillon@overkiz.com; <linux-arm-
>>>>>> kernel@lists.infradead.org> mailing list; Linux Kernel list;
>>>>>> devicetree@vger.kernel.org; robh+dt@kernel.org; pawel.moll@arm.com;
>>>>>> mark.rutland@arm.com; ijc+devicetree@hellion.org.uk;
>>>>>> galak@codeaurora.org
>>>>>> Subject: RE: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x
>>>>>>
>>>>>> Hi JC,
>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: Jean-Christophe PLAGNIOL-VILLARD
>>>>>>> [mailto:plagnioj@jcrosoft.com]
>>>>>>> Sent: Wednesday, March 05, 2014 12:58 PM
>>>>>>> To: Yang, Wenyou
>>>>>>> Cc: Jean-Christophe PLAGNIOL-VILLARD; linus.walleij@linaro.org;
>>>>>>> b.brezillon@overkiz.com; <linux-arm-kernel@lists.infradead.org>
>>>>>>> mailing list; Linux Kernel list; devicetree@vger.kernel.org;
>>>>>>> robh+dt@kernel.org; pawel.moll@arm.com; mark.rutland@arm.com;
>>>>>>> ijc+devicetree@hellion.org.uk; galak@codeaurora.org
>>>>>>> Subject: Re: [PATCH] pinctrl: at91: add the config GPIO_OUTPUT_x
>>>>>>>
>>>>>>>
>>>>>>> On Mar 5, 2014, at 9:53 AM, Wenyou Yang <wenyou.yang@atmel.com>
>>>> wrote:
>>>>>>>> In order to support the pinctrl sleep state.
>>>>>>> As I said before NACK
>>>>>>>
>>>>>>> this is not the job of the pinctrl to describe gpio output or
>>>>>>> input state
>>>>>> But according to what said in the section "GPIO mode pitfalls" of
>>>>>> Documentation/pinctrl.txt.
>>>>>> It should be handle by the pinctrl.
>>>>>>
>>>>>> If not, to deal with the sleep state will be very complicated.
>>>>>> Muxing the pins for FUNCTION to enable peripheral, then twist them
>>>>>> over to GPIO mode and use gpio_direction_output() to drive it HIGH
>>>>>> or LOW during sleep.
>>>>>>
>>>>>> --->8 ------------
>>>>>> The solution is to not think that what the datasheet calls "GPIO
>>>> mode"
>>>>>> has to be handled by the <linux/gpio.h> interface. Instead view
>>>>>> this as a certain pin config setting. Look in e.g.
>>>>>> <linux/pinctrl/pinconf- generic.h> and you find this in the
>> documentation:
>>>>>> PIN_CONFIG_OUTPUT: this will configure the pin in output, use
>>>> argument
>>>>>>     1 to indicate high level, argument 0 to indicate low level.
>>>>>>
>>>>>> So it is perfectly possible to push a pin into "GPIO mode" and
>>>>>> drive the line low as part of the usual pin control map.
>>>>>> ---<8 ------------
>>>>> Do you have any feedback?
>>>> Here the issue is that you do drive the gpio and use as a gpio
>>>>
>>>> which means you request it as a GPIO so after you can not reswitch it
>>>> to alternative function and the gpio is already requested as
>>>> alternative function
>>>>
>>>> So basically you mess-up with the gpio API and pinctrl API by
>>>> bypassing both
>>> But I don't agree with you.
>>>
>>> As I known, in mainline the other SoC vendors provide such function,
>> configure the gpio mode with output config by pinctrl.
>>> For example, ST. nomadisk.
>>> You can see it in the function: nmk_pin_config_set() of the file,
>> pinctrl-nomadik.c.
>>> It provides GPIO mode and OUTPUT config.
>>>
>>> This is a good solution, as what said in Documentation/pinctrl.txt,
>>>
>>> it is perfectly possible to push a pin into "GPIO mode" and drive the
>> line low as part of the usual pin control map.
>> This is simple if we use gpio mode as pinctrl tomorrow we will see gpio
>> configuration in pinctrl such as chip reset, default led state etc...
>>
>> The pinctrl is not here to control a *GPIO* but to describe the
>> configuration of pin.
> What you said is the usual use case.
>
> But, in the Power Management scenario, there are the following requirements to meet:
> When running time, the pins are configured as the PERIPH functions by the pinctrl default state as usaul.
> When suspending to memory, the pins are configured as GPIO output low, output high or input by the pinctrl sleep state.
> When resuming from suspended, the pins are configured back as the PERIPH functions.
>
> I just found the same implementation by Boris which is better.
> http://lists.infradead.org/pipermail/linux-arm-kernel/2013-August/194975.html
>
> Boris, Could you have something to say?

Yes.

I still think the pinconf OUTPUT state is useful in some cases, and the
one you described is obviously one of these (I needed it for a different
reason : https://lkml.org/lkml/2013/8/28/203 which appeared to be a wrong
one).

But I'm not the pinctrl subsystem or the at91 pinctrl driver maintainer...

Linus, do you have an opinion on this feature ?

>>>>>>>> Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
>>>>>>>> ---
>>>>>>>> Hi Linus,
>>>>>>>>
>>>>>>>> The patch is based on branch: for-next
>>>>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctr
>>>>>>>> l
>>>>>>>>
>>>>>>>> Best Regards,
>>>>>>>> Wenyou Yang
>>>>>>>>
>>>>>>>> drivers/pinctrl/pinctrl-at91.c     |   31
>>>>>>> +++++++++++++++++++++++++++++++
>>>>>>>> include/dt-bindings/pinctrl/at91.h |    2 ++
>>>>>>>> 2 files changed, 33 insertions(+)
>>>>>>>>
>>>>>>>> diff --git a/drivers/pinctrl/pinctrl-at91.c
>>>>>>>> b/drivers/pinctrl/pinctrl-at91.c index 5d24aae..fc51e59 100644
>>>>>>>> --- a/drivers/pinctrl/pinctrl-at91.c
>>>>>>>> +++ b/drivers/pinctrl/pinctrl-at91.c
>>>>>>>> @@ -62,6 +62,8 @@ static int gpio_banks;
>>>>>>>> #define DEGLITCH	(1 << 2)
>>>>>>>> #define PULL_DOWN	(1 << 3)
>>>>>>>> #define DIS_SCHMIT	(1 << 4)
>>>>>>>> +#define GPIO_OUTPUT_HIGH	(1 << 5)
>>>>>>>> +#define GPIO_OUTPUT_LOW		(1 << 6)
>>>>>>>> #define DEBOUNCE	(1 << 16)
>>>>>>>> #define DEBOUNCE_VAL_SHIFT	17
>>>>>>>> #define DEBOUNCE_VAL	(0x3fff << DEBOUNCE_VAL_SHIFT)
>>>>>>>> @@ -152,12 +154,15 @@ struct at91_pinctrl_mux_ops {
>>>>>>>> 	void (*set_pulldown)(void __iomem *pio, unsigned mask, bool
>> is_on);
>>>>>>>> 	bool (*get_schmitt_trig)(void __iomem *pio, unsigned pin);
>>>>>>>> 	void (*disable_schmitt_trig)(void __iomem *pio, unsigned
>> mask);
>>>>>>>> +	bool (*get_gpio_output)(void __iomem *pio, unsigned mask);
>>>>>>>> +	void (*set_gpio_output)(void __iomem *pio, unsigned mask,
>>>> bool
>>>>>>>> +is_high);
>>>>>>>> 	/* irq */
>>>>>>>> 	int (*irq_type)(struct irq_data *d, unsigned type); };
>>>>>>>>
>>>>>>>> static int gpio_irq_type(struct irq_data *d, unsigned type);
>>>>>>>> static int alt_gpio_irq_type(struct irq_data *d, unsigned type);
>>>>>>>> +static void at91_mux_gpio_enable(void __iomem *pio, unsigned
>>>>>>>> +mask, bool input);
>>>>>>>>
>>>>>>>> struct at91_pinctrl {
>>>>>>>> 	struct device		*dev;
>>>>>>>> @@ -472,6 +477,20 @@ static bool
>>>>>>>> at91_mux_pio3_get_schmitt_trig(void
>>>>>>> __iomem *pio, unsigned pin)
>>>>>>>> 	return (__raw_readl(pio + PIO_SCHMITT) >> pin) & 0x1; }
>>>>>>>>
>>>>>>>> +static bool at91_mux_pio3_get_gpio_output(void __iomem *pio,
>>>>>>>> +unsigned
>>>>>>>> +pin) {
>>>>>>>> +	return (__raw_readl(pio + PIO_ODSR) >> pin) & 0x1; }
>>>>>>>> +
>>>>>>>> +static void at91_mux_pio3_set_gpio_output(void __iomem *pio,
>>>>>>>> +						unsigned mask,
>>>>>>>> +						bool is_high)
>>>>>>>> +{
>>>>>>>> +	at91_mux_gpio_enable(pio, mask, 0);
>>>>>>>> +	writel_relaxed(mask, pio + (is_high ? PIO_SODR : PIO_CODR)); }
>>>>>>>> +
>>>>>>>> +
>>>>>>>> static struct at91_pinctrl_mux_ops at91rm9200_ops = {
>>>>>>>> 	.get_periph	= at91_mux_get_periph,
>>>>>>>> 	.mux_A_periph	= at91_mux_set_A_periph,
>>>>>>>> @@ -495,6 +514,8 @@ static struct at91_pinctrl_mux_ops
>>>>>>>> at91sam9x5_ops
>>>>>>> = {
>>>>>>>> 	.set_pulldown	= at91_mux_pio3_set_pulldown,
>>>>>>>> 	.get_schmitt_trig = at91_mux_pio3_get_schmitt_trig,
>>>>>>>> 	.disable_schmitt_trig = at91_mux_pio3_disable_schmitt_trig,
>>>>>>>> +	.get_gpio_output = at91_mux_pio3_get_gpio_output,
>>>>>>>> +	.set_gpio_output = at91_mux_pio3_set_gpio_output,
>>>>>>>> 	.irq_type	= alt_gpio_irq_type,
>>>>>>>> };
>>>>>>>>
>>>>>>>> @@ -741,6 +762,10 @@ static int at91_pinconf_get(struct
>>>>>>>> pinctrl_dev
>>>>>>> *pctldev,
>>>>>>>> 		*config |= PULL_DOWN;
>>>>>>>> 	if (info->ops->get_schmitt_trig &&
>>>>>>>> info->ops->get_schmitt_trig(pio,
>>>>>>> pin))
>>>>>>>> 		*config |= DIS_SCHMIT;
>>>>>>>> +	if (info->ops->get_gpio_output) {
>>>>>>>> +		*config |= info->ops->get_gpio_output(pio, pin) ?
>>>>>>>> +					GPIO_OUTPUT_HIGH : GPIO_OUTPUT_LOW;
>>>>>>>> +	}
>>>>>>>>
>>>>>>>> 	return 0;
>>>>>>>> }
>>>>>>>> @@ -778,6 +803,12 @@ static int at91_pinconf_set(struct
>>>>>>>> pinctrl_dev
>>>>>>> *pctldev,
>>>>>>>> 			info->ops->set_pulldown(pio, mask, config &
>> PULL_DOWN);
>>>>>>>> 		if (info->ops->disable_schmitt_trig && config &
>> DIS_SCHMIT)
>>>>>>>> 			info->ops->disable_schmitt_trig(pio, mask);
>>>>>>>> +		if (info->ops->set_gpio_output) {
>>>>>>>> +			if (config & GPIO_OUTPUT_HIGH)
>>>>>>>> +				info->ops->set_gpio_output(pio, mask, 1);
>>>>>>>> +			if (config & GPIO_OUTPUT_LOW)
>>>>>>>> +				info->ops->set_gpio_output(pio, mask, 0);
>>>>>>>> +		};
>>>>>>>>
>>>>>>>> 	} /* for each config */
>>>>>>>>
>>>>>>>> diff --git a/include/dt-bindings/pinctrl/at91.h
>>>>>>>> b/include/dt-bindings/pinctrl/at91.h
>>>>>>>> index 0fee6ff..e799268 100644
>>>>>>>> --- a/include/dt-bindings/pinctrl/at91.h
>>>>>>>> +++ b/include/dt-bindings/pinctrl/at91.h
>>>>>>>> @@ -15,6 +15,8 @@
>>>>>>>> #define AT91_PINCTRL_DEGLITCH		(1 << 2)
>>>>>>>> #define AT91_PINCTRL_PULL_DOWN		(1 << 3)
>>>>>>>> #define AT91_PINCTRL_DIS_SCHMIT		(1 << 4)
>>>>>>>> +#define AT91_PINCTRL_OUTPUT_HIGH	(1 << 5)
>>>>>>>> +#define AT91_PINCTRL_OUTPUT_LOW		(1 << 6)
>>>>>>>> #define AT91_PINCTRL_DEBOUNCE		(1 << 16)
>>>>>>>> #define AT91_PINCTRL_DEBOUNCE_VAL(x)	(x << 17)
>>>>>>>>
>>>>>>>> --
>>>>>>>> 1.7.9.5
>>>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> linux-arm-kernel mailing list
>>>>> linux-arm-kernel@lists.infradead.org
>>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
> Bes Regards,
> Wenyou Yang
>