Re: [PATCH 2/5] mmc: pwrseq_simple: Extend to support more pins

[Javier Martinez Canillas]

Hello Srinivas,

Thanks a lot for your feedback.

On 01/28/2015 03:01 PM, Srinivas Kandagatla wrote:
> Hi Javier,
> 
> You are in a lead of 3 hrs from me..
> Surprisingly I send very much same patch just few Mins ago :-)

:-)

I didn't find the posted patch you are referring too though, did you cc
linux-mmc?

> May be we can merge goods in both :-)
>

Sure, I want $subject to be generic enough to be useful for other platforms.

> On 28/01/15 10:10, Javier Martinez Canillas wrote:
>> Many WLAN attached to a SDIO/MMC interface, needs more than one pin for
>> their reset sequence. For example, is very common for chips to have two
>> pins: one for reset and one for power enable.
>>
>> This patch adds support for more reset pins to the pwrseq_simple driver
>> and instead hardcoding a fixed number, it uses the of_gpio_named_count()
>> since the MMC power sequence is only built when CONFIG_OF is enabled.
>>
>> Signed-off-by: Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx>
>> ---
>>   drivers/mmc/core/pwrseq_simple.c | 54 ++++++++++++++++++++++++++++++----------
>>   1 file changed, 41 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
>> index 0958c696137f..9e51fe1051c5 100644
>> --- a/drivers/mmc/core/pwrseq_simple.c
>> +++ b/drivers/mmc/core/pwrseq_simple.c
>> @@ -11,6 +11,7 @@
>>   #include <linux/slab.h>
>>   #include <linux/device.h>
>>   #include <linux/err.h>
>> +#include <linux/of_gpio.h>
>>   #include <linux/gpio/consumer.h>
>>
>>   #include <linux/mmc/host.h>
>> @@ -19,34 +20,44 @@
>>
>>   struct mmc_pwrseq_simple {
>>   	struct mmc_pwrseq pwrseq;
>> -	struct gpio_desc *reset_gpio;
>> +	struct gpio_desc **reset_gpio;
> 
> May be renaming it to reset_gpios makes more sense..
>

Ok

> If you make this struct gpio_desc *reset_gpios[0]; You can aviod an 
> extra kmalloc and free ..
> 
>

That's a very good idea, thanks.

>> +	int nr_gpios;
>>   };
>>
>>   static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
>>   {
> 
> [...
>>   	struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
>>   					struct mmc_pwrseq_simple, pwrseq);
>> +	int i;
>>
>> -	if (!IS_ERR(pwrseq->reset_gpio))
>> -		gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
>> +	for (i = 0; i < pwrseq->nr_gpios; i++)
>> +		if (!IS_ERR(pwrseq->reset_gpio[i]))
>> +			gpiod_set_value_cansleep(pwrseq->reset_gpio[i], 1);
> 
> ...]
> 
>>   }
>>
>>   static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
>>   {
> 
> [...
> 
>>   	struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
>>   					struct mmc_pwrseq_simple, pwrseq);
>> +	int i;
>>
>> -	if (!IS_ERR(pwrseq->reset_gpio))
>> -		gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
>> +	for (i = 0; i < pwrseq->nr_gpios; i++)
>> +		if (!IS_ERR(pwrseq->reset_gpio[i]))
>> +			gpiod_set_value_cansleep(pwrseq->reset_gpio[i], 0);
> ...]
> 
> Now that we have more code in mmc_pwrseq_simple_post_power_on() and 
> mmc_pwrseq_simple_pre_power_on(), Just move most of them into a common 
> function like:
> 
> static void __mmc_pwrseq_simple_power_on_off(struct mmc_host *host,
> 						      bool on)
> {
> 	struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
> 					struct mmc_pwrseq_simple, pwrseq);
> 	int i;
> 
> 	if (!IS_ERR(pwrseq->reset_gpios)) {
> 		for (i = 0; i < pwrseq->ngpios; i++)
> 			gpiod_set_value_cansleep(pwrseq->reset_gpios[i],
> 						 on ? : 0);
> 	}
> }
>
> static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
> {
> 	__mmc_pwrseq_simple_power_on_off(host, true);
> }
> 
> static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
> {
> 	__mmc_pwrseq_simple_power_on_off(host, false);
> }
> 
>

Sure, will do.

>>   }
>>
>>   static void mmc_pwrseq_simple_free(struct mmc_host *host)
>>   {
>>   	struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
>>   					struct mmc_pwrseq_simple, pwrseq);
>> +	int i;
>>
>> -	if (!IS_ERR(pwrseq->reset_gpio))
>> -		gpiod_put(pwrseq->reset_gpio);
>> +	if (pwrseq->nr_gpios > 0) {
>> +		for (i = 0; i < pwrseq->nr_gpios; i++)
>> +			if (!IS_ERR(pwrseq->reset_gpio[i]))
>> +				gpiod_put(pwrseq->reset_gpio[i]);
>> +		kfree(pwrseq->reset_gpio);
>> +	}
>>
>>   	kfree(pwrseq);
>>   	host->pwrseq = NULL;
>> @@ -63,17 +74,27 @@ int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
>>   {
>>   	struct mmc_pwrseq_simple *pwrseq;
>>   	int ret = 0;
>> +	int i;
>>
>>   	pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
>>   	if (!pwrseq)
>>   		return -ENOMEM;
>>
>> -	pwrseq->reset_gpio = gpiod_get_index(dev, "reset", 0, GPIOD_OUT_HIGH);
>> -	if (IS_ERR(pwrseq->reset_gpio) &&
>> -		PTR_ERR(pwrseq->reset_gpio) != -ENOENT &&
>> -		PTR_ERR(pwrseq->reset_gpio) != -ENOSYS) {
>> -		ret = PTR_ERR(pwrseq->reset_gpio);
>> -		goto free;
>> +	pwrseq->nr_gpios = of_gpio_named_count(dev->of_node, "reset-gpios");
>> +	if (pwrseq->nr_gpios > 0) {
> 
> What happens if there are no gpios? This fuction should return -ENOENT 
> and should not even try to allocate pwrseq?

Not quite, the DT binding states that the GPIOs are optional so it should
not fail if no GPIOs are defined. 

> Probably you should do of_gpio_named_count before allocating memory.
>

I didn't do that because patch #4 "mmc: pwrseq_simple: Add optional reference
clock support" will need the struct mmc_pwrseq_simple even if no GPIOs are
defined.

A SDIO attached chip could require only an external clock or someone could
extend the pwrseq_simple driver to support an external regulator for example.

>> +		pwrseq->reset_gpio = kzalloc(sizeof(struct gpio_desc *) *
>> +					     pwrseq->nr_gpios, GFP_KERNEL);
>> +
>> +		for (i = 0; i < pwrseq->nr_gpios; i++) {
>> +			pwrseq->reset_gpio[i] = gpiod_get_index(dev, "reset", i,
>> +								GPIOD_OUT_HIGH);
>> +			if (IS_ERR(pwrseq->reset_gpio[i]) &&
>> +			    PTR_ERR(pwrseq->reset_gpio[i]) != -ENOENT &&
>> +			    PTR_ERR(pwrseq->reset_gpio[i]) != -ENOSYS) {
>> +				ret = PTR_ERR(pwrseq->reset_gpio[i]);
> 
> is simple to add:
> 	while(--i)
> 		gpiod_put(pwrseq->reset_gpio[i])
> 
> 
>

That's true, will change.

>> +				goto free;
>> +			}
>> +		}
> 
> 
>>   	}
>>
>>   	pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
>> @@ -81,6 +102,13 @@ int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
>>
>>   	return 0;
>>   free:
>> +	if (pwrseq->nr_gpios > 0) {
>> +		for (i = 0; i < pwrseq->nr_gpios; i++)
>> +			if (!IS_ERR_OR_NULL(pwrseq->reset_gpio[i]))
>> +				gpiod_put(pwrseq->reset_gpio[i]);
>> +		kfree(pwrseq->reset_gpio);
>> +	}
>> +
>>   	kfree(pwrseq);
>>   	return ret;
>>   }
>>
> 
> I get a feeling that am just dumping my patch here.. If possible could 
> you have look at it too.
>

Of course, do you have a link archive since I can't find it on my inbox.

> Thanks,
> srini
>

Again, thanks a lot and best regards,
Javier

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/