linux-kernel - Re: [PATCH v5 3/6] gpiolib: acpi: Export acpi_get

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Date:   Fri, 4 Jun 2021 15:09:17 +0100
From:   Daniel Scally <djrscally@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Lee Jones <lee.jones@...aro.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Maximilian Luz <luzmaximilian@...il.com>,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, devel@...ica.org,
        Len Brown <lenb@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Wolfram Sang <wsa@...nel.org>,
        Mark Gross <mgross@...ux.intel.com>,
        Robert Moore <robert.moore@...el.com>,
        Erik Kaneda <erik.kaneda@...el.com>,
        laurent.pinchart@...asonboard.com, kieran.bingham@...asonboard.com
Subject: Re: [PATCH v5 3/6] gpiolib: acpi: Export acpi_get_gpiod()

Hi Andy

On 04/06/2021 13:59, Andy Shevchenko wrote:
> On Thu, Jun 03, 2021 at 11:40:04PM +0100, Daniel Scally wrote:
>> We need to be able to translate GPIO resources in an ACPI device's _CRS
>> into GPIO descriptor array. Those are represented in _CRS as a pathname
>> to a GPIO device plus the pin's index number: the acpi_get_gpiod()
>> function is perfect for that purpose.
>>
>> As it's currently only used internally within the GPIO layer, provide and
>> export a wrapper function that additionally holds a reference to the GPIO
>> device.
> The subject is wrong, it should be "Introduce acpi_get_and_request_gpiod()
> helper" or so. I can fix when applying.


Ah! That was sloppy, sorry.

> Btw, do I understand correctly that I may push GPIO ACPI patches independently
> (of the ACPI changes)?


They're independent yes.

>
>> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
>> Signed-off-by: Daniel Scally <djrscally@...il.com>
>> ---
>> Changes since v4:
>> 	- None
>>
>>  drivers/gpio/gpiolib-acpi.c   | 28 ++++++++++++++++++++++++++++
>>  include/linux/gpio/consumer.h |  2 ++
>>  2 files changed, 30 insertions(+)
>>
>> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
>> index 5b4111e4be3f..684ddb35d83b 100644
>> --- a/drivers/gpio/gpiolib-acpi.c
>> +++ b/drivers/gpio/gpiolib-acpi.c
>> @@ -128,6 +128,34 @@ static struct gpio_desc *acpi_get_gpiod(char *path, int pin)
>>  	return gpiochip_get_desc(chip, pin);
>>  }
>>  
>> +/**
>> + * acpi_get_and_request_gpiod() - Translate ACPI GPIO pin to GPIO descriptor
>> + *                               and hold a refcount to the GPIO device.
>> + * @path:      ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
>> + * @pin:       ACPI GPIO pin number (0-based, controller-relative)
>> + * @label:     Label to pass to gpiod_request()
>> + *
>> + * This function is a simple pass-through to acpi_get_gpiod(), except that
>> + * as it is intended for use outside of the GPIO layer (in a similar fashion to
>> + * gpiod_get_index() for example) it also holds a reference to the GPIO device.
>> + */
>> +struct gpio_desc *acpi_get_and_request_gpiod(char *path, int pin, char *label)
>> +{
>> +	struct gpio_desc *gpio;
>> +	int ret;
>> +
>> +	gpio = acpi_get_gpiod(path, pin);
>> +	if (IS_ERR(gpio))
>> +		return gpio;
>> +
>> +	ret = gpiod_request(gpio, label);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +
>> +	return gpio;
>> +}
>> +EXPORT_SYMBOL_GPL(acpi_get_and_request_gpiod);
>> +
>>  static irqreturn_t acpi_gpio_irq_handler(int irq, void *data)
>>  {
>>  	struct acpi_gpio_event *event = data;
>> diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
>> index c73b25bc9213..566feb56601f 100644
>> --- a/include/linux/gpio/consumer.h
>> +++ b/include/linux/gpio/consumer.h
>> @@ -692,6 +692,8 @@ int devm_acpi_dev_add_driver_gpios(struct device *dev,
>>  				   const struct acpi_gpio_mapping *gpios);
>>  void devm_acpi_dev_remove_driver_gpios(struct device *dev);
>>  
>> +struct gpio_desc *acpi_get_and_request_gpiod(char *path, int pin, char *label);
>> +
>>  #else  /* CONFIG_GPIOLIB && CONFIG_ACPI */
>>  
>>  struct acpi_device;
>> -- 
>> 2.25.1
>>