[v3,1/2] gpio: Add devm_fwnode_gpiod_get_optional() helpers

Add devm_fwnode_gpiod_get_optional() and
devm_fwnode_gpiod_get_index_optional() helpers, similar to regular
devm_gpiod optional versions.  Drivers getting GPIOs from a firmware
node might use it to remove some boilerplate code.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

---

Changes since v2:
1. Return NULL

Changes since v1:
1. New patch
---
 drivers/gpio/gpiolib-devres.c | 71 +++++++++++++++++++++++++++++++++++
 include/linux/gpio/consumer.h | 30 +++++++++++++++
 2 files changed, 101 insertions(+)

On Thu, Aug 27, 2020 at 9:28 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> Add devm_fwnode_gpiod_get_optional() and
> devm_fwnode_gpiod_get_index_optional() helpers, similar to regular
> devm_gpiod optional versions.  Drivers getting GPIOs from a firmware
> node might use it to remove some boilerplate code.
>

For both:
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
>
> ---
>
> Changes since v2:
> 1. Return NULL
>
> Changes since v1:
> 1. New patch
> ---
>  drivers/gpio/gpiolib-devres.c | 71 +++++++++++++++++++++++++++++++++++
>  include/linux/gpio/consumer.h | 30 +++++++++++++++
>  2 files changed, 101 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib-devres.c b/drivers/gpio/gpiolib-devres.c
> index 7dbce4c4ebdf..f8476f6a65cc 100644
> --- a/drivers/gpio/gpiolib-devres.c
> +++ b/drivers/gpio/gpiolib-devres.c
> @@ -184,6 +184,37 @@ struct gpio_desc *devm_gpiod_get_from_of_node(struct device *dev,
>  }
>  EXPORT_SYMBOL_GPL(devm_gpiod_get_from_of_node);
>
> +/**
> + * devm_fwnode_gpiod_get_optional - Resource-managed fwnode_gpiod_get_index()
> + *                                  for optional GPIO
> + * @dev:       GPIO consumer
> + * @fwnode:    firmware node containing GPIO reference
> + * @con_id:    function within the GPIO consumer
> + * @flags:     GPIO initialization flags
> + * @label:     label to attach to the requested GPIO
> + *
> + * GPIO descriptors returned from this function are automatically disposed on
> + * driver detach.
> + *
> + * This is equivalent to devm_fwnode_gpiod_get_index(), except that when no
> + * GPIO with the specified index was assigned to the requested function it will
> + * return NULL.  This is convenient for drivers that need to handle optional
> + * GPIOs.
> + *
> + * On successful request the GPIO pin is configured in accordance with
> + * provided @flags.
> + */
> +struct gpio_desc *devm_fwnode_gpiod_get_optional(struct device *dev,
> +                                                struct fwnode_handle *fwnode,
> +                                                const char *con_id,
> +                                                enum gpiod_flags flags,
> +                                                const char *label)
> +{
> +       return devm_fwnode_gpiod_get_index_optional(dev, fwnode, con_id, 0,
> +                                                   flags, label);
> +}
> +EXPORT_SYMBOL_GPL(devm_fwnode_gpiod_get_optional);
> +
>  /**
>   * devm_fwnode_gpiod_get_index - get a GPIO descriptor from a given node
>   * @dev:       GPIO consumer
> @@ -226,6 +257,46 @@ struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
>  }
>  EXPORT_SYMBOL_GPL(devm_fwnode_gpiod_get_index);
>
> +/**
> + * devm_fwnode_gpiod_get_index_optional - Resource-managed fwnode_gpiod_get_index()
> + *                                        for optional GPIO
> + * @dev:       GPIO consumer
> + * @fwnode:    firmware node containing GPIO reference
> + * @con_id:    function within the GPIO consumer
> + * @index:     index of the GPIO to obtain in the consumer
> + * @flags:     GPIO initialization flags
> + * @label:     label to attach to the requested GPIO
> + *
> + * GPIO descriptors returned from this function are automatically disposed on
> + * driver detach.
> + *
> + * This is equivalent to devm_fwnode_gpiod_get_index(), except that when no
> + * GPIO with the specified index was assigned to the requested function it will
> + * return NULL.  This is convenient for drivers that need to handle optional
> + * GPIOs.
> + *
> + * On successful request the GPIO pin is configured in accordance with
> + * provided @flags.
> + */
> +struct gpio_desc *devm_fwnode_gpiod_get_index_optional(struct device *dev,
> +                                                      struct fwnode_handle *fwnode,
> +                                                      const char *con_id, int index,
> +                                                      enum gpiod_flags flags,
> +                                                      const char *label)
> +{
> +       struct gpio_desc *desc;
> +
> +       desc = devm_fwnode_gpiod_get_index(dev, fwnode, con_id, index, flags,
> +                                          label);
> +       if (IS_ERR(desc)) {
> +               if (PTR_ERR(desc) == -ENOENT)
> +                       return NULL;
> +       }
> +
> +       return desc;
> +}
> +EXPORT_SYMBOL_GPL(devm_fwnode_gpiod_get_index_optional);
> +
>  /**
>   * devm_gpiod_get_index_optional - Resource-managed gpiod_get_index_optional()
>   * @dev: GPIO consumer
> diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
> index 901aab89d025..7854d80b1e9a 100644
> --- a/include/linux/gpio/consumer.h
> +++ b/include/linux/gpio/consumer.h
> @@ -183,11 +183,21 @@ struct gpio_desc *fwnode_gpiod_get_index(struct fwnode_handle *fwnode,
>                                          const char *con_id, int index,
>                                          enum gpiod_flags flags,
>                                          const char *label);
> +struct gpio_desc *devm_fwnode_gpiod_get_optional(struct device *dev,
> +                                                struct fwnode_handle *fwnode,
> +                                                const char *con_id,
> +                                                enum gpiod_flags flags,
> +                                                const char *label);
>  struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
>                                               struct fwnode_handle *child,
>                                               const char *con_id, int index,
>                                               enum gpiod_flags flags,
>                                               const char *label);
> +struct gpio_desc *devm_fwnode_gpiod_get_index_optional(struct device *dev,
> +                                                      struct fwnode_handle *fwnode,
> +                                                      const char *con_id, int index,
> +                                                      enum gpiod_flags flags,
> +                                                      const char *label);
>
>  #else /* CONFIG_GPIOLIB */
>
> @@ -562,6 +572,16 @@ struct gpio_desc *fwnode_gpiod_get_index(struct fwnode_handle *fwnode,
>         return ERR_PTR(-ENOSYS);
>  }
>
> +static inline
> +struct gpio_desc *devm_fwnode_gpiod_get_optional(struct device *dev,
> +                                                struct fwnode_handle *fwnode,
> +                                                const char *con_id,
> +                                                enum gpiod_flags flags,
> +                                                const char *label)
> +{
> +       return NULL;
> +}
> +
>  static inline
>  struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
>                                               struct fwnode_handle *fwnode,
> @@ -572,6 +592,16 @@ struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
>         return ERR_PTR(-ENOSYS);
>  }
>
> +static inline
> +struct gpio_desc *devm_fwnode_gpiod_get_index_optional(struct device *dev,
> +                                                      struct fwnode_handle *fwnode,
> +                                                      const char *con_id, int index,
> +                                                      enum gpiod_flags flags,
> +                                                      const char *label)
> +{
> +       return NULL;
> +}
> +
>  #endif /* CONFIG_GPIOLIB */
>
>  static inline
> --
> 2.17.1
>