[RFC] gpiolib: import gpio_request_array() from linux 3.7

[Antony Pavlov]

On 5 February 2013 14:19, Jean-Christophe PLAGNIOL-VILLARD
<plagnioj at jcrosoft.com> wrote:
> On 10:29 Tue 05 Feb     , Sascha Hauer wrote:
>> On Tue, Feb 05, 2013 at 10:10:18AM +0400, Antony Pavlov wrote:
>> > On 4 February 2013 12:37, Sascha Hauer <s.hauer at pengutronix.de> wrote:
>> > > On Mon, Feb 04, 2013 at 01:22:39AM +0400, Antony Pavlov wrote:
>> > >> On 4 February 2013 01:13, Jean-Christophe PLAGNIOL-VILLARD
>> > >> <plagnioj at jcrosoft.com> wrote:
>> > >> > On 23:16 Sun 03 Feb     , Antony Pavlov wrote:
>> > >> >> Also import related functions gpio_request_one() and
>> > >> >> gpio_free_array().
>> > >> >>
>> > >> >> Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
>> > >> >> ---
>> > >> >>  drivers/gpio/gpio.c |   66 +++++++++++++++++++++++++++++++++++++++++++++++++++
>> > >> >>  include/gpio.h      |   43 +++++++++++++++++++++++++++++++++
>> > >> >>  2 files changed, 109 insertions(+)
>> > >> >>
>> > >> >> diff --git a/drivers/gpio/gpio.c b/drivers/gpio/gpio.c
>> > >> >> index d37f5a0..631168d 100644
>> > >> >> --- a/drivers/gpio/gpio.c
>> > >> >> +++ b/drivers/gpio/gpio.c
>> > >> >> @@ -65,6 +65,72 @@ void gpio_free(unsigned gpio)
>> > >> >>       free(gi->label);
>> > >> >>  }
>> > >> >>
>> > >> >> +/**
>> > >> >> + * gpio_request_one - request a single GPIO with initial configuration
>> > >> >> + * @gpio:    the GPIO number
>> > >> >> + * @flags:   GPIO configuration as specified by GPIOF_*
>> > >> >> + * @label:   a literal description string of this GPIO
>> > >> >> + */
>> > >> >> +int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
>> > >> >> +{
>> > >> >> +     int err;
>> > >> >> +
>> > >> >> +     err = gpio_request(gpio, label);
>> > >> >> +     if (err)
>> > >> >> +             return err;
>> > >> >> +
>> > >> >> +     if (flags & GPIOF_DIR_IN)
>> > >> >> +             err = gpio_direction_input(gpio);
>> > >> >> +     else
>> > >> >> +             err = gpio_direction_output(gpio,
>> > >> >> +                             (flags & GPIOF_INIT_HIGH) ? 1 : 0);
>> > >> >> +
>> > >> >> +     if (err)
>> > >> >> +             goto free_gpio;
>> > >> >> +
>> > >> >> +     return 0;
>> > >> >> +
>> > >> >> +free_gpio:
>> > >> >> +     gpio_free(gpio);
>> > >> >> +     return err;
>> > >> >> +}
>> > >> >> +EXPORT_SYMBOL(gpio_request_one);
>> > >> >> +
>> > >> >> +/**
>> > >> >> + * gpio_request_array - request multiple GPIOs in a single call
>> > >> >> + * @array:   array of the 'struct gpio'
>> > >> >> + * @num:     how many GPIOs in the array
>> > >> >> + */
>> > >> >> +int gpio_request_array(const struct gpio *array, size_t num)
>> > >> >> +{
>> > >> >> +     int i, err;
>> > >> >> +
>> > >> >> +     for (i = 0; i < num; i++, array++) {
>> > >> >> +             err = gpio_request_one(array->gpio, array->flags, array->label);
>> > >> >> +             if (err)
>> > >> >> +                     goto err_free;
>> > >> >> +     }
>> > >> >> +     return 0;
>> > >> >> +
>> > >> >> +err_free:
>> > >> >> +     while (i--)
>> > >> >> +             gpio_free((--array)->gpio);
>> > >> >> +     return err;
>> > >> >> +}
>> > >> >> +EXPORT_SYMBOL(gpio_request_array);
>> > >> >> +
>> > >> >> +/**
>> > >> >> + * gpio_free_array - release multiple GPIOs in a single call
>> > >> >> + * @array:   array of the 'struct gpio'
>> > >> >> + * @num:     how many GPIOs in the array
>> > >> >> + */
>> > >> >> +void gpio_free_array(const struct gpio *array, size_t num)
>> > >> >> +{
>> > >> >> +     while (num--)
>> > >> >> +             gpio_free((array++)->gpio);
>> > >> >> +}
>> > >> >> +EXPORT_SYMBOL(gpio_free_array);
>> > >> >> +
>> > >> >>  void gpio_set_value(unsigned gpio, int value)
>> > >> >>  {
>> > >> >>       struct gpio_info *gi = &gpio_desc[gpio];
>> > >> >> diff --git a/include/gpio.h b/include/gpio.h
>> > >> >> index eedb980..37c151d 100644
>> > >> >> --- a/include/gpio.h
>> > >> >> +++ b/include/gpio.h
>> > >> >> @@ -3,6 +3,29 @@
>> > >> >>
>> > >> >>  #include <asm/gpio.h>
>> > >> >>
>> > >> >> +/* make these flag values available regardless of GPIO kconfig options */
>> > >> >> +#define GPIOF_DIR_OUT        (0 << 0)
>> > >> >> +#define GPIOF_DIR_IN (1 << 0)
>> > >> >> +
>> > >> >> +#define GPIOF_INIT_LOW       (0 << 1)
>> > >> >> +#define GPIOF_INIT_HIGH      (1 << 1)
>> > >> >> +
>> > >> >> +#define GPIOF_IN             (GPIOF_DIR_IN)
>> > >> >> +#define GPIOF_OUT_INIT_LOW   (GPIOF_DIR_OUT | GPIOF_INIT_LOW)
>> > >> >> +#define GPIOF_OUT_INIT_HIGH  (GPIOF_DIR_OUT | GPIOF_INIT_HIGH)
>> > >> >> +
>> > >> >> +/**
>> > >> >> + * struct gpio - a structure describing a GPIO with configuration
>> > >> >> + * @gpio:    the GPIO number
>> > >> >> + * @flags:   GPIO configuration as specified by GPIOF_*
>> > >> >> + * @label:   a literal description string of this GPIO
>> > >> >> + */
>> > >> >> +struct gpio {
>> > >> >> +     unsigned        gpio;
>> > >> >> +     unsigned long   flags;
>> > >> >> +     const char      *label;
>> > >> >> +};
>> > >> >> +
>> > >> >>  #ifndef CONFIG_GPIOLIB
>> > >> >>  static inline int gpio_request(unsigned gpio, const char *label)
>> > >> >>  {
>> > >> >> @@ -12,9 +35,29 @@ static inline int gpio_request(unsigned gpio, const char *label)
>> > >> >>  static inline void gpio_free(unsigned gpio)
>> > >> >>  {
>> > >> >>  }
>> > >> >> +
>> > >> >> +static inline int gpio_request_one(unsigned gpio,
>> > >> >> +                                     unsigned long flags, const char *label)
>> > >> >> +{
>> > >> >> +     return 0;
>> > >> >> +}
>> > >> >> +
>> > >> >> +static inline int gpio_request_array(const struct gpio *array, size_t num)
>> > >> >> +{
>> > >> >> +     return 0;
>> > >> >> +}
>> > >> > you can not do this
>> > >> >
>> > >> > as if we start to use this in generic driver where gpio_direction_input/output
>> > >> > work
>> > >> >
>> > >> > we will endup with no configuration
>> > >>
>> > >> But now in include/gpio.h we have this:
>> > >>
>> > >> static inline int gpio_request(unsigned gpio, const char *label)
>> > >> {
>> > >>     return 0;
>> > >> }
>> > >>
>> > >> Can you explain the difference?
>> > >
>> > > gpio_request is not implemented without gpiolib, still you have to
>> > > configure the direction and value.
>> >
>> > Can we use this functions only if gpiolib is enabled?
>> > Can we skip the function's definiton in the non-gpio situation?
>>
>> Sounds fine. We should get rid of the !gpiolib drivers anyway, maybe
>> this adds some motivation.
>
> until every driver are swith to gpiolib NACK as if we switch any generic
> driver to this as leds, gpio-keys, i2c-gpio etc... we break board support
> siliently

but leds, gpio-keys, i2c-gpio etc don't  use
gpio_request_one()-related functions.
If we ristrict the usage of gpio_request_one()-related functions (use
it only in board code for gpiolib-enabled machines)
we can avoid mentioned problems.

-- 
Best regards,
  Antony Pavlov