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

[Sascha Hauer <s.hauer@pengutronix.de>]

On Tue, Feb 05, 2013 at 10:10:18AM +0400, Antony Pavlov wrote:
> On 4 February 2013 12:37, Sascha Hauer <s.hauer@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@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@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.

Sascha

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