[RFC] gpiolib: import gpio_request_array() from linux 3.7
Sascha Hauer
s.hauer at pengutronix.de
Wed Feb 6 14:31:35 EST 2013
On Tue, Feb 05, 2013 at 03:02:54PM +0400, Antony Pavlov wrote:
> 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.
You should probably just provide a static inline wrapper for the
!gpiolib case. It's sufficiently easy to do and avoids that someone
who wants to use the functions in a driver has to fixup all other
gpio drivers first.
Sascha
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