Re: Add to_irq fields to gpiolib (with sample implementation)

[Ramax Lo]

2008/7/18 Ben Dooks <ben-linux@xxxxxxxxx>:
> The two patches form a pair of patches to show
> that we should consider adding an to_irq field
> to the gpio_chip structure and gpiolib support.
>

Indeed, it's necessary to add a new field to provide
a general interface.

> The reason is that if we add support for devices
> registering gpio to also register interrputs, then
> a single arch-dependant interrupt mapping is not
> going to be sufficient.
>
> Note, this set does not remove any clashing
> definitions that may have of gpio_to_irq.
>
> ---
> GPIO: Add generic gpio_to_irq call.
>
> Add gpio_to_irq() implementation allowing the
> gpio_chip registration to also specify an function
> to map GPIO offsets into IRQs.
>
> Signed-off-by: Ben Dooks <ben-linux@xxxxxxxxx>
>
> Index: linux-2.6.26-quilt3/drivers/gpio/gpiolib.c
> ===================================================================
> --- linux-2.6.26-quilt3.orig/drivers/gpio/gpiolib.c     2008-07-18 00:40:52.000000000 +0100
> +++ linux-2.6.26-quilt3/drivers/gpio/gpiolib.c  2008-07-18 00:52:07.000000000 +0100
> @@ -339,6 +339,36 @@ const char *gpiochip_is_requested(struct
>  }
>  EXPORT_SYMBOL_GPL(gpiochip_is_requested);
>
> +int gpio_to_irq(unsigned gpio)
> +{
> +       struct gpio_chip        *chip;
> +       struct gpio_desc        *desc = &gpio_desc[gpio];
> +       unsigned long           flags;
> +       int                     status = -EINVAL;
> +
> +       spin_lock_irqsave(&gpio_lock, flags);
> +
> +       if (!gpio_is_valid(gpio))
> +               goto fail;
> +
> +       chip = desc->chip;
> +       if (!chip || !chip->to_irq)
> +               goto fail;
> +
> +       gpio -= chip->base;
> +       if (gpio >= chip->ngpio)
> +               goto fail;
> +
> +       status = chip->to_irq(chip, gpio);
> +
> + fail:
> +       spin_unlock_irqrestore(&gpio_lock, flags);
> +       if (status)
> +               pr_debug("%s: gpio-%d status %d\n",
> +                       __func__, gpio, status);
> +       return status;
> +}
> +EXPORT_SYMBOL_GPL(gpio_to_irq);
>

Is it possible to define it as __gpio_to_irq(), and let people
define their macro or inline function, like the case of
__gpio_get_value(), to maintain compatibility?

>  /* Drivers MUST set GPIO direction before making get/set calls.  In
>  * some cases this is done in early boot, before IRQs are enabled.
> Index: linux-2.6.26-quilt3/include/asm-generic/gpio.h
> ===================================================================
> --- linux-2.6.26-quilt3.orig/include/asm-generic/gpio.h 2008-07-18 00:40:52.000000000 +0100
> +++ linux-2.6.26-quilt3/include/asm-generic/gpio.h      2008-07-18 00:46:32.000000000 +0100
> @@ -40,6 +40,7 @@ struct module;
>  * @dbg_show: optional routine to show contents in debugfs; default code
>  *     will be used when this is omitted, but custom code can show extra
>  *     state (such as pullup/pulldown configuration).
> + * @to_irq: convert gpio offset to IRQ number.
>  * @base: identifies the first GPIO number handled by this chip; or, if
>  *     negative during registration, requests dynamic ID allocation.
>  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
> @@ -71,6 +72,9 @@ struct gpio_chip {
>                                                unsigned offset, int value);
>        void                    (*dbg_show)(struct seq_file *s,
>                                                struct gpio_chip *chip);
> +       int                     (*to_irq)(struct gpio_chip *chip,
> +                                         unsigned offset);
> +
>        int                     base;
>        u16                     ngpio;
>        unsigned                can_sleep:1;
> @@ -97,6 +101,7 @@ extern int gpio_direction_output(unsigne
>  extern int gpio_get_value_cansleep(unsigned gpio);
>  extern void gpio_set_value_cansleep(unsigned gpio, int value);
>
> +extern int gpio_to_irq(unsigned gpio);
>
>  /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
>  * the GPIO is constant and refers to some always-present controller,
>
>
> S3C24XX: Add gpio_to_irq implementation
>
> Add the necessary to_irq fields for the S3C24XX
> GPIO banks that support IRQs.
>
> Signed-off-by: Ben Dooks <ben-linux@xxxxxxxxx>
>
> Index: linux-2.6.26-quilt3/arch/arm/plat-s3c24xx/gpiolib.c
> ===================================================================
> --- linux-2.6.26-quilt3.orig/arch/arm/plat-s3c24xx/gpiolib.c    2008-07-18 12:35:15.000000000 +0100
> +++ linux-2.6.26-quilt3/arch/arm/plat-s3c24xx/gpiolib.c 2008-07-18 12:37:39.000000000 +0100
> @@ -150,6 +150,19 @@ static int s3c24xx_gpiolib_banka_output(
>        return 0;
>  }
>
> +static int s3c24xx_gpiolib_bankf_toirq(struct gpio_chip *chip, unsigned offset)
> +{
> +       if (offset < 4)
> +               return IRQ_EINT0 + offset;
> +
> +       return IRQ_EINT4 + (offset - 4);
> +}
> +
> +static int s3c24xx_gpiolib_bankg_toirq(struct gpio_chip *chip, unsigned offset)
> +{
> +       return IRQ_EINT8 + offset;
> +}
> +
>
>  struct s3c24xx_gpio_chip gpios[] = {
>        [0] = {
> @@ -228,6 +241,7 @@ struct s3c24xx_gpio_chip gpios[] = {
>                        .direction_output       = s3c24xx_gpiolib_output,
>                        .set                    = s3c24xx_gpiolib_set,
>                        .get                    = s3c24xx_gpiolib_get,
> +                       .to_irq                 = s3c24xx_gpiolib_bankf_toirq,
>                },
>        },
>        [6] = {
> @@ -241,6 +255,7 @@ struct s3c24xx_gpio_chip gpios[] = {
>                        .direction_output       = s3c24xx_gpiolib_output,
>                        .set                    = s3c24xx_gpiolib_set,
>                        .get                    = s3c24xx_gpiolib_get,
> +                       .to_irq                 = s3c24xx_gpiolib_bankg_toirq,
>                },
>        },
>  };
>
>
> --
> Ben (ben@xxxxxxxxx, http://www.fluff.org/)
>
>  'a smiley only costs 4 bytes'
>
> -------------------------------------------------------------------
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