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Date: Wed, 12 Feb 2014 10:41:43 +0100
From: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
To: Alexandre Courbot <acourbot@...dia.com>
Cc: Linus Walleij <linus.walleij@...aro.org>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Jean-Jacques Hiblot <jjhiblot@...phandler.com>,
"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] gpiolib: add gpiochip_get_desc() driver function
Hi Alexandre,
2014-02-09 9:43 GMT+01:00 Alexandre Courbot <acourbot@...dia.com>:
> Some drivers dealing with a gpio_chip might need to act on its
> descriptors directly; one example is pinctrl drivers that need to lock a
> GPIO for being used as IRQ using gpiod_lock_as_irq().
>
> This patch exports a gpiochip_get_desc() function that returns the
> GPIO descriptor at the requested index. It also sweeps the
> gpio_to_chip() function out of the consumer interface since any holder
> of a gpio_chip reference can manipulate its GPIOs way beyond what a
> consumer should be allowed to do.
>
> As a result, gpio_chip is not visible anymore to simple GPIO consumers.
>
> Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
> ---
> Jean-Jacques, I think you will want to use this function for locking GPIOs
> in the AT91 pinctrl driver. Mika, we talked about this a while ago already,
> but here it is finally. Next patch uses it in the GPIO ACPI driver.
Thanks for the feature. At the moment though I'm still using the
wrapper gpio_lock_as_irq().
Reviewed-by: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
>
> drivers/gpio/gpiolib.c | 17 +++++++++--------
> include/linux/gpio/consumer.h | 8 --------
> include/linux/gpio/driver.h | 18 ++++++++++++++++++
> 3 files changed, 27 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 50c4922..f60d74b 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -164,16 +164,17 @@ struct gpio_desc *gpio_to_desc(unsigned gpio)
> EXPORT_SYMBOL_GPL(gpio_to_desc);
>
> /**
> - * Convert an offset on a certain chip to a corresponding descriptor
> + * Get the GPIO descriptor corresponding to the given hw number for this chip.
> */
> -static struct gpio_desc *gpiochip_offset_to_desc(struct gpio_chip *chip,
> - unsigned int offset)
> +struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip,
> + u16 hwnum)
> {
> - if (offset >= chip->ngpio)
> + if (hwnum >= chip->ngpio)
> return ERR_PTR(-EINVAL);
>
> - return &chip->desc[offset];
> + return &chip->desc[hwnum];
> }
> +EXPORT_SYMBOL_GPL(gpiochip_get_desc);
>
> /**
> * Convert a GPIO descriptor to the integer namespace.
> @@ -2161,7 +2162,7 @@ EXPORT_SYMBOL_GPL(gpiod_lock_as_irq);
>
> int gpio_lock_as_irq(struct gpio_chip *chip, unsigned int offset)
> {
> - return gpiod_lock_as_irq(gpiochip_offset_to_desc(chip, offset));
> + return gpiod_lock_as_irq(gpiochip_get_desc(chip, offset));
> }
> EXPORT_SYMBOL_GPL(gpio_lock_as_irq);
>
> @@ -2183,7 +2184,7 @@ EXPORT_SYMBOL_GPL(gpiod_unlock_as_irq);
>
> void gpio_unlock_as_irq(struct gpio_chip *chip, unsigned int offset)
> {
> - return gpiod_unlock_as_irq(gpiochip_offset_to_desc(chip, offset));
> + return gpiod_unlock_as_irq(gpiochip_get_desc(chip, offset));
> }
> EXPORT_SYMBOL_GPL(gpio_unlock_as_irq);
>
> @@ -2404,7 +2405,7 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
> return ERR_PTR(-EINVAL);
> }
>
> - desc = gpiochip_offset_to_desc(chip, p->chip_hwnum);
> + desc = gpiochip_get_desc(chip, p->chip_hwnum);
> *flags = p->flags;
>
> return desc;
> diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
> index 7a8144f..f6a9cc3 100644
> --- a/include/linux/gpio/consumer.h
> +++ b/include/linux/gpio/consumer.h
> @@ -5,7 +5,6 @@
> #include <linux/kernel.h>
>
> struct device;
> -struct gpio_chip;
>
> /**
> * Opaque descriptor for a GPIO. These are obtained using gpiod_get() and are
> @@ -59,7 +58,6 @@ int gpiod_to_irq(const struct gpio_desc *desc);
> /* Convert between the old gpio_ and new gpiod_ interfaces */
> struct gpio_desc *gpio_to_desc(unsigned gpio);
> int desc_to_gpio(const struct gpio_desc *desc);
> -struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc);
>
> #else /* CONFIG_GPIOLIB */
>
> @@ -207,12 +205,6 @@ static inline int desc_to_gpio(const struct gpio_desc *desc)
> WARN_ON(1);
> return -EINVAL;
> }
> -static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
> -{
> - /* GPIO can never have been requested */
> - WARN_ON(1);
> - return ERR_PTR(-ENODEV);
> -}
>
>
> #endif /* CONFIG_GPIOLIB */
> diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
> index a3e181e..9fe2836 100644
> --- a/include/linux/gpio/driver.h
> +++ b/include/linux/gpio/driver.h
> @@ -10,6 +10,8 @@ struct of_phandle_args;
> struct device_node;
> struct seq_file;
>
> +#ifdef CONFIG_GPIOLIB
> +
> /**
> * struct gpio_chip - abstract a GPIO controller
> * @label: for diagnostics
> @@ -129,6 +131,11 @@ extern struct gpio_chip *gpiochip_find(void *data,
> int gpiod_lock_as_irq(struct gpio_desc *desc);
> void gpiod_unlock_as_irq(struct gpio_desc *desc);
>
> +struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc);
> +
> +struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip,
> + u16 hwnum);
> +
> enum gpio_lookup_flags {
> GPIO_ACTIVE_HIGH = (0 << 0),
> GPIO_ACTIVE_LOW = (1 << 0),
> @@ -183,4 +190,15 @@ struct gpiod_lookup_table {
>
> void gpiod_add_lookup_table(struct gpiod_lookup_table *table);
>
> +#else /* CONFIG_GPIOLIB */
> +
> +static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
> +{
> + /* GPIO can never have been requested */
> + WARN_ON(1);
> + return ERR_PTR(-ENODEV);
> +}
> +
> +#endif /* CONFIG_GPIOLIB */
> +
> #endif
> --
> 1.8.5.4
>
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