| Message ID | 20230927142931.19798-6-brgl@bgdev.pl (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | gpiolib: work towards removing gpiochip_find() | expand |
On Wed, Sep 27, 2023 at 04:29:25PM +0200, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > Getting the GPIO descriptor directly from the gpio_chip struct is > dangerous as we don't take the reference to the underlying GPIO device. > In order to start working towards removing gpiochip_get_desc(), let's > provide a safer variant that works with an existing reference to struct > gpio_device. ... > +EXPORT_SYMBOL_GPL(gpiochip_get_desc); > +struct gpio_desc * > +gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum) I'm wondering if you move this to be upper than gpiochip_get_desc() and diff will look better...
On Mon, Oct 2, 2023 at 11:46 AM Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > > On Wed, Sep 27, 2023 at 04:29:25PM +0200, Bartosz Golaszewski wrote: > > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > > > Getting the GPIO descriptor directly from the gpio_chip struct is > > dangerous as we don't take the reference to the underlying GPIO device. > > In order to start working towards removing gpiochip_get_desc(), let's > > provide a safer variant that works with an existing reference to struct > > gpio_device. > > ... > > > +EXPORT_SYMBOL_GPL(gpiochip_get_desc); > > > +struct gpio_desc * > > +gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum) > > I'm wondering if you move this to be upper than gpiochip_get_desc() and > diff will look better... > There's a limit to bikeshedding in my book and "making the diff look better" is definitely it. :) Bart
On Mon, Oct 02, 2023 at 11:54:40AM +0200, Bartosz Golaszewski wrote: > On Mon, Oct 2, 2023 at 11:46 AM Andy Shevchenko > <andriy.shevchenko@linux.intel.com> wrote: > > On Wed, Sep 27, 2023 at 04:29:25PM +0200, Bartosz Golaszewski wrote: > > > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > > > > > Getting the GPIO descriptor directly from the gpio_chip struct is > > > dangerous as we don't take the reference to the underlying GPIO device. > > > In order to start working towards removing gpiochip_get_desc(), let's > > > provide a safer variant that works with an existing reference to struct > > > gpio_device. ... > > > +EXPORT_SYMBOL_GPL(gpiochip_get_desc); > > > > > +struct gpio_desc * > > > +gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum) > > > > I'm wondering if you move this to be upper than gpiochip_get_desc() and > > diff will look better... > > There's a limit to bikeshedding in my book and "making the diff look > better" is definitely it. :) Right, but if you are going to send a new version it might makes sense to try, no?
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 9f20311e4c1a..7d2574b3dbe5 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -147,27 +147,49 @@ struct gpio_desc *gpio_to_desc(unsigned gpio) } EXPORT_SYMBOL_GPL(gpio_to_desc); -/** - * gpiochip_get_desc - get the GPIO descriptor corresponding to the given - * hardware number for this chip - * @gc: GPIO chip - * @hwnum: hardware number of the GPIO for this chip - * - * Returns: - * A pointer to the GPIO descriptor or ``ERR_PTR(-EINVAL)`` if no GPIO exists - * in the given chip for the specified hardware number. - */ +/* This function is deprecated and will be removed soon, don't use. */ struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc, unsigned int hwnum) { - struct gpio_device *gdev = gc->gpiodev; + return gpio_device_get_desc(gc->gpiodev, hwnum); +} +EXPORT_SYMBOL_GPL(gpiochip_get_desc); + +/** + * gpio_device_get_desc() - get the GPIO descriptor corresponding to the given + * hardware number for this GPIO device + * @gdev: GPIO device to get the descriptor from + * @hwnum: hardware number of the GPIO for this chip + * + * Returns: + * A pointer to the GPIO descriptor or %EINVAL if no GPIO exists in the given + * chip for the specified hardware number or %ENODEV if the underlying chip + * already vanished. + * + * The reference count of struct gpio_device is *NOT* increased like when the + * GPIO is being requested for exclusive usage. It's up to the caller to make + * sure the GPIO device will stay alive together with the descriptor returned + * by this function. + */ +struct gpio_desc * +gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum) +{ + struct gpio_chip *gc; + + /* + * FIXME: This will be locked once we protect gdev->chip everywhere + * with SRCU. + */ + gc = gdev->chip; + if (!gc) + return ERR_PTR(-ENODEV); if (hwnum >= gdev->ngpio) return ERR_PTR(-EINVAL); return &gdev->descs[hwnum]; } -EXPORT_SYMBOL_GPL(gpiochip_get_desc); +EXPORT_SYMBOL_GPL(gpio_device_get_desc); /** * desc_to_gpio - convert a GPIO descriptor to the integer namespace diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index 24996cba6465..3fdf3f14bb13 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -770,6 +770,8 @@ struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *gc, void gpiochip_free_own_desc(struct gpio_desc *desc); struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc, unsigned int hwnum); +struct gpio_desc * +gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum); #ifdef CONFIG_GPIOLIB