diff options
author | Bartosz Golaszewski <bartosz.golaszewski@linaro.org> | 2023-09-27 17:29:23 +0300 |
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committer | Bartosz Golaszewski <bartosz.golaszewski@linaro.org> | 2023-10-04 14:29:31 +0300 |
commit | cfe102f63308c8c8e01199a682868a64b83f653e (patch) | |
tree | bfdbc2a94b76a3c9a971d4b2c514d153ceafaba2 /drivers/gpio/gpiolib.c | |
parent | 9e4555d1e54a18946d7ca363b9fc8ed1fe7dfde4 (diff) | |
download | linux-cfe102f63308c8c8e01199a682868a64b83f653e.tar.xz |
gpiolib: provide gpio_device_find()
gpiochip_find() is wrong and its kernel doc is misleading as the
function doesn't return a reference to the gpio_chip but just a raw
pointer. The chip itself is not guaranteed to stay alive, in fact it can
be deleted at any point. Also: other than GPIO drivers themselves,
nobody else has any business accessing gpio_chip structs.
Provide a new gpio_device_find() function that returns a real reference
to the opaque gpio_device structure that is guaranteed to stay alive for
as long as there are active users of it.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio/gpiolib.c')
-rw-r--r-- | drivers/gpio/gpiolib.c | 71 |
1 files changed, 53 insertions, 18 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index c9d8f6b57771..d5bdf9cebb29 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1014,16 +1014,10 @@ void gpiochip_remove(struct gpio_chip *gc) } EXPORT_SYMBOL_GPL(gpiochip_remove); -/** - * gpiochip_find() - iterator for locating a specific gpio_chip - * @data: data to pass to match function - * @match: Callback function to check gpio_chip +/* + * FIXME: This will be removed soon. * - * Similar to bus_find_device. It returns a reference to a gpio_chip as - * determined by a user supplied @match callback. The callback should return - * 0 if the device doesn't match and non-zero if it does. If the callback is - * non-zero, this function will return to the caller and not iterate over any - * more gpio_chips. + * This function is depracated, don't use. */ struct gpio_chip *gpiochip_find(void *data, int (*match)(struct gpio_chip *gc, @@ -1031,21 +1025,62 @@ struct gpio_chip *gpiochip_find(void *data, { struct gpio_device *gdev; struct gpio_chip *gc = NULL; - unsigned long flags; - - spin_lock_irqsave(&gpio_lock, flags); - list_for_each_entry(gdev, &gpio_devices, list) - if (gdev->chip && match(gdev->chip, data)) { - gc = gdev->chip; - break; - } - spin_unlock_irqrestore(&gpio_lock, flags); + gdev = gpio_device_find(data, match); + if (gdev) { + gc = gdev->chip; + gpio_device_put(gdev); + } return gc; } EXPORT_SYMBOL_GPL(gpiochip_find); +/** + * gpio_device_find() - find a specific GPIO device + * @data: data to pass to match function + * @match: Callback function to check gpio_chip + * + * Returns: + * New reference to struct gpio_device. + * + * Similar to bus_find_device(). It returns a reference to a gpio_device as + * determined by a user supplied @match callback. The callback should return + * 0 if the device doesn't match and non-zero if it does. If the callback + * returns non-zero, this function will return to the caller and not iterate + * over any more gpio_devices. + * + * The callback takes the GPIO chip structure as argument. During the execution + * of the callback function the chip is protected from being freed. TODO: This + * actually has yet to be implemented. + * + * If the function returns non-NULL, the returned reference must be freed by + * the caller using gpio_device_put(). + */ +struct gpio_device *gpio_device_find(void *data, + int (*match)(struct gpio_chip *gc, + void *data)) +{ + struct gpio_device *gdev; + + /* + * Not yet but in the future the spinlock below will become a mutex. + * Annotate this function before anyone tries to use it in interrupt + * context like it happened with gpiochip_find(). + */ + might_sleep(); + + guard(spinlock_irqsave)(&gpio_lock); + + list_for_each_entry(gdev, &gpio_devices, list) { + if (gdev->chip && match(gdev->chip, data)) + return gpio_device_get(gdev); + } + + return NULL; +} +EXPORT_SYMBOL_GPL(gpio_device_find); + static int gpiochip_match_name(struct gpio_chip *gc, void *data) { const char *name = data; |