diff options
| author | Jacek Anaszewski <j.anaszewski@samsung.com> | 2014-09-22 08:21:04 -0700 |
|---|---|---|
| committer | Bryan Wu <cooloney@gmail.com> | 2014-11-14 14:29:35 -0800 |
| commit | acd899e4f3066b6662f6047da5b795cc762093cb (patch) | |
| tree | 8a0cdf6849c1aec46d741ddee463067951a942ed /include/linux/leds.h | |
| parent | 3f6e42c808409c40dd0d0f8fe2022d197b27455e (diff) | |
leds: implement sysfs interface locking mechanism
Add a mechanism for locking LED subsystem sysfs interface.
This patch prepares ground for addition of LED Flash Class
extension, whose API will be integrated with V4L2 Flash API.
Such a fusion enforces introducing a locking scheme, which
will secure consistent access to the LED Flash Class device.
The mechanism being introduced allows for disabling LED
subsystem sysfs interface by calling led_sysfs_disable function
and enabling it by calling led_sysfs_enable. The functions
alter the LED_SYSFS_DISABLE flag state and must be called
under mutex lock. The state of the lock is checked with use
of led_sysfs_is_disabled function. Such a design allows for
providing immediate feedback to the user space on whether
the LED Flash Class device is available or is under V4L2 Flash
sub-device control.
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Bryan Wu <cooloney@gmail.com>
Diffstat (limited to 'include/linux/leds.h')
| -rw-r--r-- | include/linux/leds.h | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/leds.h b/include/linux/leds.h index a57611d0c94e..737f9b1051f2 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -13,6 +13,7 @@ #define __LINUX_LEDS_H_INCLUDED #include <linux/list.h> +#include <linux/mutex.h> #include <linux/rwsem.h> #include <linux/spinlock.h> #include <linux/timer.h> @@ -42,6 +43,7 @@ struct led_classdev { #define LED_BLINK_ONESHOT (1 << 17) #define LED_BLINK_ONESHOT_STOP (1 << 18) #define LED_BLINK_INVERT (1 << 19) +#define LED_SYSFS_DISABLE (1 << 20) /* Set LED brightness level */ /* Must not sleep, use a workqueue if needed */ @@ -85,6 +87,9 @@ struct led_classdev { /* true if activated - deactivate routine uses it to do cleanup */ bool activated; #endif + + /* Ensures consistent access to the LED Flash Class device */ + struct mutex led_access; }; extern int led_classdev_register(struct device *parent, @@ -151,6 +156,33 @@ extern void led_set_brightness(struct led_classdev *led_cdev, */ extern int led_update_brightness(struct led_classdev *led_cdev); +/** + * led_sysfs_disable - disable LED sysfs interface + * @led_cdev: the LED to set + * + * Disable the led_cdev's sysfs interface. + */ +extern void led_sysfs_disable(struct led_classdev *led_cdev); + +/** + * led_sysfs_enable - enable LED sysfs interface + * @led_cdev: the LED to set + * + * Enable the led_cdev's sysfs interface. + */ +extern void led_sysfs_enable(struct led_classdev *led_cdev); + +/** + * led_sysfs_is_disabled - check if LED sysfs interface is disabled + * @led_cdev: the LED to query + * + * Returns: true if the led_cdev's sysfs interface is disabled. + */ +static inline bool led_sysfs_is_disabled(struct led_classdev *led_cdev) +{ + return led_cdev->flags & LED_SYSFS_DISABLE; +} + /* * LED Triggers */ |