diff options
Diffstat (limited to 'include/linux/lcd.h')
| -rw-r--r-- | include/linux/lcd.h | 45 |
1 files changed, 36 insertions, 9 deletions
diff --git a/include/linux/lcd.h b/include/linux/lcd.h index d739b2e7eac..598793c0745 100644 --- a/include/linux/lcd.h +++ b/include/linux/lcd.h @@ -9,22 +9,38 @@ #define _LINUX_LCD_H #include <linux/device.h> +#include <linux/mutex.h> #include <linux/notifier.h> +/* Notes on locking: + * + * lcd_device->ops_lock is an internal backlight lock protecting the ops + * field and no code outside the core should need to touch it. + * + * Access to set_power() is serialised by the update_lock mutex since + * most drivers seem to need this and historically get it wrong. + * + * Most drivers don't need locking on their get_power() method. + * If yours does, you need to implement it in the driver. You can use the + * update_lock mutex if appropriate. + * + * Any other use of the locks below is probably wrong. + */ + struct lcd_device; struct fb_info; -/* This structure defines all the properties of a LCD flat panel. */ struct lcd_properties { - /* Owner module */ - struct module *owner; + /* The maximum value for contrast (read-only) */ + int max_contrast; +}; + +struct lcd_ops { /* Get the LCD panel power status (0: full on, 1..3: controller power on, flat panel power off, 4: full off), see FB_BLANK_XXX */ int (*get_power)(struct lcd_device *); /* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */ int (*set_power)(struct lcd_device *, int power); - /* The maximum value for contrast (read-only) */ - int max_contrast; /* Get the current contrast setting (0-max_contrast) */ int (*get_contrast)(struct lcd_device *); /* Set LCD panel contrast */ @@ -35,20 +51,31 @@ struct lcd_properties { }; struct lcd_device { - /* This protects the 'props' field. If 'props' is NULL, the driver that + struct lcd_properties props; + /* This protects the 'ops' field. If 'ops' is NULL, the driver that registered this device has been unloaded, and if class_get_devdata() points to something in the body of that driver, it is also invalid. */ - struct semaphore sem; + struct mutex ops_lock; /* If this is NULL, the backing module is unloaded */ - struct lcd_properties *props; + struct lcd_ops *ops; + /* Serialise access to set_power method */ + struct mutex update_lock; /* The framebuffer notifier block */ struct notifier_block fb_notif; /* The class device structure */ struct class_device class_dev; }; +static inline void lcd_set_power(struct lcd_device *ld, int power) +{ + mutex_lock(&ld->update_lock); + if (ld->ops && ld->ops->set_power) + ld->ops->set_power(ld, power); + mutex_unlock(&ld->update_lock); +} + extern struct lcd_device *lcd_device_register(const char *name, - void *devdata, struct lcd_properties *lp); + void *devdata, struct lcd_ops *ops); extern void lcd_device_unregister(struct lcd_device *ld); #define to_lcd_device(obj) container_of(obj, struct lcd_device, class_dev) |