1 /* 2 * LCD Lowlevel Control Abstraction 3 * 4 * Copyright (C) 2003,2004 Hewlett-Packard Company 5 * 6 */ 7 8 #ifndef _LINUX_LCD_H 9 #define _LINUX_LCD_H 10 11 #include <linux/device.h> 12 #include <linux/mutex.h> 13 #include <linux/notifier.h> 14 15 /* Notes on locking: 16 * 17 * lcd_device->ops_lock is an internal backlight lock protecting the ops 18 * field and no code outside the core should need to touch it. 19 * 20 * Access to set_power() is serialised by the update_lock mutex since 21 * most drivers seem to need this and historically get it wrong. 22 * 23 * Most drivers don't need locking on their get_power() method. 24 * If yours does, you need to implement it in the driver. You can use the 25 * update_lock mutex if appropriate. 26 * 27 * Any other use of the locks below is probably wrong. 28 */ 29 30 struct lcd_device; 31 struct fb_info; 32 33 struct lcd_properties { 34 /* The maximum value for contrast (read-only) */ 35 int max_contrast; 36 }; 37 38 struct lcd_ops { 39 /* Get the LCD panel power status (0: full on, 1..3: controller 40 power on, flat panel power off, 4: full off), see FB_BLANK_XXX */ 41 int (*get_power)(struct lcd_device *); 42 /* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */ 43 int (*set_power)(struct lcd_device *, int power); 44 /* Get the current contrast setting (0-max_contrast) */ 45 int (*get_contrast)(struct lcd_device *); 46 /* Set LCD panel contrast */ 47 int (*set_contrast)(struct lcd_device *, int contrast); 48 /* Check if given framebuffer device is the one LCD is bound to; 49 return 0 if not, !=0 if it is. If NULL, lcd always matches the fb. */ 50 int (*check_fb)(struct fb_info *); 51 }; 52 53 struct lcd_device { 54 struct lcd_properties props; 55 /* This protects the 'ops' field. If 'ops' is NULL, the driver that 56 registered this device has been unloaded, and if class_get_devdata() 57 points to something in the body of that driver, it is also invalid. */ 58 struct mutex ops_lock; 59 /* If this is NULL, the backing module is unloaded */ 60 struct lcd_ops *ops; 61 /* Serialise access to set_power method */ 62 struct mutex update_lock; 63 /* The framebuffer notifier block */ 64 struct notifier_block fb_notif; 65 /* The class device structure */ 66 struct class_device class_dev; 67 }; 68 69 static inline void lcd_set_power(struct lcd_device *ld, int power) 70 { 71 mutex_lock(&ld->update_lock); 72 if (ld->ops && ld->ops->set_power) 73 ld->ops->set_power(ld, power); 74 mutex_unlock(&ld->update_lock); 75 } 76 77 extern struct lcd_device *lcd_device_register(const char *name, 78 void *devdata, struct lcd_ops *ops); 79 extern void lcd_device_unregister(struct lcd_device *ld); 80 81 #define to_lcd_device(obj) container_of(obj, struct lcd_device, class_dev) 82 83 #endif 84