include/linux/lcd.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * LCD Lowlevel Control Abstraction
   4  *
   5  * Copyright (C) 2003,2004 Hewlett-Packard Company
   6  *
   7  */
   8
   9 #ifndef _LINUX_LCD_H
  10 #define _LINUX_LCD_H
  11
  12 #include <linux/device.h>
  13 #include <linux/mutex.h>
  14 #include <linux/notifier.h>
  15 #include <linux/fb.h>
  16
  17 /* Notes on locking:
  18  *
  19  * lcd_device->ops_lock is an internal backlight lock protecting the ops
  20  * field and no code outside the core should need to touch it.
  21  *
  22  * Access to set_power() is serialised by the update_lock mutex since
  23  * most drivers seem to need this and historically get it wrong.
  24  *
  25  * Most drivers don't need locking on their get_power() method.
  26  * If yours does, you need to implement it in the driver. You can use the
  27  * update_lock mutex if appropriate.
  28  *
  29  * Any other use of the locks below is probably wrong.
  30  */
  31
  32 struct lcd_device;
  33 struct fb_info;
  34
  35 struct lcd_properties {
  36         /* The maximum value for contrast (read-only) */
  37         int max_contrast;
  38 };
  39
  40 struct lcd_ops {
  41         /* Get the LCD panel power status (0: full on, 1..3: controller
  42            power on, flat panel power off, 4: full off), see FB_BLANK_XXX */
  43         int (*get_power)(struct lcd_device *);
  44         /*
  45          * Enable or disable power to the LCD(0: on; 4: off, see FB_BLANK_XXX)
  46          * and this callback would be called proir to fb driver's callback.
  47          *
  48          * P.S. note that if early_set_power is not NULL then early fb notifier
  49          *      would be registered.
  50          */
  51         int (*early_set_power)(struct lcd_device *, int power);
  52         /* revert the effects of the early blank event. */
  53         int (*r_early_set_power)(struct lcd_device *, int power);
  54         /* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */
  55         int (*set_power)(struct lcd_device *, int power);
  56         /* Get the current contrast setting (0-max_contrast) */
  57         int (*get_contrast)(struct lcd_device *);
  58         /* Set LCD panel contrast */
  59         int (*set_contrast)(struct lcd_device *, int contrast);
  60         /* Set LCD panel mode (resolutions ...) */
  61         int (*set_mode)(struct lcd_device *, struct fb_videomode *);
  62         /* Check if given framebuffer device is the one LCD is bound to;
  63            return 0 if not, !=0 if it is. If NULL, lcd always matches the fb. */
  64         int (*check_fb)(struct lcd_device *, struct fb_info *);
  65 };
  66
  67 struct lcd_device {
  68         struct lcd_properties props;
  69         /* This protects the 'ops' field. If 'ops' is NULL, the driver that
  70            registered this device has been unloaded, and if class_get_devdata()
  71            points to something in the body of that driver, it is also invalid. */
  72         struct mutex ops_lock;
  73         /* If this is NULL, the backing module is unloaded */
  74         struct lcd_ops *ops;
  75         /* Serialise access to set_power method */
  76         struct mutex update_lock;
  77         /* The framebuffer notifier block */
  78         struct notifier_block fb_notif;
  79
  80         struct device dev;
  81 };
  82
  83 struct lcd_platform_data {
  84         /* reset lcd panel device. */
  85         int (*reset)(struct lcd_device *ld);
  86         /* on or off to lcd panel. if 'enable' is 0 then
  87            lcd power off and 1, lcd power on. */
  88         int (*power_on)(struct lcd_device *ld, int enable);
  89
  90         /* it indicates whether lcd panel was enabled
  91            from bootloader or not. */
  92         int lcd_enabled;
  93         /* it means delay for stable time when it becomes low to high
  94            or high to low that is dependent on whether reset gpio is
  95            low active or high active. */
  96         unsigned int reset_delay;
  97         /* stable time needing to become lcd power on. */
  98         unsigned int power_on_delay;
  99         /* stable time needing to become lcd power off. */
 100         unsigned int power_off_delay;
 101
 102         /* it could be used for any purpose. */
 103         void *pdata;
 104 };
 105
 106 static inline void lcd_set_power(struct lcd_device *ld, int power)
 107 {
 108         mutex_lock(&ld->update_lock);
 109         if (ld->ops && ld->ops->set_power)
 110                 ld->ops->set_power(ld, power);
 111         mutex_unlock(&ld->update_lock);
 112 }
 113
 114 extern struct lcd_device *lcd_device_register(const char *name,
 115         struct device *parent, void *devdata, struct lcd_ops *ops);
 116 extern struct lcd_device *devm_lcd_device_register(struct device *dev,
 117         const char *name, struct device *parent,
 118         void *devdata, struct lcd_ops *ops);
 119 extern void lcd_device_unregister(struct lcd_device *ld);
 120 extern void devm_lcd_device_unregister(struct device *dev,
 121         struct lcd_device *ld);
 122
 123 #define to_lcd_device(obj) container_of(obj, struct lcd_device, dev)
 124
 125 static inline void * lcd_get_data(struct lcd_device *ld_dev)
 126 {
 127         return dev_get_drvdata(&ld_dev->dev);
 128 }
 129
 130
 131 #endif