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
  16 #define LCD_POWER_ON                    (0)
  17 #define LCD_POWER_REDUCED               (1) // deprecated; don't use in new code
  18 #define LCD_POWER_REDUCED_VSYNC_SUSPEND (2) // deprecated; don't use in new code
  19 #define LCD_POWER_OFF                   (4)
  20
  21 /* Notes on locking:
  22  *
  23  * lcd_device->ops_lock is an internal backlight lock protecting the ops
  24  * field and no code outside the core should need to touch it.
  25  *
  26  * Access to set_power() is serialised by the update_lock mutex since
  27  * most drivers seem to need this and historically get it wrong.
  28  *
  29  * Most drivers don't need locking on their get_power() method.
  30  * If yours does, you need to implement it in the driver. You can use the
  31  * update_lock mutex if appropriate.
  32  *
  33  * Any other use of the locks below is probably wrong.
  34  */
  35
  36 struct lcd_device;
  37
  38 struct lcd_properties {
  39         /* The maximum value for contrast (read-only) */
  40         int max_contrast;
  41 };
  42
  43 struct lcd_ops {
  44         /* Get the LCD panel power status (0: full on, 1..3: controller
  45            power on, flat panel power off, 4: full off), see FB_BLANK_XXX */
  46         int (*get_power)(struct lcd_device *);
  47         /* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */
  48         int (*set_power)(struct lcd_device *, int power);
  49         /* Get the current contrast setting (0-max_contrast) */
  50         int (*get_contrast)(struct lcd_device *);
  51         /* Set LCD panel contrast */
  52         int (*set_contrast)(struct lcd_device *, int contrast);
  53
  54         /*
  55          * Set LCD panel mode (resolutions ...)
  56          */
  57         int (*set_mode)(struct lcd_device *lcd, u32 xres, u32 yres);
  58
  59         /*
  60          * Check if the LCD controls the given display device. This
  61          * operation is optional and if not implemented it is assumed that
  62          * the display is always the one controlled by the LCD.
  63          *
  64          * RETURNS:
  65          *
  66          * If display_dev is NULL or display_dev matches the device controlled by
  67          * the LCD, return true. Otherwise return false.
  68          */
  69         bool (*controls_device)(struct lcd_device *lcd, struct device *display_device);
  70 };
  71
  72 struct lcd_device {
  73         struct lcd_properties props;
  74         /* This protects the 'ops' field. If 'ops' is NULL, the driver that
  75            registered this device has been unloaded, and if class_get_devdata()
  76            points to something in the body of that driver, it is also invalid. */
  77         struct mutex ops_lock;
  78         /* If this is NULL, the backing module is unloaded */
  79         const struct lcd_ops *ops;
  80         /* Serialise access to set_power method */
  81         struct mutex update_lock;
  82         /* The framebuffer notifier block */
  83         struct notifier_block fb_notif;
  84
  85         struct device dev;
  86 };
  87
  88 struct lcd_platform_data {
  89         /* reset lcd panel device. */
  90         int (*reset)(struct lcd_device *ld);
  91         /* on or off to lcd panel. if 'enable' is 0 then
  92            lcd power off and 1, lcd power on. */
  93         int (*power_on)(struct lcd_device *ld, int enable);
  94
  95         /* it indicates whether lcd panel was enabled
  96            from bootloader or not. */
  97         int lcd_enabled;
  98         /* it means delay for stable time when it becomes low to high
  99            or high to low that is dependent on whether reset gpio is
 100            low active or high active. */
 101         unsigned int reset_delay;
 102         /* stable time needing to become lcd power on. */
 103         unsigned int power_on_delay;
 104         /* stable time needing to become lcd power off. */
 105         unsigned int power_off_delay;
 106
 107         /* it could be used for any purpose. */
 108         void *pdata;
 109 };
 110
 111 static inline void lcd_set_power(struct lcd_device *ld, int power)
 112 {
 113         mutex_lock(&ld->update_lock);
 114         if (ld->ops && ld->ops->set_power)
 115                 ld->ops->set_power(ld, power);
 116         mutex_unlock(&ld->update_lock);
 117 }
 118
 119 extern struct lcd_device *lcd_device_register(const char *name,
 120         struct device *parent, void *devdata, const struct lcd_ops *ops);
 121 extern struct lcd_device *devm_lcd_device_register(struct device *dev,
 122         const char *name, struct device *parent,
 123         void *devdata, const struct lcd_ops *ops);
 124 extern void lcd_device_unregister(struct lcd_device *ld);
 125 extern void devm_lcd_device_unregister(struct device *dev,
 126         struct lcd_device *ld);
 127
 128 #define to_lcd_device(obj) container_of(obj, struct lcd_device, dev)
 129
 130 static inline void * lcd_get_data(struct lcd_device *ld_dev)
 131 {
 132         return dev_get_drvdata(&ld_dev->dev);
 133 }
 134
 135
 136 #endif