LXR linux/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
  32struct lcd_device;
  33struct fb_info;
  34
  35struct lcd_properties {
  36        /* The maximum value for contrast (read-only) */
  37        int max_contrast;
  38};
  39
  40struct 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        /* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */
  45        int (*set_power)(struct lcd_device *, int power);
  46        /* Get the current contrast setting (0-max_contrast) */
  47        int (*get_contrast)(struct lcd_device *);
  48        /* Set LCD panel contrast */
  49        int (*set_contrast)(struct lcd_device *, int contrast);
  50        /* Set LCD panel mode (resolutions ...) */
  51        int (*set_mode)(struct lcd_device *, struct fb_videomode *);
  52        /* Check if given framebuffer device is the one LCD is bound to;
  53           return 0 if not, !=0 if it is. If NULL, lcd always matches the fb. */
  54        int (*check_fb)(struct lcd_device *, struct fb_info *);
  55};
  56
  57struct lcd_device {
  58        struct lcd_properties props;
  59        /* This protects the 'ops' field. If 'ops' is NULL, the driver that
  60           registered this device has been unloaded, and if class_get_devdata()
  61           points to something in the body of that driver, it is also invalid. */
  62        struct mutex ops_lock;
  63        /* If this is NULL, the backing module is unloaded */
  64        struct lcd_ops *ops;
  65        /* Serialise access to set_power method */
  66        struct mutex update_lock;
  67        /* The framebuffer notifier block */
  68        struct notifier_block fb_notif;
  69
  70        struct device dev;
  71};
  72
  73struct lcd_platform_data {
  74        /* reset lcd panel device. */
  75        int (*reset)(struct lcd_device *ld);
  76        /* on or off to lcd panel. if 'enable' is 0 then
  77           lcd power off and 1, lcd power on. */
  78        int (*power_on)(struct lcd_device *ld, int enable);
  79
  80        /* it indicates whether lcd panel was enabled
  81           from bootloader or not. */
  82        int lcd_enabled;
  83        /* it means delay for stable time when it becomes low to high
  84           or high to low that is dependent on whether reset gpio is
  85           low active or high active. */
  86        unsigned int reset_delay;
  87        /* stable time needing to become lcd power on. */
  88        unsigned int power_on_delay;
  89        /* stable time needing to become lcd power off. */
  90        unsigned int power_off_delay;
  91
  92        /* it could be used for any purpose. */
  93        void *pdata;
  94};
  95
  96static inline void lcd_set_power(struct lcd_device *ld, int power)
  97{
  98        mutex_lock(&ld->update_lock);
  99        if (ld->ops && ld->ops->set_power)
 100                ld->ops->set_power(ld, power);
 101        mutex_unlock(&ld->update_lock);
 102}
 103
 104extern struct lcd_device *lcd_device_register(const char *name,
 105        struct device *parent, void *devdata, struct lcd_ops *ops);
 106extern struct lcd_device *devm_lcd_device_register(struct device *dev,
 107        const char *name, struct device *parent,
 108        void *devdata, struct lcd_ops *ops);
 109extern void lcd_device_unregister(struct lcd_device *ld);
 110extern void devm_lcd_device_unregister(struct device *dev,
 111        struct lcd_device *ld);
 112
 113#define to_lcd_device(obj) container_of(obj, struct lcd_device, dev)
 114
 115static inline void * lcd_get_data(struct lcd_device *ld_dev)
 116{
 117        return dev_get_drvdata(&ld_dev->dev);
 118}
 119
 120
 121#endif
 122