lcd.h

Go to the documentation of this file.

/*
 * LCD Lowlevel Control Abstraction
 *
 * Copyright (C) 2003,2004 Hewlett-Packard Company
 *
 */

#ifndef _LINUX_LCD_H
#define _LINUX_LCD_H

#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/fb.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;

struct lcd_properties {
    /* 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)
     * and this callback would be called proir to fb driver's callback.
     *
     * P.S. note that if early_set_power is not NULL then early fb notifier
     *  would be registered.
     */
    int (*early_set_power)(struct lcd_device *, int power);
    /* revert the effects of the early blank event. */
    int (*r_early_set_power)(struct lcd_device *, int power);
    /* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */
    int (*set_power)(struct lcd_device *, int power);
    /* Get the current contrast setting (0-max_contrast) */
    int (*get_contrast)(struct lcd_device *);
    /* Set LCD panel contrast */
        int (*set_contrast)(struct lcd_device *, int contrast);
    /* Set LCD panel mode (resolutions ...) */
    int (*set_mode)(struct lcd_device *, struct fb_videomode *);
    /* Check if given framebuffer device is the one LCD is bound to;
       return 0 if not, !=0 if it is. If NULL, lcd always matches the fb. */
    int (*check_fb)(struct lcd_device *, struct fb_info *);
};

struct lcd_device {
    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 mutex ops_lock;
    /* If this is NULL, the backing module is unloaded */
    struct lcd_ops *ops;
    /* Serialise access to set_power method */
    struct mutex update_lock;
    /* The framebuffer notifier block */
    struct notifier_block fb_notif;

    struct device dev;
};

struct lcd_platform_data {
    /* reset lcd panel device. */
    int (*reset)(struct lcd_device *ld);
    /* on or off to lcd panel. if 'enable' is 0 then
       lcd power off and 1, lcd power on. */
    int (*power_on)(struct lcd_device *ld, int enable);

    /* it indicates whether lcd panel was enabled
       from bootloader or not. */
    int lcd_enabled;
    /* it means delay for stable time when it becomes low to high
       or high to low that is dependent on whether reset gpio is
       low active or high active. */
    unsigned int reset_delay;
    /* stable time needing to become lcd power on. */
    unsigned int power_on_delay;
    /* stable time needing to become lcd power off. */
    unsigned int power_off_delay;

    /* it could be used for any purpose. */
    void *pdata;
};

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,
    struct device *parent, 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, dev)

static inline void * lcd_get_data(struct lcd_device *ld_dev)
{
    return dev_get_drvdata(&ld_dev->dev);
}


#endif