include/linux/lcd.h

Source file repositories/reference/linux-study-clean/include/linux/lcd.h

File Facts

System
Linux kernel
Corpus path
include/linux/lcd.h
Extension
.h
Size
4715 bytes
Lines
152
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

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) */
	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 *lcd, u32 xres, u32 yres);

	/*
	 * Check if the LCD controls the given display device. This
	 * operation is optional and if not implemented it is assumed that
	 * the display is always the one controlled by the LCD.
	 *
	 * RETURNS:
	 *
	 * If display_dev is NULL or display_dev matches the device controlled by
	 * the LCD, return true. Otherwise return false.
	 */
	bool (*controls_device)(struct lcd_device *lcd, struct device *display_device);
};

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 */
	const struct lcd_ops *ops;
	/* Serialise access to set_power method */
	struct mutex update_lock;

	/**
	 * @entry: List entry of all registered lcd devices
	 */
	struct list_head entry;

	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, const struct lcd_ops *ops);
extern struct lcd_device *devm_lcd_device_register(struct device *dev,
	const char *name, struct device *parent,
	void *devdata, const struct lcd_ops *ops);
extern void lcd_device_unregister(struct lcd_device *ld);

Annotation

Implementation Notes