backlight: new backlight driver for LP855x devices (7be865ab) · Commits · 戴 / test

Documentation/backlight/lp855x-driver.txt

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		Kernel driver lp855x
		====================

		Backlight driver for LP855x ICs

		Supported chips:
		Texas Instruments LP8550, LP8551, LP8552, LP8553 and LP8556

		Author: Milo(Woogyom) Kim <milo.kim@ti.com>

		Description
		-----------

		* Brightness control

		Brightness can be controlled by the pwm input or the i2c command.
		The lp855x driver supports both cases.

		* Device attributes

		1) bl_ctl_mode
		Backlight control mode.
		Value : pwm based or register based

		2) chip_id
		The lp855x chip id.
		Value : lp8550/lp8551/lp8552/lp8553/lp8556

		Platform data for lp855x
		------------------------

		For supporting platform specific data, the lp855x platform data can be used.

		* name : Backlight driver name. If it is not defined, default name is set.
		* mode : Brightness control mode. PWM or register based.
		* device_control : Value of DEVICE CONTROL register.
		* initial_brightness : Initial value of backlight brightness.
		* pwm_data : Platform specific pwm generation functions.
		Only valid when brightness is pwm input mode.
		Functions should be implemented by PWM driver.
		- pwm_set_intensity() : set duty of PWM
		- pwm_get_intensity() : get current duty of PWM
		* load_new_rom_data :
		0 : use default configuration data
		1 : update values of eeprom or eprom registers on loading driver
		* size_program : Total size of lp855x_rom_data.
		* rom_data : List of new eeprom/eprom registers.

		example 1) lp8552 platform data : i2c register mode with new eeprom data

		#define EEPROM_A5_ADDR 0xA5
		#define EEPROM_A5_VAL 0x4f /* EN_VSYNC=0 */

		static struct lp855x_rom_data lp8552_eeprom_arr[] = {
		{EEPROM_A5_ADDR, EEPROM_A5_VAL},
		};

		static struct lp855x_platform_data lp8552_pdata = {
		.name = "lcd-bl",
		.mode = REGISTER_BASED,
		.device_control = I2C_CONFIG(LP8552),
		.initial_brightness = INITIAL_BRT,
		.load_new_rom_data = 1,
		.size_program = ARRAY_SIZE(lp8552_eeprom_arr),
		.rom_data = lp8552_eeprom_arr,
		};

		example 2) lp8556 platform data : pwm input mode with default rom data

		static struct lp855x_platform_data lp8556_pdata = {
		.mode = PWM_BASED,
		.device_control = PWM_CONFIG(LP8556),
		.initial_brightness = INITIAL_BRT,
		.pwm_data = {
		.pwm_set_intensity = platform_pwm_set_intensity,
		.pwm_get_intensity = platform_pwm_get_intensity,
		},
		};

drivers/video/backlight/Kconfig

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		@@ -334,6 +334,13 @@ config BACKLIGHT_AAT2870
		If you have a AnalogicTech AAT2870 say Y to enable the
		backlight driver.

		config BACKLIGHT_LP855X
		tristate "Backlight driver for TI LP855X"
		depends on BACKLIGHT_CLASS_DEVICE && I2C
		help
		This supports TI LP8550, LP8551, LP8552, LP8553 and LP8556
		backlight driver.

		endif # BACKLIGHT_CLASS_DEVICE

		endif # BACKLIGHT_LCD_SUPPORT

drivers/video/backlight/Makefile

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		@@ -22,6 +22,7 @@ obj-$(CONFIG_BACKLIGHT_GENERIC) += generic_bl.o
		obj-$(CONFIG_BACKLIGHT_HP700) += jornada720_bl.o
		obj-$(CONFIG_BACKLIGHT_HP680) += hp680_bl.o
		obj-$(CONFIG_BACKLIGHT_LOCOMO) += locomolcd.o
		obj-$(CONFIG_BACKLIGHT_LP855X) += lp855x_bl.o
		obj-$(CONFIG_BACKLIGHT_OMAP1) += omap1_bl.o
		obj-$(CONFIG_BACKLIGHT_PROGEAR) += progear_bl.o
		obj-$(CONFIG_BACKLIGHT_CARILLO_RANCH) += cr_bllcd.o

drivers/video/backlight/lp855x_bl.c

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		/*
		* TI LP855x Backlight Driver
		*
		* Copyright (C) 2011 Texas Instruments
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*
		*/

		#include <linux/module.h>
		#include <linux/slab.h>
		#include <linux/i2c.h>
		#include <linux/backlight.h>
		#include <linux/err.h>
		#include <linux/lp855x.h>

		/* Registers */
		#define BRIGHTNESS_CTRL (0x00)
		#define DEVICE_CTRL (0x01)

		#define BUF_SIZE 20
		#define DEFAULT_BL_NAME "lcd-backlight"
		#define MAX_BRIGHTNESS 255

		struct lp855x {
		const char *chipname;
		enum lp855x_chip_id chip_id;
		struct i2c_client *client;
		struct backlight_device *bl;
		struct device *dev;
		struct mutex xfer_lock;
		struct lp855x_platform_data *pdata;
		};

		static int lp855x_read_byte(struct lp855x lp, u8 reg, u8 data)
		{
		int ret;

		mutex_lock(&lp->xfer_lock);
		ret = i2c_smbus_read_byte_data(lp->client, reg);
		if (ret < 0) {
		mutex_unlock(&lp->xfer_lock);
		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
		return ret;
		}
		mutex_unlock(&lp->xfer_lock);

		*data = (u8)ret;
		return 0;
		}

		static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
		{
		int ret;

		mutex_lock(&lp->xfer_lock);
		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
		mutex_unlock(&lp->xfer_lock);

		return ret;
		}

		static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
		{
		u8 start, end;

		switch (lp->chip_id) {
		case LP8550:
		case LP8551:
		case LP8552:
		case LP8553:
		start = EEPROM_START;
		end = EEPROM_END;
		break;
		case LP8556:
		start = EPROM_START;
		end = EPROM_END;
		break;
		default:
		return false;
		}

		return (addr >= start && addr <= end);
		}

		static int lp855x_init_registers(struct lp855x *lp)
		{
		u8 val, addr;
		int i, ret;
		struct lp855x_platform_data *pd = lp->pdata;

		val = pd->initial_brightness;
		ret = lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
		if (ret)
		return ret;

		val = pd->device_control;
		ret = lp855x_write_byte(lp, DEVICE_CTRL, val);
		if (ret)
		return ret;

		if (pd->load_new_rom_data && pd->size_program) {
		for (i = 0; i < pd->size_program; i++) {
		addr = pd->rom_data[i].addr;
		val = pd->rom_data[i].val;
		if (!lp855x_is_valid_rom_area(lp, addr))
		continue;

		ret = lp855x_write_byte(lp, addr, val);
		if (ret)
		return ret;
		}
		}

		return ret;
		}

		static int lp855x_bl_update_status(struct backlight_device *bl)
		{
		struct lp855x *lp = bl_get_data(bl);
		enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;

		if (bl->props.state & BL_CORE_SUSPENDED)
		bl->props.brightness = 0;

		if (mode == PWM_BASED) {
		struct lp855x_pwm_data *pd = &lp->pdata->pwm_data;
		int br = bl->props.brightness;
		int max_br = bl->props.max_brightness;

		if (pd->pwm_set_intensity)
		pd->pwm_set_intensity(br, max_br);

		} else if (mode == REGISTER_BASED) {
		u8 val = bl->props.brightness;
		lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
		}

		return 0;
		}

		static int lp855x_bl_get_brightness(struct backlight_device *bl)
		{
		struct lp855x *lp = bl_get_data(bl);
		enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;

		if (mode == PWM_BASED) {
		struct lp855x_pwm_data *pd = &lp->pdata->pwm_data;
		int max_br = bl->props.max_brightness;

		if (pd->pwm_get_intensity)
		bl->props.brightness = pd->pwm_get_intensity(max_br);

		} else if (mode == REGISTER_BASED) {
		u8 val = 0;

		lp855x_read_byte(lp, BRIGHTNESS_CTRL, &val);
		bl->props.brightness = val;
		}

		return bl->props.brightness;
		}

		static const struct backlight_ops lp855x_bl_ops = {
		.options = BL_CORE_SUSPENDRESUME,
		.update_status = lp855x_bl_update_status,
		.get_brightness = lp855x_bl_get_brightness,
		};

		static int lp855x_backlight_register(struct lp855x *lp)
		{
		struct backlight_device *bl;
		struct backlight_properties props;
		struct lp855x_platform_data *pdata = lp->pdata;
		char *name = pdata->name ? : DEFAULT_BL_NAME;

		props.type = BACKLIGHT_PLATFORM;
		props.max_brightness = MAX_BRIGHTNESS;

		if (pdata->initial_brightness > props.max_brightness)
		pdata->initial_brightness = props.max_brightness;

		props.brightness = pdata->initial_brightness;

		bl = backlight_device_register(name, lp->dev, lp,
		&lp855x_bl_ops, &props);
		if (IS_ERR(bl))
		return PTR_ERR(bl);

		lp->bl = bl;

		return 0;
		}

		static void lp855x_backlight_unregister(struct lp855x *lp)
		{
		if (lp->bl)
		backlight_device_unregister(lp->bl);
		}

		static ssize_t lp855x_get_chip_id(struct device *dev,
		struct device_attribute attr, char buf)
		{
		struct lp855x *lp = dev_get_drvdata(dev);
		return scnprintf(buf, BUF_SIZE, "%s\n", lp->chipname);
		}

		static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
		struct device_attribute attr, char buf)
		{
		struct lp855x *lp = dev_get_drvdata(dev);
		enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
		char *strmode = NULL;

		if (mode == PWM_BASED)
		strmode = "pwm based";
		else if (mode == REGISTER_BASED)
		strmode = "register based";

		return scnprintf(buf, BUF_SIZE, "%s\n", strmode);
		}

		static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
		static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);

		static struct attribute *lp855x_attributes[] = {
		&dev_attr_chip_id.attr,
		&dev_attr_bl_ctl_mode.attr,
		NULL,
		};

		static const struct attribute_group lp855x_attr_group = {
		.attrs = lp855x_attributes,
		};

		static int lp855x_probe(struct i2c_client cl, const struct i2c_device_id id)
		{
		struct lp855x *lp;
		struct lp855x_platform_data *pdata = cl->dev.platform_data;
		enum lp855x_brightness_ctrl_mode mode;
		int ret;

		if (!pdata) {
		dev_err(&cl->dev, "no platform data supplied\n");
		return -EINVAL;
		}

		if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
		return -EIO;

		lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
		if (!lp)
		return -ENOMEM;

		mode = pdata->mode;
		lp->client = cl;
		lp->dev = &cl->dev;
		lp->pdata = pdata;
		lp->chipname = id->name;
		lp->chip_id = id->driver_data;
		i2c_set_clientdata(cl, lp);

		mutex_init(&lp->xfer_lock);

		ret = lp855x_init_registers(lp);
		if (ret) {
		dev_err(lp->dev, "i2c communication err: %d", ret);
		if (mode == REGISTER_BASED)
		goto err_dev;
		}

		ret = lp855x_backlight_register(lp);
		if (ret) {
		dev_err(lp->dev,
		"failed to register backlight. err: %d\n", ret);
		goto err_dev;
		}

		ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
		if (ret) {
		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
		goto err_sysfs;
		}

		backlight_update_status(lp->bl);
		return 0;

		err_sysfs:
		lp855x_backlight_unregister(lp);
		err_dev:
		return ret;
		}

		static int __devexit lp855x_remove(struct i2c_client *cl)
		{
		struct lp855x *lp = i2c_get_clientdata(cl);

		lp->bl->props.brightness = 0;
		backlight_update_status(lp->bl);
		sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
		lp855x_backlight_unregister(lp);

		return 0;
		}

		static const struct i2c_device_id lp855x_ids[] = {
		{"lp8550", LP8550},
		{"lp8551", LP8551},
		{"lp8552", LP8552},
		{"lp8553", LP8553},
		{"lp8556", LP8556},
		{ }
		};
		MODULE_DEVICE_TABLE(i2c, lp855x_ids);

		static struct i2c_driver lp855x_driver = {
		.driver = {
		.name = "lp855x",
		},
		.probe = lp855x_probe,
		.remove = __devexit_p(lp855x_remove),
		.id_table = lp855x_ids,
		};

		module_i2c_driver(lp855x_driver);

		MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
		MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
		MODULE_LICENSE("GPL");

include/linux/lp855x.h

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		/*
		* LP855x Backlight Driver
		*
		* Copyright (C) 2011 Texas Instruments
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*
		*/

		#ifndef _LP855X_H
		#define _LP855X_H

		#define BL_CTL_SHFT (0)
		#define BRT_MODE_SHFT (1)
		#define BRT_MODE_MASK (0x06)

		/* Enable backlight. Only valid when BRT_MODE=10(I2C only) */
		#define ENABLE_BL (1)
		#define DISABLE_BL (0)

		#define I2C_CONFIG(id) id ## _I2C_CONFIG
		#define PWM_CONFIG(id) id ## _PWM_CONFIG

		/* DEVICE CONTROL register - LP8550 */
		#define LP8550_PWM_CONFIG (LP8550_PWM_ONLY << BRT_MODE_SHFT)
		#define LP8550_I2C_CONFIG ((ENABLE_BL << BL_CTL_SHFT) \| \
		(LP8550_I2C_ONLY << BRT_MODE_SHFT))

		/* DEVICE CONTROL register - LP8551 */
		#define LP8551_PWM_CONFIG LP8550_PWM_CONFIG
		#define LP8551_I2C_CONFIG LP8550_I2C_CONFIG

		/* DEVICE CONTROL register - LP8552 */
		#define LP8552_PWM_CONFIG LP8550_PWM_CONFIG
		#define LP8552_I2C_CONFIG LP8550_I2C_CONFIG

		/* DEVICE CONTROL register - LP8553 */
		#define LP8553_PWM_CONFIG LP8550_PWM_CONFIG
		#define LP8553_I2C_CONFIG LP8550_I2C_CONFIG

		/* DEVICE CONTROL register - LP8556 */
		#define LP8556_PWM_CONFIG (LP8556_PWM_ONLY << BRT_MODE_SHFT)
		#define LP8556_COMB1_CONFIG (LP8556_COMBINED1 << BRT_MODE_SHFT)
		#define LP8556_I2C_CONFIG ((ENABLE_BL << BL_CTL_SHFT) \| \
		(LP8556_I2C_ONLY << BRT_MODE_SHFT))
		#define LP8556_COMB2_CONFIG (LP8556_COMBINED2 << BRT_MODE_SHFT)

		/* ROM area boundary */
		#define EEPROM_START (0xA0)
		#define EEPROM_END (0xA7)
		#define EPROM_START (0xA0)
		#define EPROM_END (0xAF)

		enum lp855x_chip_id {
		LP8550,
		LP8551,
		LP8552,
		LP8553,
		LP8556,
		};

		enum lp855x_brightness_ctrl_mode {
		PWM_BASED = 1,
		REGISTER_BASED,
		};

		enum lp8550_brighntess_source {
		LP8550_PWM_ONLY,
		LP8550_I2C_ONLY = 2,
		};

		enum lp8551_brighntess_source {
		LP8551_PWM_ONLY = LP8550_PWM_ONLY,
		LP8551_I2C_ONLY = LP8550_I2C_ONLY,
		};

		enum lp8552_brighntess_source {
		LP8552_PWM_ONLY = LP8550_PWM_ONLY,
		LP8552_I2C_ONLY = LP8550_I2C_ONLY,
		};

		enum lp8553_brighntess_source {
		LP8553_PWM_ONLY = LP8550_PWM_ONLY,
		LP8553_I2C_ONLY = LP8550_I2C_ONLY,
		};

		enum lp8556_brightness_source {
		LP8556_PWM_ONLY,
		LP8556_COMBINED1, /* pwm + i2c before the shaper block */
		LP8556_I2C_ONLY,
		LP8556_COMBINED2, /* pwm + i2c after the shaper block */
		};

		struct lp855x_pwm_data {
		void (*pwm_set_intensity) (int brightness, int max_brightness);
		int (*pwm_get_intensity) (int max_brightness);
		};

		struct lp855x_rom_data {
		u8 addr;
		u8 val;
		};

		/**
		* struct lp855x_platform_data
		* @name : Backlight driver name. If it is not defined, default name is set.
		* @mode : brightness control by pwm or lp855x register
		* @device_control : value of DEVICE CONTROL register
		* @initial_brightness : initial value of backlight brightness
		* @pwm_data : platform specific pwm generation functions.
		Only valid when mode is PWM_BASED.
		* @load_new_rom_data :
		0 : use default configuration data
		1 : update values of eeprom or eprom registers on loading driver
		* @size_program : total size of lp855x_rom_data
		* @rom_data : list of new eeprom/eprom registers
		*/
		struct lp855x_platform_data {
		char *name;
		enum lp855x_brightness_ctrl_mode mode;
		u8 device_control;
		int initial_brightness;
		struct lp855x_pwm_data pwm_data;
		u8 load_new_rom_data;
		int size_program;
		struct lp855x_rom_data *rom_data;
		};

		#endif

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