2 * TI LP855x Backlight Driver
4 * Copyright (C) 2011 Texas Instruments
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/i2c.h>
15 #include <linux/backlight.h>
16 #include <linux/err.h>
17 #include <linux/platform_data/lp855x.h>
20 #define BRIGHTNESS_CTRL 0x00
21 #define DEVICE_CTRL 0x01
22 #define EEPROM_START 0xA0
23 #define EEPROM_END 0xA7
24 #define EPROM_START 0xA0
25 #define EPROM_END 0xAF
28 #define DEFAULT_BL_NAME "lcd-backlight"
29 #define MAX_BRIGHTNESS 255
33 enum lp855x_chip_id chip_id;
34 struct i2c_client *client;
35 struct backlight_device *bl;
37 struct mutex xfer_lock;
38 struct lp855x_platform_data *pdata;
41 static int lp855x_read_byte(struct lp855x *lp, u8 reg, u8 *data)
45 mutex_lock(&lp->xfer_lock);
46 ret = i2c_smbus_read_byte_data(lp->client, reg);
48 mutex_unlock(&lp->xfer_lock);
49 dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
52 mutex_unlock(&lp->xfer_lock);
58 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
62 mutex_lock(&lp->xfer_lock);
63 ret = i2c_smbus_write_byte_data(lp->client, reg, data);
64 mutex_unlock(&lp->xfer_lock);
69 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
73 switch (lp->chip_id) {
89 return (addr >= start && addr <= end);
92 static int lp855x_init_registers(struct lp855x *lp)
96 struct lp855x_platform_data *pd = lp->pdata;
98 val = pd->initial_brightness;
99 ret = lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
103 val = pd->device_control;
104 ret = lp855x_write_byte(lp, DEVICE_CTRL, val);
108 if (pd->load_new_rom_data && pd->size_program) {
109 for (i = 0; i < pd->size_program; i++) {
110 addr = pd->rom_data[i].addr;
111 val = pd->rom_data[i].val;
112 if (!lp855x_is_valid_rom_area(lp, addr))
115 ret = lp855x_write_byte(lp, addr, val);
124 static int lp855x_bl_update_status(struct backlight_device *bl)
126 struct lp855x *lp = bl_get_data(bl);
127 enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
129 if (bl->props.state & BL_CORE_SUSPENDED)
130 bl->props.brightness = 0;
132 if (mode == PWM_BASED) {
133 struct lp855x_pwm_data *pd = &lp->pdata->pwm_data;
134 int br = bl->props.brightness;
135 int max_br = bl->props.max_brightness;
137 if (pd->pwm_set_intensity)
138 pd->pwm_set_intensity(br, max_br);
140 } else if (mode == REGISTER_BASED) {
141 u8 val = bl->props.brightness;
142 lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
148 static int lp855x_bl_get_brightness(struct backlight_device *bl)
150 struct lp855x *lp = bl_get_data(bl);
151 enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
153 if (mode == PWM_BASED) {
154 struct lp855x_pwm_data *pd = &lp->pdata->pwm_data;
155 int max_br = bl->props.max_brightness;
157 if (pd->pwm_get_intensity)
158 bl->props.brightness = pd->pwm_get_intensity(max_br);
160 } else if (mode == REGISTER_BASED) {
163 lp855x_read_byte(lp, BRIGHTNESS_CTRL, &val);
164 bl->props.brightness = val;
167 return bl->props.brightness;
170 static const struct backlight_ops lp855x_bl_ops = {
171 .options = BL_CORE_SUSPENDRESUME,
172 .update_status = lp855x_bl_update_status,
173 .get_brightness = lp855x_bl_get_brightness,
176 static int lp855x_backlight_register(struct lp855x *lp)
178 struct backlight_device *bl;
179 struct backlight_properties props;
180 struct lp855x_platform_data *pdata = lp->pdata;
181 char *name = pdata->name ? : DEFAULT_BL_NAME;
183 props.type = BACKLIGHT_PLATFORM;
184 props.max_brightness = MAX_BRIGHTNESS;
186 if (pdata->initial_brightness > props.max_brightness)
187 pdata->initial_brightness = props.max_brightness;
189 props.brightness = pdata->initial_brightness;
191 bl = backlight_device_register(name, lp->dev, lp,
192 &lp855x_bl_ops, &props);
201 static void lp855x_backlight_unregister(struct lp855x *lp)
204 backlight_device_unregister(lp->bl);
207 static ssize_t lp855x_get_chip_id(struct device *dev,
208 struct device_attribute *attr, char *buf)
210 struct lp855x *lp = dev_get_drvdata(dev);
211 return scnprintf(buf, BUF_SIZE, "%s\n", lp->chipname);
214 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
215 struct device_attribute *attr, char *buf)
217 struct lp855x *lp = dev_get_drvdata(dev);
218 enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
219 char *strmode = NULL;
221 if (mode == PWM_BASED)
222 strmode = "pwm based";
223 else if (mode == REGISTER_BASED)
224 strmode = "register based";
226 return scnprintf(buf, BUF_SIZE, "%s\n", strmode);
229 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
230 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
232 static struct attribute *lp855x_attributes[] = {
233 &dev_attr_chip_id.attr,
234 &dev_attr_bl_ctl_mode.attr,
238 static const struct attribute_group lp855x_attr_group = {
239 .attrs = lp855x_attributes,
242 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
245 struct lp855x_platform_data *pdata = cl->dev.platform_data;
246 enum lp855x_brightness_ctrl_mode mode;
250 dev_err(&cl->dev, "no platform data supplied\n");
254 if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
257 lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
265 lp->chipname = id->name;
266 lp->chip_id = id->driver_data;
267 i2c_set_clientdata(cl, lp);
269 mutex_init(&lp->xfer_lock);
271 ret = lp855x_init_registers(lp);
273 dev_err(lp->dev, "i2c communication err: %d", ret);
274 if (mode == REGISTER_BASED)
278 ret = lp855x_backlight_register(lp);
281 "failed to register backlight. err: %d\n", ret);
285 ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
287 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
291 backlight_update_status(lp->bl);
295 lp855x_backlight_unregister(lp);
300 static int lp855x_remove(struct i2c_client *cl)
302 struct lp855x *lp = i2c_get_clientdata(cl);
304 lp->bl->props.brightness = 0;
305 backlight_update_status(lp->bl);
306 sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
307 lp855x_backlight_unregister(lp);
312 static const struct i2c_device_id lp855x_ids[] = {
320 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
322 static struct i2c_driver lp855x_driver = {
326 .probe = lp855x_probe,
327 .remove = lp855x_remove,
328 .id_table = lp855x_ids,
331 module_i2c_driver(lp855x_driver);
333 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
334 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
335 MODULE_LICENSE("GPL");