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>
18 #include <linux/pwm.h>
21 #define BRIGHTNESS_CTRL 0x00
22 #define DEVICE_CTRL 0x01
23 #define EEPROM_START 0xA0
24 #define EEPROM_END 0xA7
25 #define EPROM_START 0xA0
26 #define EPROM_END 0xAF
29 #define DEFAULT_BL_NAME "lcd-backlight"
30 #define MAX_BRIGHTNESS 255
34 enum lp855x_chip_id chip_id;
35 struct i2c_client *client;
36 struct backlight_device *bl;
38 struct mutex xfer_lock;
39 struct lp855x_platform_data *pdata;
40 struct pwm_device *pwm;
43 static int lp855x_read_byte(struct lp855x *lp, u8 reg, u8 *data)
47 mutex_lock(&lp->xfer_lock);
48 ret = i2c_smbus_read_byte_data(lp->client, reg);
50 mutex_unlock(&lp->xfer_lock);
51 dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
54 mutex_unlock(&lp->xfer_lock);
60 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
64 mutex_lock(&lp->xfer_lock);
65 ret = i2c_smbus_write_byte_data(lp->client, reg, data);
66 mutex_unlock(&lp->xfer_lock);
71 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
75 switch (lp->chip_id) {
91 return (addr >= start && addr <= end);
94 static int lp855x_init_registers(struct lp855x *lp)
98 struct lp855x_platform_data *pd = lp->pdata;
100 val = pd->initial_brightness;
101 ret = lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
105 val = pd->device_control;
106 ret = lp855x_write_byte(lp, DEVICE_CTRL, val);
110 if (pd->load_new_rom_data && pd->size_program) {
111 for (i = 0; i < pd->size_program; i++) {
112 addr = pd->rom_data[i].addr;
113 val = pd->rom_data[i].val;
114 if (!lp855x_is_valid_rom_area(lp, addr))
117 ret = lp855x_write_byte(lp, addr, val);
126 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
128 unsigned int period = lp->pdata->period_ns;
129 unsigned int duty = br * period / max_br;
130 struct pwm_device *pwm;
132 /* request pwm device with the consumer name */
134 pwm = devm_pwm_get(lp->dev, lp->chipname);
141 pwm_config(lp->pwm, duty, period);
142 duty == 0 ? pwm_disable(lp->pwm) : pwm_enable(lp->pwm);
145 static int lp855x_bl_update_status(struct backlight_device *bl)
147 struct lp855x *lp = bl_get_data(bl);
148 enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
150 if (bl->props.state & BL_CORE_SUSPENDED)
151 bl->props.brightness = 0;
153 if (mode == PWM_BASED) {
154 int br = bl->props.brightness;
155 int max_br = bl->props.max_brightness;
157 lp855x_pwm_ctrl(lp, br, max_br);
159 } else if (mode == REGISTER_BASED) {
160 u8 val = bl->props.brightness;
161 lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
167 static int lp855x_bl_get_brightness(struct backlight_device *bl)
169 struct lp855x *lp = bl_get_data(bl);
170 enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
172 if (mode == REGISTER_BASED) {
175 lp855x_read_byte(lp, BRIGHTNESS_CTRL, &val);
176 bl->props.brightness = val;
179 return bl->props.brightness;
182 static const struct backlight_ops lp855x_bl_ops = {
183 .options = BL_CORE_SUSPENDRESUME,
184 .update_status = lp855x_bl_update_status,
185 .get_brightness = lp855x_bl_get_brightness,
188 static int lp855x_backlight_register(struct lp855x *lp)
190 struct backlight_device *bl;
191 struct backlight_properties props;
192 struct lp855x_platform_data *pdata = lp->pdata;
193 char *name = pdata->name ? : DEFAULT_BL_NAME;
195 props.type = BACKLIGHT_PLATFORM;
196 props.max_brightness = MAX_BRIGHTNESS;
198 if (pdata->initial_brightness > props.max_brightness)
199 pdata->initial_brightness = props.max_brightness;
201 props.brightness = pdata->initial_brightness;
203 bl = backlight_device_register(name, lp->dev, lp,
204 &lp855x_bl_ops, &props);
213 static void lp855x_backlight_unregister(struct lp855x *lp)
216 backlight_device_unregister(lp->bl);
219 static ssize_t lp855x_get_chip_id(struct device *dev,
220 struct device_attribute *attr, char *buf)
222 struct lp855x *lp = dev_get_drvdata(dev);
223 return scnprintf(buf, BUF_SIZE, "%s\n", lp->chipname);
226 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
227 struct device_attribute *attr, char *buf)
229 struct lp855x *lp = dev_get_drvdata(dev);
230 enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
231 char *strmode = NULL;
233 if (mode == PWM_BASED)
234 strmode = "pwm based";
235 else if (mode == REGISTER_BASED)
236 strmode = "register based";
238 return scnprintf(buf, BUF_SIZE, "%s\n", strmode);
241 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
242 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
244 static struct attribute *lp855x_attributes[] = {
245 &dev_attr_chip_id.attr,
246 &dev_attr_bl_ctl_mode.attr,
250 static const struct attribute_group lp855x_attr_group = {
251 .attrs = lp855x_attributes,
254 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
257 struct lp855x_platform_data *pdata = cl->dev.platform_data;
258 enum lp855x_brightness_ctrl_mode mode;
262 dev_err(&cl->dev, "no platform data supplied\n");
266 if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
269 lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
277 lp->chipname = id->name;
278 lp->chip_id = id->driver_data;
279 i2c_set_clientdata(cl, lp);
281 mutex_init(&lp->xfer_lock);
283 ret = lp855x_init_registers(lp);
285 dev_err(lp->dev, "i2c communication err: %d", ret);
286 if (mode == REGISTER_BASED)
290 ret = lp855x_backlight_register(lp);
293 "failed to register backlight. err: %d\n", ret);
297 ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
299 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
303 backlight_update_status(lp->bl);
307 lp855x_backlight_unregister(lp);
312 static int __devexit lp855x_remove(struct i2c_client *cl)
314 struct lp855x *lp = i2c_get_clientdata(cl);
316 lp->bl->props.brightness = 0;
317 backlight_update_status(lp->bl);
318 sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
319 lp855x_backlight_unregister(lp);
324 static const struct i2c_device_id lp855x_ids[] = {
332 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
334 static struct i2c_driver lp855x_driver = {
338 .probe = lp855x_probe,
339 .remove = __devexit_p(lp855x_remove),
340 .id_table = lp855x_ids,
343 module_i2c_driver(lp855x_driver);
345 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
346 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
347 MODULE_LICENSE("GPL");