drivers/video/backlight/lp855x_bl.c

   1 /*
   2  * TI LP855x Backlight Driver
   3  *
   4  *                      Copyright (C) 2011 Texas Instruments
   5  *
   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.
   9  *
  10  */
  11
  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>
  19
  20 /* Registers */
  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
  27
  28 #define BUF_SIZE                20
  29 #define DEFAULT_BL_NAME         "lcd-backlight"
  30 #define MAX_BRIGHTNESS          255
  31
  32 struct lp855x {
  33         const char *chipname;
  34         enum lp855x_chip_id chip_id;
  35         struct i2c_client *client;
  36         struct backlight_device *bl;
  37         struct device *dev;
  38         struct lp855x_platform_data *pdata;
  39         struct pwm_device *pwm;
  40 };
  41
  42 static int lp855x_read_byte(struct lp855x *lp, u8 reg, u8 *data)
  43 {
  44         int ret;
  45
  46         ret = i2c_smbus_read_byte_data(lp->client, reg);
  47         if (ret < 0) {
  48                 dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
  49                 return ret;
  50         }
  51
  52         *data = (u8)ret;
  53         return 0;
  54 }
  55
  56 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
  57 {
  58         return i2c_smbus_write_byte_data(lp->client, reg, data);
  59 }
  60
  61 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
  62 {
  63         u8 start, end;
  64
  65         switch (lp->chip_id) {
  66         case LP8550:
  67         case LP8551:
  68         case LP8552:
  69         case LP8553:
  70                 start = EEPROM_START;
  71                 end = EEPROM_END;
  72                 break;
  73         case LP8556:
  74                 start = EPROM_START;
  75                 end = EPROM_END;
  76                 break;
  77         default:
  78                 return false;
  79         }
  80
  81         return (addr >= start && addr <= end);
  82 }
  83
  84 static int lp855x_init_registers(struct lp855x *lp)
  85 {
  86         u8 val, addr;
  87         int i, ret;
  88         struct lp855x_platform_data *pd = lp->pdata;
  89
  90         val = pd->initial_brightness;
  91         ret = lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
  92         if (ret)
  93                 return ret;
  94
  95         val = pd->device_control;
  96         ret = lp855x_write_byte(lp, DEVICE_CTRL, val);
  97         if (ret)
  98                 return ret;
  99
 100         if (pd->load_new_rom_data && pd->size_program) {
 101                 for (i = 0; i < pd->size_program; i++) {
 102                         addr = pd->rom_data[i].addr;
 103                         val = pd->rom_data[i].val;
 104                         if (!lp855x_is_valid_rom_area(lp, addr))
 105                                 continue;
 106
 107                         ret = lp855x_write_byte(lp, addr, val);
 108                         if (ret)
 109                                 return ret;
 110                 }
 111         }
 112
 113         return ret;
 114 }
 115
 116 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
 117 {
 118         unsigned int period = lp->pdata->period_ns;
 119         unsigned int duty = br * period / max_br;
 120         struct pwm_device *pwm;
 121
 122         /* request pwm device with the consumer name */
 123         if (!lp->pwm) {
 124                 pwm = devm_pwm_get(lp->dev, lp->chipname);
 125                 if (IS_ERR(pwm))
 126                         return;
 127
 128                 lp->pwm = pwm;
 129         }
 130
 131         pwm_config(lp->pwm, duty, period);
 132         if (duty)
 133                 pwm_enable(lp->pwm);
 134         else
 135                 pwm_disable(lp->pwm);
 136 }
 137
 138 static int lp855x_bl_update_status(struct backlight_device *bl)
 139 {
 140         struct lp855x *lp = bl_get_data(bl);
 141         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 142
 143         if (bl->props.state & BL_CORE_SUSPENDED)
 144                 bl->props.brightness = 0;
 145
 146         if (mode == PWM_BASED) {
 147                 int br = bl->props.brightness;
 148                 int max_br = bl->props.max_brightness;
 149
 150                 lp855x_pwm_ctrl(lp, br, max_br);
 151
 152         } else if (mode == REGISTER_BASED) {
 153                 u8 val = bl->props.brightness;
 154                 lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
 155         }
 156
 157         return 0;
 158 }
 159
 160 static int lp855x_bl_get_brightness(struct backlight_device *bl)
 161 {
 162         struct lp855x *lp = bl_get_data(bl);
 163         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 164
 165         if (mode == REGISTER_BASED) {
 166                 u8 val = 0;
 167
 168                 lp855x_read_byte(lp, BRIGHTNESS_CTRL, &val);
 169                 bl->props.brightness = val;
 170         }
 171
 172         return bl->props.brightness;
 173 }
 174
 175 static const struct backlight_ops lp855x_bl_ops = {
 176         .options = BL_CORE_SUSPENDRESUME,
 177         .update_status = lp855x_bl_update_status,
 178         .get_brightness = lp855x_bl_get_brightness,
 179 };
 180
 181 static int lp855x_backlight_register(struct lp855x *lp)
 182 {
 183         struct backlight_device *bl;
 184         struct backlight_properties props;
 185         struct lp855x_platform_data *pdata = lp->pdata;
 186         char *name = pdata->name ? : DEFAULT_BL_NAME;
 187
 188         props.type = BACKLIGHT_PLATFORM;
 189         props.max_brightness = MAX_BRIGHTNESS;
 190
 191         if (pdata->initial_brightness > props.max_brightness)
 192                 pdata->initial_brightness = props.max_brightness;
 193
 194         props.brightness = pdata->initial_brightness;
 195
 196         bl = backlight_device_register(name, lp->dev, lp,
 197                                        &lp855x_bl_ops, &props);
 198         if (IS_ERR(bl))
 199                 return PTR_ERR(bl);
 200
 201         lp->bl = bl;
 202
 203         return 0;
 204 }
 205
 206 static void lp855x_backlight_unregister(struct lp855x *lp)
 207 {
 208         if (lp->bl)
 209                 backlight_device_unregister(lp->bl);
 210 }
 211
 212 static ssize_t lp855x_get_chip_id(struct device *dev,
 213                                 struct device_attribute *attr, char *buf)
 214 {
 215         struct lp855x *lp = dev_get_drvdata(dev);
 216         return scnprintf(buf, BUF_SIZE, "%s\n", lp->chipname);
 217 }
 218
 219 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
 220                                      struct device_attribute *attr, char *buf)
 221 {
 222         struct lp855x *lp = dev_get_drvdata(dev);
 223         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 224         char *strmode = NULL;
 225
 226         if (mode == PWM_BASED)
 227                 strmode = "pwm based";
 228         else if (mode == REGISTER_BASED)
 229                 strmode = "register based";
 230
 231         return scnprintf(buf, BUF_SIZE, "%s\n", strmode);
 232 }
 233
 234 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
 235 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
 236
 237 static struct attribute *lp855x_attributes[] = {
 238         &dev_attr_chip_id.attr,
 239         &dev_attr_bl_ctl_mode.attr,
 240         NULL,
 241 };
 242
 243 static const struct attribute_group lp855x_attr_group = {
 244         .attrs = lp855x_attributes,
 245 };
 246
 247 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
 248 {
 249         struct lp855x *lp;
 250         struct lp855x_platform_data *pdata = cl->dev.platform_data;
 251         enum lp855x_brightness_ctrl_mode mode;
 252         int ret;
 253
 254         if (!pdata) {
 255                 dev_err(&cl->dev, "no platform data supplied\n");
 256                 return -EINVAL;
 257         }
 258
 259         if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
 260                 return -EIO;
 261
 262         lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
 263         if (!lp)
 264                 return -ENOMEM;
 265
 266         mode = pdata->mode;
 267         lp->client = cl;
 268         lp->dev = &cl->dev;
 269         lp->pdata = pdata;
 270         lp->chipname = id->name;
 271         lp->chip_id = id->driver_data;
 272         i2c_set_clientdata(cl, lp);
 273
 274         ret = lp855x_init_registers(lp);
 275         if (ret) {
 276                 dev_err(lp->dev, "i2c communication err: %d", ret);
 277                 if (mode == REGISTER_BASED)
 278                         goto err_dev;
 279         }
 280
 281         ret = lp855x_backlight_register(lp);
 282         if (ret) {
 283                 dev_err(lp->dev,
 284                         "failed to register backlight. err: %d\n", ret);
 285                 goto err_dev;
 286         }
 287
 288         ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
 289         if (ret) {
 290                 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
 291                 goto err_sysfs;
 292         }
 293
 294         backlight_update_status(lp->bl);
 295         return 0;
 296
 297 err_sysfs:
 298         lp855x_backlight_unregister(lp);
 299 err_dev:
 300         return ret;
 301 }
 302
 303 static int lp855x_remove(struct i2c_client *cl)
 304 {
 305         struct lp855x *lp = i2c_get_clientdata(cl);
 306
 307         lp->bl->props.brightness = 0;
 308         backlight_update_status(lp->bl);
 309         sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
 310         lp855x_backlight_unregister(lp);
 311
 312         return 0;
 313 }
 314
 315 static const struct i2c_device_id lp855x_ids[] = {
 316         {"lp8550", LP8550},
 317         {"lp8551", LP8551},
 318         {"lp8552", LP8552},
 319         {"lp8553", LP8553},
 320         {"lp8556", LP8556},
 321         { }
 322 };
 323 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
 324
 325 static struct i2c_driver lp855x_driver = {
 326         .driver = {
 327                    .name = "lp855x",
 328                    },
 329         .probe = lp855x_probe,
 330         .remove = lp855x_remove,
 331         .id_table = lp855x_ids,
 332 };
 333
 334 module_i2c_driver(lp855x_driver);
 335
 336 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
 337 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
 338 MODULE_LICENSE("GPL");