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
  34 /*
  35  * struct lp855x_device_config
  36  * @pre_init_device: init device function call before updating the brightness
  37  * @reg_brightness: register address for brigthenss control
  38  * @reg_devicectrl: register address for device control
  39  * @post_init_device: late init device function call
  40  */
  41 struct lp855x_device_config {
  42         int (*pre_init_device)(struct lp855x *);
  43         u8 reg_brightness;
  44         u8 reg_devicectrl;
  45         int (*post_init_device)(struct lp855x *);
  46 };
  47
  48 struct lp855x {
  49         const char *chipname;
  50         enum lp855x_chip_id chip_id;
  51         struct lp855x_device_config *cfg;
  52         struct i2c_client *client;
  53         struct backlight_device *bl;
  54         struct device *dev;
  55         struct lp855x_platform_data *pdata;
  56         struct pwm_device *pwm;
  57 };
  58
  59 static int lp855x_read_byte(struct lp855x *lp, u8 reg, u8 *data)
  60 {
  61         int ret;
  62
  63         ret = i2c_smbus_read_byte_data(lp->client, reg);
  64         if (ret < 0) {
  65                 dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
  66                 return ret;
  67         }
  68
  69         *data = (u8)ret;
  70         return 0;
  71 }
  72
  73 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
  74 {
  75         return i2c_smbus_write_byte_data(lp->client, reg, data);
  76 }
  77
  78 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
  79 {
  80         u8 start, end;
  81
  82         switch (lp->chip_id) {
  83         case LP8550:
  84         case LP8551:
  85         case LP8552:
  86         case LP8553:
  87                 start = EEPROM_START;
  88                 end = EEPROM_END;
  89                 break;
  90         case LP8556:
  91                 start = EPROM_START;
  92                 end = EPROM_END;
  93                 break;
  94         default:
  95                 return false;
  96         }
  97
  98         return (addr >= start && addr <= end);
  99 }
 100
 101 static struct lp855x_device_config lp855x_dev_cfg = {
 102         .reg_brightness = BRIGHTNESS_CTRL,
 103         .reg_devicectrl = DEVICE_CTRL,
 104 };
 105
 106 /*
 107  * Device specific configuration flow
 108  *
 109  *    a) pre_init_device(optional)
 110  *    b) update the brightness register
 111  *    c) update device control register
 112  *    d) update ROM area(optional)
 113  *    e) post_init_device(optional)
 114  *
 115  */
 116 static int lp855x_configure(struct lp855x *lp)
 117 {
 118         u8 val, addr;
 119         int i, ret;
 120         struct lp855x_platform_data *pd = lp->pdata;
 121
 122         switch (lp->chip_id) {
 123         case LP8550 ... LP8556:
 124                 lp->cfg = &lp855x_dev_cfg;
 125                 break;
 126         default:
 127                 return -EINVAL;
 128         }
 129
 130         if (lp->cfg->pre_init_device) {
 131                 ret = lp->cfg->pre_init_device(lp);
 132                 if (ret) {
 133                         dev_err(lp->dev, "pre init device err: %d\n", ret);
 134                         goto err;
 135                 }
 136         }
 137
 138         val = pd->initial_brightness;
 139         ret = lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
 140         if (ret)
 141                 goto err;
 142
 143         val = pd->device_control;
 144         ret = lp855x_write_byte(lp, lp->cfg->reg_devicectrl, val);
 145         if (ret)
 146                 goto err;
 147
 148         if (pd->load_new_rom_data && pd->size_program) {
 149                 for (i = 0; i < pd->size_program; i++) {
 150                         addr = pd->rom_data[i].addr;
 151                         val = pd->rom_data[i].val;
 152                         if (!lp855x_is_valid_rom_area(lp, addr))
 153                                 continue;
 154
 155                         ret = lp855x_write_byte(lp, addr, val);
 156                         if (ret)
 157                                 goto err;
 158                 }
 159         }
 160
 161         if (lp->cfg->post_init_device) {
 162                 ret = lp->cfg->post_init_device(lp);
 163                 if (ret) {
 164                         dev_err(lp->dev, "post init device err: %d\n", ret);
 165                         goto err;
 166                 }
 167         }
 168
 169         return 0;
 170
 171 err:
 172         return ret;
 173 }
 174
 175 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
 176 {
 177         unsigned int period = lp->pdata->period_ns;
 178         unsigned int duty = br * period / max_br;
 179         struct pwm_device *pwm;
 180
 181         /* request pwm device with the consumer name */
 182         if (!lp->pwm) {
 183                 pwm = devm_pwm_get(lp->dev, lp->chipname);
 184                 if (IS_ERR(pwm))
 185                         return;
 186
 187                 lp->pwm = pwm;
 188         }
 189
 190         pwm_config(lp->pwm, duty, period);
 191         if (duty)
 192                 pwm_enable(lp->pwm);
 193         else
 194                 pwm_disable(lp->pwm);
 195 }
 196
 197 static int lp855x_bl_update_status(struct backlight_device *bl)
 198 {
 199         struct lp855x *lp = bl_get_data(bl);
 200         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 201
 202         if (bl->props.state & BL_CORE_SUSPENDED)
 203                 bl->props.brightness = 0;
 204
 205         if (mode == PWM_BASED) {
 206                 int br = bl->props.brightness;
 207                 int max_br = bl->props.max_brightness;
 208
 209                 lp855x_pwm_ctrl(lp, br, max_br);
 210
 211         } else if (mode == REGISTER_BASED) {
 212                 u8 val = bl->props.brightness;
 213                 lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
 214         }
 215
 216         return 0;
 217 }
 218
 219 static int lp855x_bl_get_brightness(struct backlight_device *bl)
 220 {
 221         struct lp855x *lp = bl_get_data(bl);
 222         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 223
 224         if (mode == REGISTER_BASED) {
 225                 u8 val = 0;
 226
 227                 lp855x_read_byte(lp, BRIGHTNESS_CTRL, &val);
 228                 bl->props.brightness = val;
 229         }
 230
 231         return bl->props.brightness;
 232 }
 233
 234 static const struct backlight_ops lp855x_bl_ops = {
 235         .options = BL_CORE_SUSPENDRESUME,
 236         .update_status = lp855x_bl_update_status,
 237         .get_brightness = lp855x_bl_get_brightness,
 238 };
 239
 240 static int lp855x_backlight_register(struct lp855x *lp)
 241 {
 242         struct backlight_device *bl;
 243         struct backlight_properties props;
 244         struct lp855x_platform_data *pdata = lp->pdata;
 245         char *name = pdata->name ? : DEFAULT_BL_NAME;
 246
 247         props.type = BACKLIGHT_PLATFORM;
 248         props.max_brightness = MAX_BRIGHTNESS;
 249
 250         if (pdata->initial_brightness > props.max_brightness)
 251                 pdata->initial_brightness = props.max_brightness;
 252
 253         props.brightness = pdata->initial_brightness;
 254
 255         bl = backlight_device_register(name, lp->dev, lp,
 256                                        &lp855x_bl_ops, &props);
 257         if (IS_ERR(bl))
 258                 return PTR_ERR(bl);
 259
 260         lp->bl = bl;
 261
 262         return 0;
 263 }
 264
 265 static void lp855x_backlight_unregister(struct lp855x *lp)
 266 {
 267         if (lp->bl)
 268                 backlight_device_unregister(lp->bl);
 269 }
 270
 271 static ssize_t lp855x_get_chip_id(struct device *dev,
 272                                 struct device_attribute *attr, char *buf)
 273 {
 274         struct lp855x *lp = dev_get_drvdata(dev);
 275         return scnprintf(buf, BUF_SIZE, "%s\n", lp->chipname);
 276 }
 277
 278 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
 279                                      struct device_attribute *attr, char *buf)
 280 {
 281         struct lp855x *lp = dev_get_drvdata(dev);
 282         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 283         char *strmode = NULL;
 284
 285         if (mode == PWM_BASED)
 286                 strmode = "pwm based";
 287         else if (mode == REGISTER_BASED)
 288                 strmode = "register based";
 289
 290         return scnprintf(buf, BUF_SIZE, "%s\n", strmode);
 291 }
 292
 293 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
 294 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
 295
 296 static struct attribute *lp855x_attributes[] = {
 297         &dev_attr_chip_id.attr,
 298         &dev_attr_bl_ctl_mode.attr,
 299         NULL,
 300 };
 301
 302 static const struct attribute_group lp855x_attr_group = {
 303         .attrs = lp855x_attributes,
 304 };
 305
 306 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
 307 {
 308         struct lp855x *lp;
 309         struct lp855x_platform_data *pdata = cl->dev.platform_data;
 310         enum lp855x_brightness_ctrl_mode mode;
 311         int ret;
 312
 313         if (!pdata) {
 314                 dev_err(&cl->dev, "no platform data supplied\n");
 315                 return -EINVAL;
 316         }
 317
 318         if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
 319                 return -EIO;
 320
 321         lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
 322         if (!lp)
 323                 return -ENOMEM;
 324
 325         mode = pdata->mode;
 326         lp->client = cl;
 327         lp->dev = &cl->dev;
 328         lp->pdata = pdata;
 329         lp->chipname = id->name;
 330         lp->chip_id = id->driver_data;
 331         i2c_set_clientdata(cl, lp);
 332
 333         ret = lp855x_configure(lp);
 334         if (ret) {
 335                 dev_err(lp->dev, "device config err: %d", ret);
 336                 goto err_dev;
 337         }
 338
 339         ret = lp855x_backlight_register(lp);
 340         if (ret) {
 341                 dev_err(lp->dev,
 342                         "failed to register backlight. err: %d\n", ret);
 343                 goto err_dev;
 344         }
 345
 346         ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
 347         if (ret) {
 348                 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
 349                 goto err_sysfs;
 350         }
 351
 352         backlight_update_status(lp->bl);
 353         return 0;
 354
 355 err_sysfs:
 356         lp855x_backlight_unregister(lp);
 357 err_dev:
 358         return ret;
 359 }
 360
 361 static int lp855x_remove(struct i2c_client *cl)
 362 {
 363         struct lp855x *lp = i2c_get_clientdata(cl);
 364
 365         lp->bl->props.brightness = 0;
 366         backlight_update_status(lp->bl);
 367         sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
 368         lp855x_backlight_unregister(lp);
 369
 370         return 0;
 371 }
 372
 373 static const struct i2c_device_id lp855x_ids[] = {
 374         {"lp8550", LP8550},
 375         {"lp8551", LP8551},
 376         {"lp8552", LP8552},
 377         {"lp8553", LP8553},
 378         {"lp8556", LP8556},
 379         { }
 380 };
 381 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
 382
 383 static struct i2c_driver lp855x_driver = {
 384         .driver = {
 385                    .name = "lp855x",
 386                    },
 387         .probe = lp855x_probe,
 388         .remove = lp855x_remove,
 389         .id_table = lp855x_ids,
 390 };
 391
 392 module_i2c_driver(lp855x_driver);
 393
 394 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
 395 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
 396 MODULE_LICENSE("GPL");