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 mutex xfer_lock;
  39         struct lp855x_platform_data *pdata;
  40         struct pwm_device *pwm;
  41 };
  42
  43 static int lp855x_read_byte(struct lp855x *lp, u8 reg, u8 *data)
  44 {
  45         int ret;
  46
  47         mutex_lock(&lp->xfer_lock);
  48         ret = i2c_smbus_read_byte_data(lp->client, reg);
  49         if (ret < 0) {
  50                 mutex_unlock(&lp->xfer_lock);
  51                 dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
  52                 return ret;
  53         }
  54         mutex_unlock(&lp->xfer_lock);
  55
  56         *data = (u8)ret;
  57         return 0;
  58 }
  59
  60 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
  61 {
  62         int ret;
  63
  64         mutex_lock(&lp->xfer_lock);
  65         ret = i2c_smbus_write_byte_data(lp->client, reg, data);
  66         mutex_unlock(&lp->xfer_lock);
  67
  68         return ret;
  69 }
  70
  71 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
  72 {
  73         u8 start, end;
  74
  75         switch (lp->chip_id) {
  76         case LP8550:
  77         case LP8551:
  78         case LP8552:
  79         case LP8553:
  80                 start = EEPROM_START;
  81                 end = EEPROM_END;
  82                 break;
  83         case LP8556:
  84                 start = EPROM_START;
  85                 end = EPROM_END;
  86                 break;
  87         default:
  88                 return false;
  89         }
  90
  91         return (addr >= start && addr <= end);
  92 }
  93
  94 static int lp855x_init_registers(struct lp855x *lp)
  95 {
  96         u8 val, addr;
  97         int i, ret;
  98         struct lp855x_platform_data *pd = lp->pdata;
  99
 100         val = pd->initial_brightness;
 101         ret = lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
 102         if (ret)
 103                 return ret;
 104
 105         val = pd->device_control;
 106         ret = lp855x_write_byte(lp, DEVICE_CTRL, val);
 107         if (ret)
 108                 return ret;
 109
 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))
 115                                 continue;
 116
 117                         ret = lp855x_write_byte(lp, addr, val);
 118                         if (ret)
 119                                 return ret;
 120                 }
 121         }
 122
 123         return ret;
 124 }
 125
 126 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
 127 {
 128         unsigned int period = lp->pdata->period_ns;
 129         unsigned int duty = br * period / max_br;
 130         struct pwm_device *pwm;
 131
 132         /* request pwm device with the consumer name */
 133         if (!lp->pwm) {
 134                 pwm = devm_pwm_get(lp->dev, lp->chipname);
 135                 if (IS_ERR(pwm))
 136                         return;
 137
 138                 lp->pwm = pwm;
 139         }
 140
 141         pwm_config(lp->pwm, duty, period);
 142         duty == 0 ? pwm_disable(lp->pwm) : pwm_enable(lp->pwm);
 143 }
 144
 145 static int lp855x_bl_update_status(struct backlight_device *bl)
 146 {
 147         struct lp855x *lp = bl_get_data(bl);
 148         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 149
 150         if (bl->props.state & BL_CORE_SUSPENDED)
 151                 bl->props.brightness = 0;
 152
 153         if (mode == PWM_BASED) {
 154                 int br = bl->props.brightness;
 155                 int max_br = bl->props.max_brightness;
 156
 157                 lp855x_pwm_ctrl(lp, br, max_br);
 158
 159         } else if (mode == REGISTER_BASED) {
 160                 u8 val = bl->props.brightness;
 161                 lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
 162         }
 163
 164         return 0;
 165 }
 166
 167 static int lp855x_bl_get_brightness(struct backlight_device *bl)
 168 {
 169         struct lp855x *lp = bl_get_data(bl);
 170         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 171
 172         if (mode == REGISTER_BASED) {
 173                 u8 val = 0;
 174
 175                 lp855x_read_byte(lp, BRIGHTNESS_CTRL, &val);
 176                 bl->props.brightness = val;
 177         }
 178
 179         return bl->props.brightness;
 180 }
 181
 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,
 186 };
 187
 188 static int lp855x_backlight_register(struct lp855x *lp)
 189 {
 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;
 194
 195         props.type = BACKLIGHT_PLATFORM;
 196         props.max_brightness = MAX_BRIGHTNESS;
 197
 198         if (pdata->initial_brightness > props.max_brightness)
 199                 pdata->initial_brightness = props.max_brightness;
 200
 201         props.brightness = pdata->initial_brightness;
 202
 203         bl = backlight_device_register(name, lp->dev, lp,
 204                                        &lp855x_bl_ops, &props);
 205         if (IS_ERR(bl))
 206                 return PTR_ERR(bl);
 207
 208         lp->bl = bl;
 209
 210         return 0;
 211 }
 212
 213 static void lp855x_backlight_unregister(struct lp855x *lp)
 214 {
 215         if (lp->bl)
 216                 backlight_device_unregister(lp->bl);
 217 }
 218
 219 static ssize_t lp855x_get_chip_id(struct device *dev,
 220                                 struct device_attribute *attr, char *buf)
 221 {
 222         struct lp855x *lp = dev_get_drvdata(dev);
 223         return scnprintf(buf, BUF_SIZE, "%s\n", lp->chipname);
 224 }
 225
 226 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
 227                                      struct device_attribute *attr, char *buf)
 228 {
 229         struct lp855x *lp = dev_get_drvdata(dev);
 230         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 231         char *strmode = NULL;
 232
 233         if (mode == PWM_BASED)
 234                 strmode = "pwm based";
 235         else if (mode == REGISTER_BASED)
 236                 strmode = "register based";
 237
 238         return scnprintf(buf, BUF_SIZE, "%s\n", strmode);
 239 }
 240
 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);
 243
 244 static struct attribute *lp855x_attributes[] = {
 245         &dev_attr_chip_id.attr,
 246         &dev_attr_bl_ctl_mode.attr,
 247         NULL,
 248 };
 249
 250 static const struct attribute_group lp855x_attr_group = {
 251         .attrs = lp855x_attributes,
 252 };
 253
 254 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
 255 {
 256         struct lp855x *lp;
 257         struct lp855x_platform_data *pdata = cl->dev.platform_data;
 258         enum lp855x_brightness_ctrl_mode mode;
 259         int ret;
 260
 261         if (!pdata) {
 262                 dev_err(&cl->dev, "no platform data supplied\n");
 263                 return -EINVAL;
 264         }
 265
 266         if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
 267                 return -EIO;
 268
 269         lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
 270         if (!lp)
 271                 return -ENOMEM;
 272
 273         mode = pdata->mode;
 274         lp->client = cl;
 275         lp->dev = &cl->dev;
 276         lp->pdata = pdata;
 277         lp->chipname = id->name;
 278         lp->chip_id = id->driver_data;
 279         i2c_set_clientdata(cl, lp);
 280
 281         mutex_init(&lp->xfer_lock);
 282
 283         ret = lp855x_init_registers(lp);
 284         if (ret) {
 285                 dev_err(lp->dev, "i2c communication err: %d", ret);
 286                 if (mode == REGISTER_BASED)
 287                         goto err_dev;
 288         }
 289
 290         ret = lp855x_backlight_register(lp);
 291         if (ret) {
 292                 dev_err(lp->dev,
 293                         "failed to register backlight. err: %d\n", ret);
 294                 goto err_dev;
 295         }
 296
 297         ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
 298         if (ret) {
 299                 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
 300                 goto err_sysfs;
 301         }
 302
 303         backlight_update_status(lp->bl);
 304         return 0;
 305
 306 err_sysfs:
 307         lp855x_backlight_unregister(lp);
 308 err_dev:
 309         return ret;
 310 }
 311
 312 static int __devexit lp855x_remove(struct i2c_client *cl)
 313 {
 314         struct lp855x *lp = i2c_get_clientdata(cl);
 315
 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);
 320
 321         return 0;
 322 }
 323
 324 static const struct i2c_device_id lp855x_ids[] = {
 325         {"lp8550", LP8550},
 326         {"lp8551", LP8551},
 327         {"lp8552", LP8552},
 328         {"lp8553", LP8553},
 329         {"lp8556", LP8556},
 330         { }
 331 };
 332 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
 333
 334 static struct i2c_driver lp855x_driver = {
 335         .driver = {
 336                    .name = "lp855x",
 337                    },
 338         .probe = lp855x_probe,
 339         .remove = __devexit_p(lp855x_remove),
 340         .id_table = lp855x_ids,
 341 };
 342
 343 module_i2c_driver(lp855x_driver);
 344
 345 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
 346 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
 347 MODULE_LICENSE("GPL");