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         if (duty)
 143                 pwm_enable(lp->pwm);
 144         else
 145                 pwm_disable(lp->pwm);
 146 }
 147
 148 static int lp855x_bl_update_status(struct backlight_device *bl)
 149 {
 150         struct lp855x *lp = bl_get_data(bl);
 151         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 152
 153         if (bl->props.state & BL_CORE_SUSPENDED)
 154                 bl->props.brightness = 0;
 155
 156         if (mode == PWM_BASED) {
 157                 int br = bl->props.brightness;
 158                 int max_br = bl->props.max_brightness;
 159
 160                 lp855x_pwm_ctrl(lp, br, max_br);
 161
 162         } else if (mode == REGISTER_BASED) {
 163                 u8 val = bl->props.brightness;
 164                 lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
 165         }
 166
 167         return 0;
 168 }
 169
 170 static int lp855x_bl_get_brightness(struct backlight_device *bl)
 171 {
 172         struct lp855x *lp = bl_get_data(bl);
 173         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 174
 175         if (mode == REGISTER_BASED) {
 176                 u8 val = 0;
 177
 178                 lp855x_read_byte(lp, BRIGHTNESS_CTRL, &val);
 179                 bl->props.brightness = val;
 180         }
 181
 182         return bl->props.brightness;
 183 }
 184
 185 static const struct backlight_ops lp855x_bl_ops = {
 186         .options = BL_CORE_SUSPENDRESUME,
 187         .update_status = lp855x_bl_update_status,
 188         .get_brightness = lp855x_bl_get_brightness,
 189 };
 190
 191 static int lp855x_backlight_register(struct lp855x *lp)
 192 {
 193         struct backlight_device *bl;
 194         struct backlight_properties props;
 195         struct lp855x_platform_data *pdata = lp->pdata;
 196         char *name = pdata->name ? : DEFAULT_BL_NAME;
 197
 198         props.type = BACKLIGHT_PLATFORM;
 199         props.max_brightness = MAX_BRIGHTNESS;
 200
 201         if (pdata->initial_brightness > props.max_brightness)
 202                 pdata->initial_brightness = props.max_brightness;
 203
 204         props.brightness = pdata->initial_brightness;
 205
 206         bl = backlight_device_register(name, lp->dev, lp,
 207                                        &lp855x_bl_ops, &props);
 208         if (IS_ERR(bl))
 209                 return PTR_ERR(bl);
 210
 211         lp->bl = bl;
 212
 213         return 0;
 214 }
 215
 216 static void lp855x_backlight_unregister(struct lp855x *lp)
 217 {
 218         if (lp->bl)
 219                 backlight_device_unregister(lp->bl);
 220 }
 221
 222 static ssize_t lp855x_get_chip_id(struct device *dev,
 223                                 struct device_attribute *attr, char *buf)
 224 {
 225         struct lp855x *lp = dev_get_drvdata(dev);
 226         return scnprintf(buf, BUF_SIZE, "%s\n", lp->chipname);
 227 }
 228
 229 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
 230                                      struct device_attribute *attr, char *buf)
 231 {
 232         struct lp855x *lp = dev_get_drvdata(dev);
 233         enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
 234         char *strmode = NULL;
 235
 236         if (mode == PWM_BASED)
 237                 strmode = "pwm based";
 238         else if (mode == REGISTER_BASED)
 239                 strmode = "register based";
 240
 241         return scnprintf(buf, BUF_SIZE, "%s\n", strmode);
 242 }
 243
 244 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
 245 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
 246
 247 static struct attribute *lp855x_attributes[] = {
 248         &dev_attr_chip_id.attr,
 249         &dev_attr_bl_ctl_mode.attr,
 250         NULL,
 251 };
 252
 253 static const struct attribute_group lp855x_attr_group = {
 254         .attrs = lp855x_attributes,
 255 };
 256
 257 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
 258 {
 259         struct lp855x *lp;
 260         struct lp855x_platform_data *pdata = cl->dev.platform_data;
 261         enum lp855x_brightness_ctrl_mode mode;
 262         int ret;
 263
 264         if (!pdata) {
 265                 dev_err(&cl->dev, "no platform data supplied\n");
 266                 return -EINVAL;
 267         }
 268
 269         if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
 270                 return -EIO;
 271
 272         lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
 273         if (!lp)
 274                 return -ENOMEM;
 275
 276         mode = pdata->mode;
 277         lp->client = cl;
 278         lp->dev = &cl->dev;
 279         lp->pdata = pdata;
 280         lp->chipname = id->name;
 281         lp->chip_id = id->driver_data;
 282         i2c_set_clientdata(cl, lp);
 283
 284         mutex_init(&lp->xfer_lock);
 285
 286         ret = lp855x_init_registers(lp);
 287         if (ret) {
 288                 dev_err(lp->dev, "i2c communication err: %d", ret);
 289                 if (mode == REGISTER_BASED)
 290                         goto err_dev;
 291         }
 292
 293         ret = lp855x_backlight_register(lp);
 294         if (ret) {
 295                 dev_err(lp->dev,
 296                         "failed to register backlight. err: %d\n", ret);
 297                 goto err_dev;
 298         }
 299
 300         ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
 301         if (ret) {
 302                 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
 303                 goto err_sysfs;
 304         }
 305
 306         backlight_update_status(lp->bl);
 307         return 0;
 308
 309 err_sysfs:
 310         lp855x_backlight_unregister(lp);
 311 err_dev:
 312         return ret;
 313 }
 314
 315 static int __devexit lp855x_remove(struct i2c_client *cl)
 316 {
 317         struct lp855x *lp = i2c_get_clientdata(cl);
 318
 319         lp->bl->props.brightness = 0;
 320         backlight_update_status(lp->bl);
 321         sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
 322         lp855x_backlight_unregister(lp);
 323
 324         return 0;
 325 }
 326
 327 static const struct i2c_device_id lp855x_ids[] = {
 328         {"lp8550", LP8550},
 329         {"lp8551", LP8551},
 330         {"lp8552", LP8552},
 331         {"lp8553", LP8553},
 332         {"lp8556", LP8556},
 333         { }
 334 };
 335 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
 336
 337 static struct i2c_driver lp855x_driver = {
 338         .driver = {
 339                    .name = "lp855x",
 340                    },
 341         .probe = lp855x_probe,
 342         .remove = __devexit_p(lp855x_remove),
 343         .id_table = lp855x_ids,
 344 };
 345
 346 module_i2c_driver(lp855x_driver);
 347
 348 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
 349 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
 350 MODULE_LICENSE("GPL");