drivers/leds/leds-lp3944.c

   1 /*
   2  * leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip
   3  *
   4  * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
   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 /*
  13  * I2C driver for National Semiconductor LP3944 Funlight Chip
  14  * http://www.national.com/pf/LP/LP3944.html
  15  *
  16  * This helper chip can drive up to 8 leds, with two programmable DIM modes;
  17  * it could even be used as a gpio expander but this driver assumes it is used
  18  * as a led controller.
  19  *
  20  * The DIM modes are used to set _blink_ patterns for leds, the pattern is
  21  * specified supplying two parameters:
  22  *   - period: from 0s to 1.6s
  23  *   - duty cycle: percentage of the period the led is on, from 0 to 100
  24  *
  25  * LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
  26  * leds, the camera flash light and the displays backlights.
  27  */
  28
  29 #include <linux/module.h>
  30 #include <linux/i2c.h>
  31 #include <linux/slab.h>
  32 #include <linux/leds.h>
  33 #include <linux/mutex.h>
  34 #include <linux/workqueue.h>
  35 #include <linux/leds-lp3944.h>
  36
  37 /* Read Only Registers */
  38 #define LP3944_REG_INPUT1     0x00 /* LEDs 0-7 InputRegister (Read Only) */
  39 #define LP3944_REG_REGISTER1  0x01 /* None (Read Only) */
  40
  41 #define LP3944_REG_PSC0       0x02 /* Frequency Prescaler 0 (R/W) */
  42 #define LP3944_REG_PWM0       0x03 /* PWM Register 0 (R/W) */
  43 #define LP3944_REG_PSC1       0x04 /* Frequency Prescaler 1 (R/W) */
  44 #define LP3944_REG_PWM1       0x05 /* PWM Register 1 (R/W) */
  45 #define LP3944_REG_LS0        0x06 /* LEDs 0-3 Selector (R/W) */
  46 #define LP3944_REG_LS1        0x07 /* LEDs 4-7 Selector (R/W) */
  47
  48 /* These registers are not used to control leds in LP3944, they can store
  49  * arbitrary values which the chip will ignore.
  50  */
  51 #define LP3944_REG_REGISTER8  0x08
  52 #define LP3944_REG_REGISTER9  0x09
  53
  54 #define LP3944_DIM0 0
  55 #define LP3944_DIM1 1
  56
  57 /* period in ms */
  58 #define LP3944_PERIOD_MIN 0
  59 #define LP3944_PERIOD_MAX 1600
  60
  61 /* duty cycle is a percentage */
  62 #define LP3944_DUTY_CYCLE_MIN 0
  63 #define LP3944_DUTY_CYCLE_MAX 100
  64
  65 #define ldev_to_led(c)       container_of(c, struct lp3944_led_data, ldev)
  66
  67 /* Saved data */
  68 struct lp3944_led_data {
  69         u8 id;
  70         enum lp3944_type type;
  71         enum lp3944_status status;
  72         struct led_classdev ldev;
  73         struct i2c_client *client;
  74         struct work_struct work;
  75 };
  76
  77 struct lp3944_data {
  78         struct mutex lock;
  79         struct i2c_client *client;
  80         struct lp3944_led_data leds[LP3944_LEDS_MAX];
  81 };
  82
  83 static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
  84 {
  85         int tmp;
  86
  87         tmp = i2c_smbus_read_byte_data(client, reg);
  88         if (tmp < 0)
  89                 return tmp;
  90
  91         *value = tmp;
  92
  93         return 0;
  94 }
  95
  96 static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
  97 {
  98         return i2c_smbus_write_byte_data(client, reg, value);
  99 }
 100
 101 /**
 102  * Set the period for DIM status
 103  *
 104  * @client: the i2c client
 105  * @dim: either LP3944_DIM0 or LP3944_DIM1
 106  * @period: period of a blink, that is a on/off cycle, expressed in ms.
 107  */
 108 static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
 109 {
 110         u8 psc_reg;
 111         u8 psc_value;
 112         int err;
 113
 114         if (dim == LP3944_DIM0)
 115                 psc_reg = LP3944_REG_PSC0;
 116         else if (dim == LP3944_DIM1)
 117                 psc_reg = LP3944_REG_PSC1;
 118         else
 119                 return -EINVAL;
 120
 121         /* Convert period to Prescaler value */
 122         if (period > LP3944_PERIOD_MAX)
 123                 return -EINVAL;
 124
 125         psc_value = (period * 255) / LP3944_PERIOD_MAX;
 126
 127         err = lp3944_reg_write(client, psc_reg, psc_value);
 128
 129         return err;
 130 }
 131
 132 /**
 133  * Set the duty cycle for DIM status
 134  *
 135  * @client: the i2c client
 136  * @dim: either LP3944_DIM0 or LP3944_DIM1
 137  * @duty_cycle: percentage of a period during which a led is ON
 138  */
 139 static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
 140                                     u8 duty_cycle)
 141 {
 142         u8 pwm_reg;
 143         u8 pwm_value;
 144         int err;
 145
 146         if (dim == LP3944_DIM0)
 147                 pwm_reg = LP3944_REG_PWM0;
 148         else if (dim == LP3944_DIM1)
 149                 pwm_reg = LP3944_REG_PWM1;
 150         else
 151                 return -EINVAL;
 152
 153         /* Convert duty cycle to PWM value */
 154         if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
 155                 return -EINVAL;
 156
 157         pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;
 158
 159         err = lp3944_reg_write(client, pwm_reg, pwm_value);
 160
 161         return err;
 162 }
 163
 164 /**
 165  * Set the led status
 166  *
 167  * @led: a lp3944_led_data structure
 168  * @status: one of LP3944_LED_STATUS_OFF
 169  *                 LP3944_LED_STATUS_ON
 170  *                 LP3944_LED_STATUS_DIM0
 171  *                 LP3944_LED_STATUS_DIM1
 172  */
 173 static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
 174 {
 175         struct lp3944_data *data = i2c_get_clientdata(led->client);
 176         u8 id = led->id;
 177         u8 reg;
 178         u8 val = 0;
 179         int err;
 180
 181         dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
 182                 __func__, led->ldev.name, status);
 183
 184         switch (id) {
 185         case LP3944_LED0:
 186         case LP3944_LED1:
 187         case LP3944_LED2:
 188         case LP3944_LED3:
 189                 reg = LP3944_REG_LS0;
 190                 break;
 191         case LP3944_LED4:
 192         case LP3944_LED5:
 193         case LP3944_LED6:
 194         case LP3944_LED7:
 195                 id -= LP3944_LED4;
 196                 reg = LP3944_REG_LS1;
 197                 break;
 198         default:
 199                 return -EINVAL;
 200         }
 201
 202         if (status > LP3944_LED_STATUS_DIM1)
 203                 return -EINVAL;
 204
 205         /* invert only 0 and 1, leave unchanged the other values,
 206          * remember we are abusing status to set blink patterns
 207          */
 208         if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
 209                 status = 1 - status;
 210
 211         mutex_lock(&data->lock);
 212         lp3944_reg_read(led->client, reg, &val);
 213
 214         val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
 215         val |= (status << (id << 1));
 216
 217         dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
 218                 __func__, led->ldev.name, reg, id, status, val);
 219
 220         /* set led status */
 221         err = lp3944_reg_write(led->client, reg, val);
 222         mutex_unlock(&data->lock);
 223
 224         return err;
 225 }
 226
 227 static int lp3944_led_set_blink(struct led_classdev *led_cdev,
 228                                 unsigned long *delay_on,
 229                                 unsigned long *delay_off)
 230 {
 231         struct lp3944_led_data *led = ldev_to_led(led_cdev);
 232         u16 period;
 233         u8 duty_cycle;
 234         int err;
 235
 236         /* units are in ms */
 237         if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
 238                 return -EINVAL;
 239
 240         if (*delay_on == 0 && *delay_off == 0) {
 241                 /* Special case: the leds subsystem requires a default user
 242                  * friendly blink pattern for the LED.  Let's blink the led
 243                  * slowly (1Hz).
 244                  */
 245                 *delay_on = 500;
 246                 *delay_off = 500;
 247         }
 248
 249         period = (*delay_on) + (*delay_off);
 250
 251         /* duty_cycle is the percentage of period during which the led is ON */
 252         duty_cycle = 100 * (*delay_on) / period;
 253
 254         /* invert duty cycle for inverted leds, this has the same effect of
 255          * swapping delay_on and delay_off
 256          */
 257         if (led->type == LP3944_LED_TYPE_LED_INVERTED)
 258                 duty_cycle = 100 - duty_cycle;
 259
 260         /* NOTE: using always the first DIM mode, this means that all leds
 261          * will have the same blinking pattern.
 262          *
 263          * We could find a way later to have two leds blinking in hardware
 264          * with different patterns at the same time, falling back to software
 265          * control for the other ones.
 266          */
 267         err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
 268         if (err)
 269                 return err;
 270
 271         err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
 272         if (err)
 273                 return err;
 274
 275         dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
 276                 __func__);
 277
 278         led->status = LP3944_LED_STATUS_DIM0;
 279         schedule_work(&led->work);
 280
 281         return 0;
 282 }
 283
 284 static void lp3944_led_set_brightness(struct led_classdev *led_cdev,
 285                                       enum led_brightness brightness)
 286 {
 287         struct lp3944_led_data *led = ldev_to_led(led_cdev);
 288
 289         dev_dbg(&led->client->dev, "%s: %s, %d\n",
 290                 __func__, led_cdev->name, brightness);
 291
 292         led->status = !!brightness;
 293         schedule_work(&led->work);
 294 }
 295
 296 static void lp3944_led_work(struct work_struct *work)
 297 {
 298         struct lp3944_led_data *led;
 299
 300         led = container_of(work, struct lp3944_led_data, work);
 301         lp3944_led_set(led, led->status);
 302 }
 303
 304 static int lp3944_configure(struct i2c_client *client,
 305                             struct lp3944_data *data,
 306                             struct lp3944_platform_data *pdata)
 307 {
 308         int i, err = 0;
 309
 310         for (i = 0; i < pdata->leds_size; i++) {
 311                 struct lp3944_led *pled = &pdata->leds[i];
 312                 struct lp3944_led_data *led = &data->leds[i];
 313                 led->client = client;
 314                 led->id = i;
 315
 316                 switch (pled->type) {
 317
 318                 case LP3944_LED_TYPE_LED:
 319                 case LP3944_LED_TYPE_LED_INVERTED:
 320                         led->type = pled->type;
 321                         led->status = pled->status;
 322                         led->ldev.name = pled->name;
 323                         led->ldev.max_brightness = 1;
 324                         led->ldev.brightness_set = lp3944_led_set_brightness;
 325                         led->ldev.blink_set = lp3944_led_set_blink;
 326                         led->ldev.flags = LED_CORE_SUSPENDRESUME;
 327
 328                         INIT_WORK(&led->work, lp3944_led_work);
 329                         err = led_classdev_register(&client->dev, &led->ldev);
 330                         if (err < 0) {
 331                                 dev_err(&client->dev,
 332                                         "couldn't register LED %s\n",
 333                                         led->ldev.name);
 334                                 goto exit;
 335                         }
 336
 337                         /* to expose the default value to userspace */
 338                         led->ldev.brightness =
 339                                         (enum led_brightness) led->status;
 340
 341                         /* Set the default led status */
 342                         err = lp3944_led_set(led, led->status);
 343                         if (err < 0) {
 344                                 dev_err(&client->dev,
 345                                         "%s couldn't set STATUS %d\n",
 346                                         led->ldev.name, led->status);
 347                                 goto exit;
 348                         }
 349                         break;
 350
 351                 case LP3944_LED_TYPE_NONE:
 352                 default:
 353                         break;
 354
 355                 }
 356         }
 357         return 0;
 358
 359 exit:
 360         if (i > 0)
 361                 for (i = i - 1; i >= 0; i--)
 362                         switch (pdata->leds[i].type) {
 363
 364                         case LP3944_LED_TYPE_LED:
 365                         case LP3944_LED_TYPE_LED_INVERTED:
 366                                 led_classdev_unregister(&data->leds[i].ldev);
 367                                 cancel_work_sync(&data->leds[i].work);
 368                                 break;
 369
 370                         case LP3944_LED_TYPE_NONE:
 371                         default:
 372                                 break;
 373                         }
 374
 375         return err;
 376 }
 377
 378 static int lp3944_probe(struct i2c_client *client,
 379                                   const struct i2c_device_id *id)
 380 {
 381         struct lp3944_platform_data *lp3944_pdata =
 382                         dev_get_platdata(&client->dev);
 383         struct lp3944_data *data;
 384         int err;
 385
 386         if (lp3944_pdata == NULL) {
 387                 dev_err(&client->dev, "no platform data\n");
 388                 return -EINVAL;
 389         }
 390
 391         /* Let's see whether this adapter can support what we need. */
 392         if (!i2c_check_functionality(client->adapter,
 393                                 I2C_FUNC_SMBUS_BYTE_DATA)) {
 394                 dev_err(&client->dev, "insufficient functionality!\n");
 395                 return -ENODEV;
 396         }
 397
 398         data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
 399                         GFP_KERNEL);
 400         if (!data)
 401                 return -ENOMEM;
 402
 403         data->client = client;
 404         i2c_set_clientdata(client, data);
 405
 406         mutex_init(&data->lock);
 407
 408         err = lp3944_configure(client, data, lp3944_pdata);
 409         if (err < 0)
 410                 return err;
 411
 412         dev_info(&client->dev, "lp3944 enabled\n");
 413         return 0;
 414 }
 415
 416 static int lp3944_remove(struct i2c_client *client)
 417 {
 418         struct lp3944_platform_data *pdata = dev_get_platdata(&client->dev);
 419         struct lp3944_data *data = i2c_get_clientdata(client);
 420         int i;
 421
 422         for (i = 0; i < pdata->leds_size; i++)
 423                 switch (data->leds[i].type) {
 424                 case LP3944_LED_TYPE_LED:
 425                 case LP3944_LED_TYPE_LED_INVERTED:
 426                         led_classdev_unregister(&data->leds[i].ldev);
 427                         cancel_work_sync(&data->leds[i].work);
 428                         break;
 429
 430                 case LP3944_LED_TYPE_NONE:
 431                 default:
 432                         break;
 433                 }
 434
 435         return 0;
 436 }
 437
 438 /* lp3944 i2c driver struct */
 439 static const struct i2c_device_id lp3944_id[] = {
 440         {"lp3944", 0},
 441         {}
 442 };
 443
 444 MODULE_DEVICE_TABLE(i2c, lp3944_id);
 445
 446 static struct i2c_driver lp3944_driver = {
 447         .driver   = {
 448                    .name = "lp3944",
 449         },
 450         .probe    = lp3944_probe,
 451         .remove   = lp3944_remove,
 452         .id_table = lp3944_id,
 453 };
 454
 455 module_i2c_driver(lp3944_driver);
 456
 457 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
 458 MODULE_DESCRIPTION("LP3944 Fun Light Chip");
 459 MODULE_LICENSE("GPL");