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/leds.h>
  32 #include <linux/mutex.h>
  33 #include <linux/workqueue.h>
  34 #include <linux/leds-lp3944.h>
  35
  36 /* Read Only Registers */
  37 #define LP3944_REG_INPUT1     0x00 /* LEDs 0-7 InputRegister (Read Only) */
  38 #define LP3944_REG_REGISTER1  0x01 /* None (Read Only) */
  39
  40 #define LP3944_REG_PSC0       0x02 /* Frequency Prescaler 0 (R/W) */
  41 #define LP3944_REG_PWM0       0x03 /* PWM Register 0 (R/W) */
  42 #define LP3944_REG_PSC1       0x04 /* Frequency Prescaler 1 (R/W) */
  43 #define LP3944_REG_PWM1       0x05 /* PWM Register 1 (R/W) */
  44 #define LP3944_REG_LS0        0x06 /* LEDs 0-3 Selector (R/W) */
  45 #define LP3944_REG_LS1        0x07 /* LEDs 4-7 Selector (R/W) */
  46
  47 /* These registers are not used to control leds in LP3944, they can store
  48  * arbitrary values which the chip will ignore.
  49  */
  50 #define LP3944_REG_REGISTER8  0x08
  51 #define LP3944_REG_REGISTER9  0x09
  52
  53 #define LP3944_DIM0 0
  54 #define LP3944_DIM1 1
  55
  56 /* period in ms */
  57 #define LP3944_PERIOD_MIN 0
  58 #define LP3944_PERIOD_MAX 1600
  59
  60 /* duty cycle is a percentage */
  61 #define LP3944_DUTY_CYCLE_MIN 0
  62 #define LP3944_DUTY_CYCLE_MAX 100
  63
  64 #define ldev_to_led(c)       container_of(c, struct lp3944_led_data, ldev)
  65
  66 /* Saved data */
  67 struct lp3944_led_data {
  68         u8 id;
  69         enum lp3944_type type;
  70         enum lp3944_status status;
  71         struct led_classdev ldev;
  72         struct i2c_client *client;
  73         struct work_struct work;
  74 };
  75
  76 struct lp3944_data {
  77         struct mutex lock;
  78         struct i2c_client *client;
  79         struct lp3944_led_data leds[LP3944_LEDS_MAX];
  80 };
  81
  82 static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
  83 {
  84         int tmp;
  85
  86         tmp = i2c_smbus_read_byte_data(client, reg);
  87         if (tmp < 0)
  88                 return -EINVAL;
  89
  90         *value = tmp;
  91
  92         return 0;
  93 }
  94
  95 static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
  96 {
  97         return i2c_smbus_write_byte_data(client, reg, value);
  98 }
  99
 100 /**
 101  * Set the period for DIM status
 102  *
 103  * @client: the i2c client
 104  * @dim: either LP3944_DIM0 or LP3944_DIM1
 105  * @period: period of a blink, that is a on/off cycle, expressed in ms.
 106  */
 107 static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
 108 {
 109         u8 psc_reg;
 110         u8 psc_value;
 111         int err;
 112
 113         if (dim == LP3944_DIM0)
 114                 psc_reg = LP3944_REG_PSC0;
 115         else if (dim == LP3944_DIM1)
 116                 psc_reg = LP3944_REG_PSC1;
 117         else
 118                 return -EINVAL;
 119
 120         /* Convert period to Prescaler value */
 121         if (period > LP3944_PERIOD_MAX)
 122                 return -EINVAL;
 123
 124         psc_value = (period * 255) / LP3944_PERIOD_MAX;
 125
 126         err = lp3944_reg_write(client, psc_reg, psc_value);
 127
 128         return err;
 129 }
 130
 131 /**
 132  * Set the duty cycle for DIM status
 133  *
 134  * @client: the i2c client
 135  * @dim: either LP3944_DIM0 or LP3944_DIM1
 136  * @duty_cycle: percentage of a period during which a led is ON
 137  */
 138 static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
 139                                     u8 duty_cycle)
 140 {
 141         u8 pwm_reg;
 142         u8 pwm_value;
 143         int err;
 144
 145         if (dim == LP3944_DIM0)
 146                 pwm_reg = LP3944_REG_PWM0;
 147         else if (dim == LP3944_DIM1)
 148                 pwm_reg = LP3944_REG_PWM1;
 149         else
 150                 return -EINVAL;
 151
 152         /* Convert duty cycle to PWM value */
 153         if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
 154                 return -EINVAL;
 155
 156         pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;
 157
 158         err = lp3944_reg_write(client, pwm_reg, pwm_value);
 159
 160         return err;
 161 }
 162
 163 /**
 164  * Set the led status
 165  *
 166  * @led: a lp3944_led_data structure
 167  * @status: one of LP3944_LED_STATUS_OFF
 168  *                 LP3944_LED_STATUS_ON
 169  *                 LP3944_LED_STATUS_DIM0
 170  *                 LP3944_LED_STATUS_DIM1
 171  */
 172 static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
 173 {
 174         struct lp3944_data *data = i2c_get_clientdata(led->client);
 175         u8 id = led->id;
 176         u8 reg;
 177         u8 val = 0;
 178         int err;
 179
 180         dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
 181                 __func__, led->ldev.name, status);
 182
 183         switch (id) {
 184         case LP3944_LED0:
 185         case LP3944_LED1:
 186         case LP3944_LED2:
 187         case LP3944_LED3:
 188                 reg = LP3944_REG_LS0;
 189                 break;
 190         case LP3944_LED4:
 191         case LP3944_LED5:
 192         case LP3944_LED6:
 193         case LP3944_LED7:
 194                 id -= LP3944_LED4;
 195                 reg = LP3944_REG_LS1;
 196                 break;
 197         default:
 198                 return -EINVAL;
 199         }
 200
 201         if (status > LP3944_LED_STATUS_DIM1)
 202                 return -EINVAL;
 203
 204         /* invert only 0 and 1, leave unchanged the other values,
 205          * remember we are abusing status to set blink patterns
 206          */
 207         if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
 208                 status = 1 - status;
 209
 210         mutex_lock(&data->lock);
 211         lp3944_reg_read(led->client, reg, &val);
 212
 213         val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
 214         val |= (status << (id << 1));
 215
 216         dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
 217                 __func__, led->ldev.name, reg, id, status, val);
 218
 219         /* set led status */
 220         err = lp3944_reg_write(led->client, reg, val);
 221         mutex_unlock(&data->lock);
 222
 223         return err;
 224 }
 225
 226 static int lp3944_led_set_blink(struct led_classdev *led_cdev,
 227                                 unsigned long *delay_on,
 228                                 unsigned long *delay_off)
 229 {
 230         struct lp3944_led_data *led = ldev_to_led(led_cdev);
 231         u16 period;
 232         u8 duty_cycle;
 233         int err;
 234
 235         /* units are in ms */
 236         if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
 237                 return -EINVAL;
 238
 239         if (*delay_on == 0 && *delay_off == 0) {
 240                 /* Special case: the leds subsystem requires a default user
 241                  * friendly blink pattern for the LED.  Let's blink the led
 242                  * slowly (1Hz).
 243                  */
 244                 *delay_on = 500;
 245                 *delay_off = 500;
 246         }
 247
 248         period = (*delay_on) + (*delay_off);
 249
 250         /* duty_cycle is the percentage of period during which the led is ON */
 251         duty_cycle = 100 * (*delay_on) / period;
 252
 253         /* invert duty cycle for inverted leds, this has the same effect of
 254          * swapping delay_on and delay_off
 255          */
 256         if (led->type == LP3944_LED_TYPE_LED_INVERTED)
 257                 duty_cycle = 100 - duty_cycle;
 258
 259         /* NOTE: using always the first DIM mode, this means that all leds
 260          * will have the same blinking pattern.
 261          *
 262          * We could find a way later to have two leds blinking in hardware
 263          * with different patterns at the same time, falling back to software
 264          * control for the other ones.
 265          */
 266         err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
 267         if (err)
 268                 return err;
 269
 270         err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
 271         if (err)
 272                 return err;
 273
 274         dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
 275                 __func__);
 276
 277         led->status = LP3944_LED_STATUS_DIM0;
 278         schedule_work(&led->work);
 279
 280         return 0;
 281 }
 282
 283 static void lp3944_led_set_brightness(struct led_classdev *led_cdev,
 284                                       enum led_brightness brightness)
 285 {
 286         struct lp3944_led_data *led = ldev_to_led(led_cdev);
 287
 288         dev_dbg(&led->client->dev, "%s: %s, %d\n",
 289                 __func__, led_cdev->name, brightness);
 290
 291         led->status = brightness;
 292         schedule_work(&led->work);
 293 }
 294
 295 static void lp3944_led_work(struct work_struct *work)
 296 {
 297         struct lp3944_led_data *led;
 298
 299         led = container_of(work, struct lp3944_led_data, work);
 300         lp3944_led_set(led, led->status);
 301 }
 302
 303 static int lp3944_configure(struct i2c_client *client,
 304                             struct lp3944_data *data,
 305                             struct lp3944_platform_data *pdata)
 306 {
 307         int i, err = 0;
 308
 309         for (i = 0; i < pdata->leds_size; i++) {
 310                 struct lp3944_led *pled = &pdata->leds[i];
 311                 struct lp3944_led_data *led = &data->leds[i];
 312                 led->client = client;
 313                 led->id = i;
 314
 315                 switch (pled->type) {
 316
 317                 case LP3944_LED_TYPE_LED:
 318                 case LP3944_LED_TYPE_LED_INVERTED:
 319                         led->type = pled->type;
 320                         led->status = pled->status;
 321                         led->ldev.name = pled->name;
 322                         led->ldev.max_brightness = 1;
 323                         led->ldev.brightness_set = lp3944_led_set_brightness;
 324                         led->ldev.blink_set = lp3944_led_set_blink;
 325                         led->ldev.flags = LED_CORE_SUSPENDRESUME;
 326
 327                         INIT_WORK(&led->work, lp3944_led_work);
 328                         err = led_classdev_register(&client->dev, &led->ldev);
 329                         if (err < 0) {
 330                                 dev_err(&client->dev,
 331                                         "couldn't register LED %s\n",
 332                                         led->ldev.name);
 333                                 goto exit;
 334                         }
 335
 336                         /* to expose the default value to userspace */
 337                         led->ldev.brightness = led->status;
 338
 339                         /* Set the default led status */
 340                         err = lp3944_led_set(led, led->status);
 341                         if (err < 0) {
 342                                 dev_err(&client->dev,
 343                                         "%s couldn't set STATUS %d\n",
 344                                         led->ldev.name, led->status);
 345                                 goto exit;
 346                         }
 347                         break;
 348
 349                 case LP3944_LED_TYPE_NONE:
 350                 default:
 351                         break;
 352
 353                 }
 354         }
 355         return 0;
 356
 357 exit:
 358         if (i > 0)
 359                 for (i = i - 1; i >= 0; i--)
 360                         switch (pdata->leds[i].type) {
 361
 362                         case LP3944_LED_TYPE_LED:
 363                         case LP3944_LED_TYPE_LED_INVERTED:
 364                                 led_classdev_unregister(&data->leds[i].ldev);
 365                                 cancel_work_sync(&data->leds[i].work);
 366                                 break;
 367
 368                         case LP3944_LED_TYPE_NONE:
 369                         default:
 370                                 break;
 371                         }
 372
 373         return err;
 374 }
 375
 376 static int __devinit lp3944_probe(struct i2c_client *client,
 377                                   const struct i2c_device_id *id)
 378 {
 379         struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data;
 380         struct lp3944_data *data;
 381
 382         if (lp3944_pdata == NULL) {
 383                 dev_err(&client->dev, "no platform data\n");
 384                 return -EINVAL;
 385         }
 386
 387         /* Let's see whether this adapter can support what we need. */
 388         if (!i2c_check_functionality(client->adapter,
 389                                 I2C_FUNC_SMBUS_BYTE_DATA)) {
 390                 dev_err(&client->dev, "insufficient functionality!\n");
 391                 return -ENODEV;
 392         }
 393
 394         data = kzalloc(sizeof(struct lp3944_data), GFP_KERNEL);
 395         if (!data)
 396                 return -ENOMEM;
 397
 398         data->client = client;
 399         i2c_set_clientdata(client, data);
 400
 401         mutex_init(&data->lock);
 402
 403         dev_info(&client->dev, "lp3944 enabled\n");
 404
 405         lp3944_configure(client, data, lp3944_pdata);
 406         return 0;
 407 }
 408
 409 static int __devexit lp3944_remove(struct i2c_client *client)
 410 {
 411         struct lp3944_platform_data *pdata = client->dev.platform_data;
 412         struct lp3944_data *data = i2c_get_clientdata(client);
 413         int i;
 414
 415         for (i = 0; i < pdata->leds_size; i++)
 416                 switch (data->leds[i].type) {
 417                 case LP3944_LED_TYPE_LED:
 418                 case LP3944_LED_TYPE_LED_INVERTED:
 419                         led_classdev_unregister(&data->leds[i].ldev);
 420                         cancel_work_sync(&data->leds[i].work);
 421                         break;
 422
 423                 case LP3944_LED_TYPE_NONE:
 424                 default:
 425                         break;
 426                 }
 427
 428         kfree(data);
 429         i2c_set_clientdata(client, NULL);
 430
 431         return 0;
 432 }
 433
 434 /* lp3944 i2c driver struct */
 435 static const struct i2c_device_id lp3944_id[] = {
 436         {"lp3944", 0},
 437         {}
 438 };
 439
 440 MODULE_DEVICE_TABLE(i2c, lp3944_id);
 441
 442 static struct i2c_driver lp3944_driver = {
 443         .driver   = {
 444                    .name = "lp3944",
 445         },
 446         .probe    = lp3944_probe,
 447         .remove   = __devexit_p(lp3944_remove),
 448         .id_table = lp3944_id,
 449 };
 450
 451 static int __init lp3944_module_init(void)
 452 {
 453         return i2c_add_driver(&lp3944_driver);
 454 }
 455
 456 static void __exit lp3944_module_exit(void)
 457 {
 458         i2c_del_driver(&lp3944_driver);
 459 }
 460
 461 module_init(lp3944_module_init);
 462 module_exit(lp3944_module_exit);
 463
 464 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
 465 MODULE_DESCRIPTION("LP3944 Fun Light Chip");
 466 MODULE_LICENSE("GPL");