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/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         struct led_classdev ldev;
  71         struct i2c_client *client;
  72 };
  73
  74 struct lp3944_data {
  75         struct mutex lock;
  76         struct i2c_client *client;
  77         struct lp3944_led_data leds[LP3944_LEDS_MAX];
  78 };
  79
  80 static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
  81 {
  82         int tmp;
  83
  84         tmp = i2c_smbus_read_byte_data(client, reg);
  85         if (tmp < 0)
  86                 return tmp;
  87
  88         *value = tmp;
  89
  90         return 0;
  91 }
  92
  93 static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
  94 {
  95         return i2c_smbus_write_byte_data(client, reg, value);
  96 }
  97
  98 /**
  99  * Set the period for DIM status
 100  *
 101  * @client: the i2c client
 102  * @dim: either LP3944_DIM0 or LP3944_DIM1
 103  * @period: period of a blink, that is a on/off cycle, expressed in ms.
 104  */
 105 static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
 106 {
 107         u8 psc_reg;
 108         u8 psc_value;
 109         int err;
 110
 111         if (dim == LP3944_DIM0)
 112                 psc_reg = LP3944_REG_PSC0;
 113         else if (dim == LP3944_DIM1)
 114                 psc_reg = LP3944_REG_PSC1;
 115         else
 116                 return -EINVAL;
 117
 118         /* Convert period to Prescaler value */
 119         if (period > LP3944_PERIOD_MAX)
 120                 return -EINVAL;
 121
 122         psc_value = (period * 255) / LP3944_PERIOD_MAX;
 123
 124         err = lp3944_reg_write(client, psc_reg, psc_value);
 125
 126         return err;
 127 }
 128
 129 /**
 130  * Set the duty cycle for DIM status
 131  *
 132  * @client: the i2c client
 133  * @dim: either LP3944_DIM0 or LP3944_DIM1
 134  * @duty_cycle: percentage of a period during which a led is ON
 135  */
 136 static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
 137                                     u8 duty_cycle)
 138 {
 139         u8 pwm_reg;
 140         u8 pwm_value;
 141         int err;
 142
 143         if (dim == LP3944_DIM0)
 144                 pwm_reg = LP3944_REG_PWM0;
 145         else if (dim == LP3944_DIM1)
 146                 pwm_reg = LP3944_REG_PWM1;
 147         else
 148                 return -EINVAL;
 149
 150         /* Convert duty cycle to PWM value */
 151         if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
 152                 return -EINVAL;
 153
 154         pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;
 155
 156         err = lp3944_reg_write(client, pwm_reg, pwm_value);
 157
 158         return err;
 159 }
 160
 161 /**
 162  * Set the led status
 163  *
 164  * @led: a lp3944_led_data structure
 165  * @status: one of LP3944_LED_STATUS_OFF
 166  *                 LP3944_LED_STATUS_ON
 167  *                 LP3944_LED_STATUS_DIM0
 168  *                 LP3944_LED_STATUS_DIM1
 169  */
 170 static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
 171 {
 172         struct lp3944_data *data = i2c_get_clientdata(led->client);
 173         u8 id = led->id;
 174         u8 reg;
 175         u8 val = 0;
 176         int err;
 177
 178         dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
 179                 __func__, led->ldev.name, status);
 180
 181         switch (id) {
 182         case LP3944_LED0:
 183         case LP3944_LED1:
 184         case LP3944_LED2:
 185         case LP3944_LED3:
 186                 reg = LP3944_REG_LS0;
 187                 break;
 188         case LP3944_LED4:
 189         case LP3944_LED5:
 190         case LP3944_LED6:
 191         case LP3944_LED7:
 192                 id -= LP3944_LED4;
 193                 reg = LP3944_REG_LS1;
 194                 break;
 195         default:
 196                 return -EINVAL;
 197         }
 198
 199         if (status > LP3944_LED_STATUS_DIM1)
 200                 return -EINVAL;
 201
 202         /* invert only 0 and 1, leave unchanged the other values,
 203          * remember we are abusing status to set blink patterns
 204          */
 205         if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
 206                 status = 1 - status;
 207
 208         mutex_lock(&data->lock);
 209         lp3944_reg_read(led->client, reg, &val);
 210
 211         val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
 212         val |= (status << (id << 1));
 213
 214         dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
 215                 __func__, led->ldev.name, reg, id, status, val);
 216
 217         /* set led status */
 218         err = lp3944_reg_write(led->client, reg, val);
 219         mutex_unlock(&data->lock);
 220
 221         return err;
 222 }
 223
 224 static int lp3944_led_set_blink(struct led_classdev *led_cdev,
 225                                 unsigned long *delay_on,
 226                                 unsigned long *delay_off)
 227 {
 228         struct lp3944_led_data *led = ldev_to_led(led_cdev);
 229         u16 period;
 230         u8 duty_cycle;
 231         int err;
 232
 233         /* units are in ms */
 234         if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
 235                 return -EINVAL;
 236
 237         if (*delay_on == 0 && *delay_off == 0) {
 238                 /* Special case: the leds subsystem requires a default user
 239                  * friendly blink pattern for the LED.  Let's blink the led
 240                  * slowly (1Hz).
 241                  */
 242                 *delay_on = 500;
 243                 *delay_off = 500;
 244         }
 245
 246         period = (*delay_on) + (*delay_off);
 247
 248         /* duty_cycle is the percentage of period during which the led is ON */
 249         duty_cycle = 100 * (*delay_on) / period;
 250
 251         /* invert duty cycle for inverted leds, this has the same effect of
 252          * swapping delay_on and delay_off
 253          */
 254         if (led->type == LP3944_LED_TYPE_LED_INVERTED)
 255                 duty_cycle = 100 - duty_cycle;
 256
 257         /* NOTE: using always the first DIM mode, this means that all leds
 258          * will have the same blinking pattern.
 259          *
 260          * We could find a way later to have two leds blinking in hardware
 261          * with different patterns at the same time, falling back to software
 262          * control for the other ones.
 263          */
 264         err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
 265         if (err)
 266                 return err;
 267
 268         err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
 269         if (err)
 270                 return err;
 271
 272         dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
 273                 __func__);
 274
 275         lp3944_led_set(led, LP3944_LED_STATUS_DIM0);
 276
 277         return 0;
 278 }
 279
 280 static int lp3944_led_set_brightness(struct led_classdev *led_cdev,
 281                                       enum led_brightness brightness)
 282 {
 283         struct lp3944_led_data *led = ldev_to_led(led_cdev);
 284
 285         dev_dbg(&led->client->dev, "%s: %s, %d\n",
 286                 __func__, led_cdev->name, brightness);
 287
 288         return lp3944_led_set(led, !!brightness);
 289 }
 290
 291 static int lp3944_configure(struct i2c_client *client,
 292                             struct lp3944_data *data,
 293                             struct lp3944_platform_data *pdata)
 294 {
 295         int i, err = 0;
 296
 297         for (i = 0; i < pdata->leds_size; i++) {
 298                 struct lp3944_led *pled = &pdata->leds[i];
 299                 struct lp3944_led_data *led = &data->leds[i];
 300                 led->client = client;
 301                 led->id = i;
 302
 303                 switch (pled->type) {
 304
 305                 case LP3944_LED_TYPE_LED:
 306                 case LP3944_LED_TYPE_LED_INVERTED:
 307                         led->type = pled->type;
 308                         led->ldev.name = pled->name;
 309                         led->ldev.max_brightness = 1;
 310                         led->ldev.brightness_set_blocking =
 311                                                 lp3944_led_set_brightness;
 312                         led->ldev.blink_set = lp3944_led_set_blink;
 313                         led->ldev.flags = LED_CORE_SUSPENDRESUME;
 314
 315                         err = led_classdev_register(&client->dev, &led->ldev);
 316                         if (err < 0) {
 317                                 dev_err(&client->dev,
 318                                         "couldn't register LED %s\n",
 319                                         led->ldev.name);
 320                                 goto exit;
 321                         }
 322
 323                         /* to expose the default value to userspace */
 324                         led->ldev.brightness =
 325                                         (enum led_brightness) pled->status;
 326
 327                         /* Set the default led status */
 328                         err = lp3944_led_set(led, pled->status);
 329                         if (err < 0) {
 330                                 dev_err(&client->dev,
 331                                         "%s couldn't set STATUS %d\n",
 332                                         led->ldev.name, pled->status);
 333                                 goto exit;
 334                         }
 335                         break;
 336
 337                 case LP3944_LED_TYPE_NONE:
 338                 default:
 339                         break;
 340
 341                 }
 342         }
 343         return 0;
 344
 345 exit:
 346         if (i > 0)
 347                 for (i = i - 1; i >= 0; i--)
 348                         switch (pdata->leds[i].type) {
 349
 350                         case LP3944_LED_TYPE_LED:
 351                         case LP3944_LED_TYPE_LED_INVERTED:
 352                                 led_classdev_unregister(&data->leds[i].ldev);
 353                                 break;
 354
 355                         case LP3944_LED_TYPE_NONE:
 356                         default:
 357                                 break;
 358                         }
 359
 360         return err;
 361 }
 362
 363 static int lp3944_probe(struct i2c_client *client,
 364                                   const struct i2c_device_id *id)
 365 {
 366         struct lp3944_platform_data *lp3944_pdata =
 367                         dev_get_platdata(&client->dev);
 368         struct lp3944_data *data;
 369         int err;
 370
 371         if (lp3944_pdata == NULL) {
 372                 dev_err(&client->dev, "no platform data\n");
 373                 return -EINVAL;
 374         }
 375
 376         /* Let's see whether this adapter can support what we need. */
 377         if (!i2c_check_functionality(client->adapter,
 378                                 I2C_FUNC_SMBUS_BYTE_DATA)) {
 379                 dev_err(&client->dev, "insufficient functionality!\n");
 380                 return -ENODEV;
 381         }
 382
 383         data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
 384                         GFP_KERNEL);
 385         if (!data)
 386                 return -ENOMEM;
 387
 388         data->client = client;
 389         i2c_set_clientdata(client, data);
 390
 391         mutex_init(&data->lock);
 392
 393         err = lp3944_configure(client, data, lp3944_pdata);
 394         if (err < 0)
 395                 return err;
 396
 397         dev_info(&client->dev, "lp3944 enabled\n");
 398         return 0;
 399 }
 400
 401 static int lp3944_remove(struct i2c_client *client)
 402 {
 403         struct lp3944_platform_data *pdata = dev_get_platdata(&client->dev);
 404         struct lp3944_data *data = i2c_get_clientdata(client);
 405         int i;
 406
 407         for (i = 0; i < pdata->leds_size; i++)
 408                 switch (data->leds[i].type) {
 409                 case LP3944_LED_TYPE_LED:
 410                 case LP3944_LED_TYPE_LED_INVERTED:
 411                         led_classdev_unregister(&data->leds[i].ldev);
 412                         break;
 413
 414                 case LP3944_LED_TYPE_NONE:
 415                 default:
 416                         break;
 417                 }
 418
 419         return 0;
 420 }
 421
 422 /* lp3944 i2c driver struct */
 423 static const struct i2c_device_id lp3944_id[] = {
 424         {"lp3944", 0},
 425         {}
 426 };
 427
 428 MODULE_DEVICE_TABLE(i2c, lp3944_id);
 429
 430 static struct i2c_driver lp3944_driver = {
 431         .driver   = {
 432                    .name = "lp3944",
 433         },
 434         .probe    = lp3944_probe,
 435         .remove   = lp3944_remove,
 436         .id_table = lp3944_id,
 437 };
 438
 439 module_i2c_driver(lp3944_driver);
 440
 441 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
 442 MODULE_DESCRIPTION("LP3944 Fun Light Chip");
 443 MODULE_LICENSE("GPL");