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         /*
 203          * Invert status only when it's < 2 (i.e. 0 or 1) which means it's
 204          * controlling the on/off state directly.
 205          * When, instead, status is >= 2 don't invert it because it would mean
 206          * to mess with the hardware blinking mode.
 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         lp3944_led_set(led, LP3944_LED_STATUS_DIM0);
 279
 280         return 0;
 281 }
 282
 283 static int 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         return lp3944_led_set(led, !!brightness);
 292 }
 293
 294 static int lp3944_configure(struct i2c_client *client,
 295                             struct lp3944_data *data,
 296                             struct lp3944_platform_data *pdata)
 297 {
 298         int i, err = 0;
 299
 300         for (i = 0; i < pdata->leds_size; i++) {
 301                 struct lp3944_led *pled = &pdata->leds[i];
 302                 struct lp3944_led_data *led = &data->leds[i];
 303                 led->client = client;
 304                 led->id = i;
 305
 306                 switch (pled->type) {
 307
 308                 case LP3944_LED_TYPE_LED:
 309                 case LP3944_LED_TYPE_LED_INVERTED:
 310                         led->type = pled->type;
 311                         led->ldev.name = pled->name;
 312                         led->ldev.max_brightness = 1;
 313                         led->ldev.brightness_set_blocking =
 314                                                 lp3944_led_set_brightness;
 315                         led->ldev.blink_set = lp3944_led_set_blink;
 316                         led->ldev.flags = LED_CORE_SUSPENDRESUME;
 317
 318                         err = led_classdev_register(&client->dev, &led->ldev);
 319                         if (err < 0) {
 320                                 dev_err(&client->dev,
 321                                         "couldn't register LED %s\n",
 322                                         led->ldev.name);
 323                                 goto exit;
 324                         }
 325
 326                         /* to expose the default value to userspace */
 327                         led->ldev.brightness =
 328                                         (enum led_brightness) pled->status;
 329
 330                         /* Set the default led status */
 331                         err = lp3944_led_set(led, pled->status);
 332                         if (err < 0) {
 333                                 dev_err(&client->dev,
 334                                         "%s couldn't set STATUS %d\n",
 335                                         led->ldev.name, pled->status);
 336                                 goto exit;
 337                         }
 338                         break;
 339
 340                 case LP3944_LED_TYPE_NONE:
 341                 default:
 342                         break;
 343
 344                 }
 345         }
 346         return 0;
 347
 348 exit:
 349         if (i > 0)
 350                 for (i = i - 1; i >= 0; i--)
 351                         switch (pdata->leds[i].type) {
 352
 353                         case LP3944_LED_TYPE_LED:
 354                         case LP3944_LED_TYPE_LED_INVERTED:
 355                                 led_classdev_unregister(&data->leds[i].ldev);
 356                                 break;
 357
 358                         case LP3944_LED_TYPE_NONE:
 359                         default:
 360                                 break;
 361                         }
 362
 363         return err;
 364 }
 365
 366 static int lp3944_probe(struct i2c_client *client,
 367                                   const struct i2c_device_id *id)
 368 {
 369         struct lp3944_platform_data *lp3944_pdata =
 370                         dev_get_platdata(&client->dev);
 371         struct lp3944_data *data;
 372         int err;
 373
 374         if (lp3944_pdata == NULL) {
 375                 dev_err(&client->dev, "no platform data\n");
 376                 return -EINVAL;
 377         }
 378
 379         /* Let's see whether this adapter can support what we need. */
 380         if (!i2c_check_functionality(client->adapter,
 381                                 I2C_FUNC_SMBUS_BYTE_DATA)) {
 382                 dev_err(&client->dev, "insufficient functionality!\n");
 383                 return -ENODEV;
 384         }
 385
 386         data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
 387                         GFP_KERNEL);
 388         if (!data)
 389                 return -ENOMEM;
 390
 391         data->client = client;
 392         i2c_set_clientdata(client, data);
 393
 394         mutex_init(&data->lock);
 395
 396         err = lp3944_configure(client, data, lp3944_pdata);
 397         if (err < 0)
 398                 return err;
 399
 400         dev_info(&client->dev, "lp3944 enabled\n");
 401         return 0;
 402 }
 403
 404 static int lp3944_remove(struct i2c_client *client)
 405 {
 406         struct lp3944_platform_data *pdata = dev_get_platdata(&client->dev);
 407         struct lp3944_data *data = i2c_get_clientdata(client);
 408         int i;
 409
 410         for (i = 0; i < pdata->leds_size; i++)
 411                 switch (data->leds[i].type) {
 412                 case LP3944_LED_TYPE_LED:
 413                 case LP3944_LED_TYPE_LED_INVERTED:
 414                         led_classdev_unregister(&data->leds[i].ldev);
 415                         break;
 416
 417                 case LP3944_LED_TYPE_NONE:
 418                 default:
 419                         break;
 420                 }
 421
 422         return 0;
 423 }
 424
 425 /* lp3944 i2c driver struct */
 426 static const struct i2c_device_id lp3944_id[] = {
 427         {"lp3944", 0},
 428         {}
 429 };
 430
 431 MODULE_DEVICE_TABLE(i2c, lp3944_id);
 432
 433 static struct i2c_driver lp3944_driver = {
 434         .driver   = {
 435                    .name = "lp3944",
 436         },
 437         .probe    = lp3944_probe,
 438         .remove   = lp3944_remove,
 439         .id_table = lp3944_id,
 440 };
 441
 442 module_i2c_driver(lp3944_driver);
 443
 444 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
 445 MODULE_DESCRIPTION("LP3944 Fun Light Chip");
 446 MODULE_LICENSE("GPL");