linux/drivers/leds/leds-lp3944.c
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   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 */
  68struct 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
  77struct lp3944_data {
  78        struct mutex lock;
  79        struct i2c_client *client;
  80        struct lp3944_led_data leds[LP3944_LEDS_MAX];
  81};
  82
  83static 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
  96static 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 */
 108static 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 */
 139static 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 */
 173static 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
 227static 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
 284static 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
 296static 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
 304static 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 = led->status;
 339
 340                        /* Set the default led status */
 341                        err = lp3944_led_set(led, led->status);
 342                        if (err < 0) {
 343                                dev_err(&client->dev,
 344                                        "%s couldn't set STATUS %d\n",
 345                                        led->ldev.name, led->status);
 346                                goto exit;
 347                        }
 348                        break;
 349
 350                case LP3944_LED_TYPE_NONE:
 351                default:
 352                        break;
 353
 354                }
 355        }
 356        return 0;
 357
 358exit:
 359        if (i > 0)
 360                for (i = i - 1; i >= 0; i--)
 361                        switch (pdata->leds[i].type) {
 362
 363                        case LP3944_LED_TYPE_LED:
 364                        case LP3944_LED_TYPE_LED_INVERTED:
 365                                led_classdev_unregister(&data->leds[i].ldev);
 366                                cancel_work_sync(&data->leds[i].work);
 367                                break;
 368
 369                        case LP3944_LED_TYPE_NONE:
 370                        default:
 371                                break;
 372                        }
 373
 374        return err;
 375}
 376
 377static int lp3944_probe(struct i2c_client *client,
 378                                  const struct i2c_device_id *id)
 379{
 380        struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data;
 381        struct lp3944_data *data;
 382        int err;
 383
 384        if (lp3944_pdata == NULL) {
 385                dev_err(&client->dev, "no platform data\n");
 386                return -EINVAL;
 387        }
 388
 389        /* Let's see whether this adapter can support what we need. */
 390        if (!i2c_check_functionality(client->adapter,
 391                                I2C_FUNC_SMBUS_BYTE_DATA)) {
 392                dev_err(&client->dev, "insufficient functionality!\n");
 393                return -ENODEV;
 394        }
 395
 396        data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
 397                        GFP_KERNEL);
 398        if (!data)
 399                return -ENOMEM;
 400
 401        data->client = client;
 402        i2c_set_clientdata(client, data);
 403
 404        mutex_init(&data->lock);
 405
 406        err = lp3944_configure(client, data, lp3944_pdata);
 407        if (err < 0)
 408                return err;
 409
 410        dev_info(&client->dev, "lp3944 enabled\n");
 411        return 0;
 412}
 413
 414static int lp3944_remove(struct i2c_client *client)
 415{
 416        struct lp3944_platform_data *pdata = client->dev.platform_data;
 417        struct lp3944_data *data = i2c_get_clientdata(client);
 418        int i;
 419
 420        for (i = 0; i < pdata->leds_size; i++)
 421                switch (data->leds[i].type) {
 422                case LP3944_LED_TYPE_LED:
 423                case LP3944_LED_TYPE_LED_INVERTED:
 424                        led_classdev_unregister(&data->leds[i].ldev);
 425                        cancel_work_sync(&data->leds[i].work);
 426                        break;
 427
 428                case LP3944_LED_TYPE_NONE:
 429                default:
 430                        break;
 431                }
 432
 433        return 0;
 434}
 435
 436/* lp3944 i2c driver struct */
 437static const struct i2c_device_id lp3944_id[] = {
 438        {"lp3944", 0},
 439        {}
 440};
 441
 442MODULE_DEVICE_TABLE(i2c, lp3944_id);
 443
 444static struct i2c_driver lp3944_driver = {
 445        .driver   = {
 446                   .name = "lp3944",
 447        },
 448        .probe    = lp3944_probe,
 449        .remove   = lp3944_remove,
 450        .id_table = lp3944_id,
 451};
 452
 453module_i2c_driver(lp3944_driver);
 454
 455MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
 456MODULE_DESCRIPTION("LP3944 Fun Light Chip");
 457MODULE_LICENSE("GPL");
 458
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