drivers/iio/adc/sc27xx_adc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2018 Spreadtrum Communications Inc.
   3
   4 #include <linux/hwspinlock.h>
   5 #include <linux/iio/iio.h>
   6 #include <linux/module.h>
   7 #include <linux/nvmem-consumer.h>
   8 #include <linux/of.h>
   9 #include <linux/of_device.h>
  10 #include <linux/platform_device.h>
  11 #include <linux/regmap.h>
  12 #include <linux/slab.h>
  13
  14 /* PMIC global registers definition */
  15 #define SC27XX_MODULE_EN                0xc08
  16 #define SC27XX_MODULE_ADC_EN            BIT(5)
  17 #define SC27XX_ARM_CLK_EN               0xc10
  18 #define SC27XX_CLK_ADC_EN               BIT(5)
  19 #define SC27XX_CLK_ADC_CLK_EN           BIT(6)
  20
  21 /* ADC controller registers definition */
  22 #define SC27XX_ADC_CTL                  0x0
  23 #define SC27XX_ADC_CH_CFG               0x4
  24 #define SC27XX_ADC_DATA                 0x4c
  25 #define SC27XX_ADC_INT_EN               0x50
  26 #define SC27XX_ADC_INT_CLR              0x54
  27 #define SC27XX_ADC_INT_STS              0x58
  28 #define SC27XX_ADC_INT_RAW              0x5c
  29
  30 /* Bits and mask definition for SC27XX_ADC_CTL register */
  31 #define SC27XX_ADC_EN                   BIT(0)
  32 #define SC27XX_ADC_CHN_RUN              BIT(1)
  33 #define SC27XX_ADC_12BIT_MODE           BIT(2)
  34 #define SC27XX_ADC_RUN_NUM_MASK         GENMASK(7, 4)
  35 #define SC27XX_ADC_RUN_NUM_SHIFT        4
  36
  37 /* Bits and mask definition for SC27XX_ADC_CH_CFG register */
  38 #define SC27XX_ADC_CHN_ID_MASK          GENMASK(4, 0)
  39 #define SC27XX_ADC_SCALE_MASK           GENMASK(10, 8)
  40 #define SC27XX_ADC_SCALE_SHIFT          8
  41
  42 /* Bits definitions for SC27XX_ADC_INT_EN registers */
  43 #define SC27XX_ADC_IRQ_EN               BIT(0)
  44
  45 /* Bits definitions for SC27XX_ADC_INT_CLR registers */
  46 #define SC27XX_ADC_IRQ_CLR              BIT(0)
  47
  48 /* Bits definitions for SC27XX_ADC_INT_RAW registers */
  49 #define SC27XX_ADC_IRQ_RAW              BIT(0)
  50
  51 /* Mask definition for SC27XX_ADC_DATA register */
  52 #define SC27XX_ADC_DATA_MASK            GENMASK(11, 0)
  53
  54 /* Timeout (ms) for the trylock of hardware spinlocks */
  55 #define SC27XX_ADC_HWLOCK_TIMEOUT       5000
  56
  57 /* Timeout (us) for ADC data conversion according to ADC datasheet */
  58 #define SC27XX_ADC_RDY_TIMEOUT          1000000
  59 #define SC27XX_ADC_POLL_RAW_STATUS      500
  60
  61 /* Maximum ADC channel number */
  62 #define SC27XX_ADC_CHANNEL_MAX          32
  63
  64 /* ADC voltage ratio definition */
  65 #define SC27XX_VOLT_RATIO(n, d)         \
  66         (((n) << SC27XX_RATIO_NUMERATOR_OFFSET) | (d))
  67 #define SC27XX_RATIO_NUMERATOR_OFFSET   16
  68 #define SC27XX_RATIO_DENOMINATOR_MASK   GENMASK(15, 0)
  69
  70 struct sc27xx_adc_data {
  71         struct device *dev;
  72         struct regmap *regmap;
  73         /*
  74          * One hardware spinlock to synchronize between the multiple
  75          * subsystems which will access the unique ADC controller.
  76          */
  77         struct hwspinlock *hwlock;
  78         int channel_scale[SC27XX_ADC_CHANNEL_MAX];
  79         u32 base;
  80         int irq;
  81 };
  82
  83 struct sc27xx_adc_linear_graph {
  84         int volt0;
  85         int adc0;
  86         int volt1;
  87         int adc1;
  88 };
  89
  90 /*
  91  * According to the datasheet, we can convert one ADC value to one voltage value
  92  * through 2 points in the linear graph. If the voltage is less than 1.2v, we
  93  * should use the small-scale graph, and if more than 1.2v, we should use the
  94  * big-scale graph.
  95  */
  96 static struct sc27xx_adc_linear_graph big_scale_graph = {
  97         4200, 3310,
  98         3600, 2832,
  99 };
 100
 101 static struct sc27xx_adc_linear_graph small_scale_graph = {
 102         1000, 3413,
 103         100, 341,
 104 };
 105
 106 static const struct sc27xx_adc_linear_graph big_scale_graph_calib = {
 107         4200, 856,
 108         3600, 733,
 109 };
 110
 111 static const struct sc27xx_adc_linear_graph small_scale_graph_calib = {
 112         1000, 833,
 113         100, 80,
 114 };
 115
 116 static int sc27xx_adc_get_calib_data(u32 calib_data, int calib_adc)
 117 {
 118         return ((calib_data & 0xff) + calib_adc - 128) * 4;
 119 }
 120
 121 static int sc27xx_adc_scale_calibration(struct sc27xx_adc_data *data,
 122                                         bool big_scale)
 123 {
 124         const struct sc27xx_adc_linear_graph *calib_graph;
 125         struct sc27xx_adc_linear_graph *graph;
 126         struct nvmem_cell *cell;
 127         const char *cell_name;
 128         u32 calib_data = 0;
 129         void *buf;
 130         size_t len;
 131
 132         if (big_scale) {
 133                 calib_graph = &big_scale_graph_calib;
 134                 graph = &big_scale_graph;
 135                 cell_name = "big_scale_calib";
 136         } else {
 137                 calib_graph = &small_scale_graph_calib;
 138                 graph = &small_scale_graph;
 139                 cell_name = "small_scale_calib";
 140         }
 141
 142         cell = nvmem_cell_get(data->dev, cell_name);
 143         if (IS_ERR(cell))
 144                 return PTR_ERR(cell);
 145
 146         buf = nvmem_cell_read(cell, &len);
 147         nvmem_cell_put(cell);
 148
 149         if (IS_ERR(buf))
 150                 return PTR_ERR(buf);
 151
 152         memcpy(&calib_data, buf, min(len, sizeof(u32)));
 153
 154         /* Only need to calibrate the adc values in the linear graph. */
 155         graph->adc0 = sc27xx_adc_get_calib_data(calib_data, calib_graph->adc0);
 156         graph->adc1 = sc27xx_adc_get_calib_data(calib_data >> 8,
 157                                                 calib_graph->adc1);
 158
 159         kfree(buf);
 160         return 0;
 161 }
 162
 163 static int sc27xx_adc_get_ratio(int channel, int scale)
 164 {
 165         switch (channel) {
 166         case 1:
 167         case 2:
 168         case 3:
 169         case 4:
 170                 return scale ? SC27XX_VOLT_RATIO(400, 1025) :
 171                         SC27XX_VOLT_RATIO(1, 1);
 172         case 5:
 173                 return SC27XX_VOLT_RATIO(7, 29);
 174         case 6:
 175                 return SC27XX_VOLT_RATIO(375, 9000);
 176         case 7:
 177         case 8:
 178                 return scale ? SC27XX_VOLT_RATIO(100, 125) :
 179                         SC27XX_VOLT_RATIO(1, 1);
 180         case 19:
 181                 return SC27XX_VOLT_RATIO(1, 3);
 182         default:
 183                 return SC27XX_VOLT_RATIO(1, 1);
 184         }
 185         return SC27XX_VOLT_RATIO(1, 1);
 186 }
 187
 188 static int sc27xx_adc_read(struct sc27xx_adc_data *data, int channel,
 189                            int scale, int *val)
 190 {
 191         int ret;
 192         u32 tmp, value, status;
 193
 194         ret = hwspin_lock_timeout_raw(data->hwlock, SC27XX_ADC_HWLOCK_TIMEOUT);
 195         if (ret) {
 196                 dev_err(data->dev, "timeout to get the hwspinlock\n");
 197                 return ret;
 198         }
 199
 200         ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
 201                                  SC27XX_ADC_EN, SC27XX_ADC_EN);
 202         if (ret)
 203                 goto unlock_adc;
 204
 205         ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_INT_CLR,
 206                                  SC27XX_ADC_IRQ_CLR, SC27XX_ADC_IRQ_CLR);
 207         if (ret)
 208                 goto disable_adc;
 209
 210         /* Configure the channel id and scale */
 211         tmp = (scale << SC27XX_ADC_SCALE_SHIFT) & SC27XX_ADC_SCALE_MASK;
 212         tmp |= channel & SC27XX_ADC_CHN_ID_MASK;
 213         ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CH_CFG,
 214                                  SC27XX_ADC_CHN_ID_MASK | SC27XX_ADC_SCALE_MASK,
 215                                  tmp);
 216         if (ret)
 217                 goto disable_adc;
 218
 219         /* Select 12bit conversion mode, and only sample 1 time */
 220         tmp = SC27XX_ADC_12BIT_MODE;
 221         tmp |= (0 << SC27XX_ADC_RUN_NUM_SHIFT) & SC27XX_ADC_RUN_NUM_MASK;
 222         ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
 223                                  SC27XX_ADC_RUN_NUM_MASK | SC27XX_ADC_12BIT_MODE,
 224                                  tmp);
 225         if (ret)
 226                 goto disable_adc;
 227
 228         ret = regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
 229                                  SC27XX_ADC_CHN_RUN, SC27XX_ADC_CHN_RUN);
 230         if (ret)
 231                 goto disable_adc;
 232
 233         ret = regmap_read_poll_timeout(data->regmap,
 234                                        data->base + SC27XX_ADC_INT_RAW,
 235                                        status, (status & SC27XX_ADC_IRQ_RAW),
 236                                        SC27XX_ADC_POLL_RAW_STATUS,
 237                                        SC27XX_ADC_RDY_TIMEOUT);
 238         if (ret) {
 239                 dev_err(data->dev, "read adc timeout, status = 0x%x\n", status);
 240                 goto disable_adc;
 241         }
 242
 243         ret = regmap_read(data->regmap, data->base + SC27XX_ADC_DATA, &value);
 244         if (ret)
 245                 goto disable_adc;
 246
 247         value &= SC27XX_ADC_DATA_MASK;
 248
 249 disable_adc:
 250         regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,
 251                            SC27XX_ADC_EN, 0);
 252 unlock_adc:
 253         hwspin_unlock_raw(data->hwlock);
 254
 255         if (!ret)
 256                 *val = value;
 257
 258         return ret;
 259 }
 260
 261 static void sc27xx_adc_volt_ratio(struct sc27xx_adc_data *data,
 262                                   int channel, int scale,
 263                                   u32 *div_numerator, u32 *div_denominator)
 264 {
 265         u32 ratio = sc27xx_adc_get_ratio(channel, scale);
 266
 267         *div_numerator = ratio >> SC27XX_RATIO_NUMERATOR_OFFSET;
 268         *div_denominator = ratio & SC27XX_RATIO_DENOMINATOR_MASK;
 269 }
 270
 271 static int sc27xx_adc_to_volt(struct sc27xx_adc_linear_graph *graph,
 272                               int raw_adc)
 273 {
 274         int tmp;
 275
 276         tmp = (graph->volt0 - graph->volt1) * (raw_adc - graph->adc1);
 277         tmp /= (graph->adc0 - graph->adc1);
 278         tmp += graph->volt1;
 279
 280         return tmp < 0 ? 0 : tmp;
 281 }
 282
 283 static int sc27xx_adc_convert_volt(struct sc27xx_adc_data *data, int channel,
 284                                    int scale, int raw_adc)
 285 {
 286         u32 numerator, denominator;
 287         u32 volt;
 288
 289         /*
 290          * Convert ADC values to voltage values according to the linear graph,
 291          * and channel 5 and channel 1 has been calibrated, so we can just
 292          * return the voltage values calculated by the linear graph. But other
 293          * channels need be calculated to the real voltage values with the
 294          * voltage ratio.
 295          */
 296         switch (channel) {
 297         case 5:
 298                 return sc27xx_adc_to_volt(&big_scale_graph, raw_adc);
 299
 300         case 1:
 301                 return sc27xx_adc_to_volt(&small_scale_graph, raw_adc);
 302
 303         default:
 304                 volt = sc27xx_adc_to_volt(&small_scale_graph, raw_adc);
 305                 break;
 306         }
 307
 308         sc27xx_adc_volt_ratio(data, channel, scale, &numerator, &denominator);
 309
 310         return (volt * denominator + numerator / 2) / numerator;
 311 }
 312
 313 static int sc27xx_adc_read_processed(struct sc27xx_adc_data *data,
 314                                      int channel, int scale, int *val)
 315 {
 316         int ret, raw_adc;
 317
 318         ret = sc27xx_adc_read(data, channel, scale, &raw_adc);
 319         if (ret)
 320                 return ret;
 321
 322         *val = sc27xx_adc_convert_volt(data, channel, scale, raw_adc);
 323         return 0;
 324 }
 325
 326 static int sc27xx_adc_read_raw(struct iio_dev *indio_dev,
 327                                struct iio_chan_spec const *chan,
 328                                int *val, int *val2, long mask)
 329 {
 330         struct sc27xx_adc_data *data = iio_priv(indio_dev);
 331         int scale = data->channel_scale[chan->channel];
 332         int ret, tmp;
 333
 334         switch (mask) {
 335         case IIO_CHAN_INFO_RAW:
 336                 mutex_lock(&indio_dev->mlock);
 337                 ret = sc27xx_adc_read(data, chan->channel, scale, &tmp);
 338                 mutex_unlock(&indio_dev->mlock);
 339
 340                 if (ret)
 341                         return ret;
 342
 343                 *val = tmp;
 344                 return IIO_VAL_INT;
 345
 346         case IIO_CHAN_INFO_PROCESSED:
 347                 mutex_lock(&indio_dev->mlock);
 348                 ret = sc27xx_adc_read_processed(data, chan->channel, scale,
 349                                                 &tmp);
 350                 mutex_unlock(&indio_dev->mlock);
 351
 352                 if (ret)
 353                         return ret;
 354
 355                 *val = tmp;
 356                 return IIO_VAL_INT;
 357
 358         case IIO_CHAN_INFO_SCALE:
 359                 *val = scale;
 360                 return IIO_VAL_INT;
 361
 362         default:
 363                 return -EINVAL;
 364         }
 365 }
 366
 367 static int sc27xx_adc_write_raw(struct iio_dev *indio_dev,
 368                                 struct iio_chan_spec const *chan,
 369                                 int val, int val2, long mask)
 370 {
 371         struct sc27xx_adc_data *data = iio_priv(indio_dev);
 372
 373         switch (mask) {
 374         case IIO_CHAN_INFO_SCALE:
 375                 data->channel_scale[chan->channel] = val;
 376                 return IIO_VAL_INT;
 377
 378         default:
 379                 return -EINVAL;
 380         }
 381 }
 382
 383 static const struct iio_info sc27xx_info = {
 384         .read_raw = &sc27xx_adc_read_raw,
 385         .write_raw = &sc27xx_adc_write_raw,
 386 };
 387
 388 #define SC27XX_ADC_CHANNEL(index, mask) {                       \
 389         .type = IIO_VOLTAGE,                                    \
 390         .channel = index,                                       \
 391         .info_mask_separate = mask | BIT(IIO_CHAN_INFO_SCALE),  \
 392         .datasheet_name = "CH##index",                          \
 393         .indexed = 1,                                           \
 394 }
 395
 396 static const struct iio_chan_spec sc27xx_channels[] = {
 397         SC27XX_ADC_CHANNEL(0, BIT(IIO_CHAN_INFO_PROCESSED)),
 398         SC27XX_ADC_CHANNEL(1, BIT(IIO_CHAN_INFO_PROCESSED)),
 399         SC27XX_ADC_CHANNEL(2, BIT(IIO_CHAN_INFO_PROCESSED)),
 400         SC27XX_ADC_CHANNEL(3, BIT(IIO_CHAN_INFO_PROCESSED)),
 401         SC27XX_ADC_CHANNEL(4, BIT(IIO_CHAN_INFO_PROCESSED)),
 402         SC27XX_ADC_CHANNEL(5, BIT(IIO_CHAN_INFO_PROCESSED)),
 403         SC27XX_ADC_CHANNEL(6, BIT(IIO_CHAN_INFO_PROCESSED)),
 404         SC27XX_ADC_CHANNEL(7, BIT(IIO_CHAN_INFO_PROCESSED)),
 405         SC27XX_ADC_CHANNEL(8, BIT(IIO_CHAN_INFO_PROCESSED)),
 406         SC27XX_ADC_CHANNEL(9, BIT(IIO_CHAN_INFO_PROCESSED)),
 407         SC27XX_ADC_CHANNEL(10, BIT(IIO_CHAN_INFO_PROCESSED)),
 408         SC27XX_ADC_CHANNEL(11, BIT(IIO_CHAN_INFO_PROCESSED)),
 409         SC27XX_ADC_CHANNEL(12, BIT(IIO_CHAN_INFO_PROCESSED)),
 410         SC27XX_ADC_CHANNEL(13, BIT(IIO_CHAN_INFO_PROCESSED)),
 411         SC27XX_ADC_CHANNEL(14, BIT(IIO_CHAN_INFO_PROCESSED)),
 412         SC27XX_ADC_CHANNEL(15, BIT(IIO_CHAN_INFO_PROCESSED)),
 413         SC27XX_ADC_CHANNEL(16, BIT(IIO_CHAN_INFO_PROCESSED)),
 414         SC27XX_ADC_CHANNEL(17, BIT(IIO_CHAN_INFO_PROCESSED)),
 415         SC27XX_ADC_CHANNEL(18, BIT(IIO_CHAN_INFO_PROCESSED)),
 416         SC27XX_ADC_CHANNEL(19, BIT(IIO_CHAN_INFO_PROCESSED)),
 417         SC27XX_ADC_CHANNEL(20, BIT(IIO_CHAN_INFO_RAW)),
 418         SC27XX_ADC_CHANNEL(21, BIT(IIO_CHAN_INFO_PROCESSED)),
 419         SC27XX_ADC_CHANNEL(22, BIT(IIO_CHAN_INFO_PROCESSED)),
 420         SC27XX_ADC_CHANNEL(23, BIT(IIO_CHAN_INFO_PROCESSED)),
 421         SC27XX_ADC_CHANNEL(24, BIT(IIO_CHAN_INFO_PROCESSED)),
 422         SC27XX_ADC_CHANNEL(25, BIT(IIO_CHAN_INFO_PROCESSED)),
 423         SC27XX_ADC_CHANNEL(26, BIT(IIO_CHAN_INFO_PROCESSED)),
 424         SC27XX_ADC_CHANNEL(27, BIT(IIO_CHAN_INFO_PROCESSED)),
 425         SC27XX_ADC_CHANNEL(28, BIT(IIO_CHAN_INFO_PROCESSED)),
 426         SC27XX_ADC_CHANNEL(29, BIT(IIO_CHAN_INFO_PROCESSED)),
 427         SC27XX_ADC_CHANNEL(30, BIT(IIO_CHAN_INFO_PROCESSED)),
 428         SC27XX_ADC_CHANNEL(31, BIT(IIO_CHAN_INFO_PROCESSED)),
 429 };
 430
 431 static int sc27xx_adc_enable(struct sc27xx_adc_data *data)
 432 {
 433         int ret;
 434
 435         ret = regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
 436                                  SC27XX_MODULE_ADC_EN, SC27XX_MODULE_ADC_EN);
 437         if (ret)
 438                 return ret;
 439
 440         /* Enable ADC work clock and controller clock */
 441         ret = regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
 442                                  SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN,
 443                                  SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN);
 444         if (ret)
 445                 goto disable_adc;
 446
 447         /* ADC channel scales' calibration from nvmem device */
 448         ret = sc27xx_adc_scale_calibration(data, true);
 449         if (ret)
 450                 goto disable_clk;
 451
 452         ret = sc27xx_adc_scale_calibration(data, false);
 453         if (ret)
 454                 goto disable_clk;
 455
 456         return 0;
 457
 458 disable_clk:
 459         regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
 460                            SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN, 0);
 461 disable_adc:
 462         regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
 463                            SC27XX_MODULE_ADC_EN, 0);
 464
 465         return ret;
 466 }
 467
 468 static void sc27xx_adc_disable(void *_data)
 469 {
 470         struct sc27xx_adc_data *data = _data;
 471
 472         /* Disable ADC work clock and controller clock */
 473         regmap_update_bits(data->regmap, SC27XX_ARM_CLK_EN,
 474                            SC27XX_CLK_ADC_EN | SC27XX_CLK_ADC_CLK_EN, 0);
 475
 476         regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
 477                            SC27XX_MODULE_ADC_EN, 0);
 478 }
 479
 480 static int sc27xx_adc_probe(struct platform_device *pdev)
 481 {
 482         struct device *dev = &pdev->dev;
 483         struct device_node *np = dev->of_node;
 484         struct sc27xx_adc_data *sc27xx_data;
 485         struct iio_dev *indio_dev;
 486         int ret;
 487
 488         indio_dev = devm_iio_device_alloc(dev, sizeof(*sc27xx_data));
 489         if (!indio_dev)
 490                 return -ENOMEM;
 491
 492         sc27xx_data = iio_priv(indio_dev);
 493
 494         sc27xx_data->regmap = dev_get_regmap(dev->parent, NULL);
 495         if (!sc27xx_data->regmap) {
 496                 dev_err(dev, "failed to get ADC regmap\n");
 497                 return -ENODEV;
 498         }
 499
 500         ret = of_property_read_u32(np, "reg", &sc27xx_data->base);
 501         if (ret) {
 502                 dev_err(dev, "failed to get ADC base address\n");
 503                 return ret;
 504         }
 505
 506         sc27xx_data->irq = platform_get_irq(pdev, 0);
 507         if (sc27xx_data->irq < 0)
 508                 return sc27xx_data->irq;
 509
 510         ret = of_hwspin_lock_get_id(np, 0);
 511         if (ret < 0) {
 512                 dev_err(dev, "failed to get hwspinlock id\n");
 513                 return ret;
 514         }
 515
 516         sc27xx_data->hwlock = devm_hwspin_lock_request_specific(dev, ret);
 517         if (!sc27xx_data->hwlock) {
 518                 dev_err(dev, "failed to request hwspinlock\n");
 519                 return -ENXIO;
 520         }
 521
 522         sc27xx_data->dev = dev;
 523
 524         ret = sc27xx_adc_enable(sc27xx_data);
 525         if (ret) {
 526                 dev_err(dev, "failed to enable ADC module\n");
 527                 return ret;
 528         }
 529
 530         ret = devm_add_action_or_reset(dev, sc27xx_adc_disable, sc27xx_data);
 531         if (ret) {
 532                 dev_err(dev, "failed to add ADC disable action\n");
 533                 return ret;
 534         }
 535
 536         indio_dev->name = dev_name(dev);
 537         indio_dev->modes = INDIO_DIRECT_MODE;
 538         indio_dev->info = &sc27xx_info;
 539         indio_dev->channels = sc27xx_channels;
 540         indio_dev->num_channels = ARRAY_SIZE(sc27xx_channels);
 541         ret = devm_iio_device_register(dev, indio_dev);
 542         if (ret)
 543                 dev_err(dev, "could not register iio (ADC)");
 544
 545         return ret;
 546 }
 547
 548 static const struct of_device_id sc27xx_adc_of_match[] = {
 549         { .compatible = "sprd,sc2731-adc", },
 550         { }
 551 };
 552
 553 static struct platform_driver sc27xx_adc_driver = {
 554         .probe = sc27xx_adc_probe,
 555         .driver = {
 556                 .name = "sc27xx-adc",
 557                 .of_match_table = sc27xx_adc_of_match,
 558         },
 559 };
 560
 561 module_platform_driver(sc27xx_adc_driver);
 562
 563 MODULE_AUTHOR("Freeman Liu <freeman.liu@spreadtrum.com>");
 564 MODULE_DESCRIPTION("Spreadtrum SC27XX ADC Driver");
 565 MODULE_LICENSE("GPL v2");