drivers/iio/adc/at91_adc.c

   1 /*
   2  * Driver for the ADC present in the Atmel AT91 evaluation boards.
   3  *
   4  * Copyright 2011 Free Electrons
   5  *
   6  * Licensed under the GPLv2 or later.
   7  */
   8
   9 #include <linux/bitmap.h>
  10 #include <linux/bitops.h>
  11 #include <linux/clk.h>
  12 #include <linux/err.h>
  13 #include <linux/io.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/jiffies.h>
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/of_device.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/sched.h>
  22 #include <linux/slab.h>
  23 #include <linux/wait.h>
  24
  25 #include <linux/platform_data/at91_adc.h>
  26
  27 #include <linux/iio/iio.h>
  28 #include <linux/iio/buffer.h>
  29 #include <linux/iio/trigger.h>
  30 #include <linux/iio/trigger_consumer.h>
  31 #include <linux/iio/triggered_buffer.h>
  32
  33 #include <mach/at91_adc.h>
  34
  35 #define AT91_ADC_CHAN(st, ch) \
  36         (st->registers->channel_base + (ch * 4))
  37 #define at91_adc_readl(st, reg) \
  38         (readl_relaxed(st->reg_base + reg))
  39 #define at91_adc_writel(st, reg, val) \
  40         (writel_relaxed(val, st->reg_base + reg))
  41
  42 struct at91_adc_state {
  43         struct clk              *adc_clk;
  44         u16                     *buffer;
  45         unsigned long           channels_mask;
  46         struct clk              *clk;
  47         bool                    done;
  48         int                     irq;
  49         u16                     last_value;
  50         struct mutex            lock;
  51         u8                      num_channels;
  52         void __iomem            *reg_base;
  53         struct at91_adc_reg_desc *registers;
  54         u8                      startup_time;
  55         u8                      sample_hold_time;
  56         bool                    sleep_mode;
  57         struct iio_trigger      **trig;
  58         struct at91_adc_trigger *trigger_list;
  59         u32                     trigger_number;
  60         bool                    use_external;
  61         u32                     vref_mv;
  62         u32                     res;            /* resolution used for convertions */
  63         bool                    low_res;        /* the resolution corresponds to the lowest one */
  64         wait_queue_head_t       wq_data_avail;
  65 };
  66
  67 static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
  68 {
  69         struct iio_poll_func *pf = p;
  70         struct iio_dev *idev = pf->indio_dev;
  71         struct at91_adc_state *st = iio_priv(idev);
  72         int i, j = 0;
  73
  74         for (i = 0; i < idev->masklength; i++) {
  75                 if (!test_bit(i, idev->active_scan_mask))
  76                         continue;
  77                 st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, i));
  78                 j++;
  79         }
  80
  81         if (idev->scan_timestamp) {
  82                 s64 *timestamp = (s64 *)((u8 *)st->buffer +
  83                                         ALIGN(j, sizeof(s64)));
  84                 *timestamp = pf->timestamp;
  85         }
  86
  87         iio_push_to_buffers(idev, (u8 *)st->buffer);
  88
  89         iio_trigger_notify_done(idev->trig);
  90
  91         /* Needed to ACK the DRDY interruption */
  92         at91_adc_readl(st, AT91_ADC_LCDR);
  93
  94         enable_irq(st->irq);
  95
  96         return IRQ_HANDLED;
  97 }
  98
  99 static irqreturn_t at91_adc_eoc_trigger(int irq, void *private)
 100 {
 101         struct iio_dev *idev = private;
 102         struct at91_adc_state *st = iio_priv(idev);
 103         u32 status = at91_adc_readl(st, st->registers->status_register);
 104
 105         if (!(status & st->registers->drdy_mask))
 106                 return IRQ_HANDLED;
 107
 108         if (iio_buffer_enabled(idev)) {
 109                 disable_irq_nosync(irq);
 110                 iio_trigger_poll(idev->trig, iio_get_time_ns());
 111         } else {
 112                 st->last_value = at91_adc_readl(st, AT91_ADC_LCDR);
 113                 st->done = true;
 114                 wake_up_interruptible(&st->wq_data_avail);
 115         }
 116
 117         return IRQ_HANDLED;
 118 }
 119
 120 static int at91_adc_channel_init(struct iio_dev *idev)
 121 {
 122         struct at91_adc_state *st = iio_priv(idev);
 123         struct iio_chan_spec *chan_array, *timestamp;
 124         int bit, idx = 0;
 125
 126         idev->num_channels = bitmap_weight(&st->channels_mask,
 127                                            st->num_channels) + 1;
 128
 129         chan_array = devm_kzalloc(&idev->dev,
 130                                   ((idev->num_channels + 1) *
 131                                         sizeof(struct iio_chan_spec)),
 132                                   GFP_KERNEL);
 133
 134         if (!chan_array)
 135                 return -ENOMEM;
 136
 137         for_each_set_bit(bit, &st->channels_mask, st->num_channels) {
 138                 struct iio_chan_spec *chan = chan_array + idx;
 139
 140                 chan->type = IIO_VOLTAGE;
 141                 chan->indexed = 1;
 142                 chan->channel = bit;
 143                 chan->scan_index = idx;
 144                 chan->scan_type.sign = 'u';
 145                 chan->scan_type.realbits = st->res;
 146                 chan->scan_type.storagebits = 16;
 147                 chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
 148                 chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
 149                 idx++;
 150         }
 151         timestamp = chan_array + idx;
 152
 153         timestamp->type = IIO_TIMESTAMP;
 154         timestamp->channel = -1;
 155         timestamp->scan_index = idx;
 156         timestamp->scan_type.sign = 's';
 157         timestamp->scan_type.realbits = 64;
 158         timestamp->scan_type.storagebits = 64;
 159
 160         idev->channels = chan_array;
 161         return idev->num_channels;
 162 }
 163
 164 static int at91_adc_get_trigger_value_by_name(struct iio_dev *idev,
 165                                              struct at91_adc_trigger *triggers,
 166                                              const char *trigger_name)
 167 {
 168         struct at91_adc_state *st = iio_priv(idev);
 169         int i;
 170
 171         for (i = 0; i < st->trigger_number; i++) {
 172                 char *name = kasprintf(GFP_KERNEL,
 173                                 "%s-dev%d-%s",
 174                                 idev->name,
 175                                 idev->id,
 176                                 triggers[i].name);
 177                 if (!name)
 178                         return -ENOMEM;
 179
 180                 if (strcmp(trigger_name, name) == 0) {
 181                         kfree(name);
 182                         if (triggers[i].value == 0)
 183                                 return -EINVAL;
 184                         return triggers[i].value;
 185                 }
 186
 187                 kfree(name);
 188         }
 189
 190         return -EINVAL;
 191 }
 192
 193 static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 194 {
 195         struct iio_dev *idev = iio_trigger_get_drvdata(trig);
 196         struct at91_adc_state *st = iio_priv(idev);
 197         struct iio_buffer *buffer = idev->buffer;
 198         struct at91_adc_reg_desc *reg = st->registers;
 199         u32 status = at91_adc_readl(st, reg->trigger_register);
 200         int value;
 201         u8 bit;
 202
 203         value = at91_adc_get_trigger_value_by_name(idev,
 204                                                    st->trigger_list,
 205                                                    idev->trig->name);
 206         if (value < 0)
 207                 return value;
 208
 209         if (state) {
 210                 st->buffer = kmalloc(idev->scan_bytes, GFP_KERNEL);
 211                 if (st->buffer == NULL)
 212                         return -ENOMEM;
 213
 214                 at91_adc_writel(st, reg->trigger_register,
 215                                 status | value);
 216
 217                 for_each_set_bit(bit, buffer->scan_mask,
 218                                  st->num_channels) {
 219                         struct iio_chan_spec const *chan = idev->channels + bit;
 220                         at91_adc_writel(st, AT91_ADC_CHER,
 221                                         AT91_ADC_CH(chan->channel));
 222                 }
 223
 224                 at91_adc_writel(st, AT91_ADC_IER, reg->drdy_mask);
 225
 226         } else {
 227                 at91_adc_writel(st, AT91_ADC_IDR, reg->drdy_mask);
 228
 229                 at91_adc_writel(st, reg->trigger_register,
 230                                 status & ~value);
 231
 232                 for_each_set_bit(bit, buffer->scan_mask,
 233                                  st->num_channels) {
 234                         struct iio_chan_spec const *chan = idev->channels + bit;
 235                         at91_adc_writel(st, AT91_ADC_CHDR,
 236                                         AT91_ADC_CH(chan->channel));
 237                 }
 238                 kfree(st->buffer);
 239         }
 240
 241         return 0;
 242 }
 243
 244 static const struct iio_trigger_ops at91_adc_trigger_ops = {
 245         .owner = THIS_MODULE,
 246         .set_trigger_state = &at91_adc_configure_trigger,
 247 };
 248
 249 static struct iio_trigger *at91_adc_allocate_trigger(struct iio_dev *idev,
 250                                                      struct at91_adc_trigger *trigger)
 251 {
 252         struct iio_trigger *trig;
 253         int ret;
 254
 255         trig = iio_trigger_alloc("%s-dev%d-%s", idev->name,
 256                                  idev->id, trigger->name);
 257         if (trig == NULL)
 258                 return NULL;
 259
 260         trig->dev.parent = idev->dev.parent;
 261         iio_trigger_set_drvdata(trig, idev);
 262         trig->ops = &at91_adc_trigger_ops;
 263
 264         ret = iio_trigger_register(trig);
 265         if (ret)
 266                 return NULL;
 267
 268         return trig;
 269 }
 270
 271 static int at91_adc_trigger_init(struct iio_dev *idev)
 272 {
 273         struct at91_adc_state *st = iio_priv(idev);
 274         int i, ret;
 275
 276         st->trig = devm_kzalloc(&idev->dev,
 277                                 st->trigger_number * sizeof(st->trig),
 278                                 GFP_KERNEL);
 279
 280         if (st->trig == NULL) {
 281                 ret = -ENOMEM;
 282                 goto error_ret;
 283         }
 284
 285         for (i = 0; i < st->trigger_number; i++) {
 286                 if (st->trigger_list[i].is_external && !(st->use_external))
 287                         continue;
 288
 289                 st->trig[i] = at91_adc_allocate_trigger(idev,
 290                                                         st->trigger_list + i);
 291                 if (st->trig[i] == NULL) {
 292                         dev_err(&idev->dev,
 293                                 "Could not allocate trigger %d\n", i);
 294                         ret = -ENOMEM;
 295                         goto error_trigger;
 296                 }
 297         }
 298
 299         return 0;
 300
 301 error_trigger:
 302         for (i--; i >= 0; i--) {
 303                 iio_trigger_unregister(st->trig[i]);
 304                 iio_trigger_free(st->trig[i]);
 305         }
 306 error_ret:
 307         return ret;
 308 }
 309
 310 static void at91_adc_trigger_remove(struct iio_dev *idev)
 311 {
 312         struct at91_adc_state *st = iio_priv(idev);
 313         int i;
 314
 315         for (i = 0; i < st->trigger_number; i++) {
 316                 iio_trigger_unregister(st->trig[i]);
 317                 iio_trigger_free(st->trig[i]);
 318         }
 319 }
 320
 321 static int at91_adc_buffer_init(struct iio_dev *idev)
 322 {
 323         return iio_triggered_buffer_setup(idev, &iio_pollfunc_store_time,
 324                 &at91_adc_trigger_handler, NULL);
 325 }
 326
 327 static void at91_adc_buffer_remove(struct iio_dev *idev)
 328 {
 329         iio_triggered_buffer_cleanup(idev);
 330 }
 331
 332 static int at91_adc_read_raw(struct iio_dev *idev,
 333                              struct iio_chan_spec const *chan,
 334                              int *val, int *val2, long mask)
 335 {
 336         struct at91_adc_state *st = iio_priv(idev);
 337         int ret;
 338
 339         switch (mask) {
 340         case IIO_CHAN_INFO_RAW:
 341                 mutex_lock(&st->lock);
 342
 343                 at91_adc_writel(st, AT91_ADC_CHER,
 344                                 AT91_ADC_CH(chan->channel));
 345                 at91_adc_writel(st, AT91_ADC_IER, st->registers->drdy_mask);
 346                 at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_START);
 347
 348                 ret = wait_event_interruptible_timeout(st->wq_data_avail,
 349                                                        st->done,
 350                                                        msecs_to_jiffies(1000));
 351                 if (ret == 0)
 352                         ret = -ETIMEDOUT;
 353                 if (ret < 0) {
 354                         mutex_unlock(&st->lock);
 355                         return ret;
 356                 }
 357
 358                 *val = st->last_value;
 359
 360                 at91_adc_writel(st, AT91_ADC_CHDR,
 361                                 AT91_ADC_CH(chan->channel));
 362                 at91_adc_writel(st, AT91_ADC_IDR, st->registers->drdy_mask);
 363
 364                 st->last_value = 0;
 365                 st->done = false;
 366                 mutex_unlock(&st->lock);
 367                 return IIO_VAL_INT;
 368
 369         case IIO_CHAN_INFO_SCALE:
 370                 *val = (st->vref_mv * 1000) >> chan->scan_type.realbits;
 371                 *val2 = 0;
 372                 return IIO_VAL_INT_PLUS_MICRO;
 373         default:
 374                 break;
 375         }
 376         return -EINVAL;
 377 }
 378
 379 static int at91_adc_of_get_resolution(struct at91_adc_state *st,
 380                                       struct platform_device *pdev)
 381 {
 382         struct iio_dev *idev = iio_priv_to_dev(st);
 383         struct device_node *np = pdev->dev.of_node;
 384         int count, i, ret = 0;
 385         char *res_name, *s;
 386         u32 *resolutions;
 387
 388         count = of_property_count_strings(np, "atmel,adc-res-names");
 389         if (count < 2) {
 390                 dev_err(&idev->dev, "You must specified at least two resolution names for "
 391                                     "adc-res-names property in the DT\n");
 392                 return count;
 393         }
 394
 395         resolutions = kmalloc(count * sizeof(*resolutions), GFP_KERNEL);
 396         if (!resolutions)
 397                 return -ENOMEM;
 398
 399         if (of_property_read_u32_array(np, "atmel,adc-res", resolutions, count)) {
 400                 dev_err(&idev->dev, "Missing adc-res property in the DT.\n");
 401                 ret = -ENODEV;
 402                 goto ret;
 403         }
 404
 405         if (of_property_read_string(np, "atmel,adc-use-res", (const char **)&res_name))
 406                 res_name = "highres";
 407
 408         for (i = 0; i < count; i++) {
 409                 if (of_property_read_string_index(np, "atmel,adc-res-names", i, (const char **)&s))
 410                         continue;
 411
 412                 if (strcmp(res_name, s))
 413                         continue;
 414
 415                 st->res = resolutions[i];
 416                 if (!strcmp(res_name, "lowres"))
 417                         st->low_res = true;
 418                 else
 419                         st->low_res = false;
 420
 421                 dev_info(&idev->dev, "Resolution used: %u bits\n", st->res);
 422                 goto ret;
 423         }
 424
 425         dev_err(&idev->dev, "There is no resolution for %s\n", res_name);
 426
 427 ret:
 428         kfree(resolutions);
 429         return ret;
 430 }
 431
 432 static int at91_adc_probe_dt(struct at91_adc_state *st,
 433                              struct platform_device *pdev)
 434 {
 435         struct iio_dev *idev = iio_priv_to_dev(st);
 436         struct device_node *node = pdev->dev.of_node;
 437         struct device_node *trig_node;
 438         int i = 0, ret;
 439         u32 prop;
 440
 441         if (!node)
 442                 return -EINVAL;
 443
 444         st->use_external = of_property_read_bool(node, "atmel,adc-use-external-triggers");
 445
 446         if (of_property_read_u32(node, "atmel,adc-channels-used", &prop)) {
 447                 dev_err(&idev->dev, "Missing adc-channels-used property in the DT.\n");
 448                 ret = -EINVAL;
 449                 goto error_ret;
 450         }
 451         st->channels_mask = prop;
 452
 453         if (of_property_read_u32(node, "atmel,adc-num-channels", &prop)) {
 454                 dev_err(&idev->dev, "Missing adc-num-channels property in the DT.\n");
 455                 ret = -EINVAL;
 456                 goto error_ret;
 457         }
 458         st->num_channels = prop;
 459
 460         st->sleep_mode = of_property_read_bool(node, "atmel,adc-sleep-mode");
 461
 462         if (of_property_read_u32(node, "atmel,adc-startup-time", &prop)) {
 463                 dev_err(&idev->dev, "Missing adc-startup-time property in the DT.\n");
 464                 ret = -EINVAL;
 465                 goto error_ret;
 466         }
 467         st->startup_time = prop;
 468
 469         prop = 0;
 470         of_property_read_u32(node, "atmel,adc-sample-hold-time", &prop);
 471         st->sample_hold_time = prop;
 472
 473         if (of_property_read_u32(node, "atmel,adc-vref", &prop)) {
 474                 dev_err(&idev->dev, "Missing adc-vref property in the DT.\n");
 475                 ret = -EINVAL;
 476                 goto error_ret;
 477         }
 478         st->vref_mv = prop;
 479
 480         ret = at91_adc_of_get_resolution(st, pdev);
 481         if (ret)
 482                 goto error_ret;
 483
 484         st->registers = devm_kzalloc(&idev->dev,
 485                                      sizeof(struct at91_adc_reg_desc),
 486                                      GFP_KERNEL);
 487         if (!st->registers) {
 488                 dev_err(&idev->dev, "Could not allocate register memory.\n");
 489                 ret = -ENOMEM;
 490                 goto error_ret;
 491         }
 492
 493         if (of_property_read_u32(node, "atmel,adc-channel-base", &prop)) {
 494                 dev_err(&idev->dev, "Missing adc-channel-base property in the DT.\n");
 495                 ret = -EINVAL;
 496                 goto error_ret;
 497         }
 498         st->registers->channel_base = prop;
 499
 500         if (of_property_read_u32(node, "atmel,adc-drdy-mask", &prop)) {
 501                 dev_err(&idev->dev, "Missing adc-drdy-mask property in the DT.\n");
 502                 ret = -EINVAL;
 503                 goto error_ret;
 504         }
 505         st->registers->drdy_mask = prop;
 506
 507         if (of_property_read_u32(node, "atmel,adc-status-register", &prop)) {
 508                 dev_err(&idev->dev, "Missing adc-status-register property in the DT.\n");
 509                 ret = -EINVAL;
 510                 goto error_ret;
 511         }
 512         st->registers->status_register = prop;
 513
 514         if (of_property_read_u32(node, "atmel,adc-trigger-register", &prop)) {
 515                 dev_err(&idev->dev, "Missing adc-trigger-register property in the DT.\n");
 516                 ret = -EINVAL;
 517                 goto error_ret;
 518         }
 519         st->registers->trigger_register = prop;
 520
 521         st->trigger_number = of_get_child_count(node);
 522         st->trigger_list = devm_kzalloc(&idev->dev, st->trigger_number *
 523                                         sizeof(struct at91_adc_trigger),
 524                                         GFP_KERNEL);
 525         if (!st->trigger_list) {
 526                 dev_err(&idev->dev, "Could not allocate trigger list memory.\n");
 527                 ret = -ENOMEM;
 528                 goto error_ret;
 529         }
 530
 531         for_each_child_of_node(node, trig_node) {
 532                 struct at91_adc_trigger *trig = st->trigger_list + i;
 533                 const char *name;
 534
 535                 if (of_property_read_string(trig_node, "trigger-name", &name)) {
 536                         dev_err(&idev->dev, "Missing trigger-name property in the DT.\n");
 537                         ret = -EINVAL;
 538                         goto error_ret;
 539                 }
 540                 trig->name = name;
 541
 542                 if (of_property_read_u32(trig_node, "trigger-value", &prop)) {
 543                         dev_err(&idev->dev, "Missing trigger-value property in the DT.\n");
 544                         ret = -EINVAL;
 545                         goto error_ret;
 546                 }
 547                 trig->value = prop;
 548                 trig->is_external = of_property_read_bool(trig_node, "trigger-external");
 549                 i++;
 550         }
 551
 552         return 0;
 553
 554 error_ret:
 555         return ret;
 556 }
 557
 558 static int at91_adc_probe_pdata(struct at91_adc_state *st,
 559                                 struct platform_device *pdev)
 560 {
 561         struct at91_adc_data *pdata = pdev->dev.platform_data;
 562
 563         if (!pdata)
 564                 return -EINVAL;
 565
 566         st->use_external = pdata->use_external_triggers;
 567         st->vref_mv = pdata->vref;
 568         st->channels_mask = pdata->channels_used;
 569         st->num_channels = pdata->num_channels;
 570         st->startup_time = pdata->startup_time;
 571         st->trigger_number = pdata->trigger_number;
 572         st->trigger_list = pdata->trigger_list;
 573         st->registers = pdata->registers;
 574
 575         return 0;
 576 }
 577
 578 static const struct iio_info at91_adc_info = {
 579         .driver_module = THIS_MODULE,
 580         .read_raw = &at91_adc_read_raw,
 581 };
 582
 583 static int at91_adc_probe(struct platform_device *pdev)
 584 {
 585         unsigned int prsc, mstrclk, ticks, adc_clk, shtim;
 586         int ret;
 587         struct iio_dev *idev;
 588         struct at91_adc_state *st;
 589         struct resource *res;
 590         u32 reg;
 591
 592         idev = iio_device_alloc(sizeof(struct at91_adc_state));
 593         if (idev == NULL) {
 594                 ret = -ENOMEM;
 595                 goto error_ret;
 596         }
 597
 598         st = iio_priv(idev);
 599
 600         if (pdev->dev.of_node)
 601                 ret = at91_adc_probe_dt(st, pdev);
 602         else
 603                 ret = at91_adc_probe_pdata(st, pdev);
 604
 605         if (ret) {
 606                 dev_err(&pdev->dev, "No platform data available.\n");
 607                 ret = -EINVAL;
 608                 goto error_free_device;
 609         }
 610
 611         platform_set_drvdata(pdev, idev);
 612
 613         idev->dev.parent = &pdev->dev;
 614         idev->name = dev_name(&pdev->dev);
 615         idev->modes = INDIO_DIRECT_MODE;
 616         idev->info = &at91_adc_info;
 617
 618         st->irq = platform_get_irq(pdev, 0);
 619         if (st->irq < 0) {
 620                 dev_err(&pdev->dev, "No IRQ ID is designated\n");
 621                 ret = -ENODEV;
 622                 goto error_free_device;
 623         }
 624
 625         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 626
 627         st->reg_base = devm_ioremap_resource(&pdev->dev, res);
 628         if (IS_ERR(st->reg_base)) {
 629                 ret = PTR_ERR(st->reg_base);
 630                 goto error_free_device;
 631         }
 632
 633         /*
 634          * Disable all IRQs before setting up the handler
 635          */
 636         at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_SWRST);
 637         at91_adc_writel(st, AT91_ADC_IDR, 0xFFFFFFFF);
 638         ret = request_irq(st->irq,
 639                           at91_adc_eoc_trigger,
 640                           0,
 641                           pdev->dev.driver->name,
 642                           idev);
 643         if (ret) {
 644                 dev_err(&pdev->dev, "Failed to allocate IRQ.\n");
 645                 goto error_free_device;
 646         }
 647
 648         st->clk = devm_clk_get(&pdev->dev, "adc_clk");
 649         if (IS_ERR(st->clk)) {
 650                 dev_err(&pdev->dev, "Failed to get the clock.\n");
 651                 ret = PTR_ERR(st->clk);
 652                 goto error_free_irq;
 653         }
 654
 655         ret = clk_prepare_enable(st->clk);
 656         if (ret) {
 657                 dev_err(&pdev->dev,
 658                         "Could not prepare or enable the clock.\n");
 659                 goto error_free_irq;
 660         }
 661
 662         st->adc_clk = devm_clk_get(&pdev->dev, "adc_op_clk");
 663         if (IS_ERR(st->adc_clk)) {
 664                 dev_err(&pdev->dev, "Failed to get the ADC clock.\n");
 665                 ret = PTR_ERR(st->adc_clk);
 666                 goto error_disable_clk;
 667         }
 668
 669         ret = clk_prepare_enable(st->adc_clk);
 670         if (ret) {
 671                 dev_err(&pdev->dev,
 672                         "Could not prepare or enable the ADC clock.\n");
 673                 goto error_disable_clk;
 674         }
 675
 676         /*
 677          * Prescaler rate computation using the formula from the Atmel's
 678          * datasheet : ADC Clock = MCK / ((Prescaler + 1) * 2), ADC Clock being
 679          * specified by the electrical characteristics of the board.
 680          */
 681         mstrclk = clk_get_rate(st->clk);
 682         adc_clk = clk_get_rate(st->adc_clk);
 683         prsc = (mstrclk / (2 * adc_clk)) - 1;
 684
 685         if (!st->startup_time) {
 686                 dev_err(&pdev->dev, "No startup time available.\n");
 687                 ret = -EINVAL;
 688                 goto error_disable_adc_clk;
 689         }
 690
 691         /*
 692          * Number of ticks needed to cover the startup time of the ADC as
 693          * defined in the electrical characteristics of the board, divided by 8.
 694          * The formula thus is : Startup Time = (ticks + 1) * 8 / ADC Clock
 695          */
 696         ticks = round_up((st->startup_time * adc_clk /
 697                           1000000) - 1, 8) / 8;
 698         /*
 699          * a minimal Sample and Hold Time is necessary for the ADC to guarantee
 700          * the best converted final value between two channels selection
 701          * The formula thus is : Sample and Hold Time = (shtim + 1) / ADCClock
 702          */
 703         shtim = round_up((st->sample_hold_time * adc_clk /
 704                           1000000) - 1, 1);
 705
 706         reg = AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL;
 707         reg |= AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP;
 708         if (st->low_res)
 709                 reg |= AT91_ADC_LOWRES;
 710         if (st->sleep_mode)
 711                 reg |= AT91_ADC_SLEEP;
 712         reg |= AT91_ADC_SHTIM_(shtim) & AT91_ADC_SHTIM;
 713         at91_adc_writel(st, AT91_ADC_MR, reg);
 714
 715         /* Setup the ADC channels available on the board */
 716         ret = at91_adc_channel_init(idev);
 717         if (ret < 0) {
 718                 dev_err(&pdev->dev, "Couldn't initialize the channels.\n");
 719                 goto error_disable_adc_clk;
 720         }
 721
 722         init_waitqueue_head(&st->wq_data_avail);
 723         mutex_init(&st->lock);
 724
 725         ret = at91_adc_buffer_init(idev);
 726         if (ret < 0) {
 727                 dev_err(&pdev->dev, "Couldn't initialize the buffer.\n");
 728                 goto error_disable_adc_clk;
 729         }
 730
 731         ret = at91_adc_trigger_init(idev);
 732         if (ret < 0) {
 733                 dev_err(&pdev->dev, "Couldn't setup the triggers.\n");
 734                 goto error_unregister_buffer;
 735         }
 736
 737         ret = iio_device_register(idev);
 738         if (ret < 0) {
 739                 dev_err(&pdev->dev, "Couldn't register the device.\n");
 740                 goto error_remove_triggers;
 741         }
 742
 743         return 0;
 744
 745 error_remove_triggers:
 746         at91_adc_trigger_remove(idev);
 747 error_unregister_buffer:
 748         at91_adc_buffer_remove(idev);
 749 error_disable_adc_clk:
 750         clk_disable_unprepare(st->adc_clk);
 751 error_disable_clk:
 752         clk_disable_unprepare(st->clk);
 753 error_free_irq:
 754         free_irq(st->irq, idev);
 755 error_free_device:
 756         iio_device_free(idev);
 757 error_ret:
 758         return ret;
 759 }
 760
 761 static int at91_adc_remove(struct platform_device *pdev)
 762 {
 763         struct iio_dev *idev = platform_get_drvdata(pdev);
 764         struct at91_adc_state *st = iio_priv(idev);
 765
 766         iio_device_unregister(idev);
 767         at91_adc_trigger_remove(idev);
 768         at91_adc_buffer_remove(idev);
 769         clk_disable_unprepare(st->adc_clk);
 770         clk_disable_unprepare(st->clk);
 771         free_irq(st->irq, idev);
 772         iio_device_free(idev);
 773
 774         return 0;
 775 }
 776
 777 static const struct of_device_id at91_adc_dt_ids[] = {
 778         { .compatible = "atmel,at91sam9260-adc" },
 779         {},
 780 };
 781 MODULE_DEVICE_TABLE(of, at91_adc_dt_ids);
 782
 783 static struct platform_driver at91_adc_driver = {
 784         .probe = at91_adc_probe,
 785         .remove = at91_adc_remove,
 786         .driver = {
 787                    .name = "at91_adc",
 788                    .of_match_table = of_match_ptr(at91_adc_dt_ids),
 789         },
 790 };
 791
 792 module_platform_driver(at91_adc_driver);
 793
 794 MODULE_LICENSE("GPL");
 795 MODULE_DESCRIPTION("Atmel AT91 ADC Driver");
 796 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");