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/kfifo_buf.h>
  30 #include <linux/iio/trigger.h>
  31 #include <linux/iio/trigger_consumer.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         bool                    irq_enabled;
  50         u16                     last_value;
  51         struct mutex            lock;
  52         u8                      num_channels;
  53         void __iomem            *reg_base;
  54         struct at91_adc_reg_desc *registers;
  55         u8                      startup_time;
  56         struct iio_trigger      **trig;
  57         struct at91_adc_trigger *trigger_list;
  58         u32                     trigger_number;
  59         bool                    use_external;
  60         u32                     vref_mv;
  61         wait_queue_head_t       wq_data_avail;
  62 };
  63
  64 static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
  65 {
  66         struct iio_poll_func *pf = p;
  67         struct iio_dev *idev = pf->indio_dev;
  68         struct at91_adc_state *st = iio_priv(idev);
  69         struct iio_buffer *buffer = idev->buffer;
  70         int i, j = 0;
  71
  72         for (i = 0; i < idev->masklength; i++) {
  73                 if (!test_bit(i, idev->active_scan_mask))
  74                         continue;
  75                 st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, i));
  76                 j++;
  77         }
  78
  79         if (idev->scan_timestamp) {
  80                 s64 *timestamp = (s64 *)((u8 *)st->buffer +
  81                                         ALIGN(j, sizeof(s64)));
  82                 *timestamp = pf->timestamp;
  83         }
  84
  85         buffer->access->store_to(buffer, (u8 *)st->buffer, pf->timestamp);
  86
  87         iio_trigger_notify_done(idev->trig);
  88         st->irq_enabled = true;
  89
  90         /* Needed to ACK the DRDY interruption */
  91         at91_adc_readl(st, AT91_ADC_LCDR);
  92
  93         enable_irq(st->irq);
  94
  95         return IRQ_HANDLED;
  96 }
  97
  98 static irqreturn_t at91_adc_eoc_trigger(int irq, void *private)
  99 {
 100         struct iio_dev *idev = private;
 101         struct at91_adc_state *st = iio_priv(idev);
 102         u32 status = at91_adc_readl(st, st->registers->status_register);
 103
 104         if (!(status & st->registers->drdy_mask))
 105                 return IRQ_HANDLED;
 106
 107         if (iio_buffer_enabled(idev)) {
 108                 disable_irq_nosync(irq);
 109                 st->irq_enabled = false;
 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 = 10;
 146                 chan->scan_type.storagebits = 16;
 147                 chan->info_mask = IIO_CHAN_INFO_SCALE_SHARED_BIT |
 148                         IIO_CHAN_INFO_RAW_SEPARATE_BIT;
 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 u8 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         u8 value = 0;
 170         int i;
 171
 172         for (i = 0; i < st->trigger_number; i++) {
 173                 char *name = kasprintf(GFP_KERNEL,
 174                                 "%s-dev%d-%s",
 175                                 idev->name,
 176                                 idev->id,
 177                                 triggers[i].name);
 178                 if (!name)
 179                         return -ENOMEM;
 180
 181                 if (strcmp(trigger_name, name) == 0) {
 182                         value = triggers[i].value;
 183                         kfree(name);
 184                         break;
 185                 }
 186
 187                 kfree(name);
 188         }
 189
 190         return value;
 191 }
 192
 193 static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 194 {
 195         struct iio_dev *idev = trig->private_data;
 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         u8 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 -EINVAL;
 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         trig->private_data = 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 const struct iio_buffer_setup_ops at91_adc_buffer_ops = {
 322         .preenable = &iio_sw_buffer_preenable,
 323         .postenable = &iio_triggered_buffer_postenable,
 324         .predisable = &iio_triggered_buffer_predisable,
 325 };
 326
 327 static int at91_adc_buffer_init(struct iio_dev *idev)
 328 {
 329         int ret;
 330
 331         idev->buffer = iio_kfifo_allocate(idev);
 332         if (!idev->buffer) {
 333                 ret = -ENOMEM;
 334                 goto error_ret;
 335         }
 336
 337         idev->pollfunc = iio_alloc_pollfunc(&iio_pollfunc_store_time,
 338                                             &at91_adc_trigger_handler,
 339                                             IRQF_ONESHOT,
 340                                             idev,
 341                                             "%s-consumer%d",
 342                                             idev->name,
 343                                             idev->id);
 344         if (idev->pollfunc == NULL) {
 345                 ret = -ENOMEM;
 346                 goto error_pollfunc;
 347         }
 348
 349         idev->setup_ops = &at91_adc_buffer_ops;
 350         idev->modes |= INDIO_BUFFER_TRIGGERED;
 351
 352         ret = iio_buffer_register(idev,
 353                                   idev->channels,
 354                                   idev->num_channels);
 355         if (ret)
 356                 goto error_register;
 357
 358         return 0;
 359
 360 error_register:
 361         iio_dealloc_pollfunc(idev->pollfunc);
 362 error_pollfunc:
 363         iio_kfifo_free(idev->buffer);
 364 error_ret:
 365         return ret;
 366 }
 367
 368 static void at91_adc_buffer_remove(struct iio_dev *idev)
 369 {
 370         iio_buffer_unregister(idev);
 371         iio_dealloc_pollfunc(idev->pollfunc);
 372         iio_kfifo_free(idev->buffer);
 373 }
 374
 375 static int at91_adc_read_raw(struct iio_dev *idev,
 376                              struct iio_chan_spec const *chan,
 377                              int *val, int *val2, long mask)
 378 {
 379         struct at91_adc_state *st = iio_priv(idev);
 380         int ret;
 381
 382         switch (mask) {
 383         case IIO_CHAN_INFO_RAW:
 384                 mutex_lock(&st->lock);
 385
 386                 at91_adc_writel(st, AT91_ADC_CHER,
 387                                 AT91_ADC_CH(chan->channel));
 388                 at91_adc_writel(st, AT91_ADC_IER, st->registers->drdy_mask);
 389                 at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_START);
 390
 391                 ret = wait_event_interruptible_timeout(st->wq_data_avail,
 392                                                        st->done,
 393                                                        msecs_to_jiffies(1000));
 394                 if (ret == 0)
 395                         return -ETIMEDOUT;
 396                 else if (ret < 0)
 397                         return ret;
 398
 399                 *val = st->last_value;
 400
 401                 at91_adc_writel(st, AT91_ADC_CHDR,
 402                                 AT91_ADC_CH(chan->channel));
 403                 at91_adc_writel(st, AT91_ADC_IDR, st->registers->drdy_mask);
 404
 405                 st->last_value = 0;
 406                 st->done = false;
 407                 mutex_unlock(&st->lock);
 408                 return IIO_VAL_INT;
 409
 410         case IIO_CHAN_INFO_SCALE:
 411                 *val = (st->vref_mv * 1000) >> chan->scan_type.realbits;
 412                 *val2 = 0;
 413                 return IIO_VAL_INT_PLUS_MICRO;
 414         default:
 415                 break;
 416         }
 417         return -EINVAL;
 418 }
 419
 420 static int at91_adc_probe_dt(struct at91_adc_state *st,
 421                              struct platform_device *pdev)
 422 {
 423         struct iio_dev *idev = iio_priv_to_dev(st);
 424         struct device_node *node = pdev->dev.of_node;
 425         struct device_node *trig_node;
 426         int i = 0, ret;
 427         u32 prop;
 428
 429         if (!node)
 430                 return -EINVAL;
 431
 432         st->use_external = of_property_read_bool(node, "atmel,adc-use-external-triggers");
 433
 434         if (of_property_read_u32(node, "atmel,adc-channels-used", &prop)) {
 435                 dev_err(&idev->dev, "Missing adc-channels-used property in the DT.\n");
 436                 ret = -EINVAL;
 437                 goto error_ret;
 438         }
 439         st->channels_mask = prop;
 440
 441         if (of_property_read_u32(node, "atmel,adc-num-channels", &prop)) {
 442                 dev_err(&idev->dev, "Missing adc-num-channels property in the DT.\n");
 443                 ret = -EINVAL;
 444                 goto error_ret;
 445         }
 446         st->num_channels = prop;
 447
 448         if (of_property_read_u32(node, "atmel,adc-startup-time", &prop)) {
 449                 dev_err(&idev->dev, "Missing adc-startup-time property in the DT.\n");
 450                 ret = -EINVAL;
 451                 goto error_ret;
 452         }
 453         st->startup_time = prop;
 454
 455
 456         if (of_property_read_u32(node, "atmel,adc-vref", &prop)) {
 457                 dev_err(&idev->dev, "Missing adc-vref property in the DT.\n");
 458                 ret = -EINVAL;
 459                 goto error_ret;
 460         }
 461         st->vref_mv = prop;
 462
 463         st->registers = devm_kzalloc(&idev->dev,
 464                                      sizeof(struct at91_adc_reg_desc),
 465                                      GFP_KERNEL);
 466         if (!st->registers) {
 467                 dev_err(&idev->dev, "Could not allocate register memory.\n");
 468                 ret = -ENOMEM;
 469                 goto error_ret;
 470         }
 471
 472         if (of_property_read_u32(node, "atmel,adc-channel-base", &prop)) {
 473                 dev_err(&idev->dev, "Missing adc-channel-base property in the DT.\n");
 474                 ret = -EINVAL;
 475                 goto error_ret;
 476         }
 477         st->registers->channel_base = prop;
 478
 479         if (of_property_read_u32(node, "atmel,adc-drdy-mask", &prop)) {
 480                 dev_err(&idev->dev, "Missing adc-drdy-mask property in the DT.\n");
 481                 ret = -EINVAL;
 482                 goto error_ret;
 483         }
 484         st->registers->drdy_mask = prop;
 485
 486         if (of_property_read_u32(node, "atmel,adc-status-register", &prop)) {
 487                 dev_err(&idev->dev, "Missing adc-status-register property in the DT.\n");
 488                 ret = -EINVAL;
 489                 goto error_ret;
 490         }
 491         st->registers->status_register = prop;
 492
 493         if (of_property_read_u32(node, "atmel,adc-trigger-register", &prop)) {
 494                 dev_err(&idev->dev, "Missing adc-trigger-register property in the DT.\n");
 495                 ret = -EINVAL;
 496                 goto error_ret;
 497         }
 498         st->registers->trigger_register = prop;
 499
 500         st->trigger_number = of_get_child_count(node);
 501         st->trigger_list = devm_kzalloc(&idev->dev, st->trigger_number *
 502                                         sizeof(struct at91_adc_trigger),
 503                                         GFP_KERNEL);
 504         if (!st->trigger_list) {
 505                 dev_err(&idev->dev, "Could not allocate trigger list memory.\n");
 506                 ret = -ENOMEM;
 507                 goto error_ret;
 508         }
 509
 510         for_each_child_of_node(node, trig_node) {
 511                 struct at91_adc_trigger *trig = st->trigger_list + i;
 512                 const char *name;
 513
 514                 if (of_property_read_string(trig_node, "trigger-name", &name)) {
 515                         dev_err(&idev->dev, "Missing trigger-name property in the DT.\n");
 516                         ret = -EINVAL;
 517                         goto error_ret;
 518                 }
 519                 trig->name = name;
 520
 521                 if (of_property_read_u32(trig_node, "trigger-value", &prop)) {
 522                         dev_err(&idev->dev, "Missing trigger-value property in the DT.\n");
 523                         ret = -EINVAL;
 524                         goto error_ret;
 525                 }
 526                 trig->value = prop;
 527                 trig->is_external = of_property_read_bool(trig_node, "trigger-external");
 528                 i++;
 529         }
 530
 531         return 0;
 532
 533 error_ret:
 534         return ret;
 535 }
 536
 537 static int at91_adc_probe_pdata(struct at91_adc_state *st,
 538                                 struct platform_device *pdev)
 539 {
 540         struct at91_adc_data *pdata = pdev->dev.platform_data;
 541
 542         if (!pdata)
 543                 return -EINVAL;
 544
 545         st->use_external = pdata->use_external_triggers;
 546         st->vref_mv = pdata->vref;
 547         st->channels_mask = pdata->channels_used;
 548         st->num_channels = pdata->num_channels;
 549         st->startup_time = pdata->startup_time;
 550         st->trigger_number = pdata->trigger_number;
 551         st->trigger_list = pdata->trigger_list;
 552         st->registers = pdata->registers;
 553
 554         return 0;
 555 }
 556
 557 static const struct iio_info at91_adc_info = {
 558         .driver_module = THIS_MODULE,
 559         .read_raw = &at91_adc_read_raw,
 560 };
 561
 562 static int __devinit at91_adc_probe(struct platform_device *pdev)
 563 {
 564         unsigned int prsc, mstrclk, ticks, adc_clk;
 565         int ret;
 566         struct iio_dev *idev;
 567         struct at91_adc_state *st;
 568         struct resource *res;
 569
 570         idev = iio_device_alloc(sizeof(struct at91_adc_state));
 571         if (idev == NULL) {
 572                 ret = -ENOMEM;
 573                 goto error_ret;
 574         }
 575
 576         st = iio_priv(idev);
 577
 578         if (pdev->dev.of_node)
 579                 ret = at91_adc_probe_dt(st, pdev);
 580         else
 581                 ret = at91_adc_probe_pdata(st, pdev);
 582
 583         if (ret) {
 584                 dev_err(&pdev->dev, "No platform data available.\n");
 585                 ret = -EINVAL;
 586                 goto error_free_device;
 587         }
 588
 589         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 590         if (!res) {
 591                 dev_err(&pdev->dev, "No resource defined\n");
 592                 ret = -ENXIO;
 593                 goto error_ret;
 594         }
 595
 596         platform_set_drvdata(pdev, idev);
 597
 598         idev->dev.parent = &pdev->dev;
 599         idev->name = dev_name(&pdev->dev);
 600         idev->modes = INDIO_DIRECT_MODE;
 601         idev->info = &at91_adc_info;
 602
 603         st->irq = platform_get_irq(pdev, 0);
 604         if (st->irq < 0) {
 605                 dev_err(&pdev->dev, "No IRQ ID is designated\n");
 606                 ret = -ENODEV;
 607                 goto error_free_device;
 608         }
 609
 610         if (!request_mem_region(res->start, resource_size(res),
 611                                 "AT91 adc registers")) {
 612                 dev_err(&pdev->dev, "Resources are unavailable.\n");
 613                 ret = -EBUSY;
 614                 goto error_free_device;
 615         }
 616
 617         st->reg_base = ioremap(res->start, resource_size(res));
 618         if (!st->reg_base) {
 619                 dev_err(&pdev->dev, "Failed to map registers.\n");
 620                 ret = -ENOMEM;
 621                 goto error_release_mem;
 622         }
 623
 624         /*
 625          * Disable all IRQs before setting up the handler
 626          */
 627         at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_SWRST);
 628         at91_adc_writel(st, AT91_ADC_IDR, 0xFFFFFFFF);
 629         ret = request_irq(st->irq,
 630                           at91_adc_eoc_trigger,
 631                           0,
 632                           pdev->dev.driver->name,
 633                           idev);
 634         if (ret) {
 635                 dev_err(&pdev->dev, "Failed to allocate IRQ.\n");
 636                 goto error_unmap_reg;
 637         }
 638
 639         st->clk = clk_get(&pdev->dev, "adc_clk");
 640         if (IS_ERR(st->clk)) {
 641                 dev_err(&pdev->dev, "Failed to get the clock.\n");
 642                 ret = PTR_ERR(st->clk);
 643                 goto error_free_irq;
 644         }
 645
 646         ret = clk_prepare(st->clk);
 647         if (ret) {
 648                 dev_err(&pdev->dev, "Could not prepare the clock.\n");
 649                 goto error_free_clk;
 650         }
 651
 652         ret = clk_enable(st->clk);
 653         if (ret) {
 654                 dev_err(&pdev->dev, "Could not enable the clock.\n");
 655                 goto error_unprepare_clk;
 656         }
 657
 658         st->adc_clk = clk_get(&pdev->dev, "adc_op_clk");
 659         if (IS_ERR(st->adc_clk)) {
 660                 dev_err(&pdev->dev, "Failed to get the ADC clock.\n");
 661                 ret = PTR_ERR(st->clk);
 662                 goto error_disable_clk;
 663         }
 664
 665         ret = clk_prepare(st->adc_clk);
 666         if (ret) {
 667                 dev_err(&pdev->dev, "Could not prepare the ADC clock.\n");
 668                 goto error_free_adc_clk;
 669         }
 670
 671         ret = clk_enable(st->adc_clk);
 672         if (ret) {
 673                 dev_err(&pdev->dev, "Could not enable the ADC clock.\n");
 674                 goto error_unprepare_adc_clk;
 675         }
 676
 677         /*
 678          * Prescaler rate computation using the formula from the Atmel's
 679          * datasheet : ADC Clock = MCK / ((Prescaler + 1) * 2), ADC Clock being
 680          * specified by the electrical characteristics of the board.
 681          */
 682         mstrclk = clk_get_rate(st->clk);
 683         adc_clk = clk_get_rate(st->adc_clk);
 684         prsc = (mstrclk / (2 * adc_clk)) - 1;
 685
 686         if (!st->startup_time) {
 687                 dev_err(&pdev->dev, "No startup time available.\n");
 688                 ret = -EINVAL;
 689                 goto error_disable_adc_clk;
 690         }
 691
 692         /*
 693          * Number of ticks needed to cover the startup time of the ADC as
 694          * defined in the electrical characteristics of the board, divided by 8.
 695          * The formula thus is : Startup Time = (ticks + 1) * 8 / ADC Clock
 696          */
 697         ticks = round_up((st->startup_time * adc_clk /
 698                           1000000) - 1, 8) / 8;
 699         at91_adc_writel(st, AT91_ADC_MR,
 700                         (AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
 701                         (AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
 702
 703         /* Setup the ADC channels available on the board */
 704         ret = at91_adc_channel_init(idev);
 705         if (ret < 0) {
 706                 dev_err(&pdev->dev, "Couldn't initialize the channels.\n");
 707                 goto error_disable_adc_clk;
 708         }
 709
 710         init_waitqueue_head(&st->wq_data_avail);
 711         mutex_init(&st->lock);
 712
 713         ret = at91_adc_buffer_init(idev);
 714         if (ret < 0) {
 715                 dev_err(&pdev->dev, "Couldn't initialize the buffer.\n");
 716                 goto error_disable_adc_clk;
 717         }
 718
 719         ret = at91_adc_trigger_init(idev);
 720         if (ret < 0) {
 721                 dev_err(&pdev->dev, "Couldn't setup the triggers.\n");
 722                 goto error_unregister_buffer;
 723         }
 724
 725         ret = iio_device_register(idev);
 726         if (ret < 0) {
 727                 dev_err(&pdev->dev, "Couldn't register the device.\n");
 728                 goto error_remove_triggers;
 729         }
 730
 731         return 0;
 732
 733 error_remove_triggers:
 734         at91_adc_trigger_remove(idev);
 735 error_unregister_buffer:
 736         at91_adc_buffer_remove(idev);
 737 error_disable_adc_clk:
 738         clk_disable(st->adc_clk);
 739 error_unprepare_adc_clk:
 740         clk_unprepare(st->adc_clk);
 741 error_free_adc_clk:
 742         clk_put(st->adc_clk);
 743 error_disable_clk:
 744         clk_disable(st->clk);
 745 error_unprepare_clk:
 746         clk_unprepare(st->clk);
 747 error_free_clk:
 748         clk_put(st->clk);
 749 error_free_irq:
 750         free_irq(st->irq, idev);
 751 error_unmap_reg:
 752         iounmap(st->reg_base);
 753 error_release_mem:
 754         release_mem_region(res->start, resource_size(res));
 755 error_free_device:
 756         iio_device_free(idev);
 757 error_ret:
 758         return ret;
 759 }
 760
 761 static int __devexit at91_adc_remove(struct platform_device *pdev)
 762 {
 763         struct iio_dev *idev = platform_get_drvdata(pdev);
 764         struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 765         struct at91_adc_state *st = iio_priv(idev);
 766
 767         iio_device_unregister(idev);
 768         at91_adc_trigger_remove(idev);
 769         at91_adc_buffer_remove(idev);
 770         clk_disable_unprepare(st->adc_clk);
 771         clk_put(st->adc_clk);
 772         clk_disable(st->clk);
 773         clk_unprepare(st->clk);
 774         clk_put(st->clk);
 775         free_irq(st->irq, idev);
 776         iounmap(st->reg_base);
 777         release_mem_region(res->start, resource_size(res));
 778         iio_device_free(idev);
 779
 780         return 0;
 781 }
 782
 783 static const struct of_device_id at91_adc_dt_ids[] = {
 784         { .compatible = "atmel,at91sam9260-adc" },
 785         {},
 786 };
 787 MODULE_DEVICE_TABLE(of, at91_adc_dt_ids);
 788
 789 static struct platform_driver at91_adc_driver = {
 790         .probe = at91_adc_probe,
 791         .remove = __devexit_p(at91_adc_remove),
 792         .driver = {
 793                    .name = "at91_adc",
 794                    .of_match_table = of_match_ptr(at91_adc_dt_ids),
 795         },
 796 };
 797
 798 module_platform_driver(at91_adc_driver);
 799
 800 MODULE_LICENSE("GPL");
 801 MODULE_DESCRIPTION("Atmel AT91 ADC Driver");
 802 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");