linux/drivers/iio/adc/at91_adc.c
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   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
  42struct 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
  67static 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
  99static 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
 120static 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
 164static 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
 193static 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        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
 244static const struct iio_trigger_ops at91_adc_trigger_ops = {
 245        .owner = THIS_MODULE,
 246        .set_trigger_state = &at91_adc_configure_trigger,
 247};
 248
 249static 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
 271static 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
 301error_trigger:
 302        for (i--; i >= 0; i--) {
 303                iio_trigger_unregister(st->trig[i]);
 304                iio_trigger_free(st->trig[i]);
 305        }
 306error_ret:
 307        return ret;
 308}
 309
 310static 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
 321static 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
 327static void at91_adc_buffer_remove(struct iio_dev *idev)
 328{
 329        iio_triggered_buffer_cleanup(idev);
 330}
 331
 332static 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
 379static 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
 427ret:
 428        kfree(resolutions);
 429        return ret;
 430}
 431
 432static 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
 554error_ret:
 555        return ret;
 556}
 557
 558static 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
 578static const struct iio_info at91_adc_info = {
 579        .driver_module = THIS_MODULE,
 580        .read_raw = &at91_adc_read_raw,
 581};
 582
 583static 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
 745error_remove_triggers:
 746        at91_adc_trigger_remove(idev);
 747error_unregister_buffer:
 748        at91_adc_buffer_remove(idev);
 749error_disable_adc_clk:
 750        clk_disable_unprepare(st->adc_clk);
 751error_disable_clk:
 752        clk_disable_unprepare(st->clk);
 753error_free_irq:
 754        free_irq(st->irq, idev);
 755error_free_device:
 756        iio_device_free(idev);
 757error_ret:
 758        return ret;
 759}
 760
 761static 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
 777static const struct of_device_id at91_adc_dt_ids[] = {
 778        { .compatible = "atmel,at91sam9260-adc" },
 779        {},
 780};
 781MODULE_DEVICE_TABLE(of, at91_adc_dt_ids);
 782
 783static 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
 792module_platform_driver(at91_adc_driver);
 793
 794MODULE_LICENSE("GPL");
 795MODULE_DESCRIPTION("Atmel AT91 ADC Driver");
 796MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
 797