drivers/iio/adc/cc10001_adc.c

   1 /*
   2  * Copyright (c) 2014-2015 Imagination Technologies Ltd.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 as published by
   6  * the Free Software Foundation.
   7  *
   8  */
   9
  10 #include <linux/clk.h>
  11 #include <linux/delay.h>
  12 #include <linux/err.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/of_device.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/regulator/consumer.h>
  19 #include <linux/slab.h>
  20
  21 #include <linux/iio/buffer.h>
  22 #include <linux/iio/iio.h>
  23 #include <linux/iio/sysfs.h>
  24 #include <linux/iio/trigger.h>
  25 #include <linux/iio/trigger_consumer.h>
  26 #include <linux/iio/triggered_buffer.h>
  27
  28 /* Registers */
  29 #define CC10001_ADC_CONFIG              0x00
  30 #define CC10001_ADC_START_CONV          BIT(4)
  31 #define CC10001_ADC_MODE_SINGLE_CONV    BIT(5)
  32
  33 #define CC10001_ADC_DDATA_OUT           0x04
  34 #define CC10001_ADC_EOC                 0x08
  35 #define CC10001_ADC_EOC_SET             BIT(0)
  36
  37 #define CC10001_ADC_CHSEL_SAMPLED       0x0c
  38 #define CC10001_ADC_POWER_DOWN          0x10
  39 #define CC10001_ADC_POWER_DOWN_SET      BIT(0)
  40
  41 #define CC10001_ADC_DEBUG               0x14
  42 #define CC10001_ADC_DATA_COUNT          0x20
  43
  44 #define CC10001_ADC_DATA_MASK           GENMASK(9, 0)
  45 #define CC10001_ADC_NUM_CHANNELS        8
  46 #define CC10001_ADC_CH_MASK             GENMASK(2, 0)
  47
  48 #define CC10001_INVALID_SAMPLED         0xffff
  49 #define CC10001_MAX_POLL_COUNT          20
  50
  51 /*
  52  * As per device specification, wait six clock cycles after power-up to
  53  * activate START. Since adding two more clock cycles delay does not
  54  * impact the performance too much, we are adding two additional cycles delay
  55  * intentionally here.
  56  */
  57 #define CC10001_WAIT_CYCLES             8
  58
  59 struct cc10001_adc_device {
  60         void __iomem *reg_base;
  61         struct clk *adc_clk;
  62         struct regulator *reg;
  63         u16 *buf;
  64
  65         bool shared;
  66         struct mutex lock;
  67         unsigned int start_delay_ns;
  68         unsigned int eoc_delay_ns;
  69 };
  70
  71 static inline void cc10001_adc_write_reg(struct cc10001_adc_device *adc_dev,
  72                                          u32 reg, u32 val)
  73 {
  74         writel(val, adc_dev->reg_base + reg);
  75 }
  76
  77 static inline u32 cc10001_adc_read_reg(struct cc10001_adc_device *adc_dev,
  78                                        u32 reg)
  79 {
  80         return readl(adc_dev->reg_base + reg);
  81 }
  82
  83 static void cc10001_adc_power_up(struct cc10001_adc_device *adc_dev)
  84 {
  85         cc10001_adc_write_reg(adc_dev, CC10001_ADC_POWER_DOWN, 0);
  86         ndelay(adc_dev->start_delay_ns);
  87 }
  88
  89 static void cc10001_adc_power_down(struct cc10001_adc_device *adc_dev)
  90 {
  91         cc10001_adc_write_reg(adc_dev, CC10001_ADC_POWER_DOWN,
  92                               CC10001_ADC_POWER_DOWN_SET);
  93 }
  94
  95 static void cc10001_adc_start(struct cc10001_adc_device *adc_dev,
  96                               unsigned int channel)
  97 {
  98         u32 val;
  99
 100         /* Channel selection and mode of operation */
 101         val = (channel & CC10001_ADC_CH_MASK) | CC10001_ADC_MODE_SINGLE_CONV;
 102         cc10001_adc_write_reg(adc_dev, CC10001_ADC_CONFIG, val);
 103
 104         udelay(1);
 105         val = cc10001_adc_read_reg(adc_dev, CC10001_ADC_CONFIG);
 106         val = val | CC10001_ADC_START_CONV;
 107         cc10001_adc_write_reg(adc_dev, CC10001_ADC_CONFIG, val);
 108 }
 109
 110 static u16 cc10001_adc_poll_done(struct iio_dev *indio_dev,
 111                                  unsigned int channel,
 112                                  unsigned int delay)
 113 {
 114         struct cc10001_adc_device *adc_dev = iio_priv(indio_dev);
 115         unsigned int poll_count = 0;
 116
 117         while (!(cc10001_adc_read_reg(adc_dev, CC10001_ADC_EOC) &
 118                         CC10001_ADC_EOC_SET)) {
 119
 120                 ndelay(delay);
 121                 if (poll_count++ == CC10001_MAX_POLL_COUNT)
 122                         return CC10001_INVALID_SAMPLED;
 123         }
 124
 125         poll_count = 0;
 126         while ((cc10001_adc_read_reg(adc_dev, CC10001_ADC_CHSEL_SAMPLED) &
 127                         CC10001_ADC_CH_MASK) != channel) {
 128
 129                 ndelay(delay);
 130                 if (poll_count++ == CC10001_MAX_POLL_COUNT)
 131                         return CC10001_INVALID_SAMPLED;
 132         }
 133
 134         /* Read the 10 bit output register */
 135         return cc10001_adc_read_reg(adc_dev, CC10001_ADC_DDATA_OUT) &
 136                                CC10001_ADC_DATA_MASK;
 137 }
 138
 139 static irqreturn_t cc10001_adc_trigger_h(int irq, void *p)
 140 {
 141         struct cc10001_adc_device *adc_dev;
 142         struct iio_poll_func *pf = p;
 143         struct iio_dev *indio_dev;
 144         unsigned int delay_ns;
 145         unsigned int channel;
 146         unsigned int scan_idx;
 147         bool sample_invalid;
 148         u16 *data;
 149         int i;
 150
 151         indio_dev = pf->indio_dev;
 152         adc_dev = iio_priv(indio_dev);
 153         data = adc_dev->buf;
 154
 155         mutex_lock(&adc_dev->lock);
 156
 157         if (!adc_dev->shared)
 158                 cc10001_adc_power_up(adc_dev);
 159
 160         /* Calculate delay step for eoc and sampled data */
 161         delay_ns = adc_dev->eoc_delay_ns / CC10001_MAX_POLL_COUNT;
 162
 163         i = 0;
 164         sample_invalid = false;
 165         for_each_set_bit(scan_idx, indio_dev->active_scan_mask,
 166                                   indio_dev->masklength) {
 167
 168                 channel = indio_dev->channels[scan_idx].channel;
 169                 cc10001_adc_start(adc_dev, channel);
 170
 171                 data[i] = cc10001_adc_poll_done(indio_dev, channel, delay_ns);
 172                 if (data[i] == CC10001_INVALID_SAMPLED) {
 173                         dev_warn(&indio_dev->dev,
 174                                  "invalid sample on channel %d\n", channel);
 175                         sample_invalid = true;
 176                         goto done;
 177                 }
 178                 i++;
 179         }
 180
 181 done:
 182         if (!adc_dev->shared)
 183                 cc10001_adc_power_down(adc_dev);
 184
 185         mutex_unlock(&adc_dev->lock);
 186
 187         if (!sample_invalid)
 188                 iio_push_to_buffers_with_timestamp(indio_dev, data,
 189                                                    iio_get_time_ns());
 190         iio_trigger_notify_done(indio_dev->trig);
 191
 192         return IRQ_HANDLED;
 193 }
 194
 195 static u16 cc10001_adc_read_raw_voltage(struct iio_dev *indio_dev,
 196                                         struct iio_chan_spec const *chan)
 197 {
 198         struct cc10001_adc_device *adc_dev = iio_priv(indio_dev);
 199         unsigned int delay_ns;
 200         u16 val;
 201
 202         if (!adc_dev->shared)
 203                 cc10001_adc_power_up(adc_dev);
 204
 205         /* Calculate delay step for eoc and sampled data */
 206         delay_ns = adc_dev->eoc_delay_ns / CC10001_MAX_POLL_COUNT;
 207
 208         cc10001_adc_start(adc_dev, chan->channel);
 209
 210         val = cc10001_adc_poll_done(indio_dev, chan->channel, delay_ns);
 211
 212         if (!adc_dev->shared)
 213                 cc10001_adc_power_down(adc_dev);
 214
 215         return val;
 216 }
 217
 218 static int cc10001_adc_read_raw(struct iio_dev *indio_dev,
 219                                  struct iio_chan_spec const *chan,
 220                                  int *val, int *val2, long mask)
 221 {
 222         struct cc10001_adc_device *adc_dev = iio_priv(indio_dev);
 223         int ret;
 224
 225         switch (mask) {
 226         case IIO_CHAN_INFO_RAW:
 227                 if (iio_buffer_enabled(indio_dev))
 228                         return -EBUSY;
 229                 mutex_lock(&adc_dev->lock);
 230                 *val = cc10001_adc_read_raw_voltage(indio_dev, chan);
 231                 mutex_unlock(&adc_dev->lock);
 232
 233                 if (*val == CC10001_INVALID_SAMPLED)
 234                         return -EIO;
 235                 return IIO_VAL_INT;
 236
 237         case IIO_CHAN_INFO_SCALE:
 238                 ret = regulator_get_voltage(adc_dev->reg);
 239                 if (ret < 0)
 240                         return ret;
 241
 242                 *val = ret / 1000;
 243                 *val2 = chan->scan_type.realbits;
 244                 return IIO_VAL_FRACTIONAL_LOG2;
 245
 246         default:
 247                 return -EINVAL;
 248         }
 249 }
 250
 251 static int cc10001_update_scan_mode(struct iio_dev *indio_dev,
 252                                     const unsigned long *scan_mask)
 253 {
 254         struct cc10001_adc_device *adc_dev = iio_priv(indio_dev);
 255
 256         kfree(adc_dev->buf);
 257         adc_dev->buf = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
 258         if (!adc_dev->buf)
 259                 return -ENOMEM;
 260
 261         return 0;
 262 }
 263
 264 static const struct iio_info cc10001_adc_info = {
 265         .driver_module = THIS_MODULE,
 266         .read_raw = &cc10001_adc_read_raw,
 267         .update_scan_mode = &cc10001_update_scan_mode,
 268 };
 269
 270 static int cc10001_adc_channel_init(struct iio_dev *indio_dev,
 271                                     unsigned long channel_map)
 272 {
 273         struct iio_chan_spec *chan_array, *timestamp;
 274         unsigned int bit, idx = 0;
 275
 276         indio_dev->num_channels = bitmap_weight(&channel_map,
 277                                                 CC10001_ADC_NUM_CHANNELS) + 1;
 278
 279         chan_array = devm_kcalloc(&indio_dev->dev, indio_dev->num_channels,
 280                                   sizeof(struct iio_chan_spec),
 281                                   GFP_KERNEL);
 282         if (!chan_array)
 283                 return -ENOMEM;
 284
 285         for_each_set_bit(bit, &channel_map, CC10001_ADC_NUM_CHANNELS) {
 286                 struct iio_chan_spec *chan = &chan_array[idx];
 287
 288                 chan->type = IIO_VOLTAGE;
 289                 chan->indexed = 1;
 290                 chan->channel = bit;
 291                 chan->scan_index = idx;
 292                 chan->scan_type.sign = 'u';
 293                 chan->scan_type.realbits = 10;
 294                 chan->scan_type.storagebits = 16;
 295                 chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
 296                 chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
 297                 idx++;
 298         }
 299
 300         timestamp = &chan_array[idx];
 301         timestamp->type = IIO_TIMESTAMP;
 302         timestamp->channel = -1;
 303         timestamp->scan_index = idx;
 304         timestamp->scan_type.sign = 's';
 305         timestamp->scan_type.realbits = 64;
 306         timestamp->scan_type.storagebits = 64;
 307
 308         indio_dev->channels = chan_array;
 309
 310         return 0;
 311 }
 312
 313 static int cc10001_adc_probe(struct platform_device *pdev)
 314 {
 315         struct device_node *node = pdev->dev.of_node;
 316         struct cc10001_adc_device *adc_dev;
 317         unsigned long adc_clk_rate;
 318         struct resource *res;
 319         struct iio_dev *indio_dev;
 320         unsigned long channel_map;
 321         int ret;
 322
 323         indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc_dev));
 324         if (indio_dev == NULL)
 325                 return -ENOMEM;
 326
 327         adc_dev = iio_priv(indio_dev);
 328
 329         channel_map = GENMASK(CC10001_ADC_NUM_CHANNELS - 1, 0);
 330         if (!of_property_read_u32(node, "adc-reserved-channels", &ret)) {
 331                 adc_dev->shared = true;
 332                 channel_map &= ~ret;
 333         }
 334
 335         adc_dev->reg = devm_regulator_get(&pdev->dev, "vref");
 336         if (IS_ERR(adc_dev->reg))
 337                 return PTR_ERR(adc_dev->reg);
 338
 339         ret = regulator_enable(adc_dev->reg);
 340         if (ret)
 341                 return ret;
 342
 343         indio_dev->dev.parent = &pdev->dev;
 344         indio_dev->name = dev_name(&pdev->dev);
 345         indio_dev->info = &cc10001_adc_info;
 346         indio_dev->modes = INDIO_DIRECT_MODE;
 347
 348         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 349         adc_dev->reg_base = devm_ioremap_resource(&pdev->dev, res);
 350         if (IS_ERR(adc_dev->reg_base)) {
 351                 ret = PTR_ERR(adc_dev->reg_base);
 352                 goto err_disable_reg;
 353         }
 354
 355         adc_dev->adc_clk = devm_clk_get(&pdev->dev, "adc");
 356         if (IS_ERR(adc_dev->adc_clk)) {
 357                 dev_err(&pdev->dev, "failed to get the clock\n");
 358                 ret = PTR_ERR(adc_dev->adc_clk);
 359                 goto err_disable_reg;
 360         }
 361
 362         ret = clk_prepare_enable(adc_dev->adc_clk);
 363         if (ret) {
 364                 dev_err(&pdev->dev, "failed to enable the clock\n");
 365                 goto err_disable_reg;
 366         }
 367
 368         adc_clk_rate = clk_get_rate(adc_dev->adc_clk);
 369         if (!adc_clk_rate) {
 370                 ret = -EINVAL;
 371                 dev_err(&pdev->dev, "null clock rate!\n");
 372                 goto err_disable_clk;
 373         }
 374
 375         adc_dev->eoc_delay_ns = NSEC_PER_SEC / adc_clk_rate;
 376         adc_dev->start_delay_ns = adc_dev->eoc_delay_ns * CC10001_WAIT_CYCLES;
 377
 378         /*
 379          * There is only one register to power-up/power-down the AUX ADC.
 380          * If the ADC is shared among multiple CPUs, always power it up here.
 381          * If the ADC is used only by the MIPS, power-up/power-down at runtime.
 382          */
 383         if (adc_dev->shared)
 384                 cc10001_adc_power_up(adc_dev);
 385
 386         /* Setup the ADC channels available on the device */
 387         ret = cc10001_adc_channel_init(indio_dev, channel_map);
 388         if (ret < 0)
 389                 goto err_disable_clk;
 390
 391         mutex_init(&adc_dev->lock);
 392
 393         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 394                                          &cc10001_adc_trigger_h, NULL);
 395         if (ret < 0)
 396                 goto err_disable_clk;
 397
 398         ret = iio_device_register(indio_dev);
 399         if (ret < 0)
 400                 goto err_cleanup_buffer;
 401
 402         platform_set_drvdata(pdev, indio_dev);
 403
 404         return 0;
 405
 406 err_cleanup_buffer:
 407         iio_triggered_buffer_cleanup(indio_dev);
 408 err_disable_clk:
 409         clk_disable_unprepare(adc_dev->adc_clk);
 410 err_disable_reg:
 411         regulator_disable(adc_dev->reg);
 412         return ret;
 413 }
 414
 415 static int cc10001_adc_remove(struct platform_device *pdev)
 416 {
 417         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 418         struct cc10001_adc_device *adc_dev = iio_priv(indio_dev);
 419
 420         cc10001_adc_power_down(adc_dev);
 421         iio_device_unregister(indio_dev);
 422         iio_triggered_buffer_cleanup(indio_dev);
 423         clk_disable_unprepare(adc_dev->adc_clk);
 424         regulator_disable(adc_dev->reg);
 425
 426         return 0;
 427 }
 428
 429 static const struct of_device_id cc10001_adc_dt_ids[] = {
 430         { .compatible = "cosmic,10001-adc", },
 431         { }
 432 };
 433 MODULE_DEVICE_TABLE(of, cc10001_adc_dt_ids);
 434
 435 static struct platform_driver cc10001_adc_driver = {
 436         .driver = {
 437                 .name   = "cc10001-adc",
 438                 .of_match_table = cc10001_adc_dt_ids,
 439         },
 440         .probe  = cc10001_adc_probe,
 441         .remove = cc10001_adc_remove,
 442 };
 443 module_platform_driver(cc10001_adc_driver);
 444
 445 MODULE_AUTHOR("Phani Movva <Phani.Movva@imgtec.com>");
 446 MODULE_DESCRIPTION("Cosmic Circuits ADC driver");
 447 MODULE_LICENSE("GPL v2");