drivers/iio/adc/ti-adc108s102.c

   1 /*
   2  * TI ADC108S102 SPI ADC driver
   3  *
   4  * Copyright (c) 2013-2015 Intel Corporation.
   5  * Copyright (c) 2017 Siemens AG
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms and conditions of the GNU General Public License,
   9  * version 2, as published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14  * more details.
  15  *
  16  * This IIO device driver is designed to work with the following
  17  * analog to digital converters from Texas Instruments:
  18  *  ADC108S102
  19  *  ADC128S102
  20  * The communication with ADC chip is via the SPI bus (mode 3).
  21  */
  22
  23 #include <linux/acpi.h>
  24 #include <linux/iio/iio.h>
  25 #include <linux/iio/buffer.h>
  26 #include <linux/iio/types.h>
  27 #include <linux/iio/triggered_buffer.h>
  28 #include <linux/iio/trigger_consumer.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/module.h>
  31 #include <linux/property.h>
  32 #include <linux/regulator/consumer.h>
  33 #include <linux/spi/spi.h>
  34
  35 /*
  36  * In case of ACPI, we use the hard-wired 5000 mV of the Galileo and IOT2000
  37  * boards as default for the reference pin VA. Device tree users encode that
  38  * via the vref-supply regulator.
  39  */
  40 #define ADC108S102_VA_MV_ACPI_DEFAULT   5000
  41
  42 /*
  43  * Defining the ADC resolution being 12 bits, we can use the same driver for
  44  * both ADC108S102 (10 bits resolution) and ADC128S102 (12 bits resolution)
  45  * chips. The ADC108S102 effectively returns a 12-bit result with the 2
  46  * least-significant bits unset.
  47  */
  48 #define ADC108S102_BITS         12
  49 #define ADC108S102_MAX_CHANNELS 8
  50
  51 /*
  52  * 16-bit SPI command format:
  53  *   [15:14] Ignored
  54  *   [13:11] 3-bit channel address
  55  *   [10:0]  Ignored
  56  */
  57 #define ADC108S102_CMD(ch)              ((u16)(ch) << 11)
  58
  59 /*
  60  * 16-bit SPI response format:
  61  *   [15:12] Zeros
  62  *   [11:0]  12-bit ADC sample (for ADC108S102, [1:0] will always be 0).
  63  */
  64 #define ADC108S102_RES_DATA(res)        ((u16)res & GENMASK(11, 0))
  65
  66 struct adc108s102_state {
  67         struct spi_device               *spi;
  68         struct regulator                *reg;
  69         u32                             va_millivolt;
  70         /* SPI transfer used by triggered buffer handler*/
  71         struct spi_transfer             ring_xfer;
  72         /* SPI transfer used by direct scan */
  73         struct spi_transfer             scan_single_xfer;
  74         /* SPI message used by ring_xfer SPI transfer */
  75         struct spi_message              ring_msg;
  76         /* SPI message used by scan_single_xfer SPI transfer */
  77         struct spi_message              scan_single_msg;
  78
  79         /*
  80          * SPI message buffers:
  81          *  tx_buf: |C0|C1|C2|C3|C4|C5|C6|C7|XX|
  82          *  rx_buf: |XX|R0|R1|R2|R3|R4|R5|R6|R7|tt|tt|tt|tt|
  83          *
  84          *  tx_buf: 8 channel read commands, plus 1 dummy command
  85          *  rx_buf: 1 dummy response, 8 channel responses, plus 64-bit timestamp
  86          */
  87         __be16                          rx_buf[13] ____cacheline_aligned;
  88         __be16                          tx_buf[9] ____cacheline_aligned;
  89 };
  90
  91 #define ADC108S102_V_CHAN(index)                                        \
  92         {                                                               \
  93                 .type = IIO_VOLTAGE,                                    \
  94                 .indexed = 1,                                           \
  95                 .channel = index,                                       \
  96                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |          \
  97                         BIT(IIO_CHAN_INFO_SCALE),                       \
  98                 .address = index,                                       \
  99                 .scan_index = index,                                    \
 100                 .scan_type = {                                          \
 101                         .sign = 'u',                                    \
 102                         .realbits = ADC108S102_BITS,                    \
 103                         .storagebits = 16,                              \
 104                         .endianness = IIO_BE,                           \
 105                 },                                                      \
 106         }
 107
 108 static const struct iio_chan_spec adc108s102_channels[] = {
 109         ADC108S102_V_CHAN(0),
 110         ADC108S102_V_CHAN(1),
 111         ADC108S102_V_CHAN(2),
 112         ADC108S102_V_CHAN(3),
 113         ADC108S102_V_CHAN(4),
 114         ADC108S102_V_CHAN(5),
 115         ADC108S102_V_CHAN(6),
 116         ADC108S102_V_CHAN(7),
 117         IIO_CHAN_SOFT_TIMESTAMP(8),
 118 };
 119
 120 static int adc108s102_update_scan_mode(struct iio_dev *indio_dev,
 121                 unsigned long const *active_scan_mask)
 122 {
 123         struct adc108s102_state *st = iio_priv(indio_dev);
 124         unsigned int bit, cmds;
 125
 126         /*
 127          * Fill in the first x shorts of tx_buf with the number of channels
 128          * enabled for sampling by the triggered buffer.
 129          */
 130         cmds = 0;
 131         for_each_set_bit(bit, active_scan_mask, ADC108S102_MAX_CHANNELS)
 132                 st->tx_buf[cmds++] = cpu_to_be16(ADC108S102_CMD(bit));
 133
 134         /* One dummy command added, to clock in the last response */
 135         st->tx_buf[cmds++] = 0x00;
 136
 137         /* build SPI ring message */
 138         st->ring_xfer.tx_buf = &st->tx_buf[0];
 139         st->ring_xfer.rx_buf = &st->rx_buf[0];
 140         st->ring_xfer.len = cmds * sizeof(st->tx_buf[0]);
 141
 142         spi_message_init_with_transfers(&st->ring_msg, &st->ring_xfer, 1);
 143
 144         return 0;
 145 }
 146
 147 static irqreturn_t adc108s102_trigger_handler(int irq, void *p)
 148 {
 149         struct iio_poll_func *pf = p;
 150         struct iio_dev *indio_dev = pf->indio_dev;
 151         struct adc108s102_state *st = iio_priv(indio_dev);
 152         int ret;
 153
 154         ret = spi_sync(st->spi, &st->ring_msg);
 155         if (ret < 0)
 156                 goto out_notify;
 157
 158         /* Skip the dummy response in the first slot */
 159         iio_push_to_buffers_with_timestamp(indio_dev,
 160                                            (u8 *)&st->rx_buf[1],
 161                                            iio_get_time_ns(indio_dev));
 162
 163 out_notify:
 164         iio_trigger_notify_done(indio_dev->trig);
 165
 166         return IRQ_HANDLED;
 167 }
 168
 169 static int adc108s102_scan_direct(struct adc108s102_state *st, unsigned int ch)
 170 {
 171         int ret;
 172
 173         st->tx_buf[0] = cpu_to_be16(ADC108S102_CMD(ch));
 174         ret = spi_sync(st->spi, &st->scan_single_msg);
 175         if (ret)
 176                 return ret;
 177
 178         /* Skip the dummy response in the first slot */
 179         return be16_to_cpu(st->rx_buf[1]);
 180 }
 181
 182 static int adc108s102_read_raw(struct iio_dev *indio_dev,
 183                                struct iio_chan_spec const *chan,
 184                                int *val, int *val2, long m)
 185 {
 186         struct adc108s102_state *st = iio_priv(indio_dev);
 187         int ret;
 188
 189         switch (m) {
 190         case IIO_CHAN_INFO_RAW:
 191                 ret = iio_device_claim_direct_mode(indio_dev);
 192                 if (ret)
 193                         return ret;
 194
 195                 ret = adc108s102_scan_direct(st, chan->address);
 196
 197                 iio_device_release_direct_mode(indio_dev);
 198
 199                 if (ret < 0)
 200                         return ret;
 201
 202                 *val = ADC108S102_RES_DATA(ret);
 203
 204                 return IIO_VAL_INT;
 205         case IIO_CHAN_INFO_SCALE:
 206                 if (chan->type != IIO_VOLTAGE)
 207                         break;
 208
 209                 *val = st->va_millivolt;
 210                 *val2 = chan->scan_type.realbits;
 211
 212                 return IIO_VAL_FRACTIONAL_LOG2;
 213         default:
 214                 break;
 215         }
 216
 217         return -EINVAL;
 218 }
 219
 220 static const struct iio_info adc108s102_info = {
 221         .read_raw               = &adc108s102_read_raw,
 222         .update_scan_mode       = &adc108s102_update_scan_mode,
 223         .driver_module          = THIS_MODULE,
 224 };
 225
 226 static int adc108s102_probe(struct spi_device *spi)
 227 {
 228         struct adc108s102_state *st;
 229         struct iio_dev *indio_dev;
 230         int ret;
 231
 232         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 233         if (!indio_dev)
 234                 return -ENOMEM;
 235
 236         st = iio_priv(indio_dev);
 237
 238         if (ACPI_COMPANION(&spi->dev)) {
 239                 st->va_millivolt = ADC108S102_VA_MV_ACPI_DEFAULT;
 240         } else {
 241                 st->reg = devm_regulator_get(&spi->dev, "vref");
 242                 if (IS_ERR(st->reg))
 243                         return PTR_ERR(st->reg);
 244
 245                 ret = regulator_enable(st->reg);
 246                 if (ret < 0) {
 247                         dev_err(&spi->dev, "Cannot enable vref regulator\n");
 248                         return ret;
 249                 }
 250
 251                 ret = regulator_get_voltage(st->reg);
 252                 if (ret < 0) {
 253                         dev_err(&spi->dev, "vref get voltage failed\n");
 254                         return ret;
 255                 }
 256
 257                 st->va_millivolt = ret / 1000;
 258         }
 259
 260         spi_set_drvdata(spi, indio_dev);
 261         st->spi = spi;
 262
 263         indio_dev->name = spi->modalias;
 264         indio_dev->dev.parent = &spi->dev;
 265         indio_dev->modes = INDIO_DIRECT_MODE;
 266         indio_dev->channels = adc108s102_channels;
 267         indio_dev->num_channels = ARRAY_SIZE(adc108s102_channels);
 268         indio_dev->info = &adc108s102_info;
 269
 270         /* Setup default message */
 271         st->scan_single_xfer.tx_buf = st->tx_buf;
 272         st->scan_single_xfer.rx_buf = st->rx_buf;
 273         st->scan_single_xfer.len = 2 * sizeof(st->tx_buf[0]);
 274
 275         spi_message_init_with_transfers(&st->scan_single_msg,
 276                                         &st->scan_single_xfer, 1);
 277
 278         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 279                                          &adc108s102_trigger_handler, NULL);
 280         if (ret)
 281                 goto error_disable_reg;
 282
 283         ret = iio_device_register(indio_dev);
 284         if (ret) {
 285                 dev_err(&spi->dev, "Failed to register IIO device\n");
 286                 goto error_cleanup_triggered_buffer;
 287         }
 288         return 0;
 289
 290 error_cleanup_triggered_buffer:
 291         iio_triggered_buffer_cleanup(indio_dev);
 292
 293 error_disable_reg:
 294         regulator_disable(st->reg);
 295
 296         return ret;
 297 }
 298
 299 static int adc108s102_remove(struct spi_device *spi)
 300 {
 301         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 302         struct adc108s102_state *st = iio_priv(indio_dev);
 303
 304         iio_device_unregister(indio_dev);
 305         iio_triggered_buffer_cleanup(indio_dev);
 306
 307         regulator_disable(st->reg);
 308
 309         return 0;
 310 }
 311
 312 #ifdef CONFIG_OF
 313 static const struct of_device_id adc108s102_of_match[] = {
 314         { .compatible = "ti,adc108s102" },
 315         { }
 316 };
 317 MODULE_DEVICE_TABLE(of, adc108s102_of_match);
 318 #endif
 319
 320 #ifdef CONFIG_ACPI
 321 static const struct acpi_device_id adc108s102_acpi_ids[] = {
 322         { "INT3495", 0 },
 323         { }
 324 };
 325 MODULE_DEVICE_TABLE(acpi, adc108s102_acpi_ids);
 326 #endif
 327
 328 static const struct spi_device_id adc108s102_id[] = {
 329         { "adc108s102", 0 },
 330         { }
 331 };
 332 MODULE_DEVICE_TABLE(spi, adc108s102_id);
 333
 334 static struct spi_driver adc108s102_driver = {
 335         .driver = {
 336                 .name   = "adc108s102",
 337                 .of_match_table = of_match_ptr(adc108s102_of_match),
 338                 .acpi_match_table = ACPI_PTR(adc108s102_acpi_ids),
 339         },
 340         .probe          = adc108s102_probe,
 341         .remove         = adc108s102_remove,
 342         .id_table       = adc108s102_id,
 343 };
 344 module_spi_driver(adc108s102_driver);
 345
 346 MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@emutex.com>");
 347 MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102 driver");
 348 MODULE_LICENSE("GPL v2");