drivers/staging/iio/adc/ad7298_core.c

   1 /*
   2  * AD7298 SPI ADC driver
   3  *
   4  * Copyright 2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/sysfs.h>
  13 #include <linux/spi/spi.h>
  14 #include <linux/regulator/consumer.h>
  15 #include <linux/err.h>
  16 #include <linux/delay.h>
  17 #include <linux/module.h>
  18
  19 #include <linux/iio/iio.h>
  20 #include <linux/iio/sysfs.h>
  21 #include <linux/iio/buffer.h>
  22
  23 #include "ad7298.h"
  24
  25 #define AD7298_V_CHAN(index)                                            \
  26         {                                                               \
  27                 .type = IIO_VOLTAGE,                                    \
  28                 .indexed = 1,                                           \
  29                 .channel = index,                                       \
  30                 .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |           \
  31                 IIO_CHAN_INFO_SCALE_SHARED_BIT,                         \
  32                 .address = index,                                       \
  33                 .scan_index = index,                                    \
  34                 .scan_type = {                                          \
  35                         .sign = 'u',                                    \
  36                         .realbits = 12,                                 \
  37                         .storagebits = 16,                              \
  38                 },                                                      \
  39         }
  40
  41 static struct iio_chan_spec ad7298_channels[] = {
  42         {
  43                 .type = IIO_TEMP,
  44                 .indexed = 1,
  45                 .channel = 0,
  46                 .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |
  47                 IIO_CHAN_INFO_SCALE_SEPARATE_BIT,
  48                 .address = AD7298_CH_TEMP,
  49                 .scan_index = -1,
  50                 .scan_type = {
  51                         .sign = 's',
  52                         .realbits = 32,
  53                         .storagebits = 32,
  54                 },
  55         },
  56         AD7298_V_CHAN(0),
  57         AD7298_V_CHAN(1),
  58         AD7298_V_CHAN(2),
  59         AD7298_V_CHAN(3),
  60         AD7298_V_CHAN(4),
  61         AD7298_V_CHAN(5),
  62         AD7298_V_CHAN(6),
  63         AD7298_V_CHAN(7),
  64         IIO_CHAN_SOFT_TIMESTAMP(8),
  65 };
  66
  67 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
  68 {
  69         int ret;
  70         st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
  71                                    (AD7298_CH(0) >> ch));
  72
  73         ret = spi_sync(st->spi, &st->scan_single_msg);
  74         if (ret)
  75                 return ret;
  76
  77         return be16_to_cpu(st->rx_buf[0]);
  78 }
  79
  80 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
  81 {
  82         int tmp, ret;
  83         __be16 buf;
  84
  85         buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
  86                           AD7298_TAVG | st->ext_ref);
  87
  88         ret = spi_write(st->spi, (u8 *)&buf, 2);
  89         if (ret)
  90                 return ret;
  91
  92         buf = cpu_to_be16(0);
  93
  94         ret = spi_write(st->spi, (u8 *)&buf, 2);
  95         if (ret)
  96                 return ret;
  97
  98         usleep_range(101, 1000); /* sleep > 100us */
  99
 100         ret = spi_read(st->spi, (u8 *)&buf, 2);
 101         if (ret)
 102                 return ret;
 103
 104         tmp = be16_to_cpu(buf) & RES_MASK(AD7298_BITS);
 105
 106         /*
 107          * One LSB of the ADC corresponds to 0.25 deg C.
 108          * The temperature reading is in 12-bit twos complement format
 109          */
 110
 111         if (tmp & (1 << (AD7298_BITS - 1))) {
 112                 tmp = (4096 - tmp) * 250;
 113                 tmp -= (2 * tmp);
 114
 115         } else {
 116                 tmp *= 250; /* temperature in milli degrees Celsius */
 117         }
 118
 119         *val = tmp;
 120
 121         return 0;
 122 }
 123
 124 static int ad7298_read_raw(struct iio_dev *indio_dev,
 125                            struct iio_chan_spec const *chan,
 126                            int *val,
 127                            int *val2,
 128                            long m)
 129 {
 130         int ret;
 131         struct ad7298_state *st = iio_priv(indio_dev);
 132         unsigned int scale_uv;
 133
 134         switch (m) {
 135         case IIO_CHAN_INFO_RAW:
 136                 mutex_lock(&indio_dev->mlock);
 137                 if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
 138                         ret = -EBUSY;
 139                 } else {
 140                         if (chan->address == AD7298_CH_TEMP)
 141                                 ret = ad7298_scan_temp(st, val);
 142                         else
 143                                 ret = ad7298_scan_direct(st, chan->address);
 144                 }
 145                 mutex_unlock(&indio_dev->mlock);
 146
 147                 if (ret < 0)
 148                         return ret;
 149
 150                 if (chan->address != AD7298_CH_TEMP)
 151                         *val = ret & RES_MASK(AD7298_BITS);
 152
 153                 return IIO_VAL_INT;
 154         case IIO_CHAN_INFO_SCALE:
 155                 switch (chan->type) {
 156                 case IIO_VOLTAGE:
 157                         scale_uv = (st->int_vref_mv * 1000) >> AD7298_BITS;
 158                         *val =  scale_uv / 1000;
 159                         *val2 = (scale_uv % 1000) * 1000;
 160                         return IIO_VAL_INT_PLUS_MICRO;
 161                 case IIO_TEMP:
 162                         *val =  1;
 163                         *val2 = 0;
 164                         return IIO_VAL_INT_PLUS_MICRO;
 165                 default:
 166                         return -EINVAL;
 167                 }
 168         }
 169         return -EINVAL;
 170 }
 171
 172 static const struct iio_info ad7298_info = {
 173         .read_raw = &ad7298_read_raw,
 174         .update_scan_mode = ad7298_update_scan_mode,
 175         .driver_module = THIS_MODULE,
 176 };
 177
 178 static int __devinit ad7298_probe(struct spi_device *spi)
 179 {
 180         struct ad7298_platform_data *pdata = spi->dev.platform_data;
 181         struct ad7298_state *st;
 182         int ret;
 183         struct iio_dev *indio_dev = iio_device_alloc(sizeof(*st));
 184
 185         if (indio_dev == NULL)
 186                 return -ENOMEM;
 187
 188         st = iio_priv(indio_dev);
 189
 190         st->reg = regulator_get(&spi->dev, "vcc");
 191         if (!IS_ERR(st->reg)) {
 192                 ret = regulator_enable(st->reg);
 193                 if (ret)
 194                         goto error_put_reg;
 195         }
 196
 197         spi_set_drvdata(spi, indio_dev);
 198
 199         st->spi = spi;
 200
 201         indio_dev->name = spi_get_device_id(spi)->name;
 202         indio_dev->dev.parent = &spi->dev;
 203         indio_dev->modes = INDIO_DIRECT_MODE;
 204         indio_dev->channels = ad7298_channels;
 205         indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
 206         indio_dev->info = &ad7298_info;
 207
 208         /* Setup default message */
 209
 210         st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
 211         st->scan_single_xfer[0].len = 2;
 212         st->scan_single_xfer[0].cs_change = 1;
 213         st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
 214         st->scan_single_xfer[1].len = 2;
 215         st->scan_single_xfer[1].cs_change = 1;
 216         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 217         st->scan_single_xfer[2].len = 2;
 218
 219         spi_message_init(&st->scan_single_msg);
 220         spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
 221         spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
 222         spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
 223
 224         if (pdata && pdata->vref_mv) {
 225                 st->int_vref_mv = pdata->vref_mv;
 226                 st->ext_ref = AD7298_EXTREF;
 227         } else {
 228                 st->int_vref_mv = AD7298_INTREF_mV;
 229         }
 230
 231         ret = ad7298_register_ring_funcs_and_init(indio_dev);
 232         if (ret)
 233                 goto error_disable_reg;
 234
 235         ret = iio_device_register(indio_dev);
 236         if (ret)
 237                 goto error_cleanup_ring;
 238
 239         return 0;
 240
 241 error_cleanup_ring:
 242         ad7298_ring_cleanup(indio_dev);
 243 error_disable_reg:
 244         if (!IS_ERR(st->reg))
 245                 regulator_disable(st->reg);
 246 error_put_reg:
 247         if (!IS_ERR(st->reg))
 248                 regulator_put(st->reg);
 249         iio_device_free(indio_dev);
 250
 251         return ret;
 252 }
 253
 254 static int __devexit ad7298_remove(struct spi_device *spi)
 255 {
 256         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 257         struct ad7298_state *st = iio_priv(indio_dev);
 258
 259         iio_device_unregister(indio_dev);
 260         ad7298_ring_cleanup(indio_dev);
 261         if (!IS_ERR(st->reg)) {
 262                 regulator_disable(st->reg);
 263                 regulator_put(st->reg);
 264         }
 265         iio_device_free(indio_dev);
 266
 267         return 0;
 268 }
 269
 270 static const struct spi_device_id ad7298_id[] = {
 271         {"ad7298", 0},
 272         {}
 273 };
 274 MODULE_DEVICE_TABLE(spi, ad7298_id);
 275
 276 static struct spi_driver ad7298_driver = {
 277         .driver = {
 278                 .name   = "ad7298",
 279                 .owner  = THIS_MODULE,
 280         },
 281         .probe          = ad7298_probe,
 282         .remove         = __devexit_p(ad7298_remove),
 283         .id_table       = ad7298_id,
 284 };
 285 module_spi_driver(ad7298_driver);
 286
 287 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 288 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
 289 MODULE_LICENSE("GPL v2");