drivers/iio/adc/ltc2497.c

   1 /*
   2  * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
   3  *
   4  * Copyright (C) 2017 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  *
   8  * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
   9  */
  10
  11 #include <linux/delay.h>
  12 #include <linux/i2c.h>
  13 #include <linux/iio/iio.h>
  14 #include <linux/iio/driver.h>
  15 #include <linux/iio/sysfs.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/regulator/consumer.h>
  19
  20 #define LTC2497_ENABLE                  0xA0
  21 #define LTC2497_SGL                     BIT(4)
  22 #define LTC2497_DIFF                    0
  23 #define LTC2497_SIGN                    BIT(3)
  24 #define LTC2497_CONFIG_DEFAULT          LTC2497_ENABLE
  25 #define LTC2497_CONVERSION_TIME_MS      150ULL
  26
  27 struct ltc2497_st {
  28         struct i2c_client *client;
  29         struct regulator *ref;
  30         ktime_t time_prev;
  31         u8 addr_prev;
  32         /*
  33          * DMA (thus cache coherency maintenance) requires the
  34          * transfer buffers to live in their own cache lines.
  35          */
  36         __be32 buf ____cacheline_aligned;
  37 };
  38
  39 static int ltc2497_wait_conv(struct ltc2497_st *st)
  40 {
  41         s64 time_elapsed;
  42
  43         time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev);
  44
  45         if (time_elapsed < LTC2497_CONVERSION_TIME_MS) {
  46                 /* delay if conversion time not passed
  47                  * since last read or write
  48                  */
  49                 if (msleep_interruptible(
  50                     LTC2497_CONVERSION_TIME_MS - time_elapsed))
  51                         return -ERESTARTSYS;
  52
  53                 return 0;
  54         }
  55
  56         if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) {
  57                 /* We're in automatic mode -
  58                  * so the last reading is stil not outdated
  59                  */
  60                 return 0;
  61         }
  62
  63         return 1;
  64 }
  65
  66 static int ltc2497_read(struct ltc2497_st *st, u8 address, int *val)
  67 {
  68         struct i2c_client *client = st->client;
  69         int ret;
  70
  71         ret = ltc2497_wait_conv(st);
  72         if (ret < 0)
  73                 return ret;
  74
  75         if (ret || st->addr_prev != address) {
  76                 ret = i2c_smbus_write_byte(st->client,
  77                                            LTC2497_ENABLE | address);
  78                 if (ret < 0)
  79                         return ret;
  80                 st->addr_prev = address;
  81                 if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS))
  82                         return -ERESTARTSYS;
  83         }
  84         ret = i2c_master_recv(client, (char *)&st->buf, 3);
  85         if (ret < 0)  {
  86                 dev_err(&client->dev, "i2c_master_recv failed\n");
  87                 return ret;
  88         }
  89         st->time_prev = ktime_get();
  90
  91         /* convert and shift the result,
  92          * and finally convert from offset binary to signed integer
  93          */
  94         *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
  95
  96         return ret;
  97 }
  98
  99 static int ltc2497_read_raw(struct iio_dev *indio_dev,
 100                             struct iio_chan_spec const *chan,
 101                             int *val, int *val2, long mask)
 102 {
 103         struct ltc2497_st *st = iio_priv(indio_dev);
 104         int ret;
 105
 106         switch (mask) {
 107         case IIO_CHAN_INFO_RAW:
 108                 mutex_lock(&indio_dev->mlock);
 109                 ret = ltc2497_read(st, chan->address, val);
 110                 mutex_unlock(&indio_dev->mlock);
 111                 if (ret < 0)
 112                         return ret;
 113
 114                 return IIO_VAL_INT;
 115
 116         case IIO_CHAN_INFO_SCALE:
 117                 ret = regulator_get_voltage(st->ref);
 118                 if (ret < 0)
 119                         return ret;
 120
 121                 *val = ret / 1000;
 122                 *val2 = 17;
 123
 124                 return IIO_VAL_FRACTIONAL_LOG2;
 125
 126         default:
 127                 return -EINVAL;
 128         }
 129 }
 130
 131 #define LTC2497_CHAN(_chan, _addr, _ds_name) { \
 132         .type = IIO_VOLTAGE, \
 133         .indexed = 1, \
 134         .channel = (_chan), \
 135         .address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN : 0)), \
 136         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 137         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
 138         .datasheet_name = (_ds_name), \
 139 }
 140
 141 #define LTC2497_CHAN_DIFF(_chan, _addr) { \
 142         .type = IIO_VOLTAGE, \
 143         .indexed = 1, \
 144         .channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \
 145         .channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\
 146         .address = (_addr | _chan), \
 147         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 148         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
 149         .differential = 1, \
 150 }
 151
 152 static const struct iio_chan_spec ltc2497_channel[] = {
 153         LTC2497_CHAN(0, LTC2497_SGL, "CH0"),
 154         LTC2497_CHAN(1, LTC2497_SGL, "CH1"),
 155         LTC2497_CHAN(2, LTC2497_SGL, "CH2"),
 156         LTC2497_CHAN(3, LTC2497_SGL, "CH3"),
 157         LTC2497_CHAN(4, LTC2497_SGL, "CH4"),
 158         LTC2497_CHAN(5, LTC2497_SGL, "CH5"),
 159         LTC2497_CHAN(6, LTC2497_SGL, "CH6"),
 160         LTC2497_CHAN(7, LTC2497_SGL, "CH7"),
 161         LTC2497_CHAN(8, LTC2497_SGL, "CH8"),
 162         LTC2497_CHAN(9, LTC2497_SGL, "CH9"),
 163         LTC2497_CHAN(10, LTC2497_SGL, "CH10"),
 164         LTC2497_CHAN(11, LTC2497_SGL, "CH11"),
 165         LTC2497_CHAN(12, LTC2497_SGL, "CH12"),
 166         LTC2497_CHAN(13, LTC2497_SGL, "CH13"),
 167         LTC2497_CHAN(14, LTC2497_SGL, "CH14"),
 168         LTC2497_CHAN(15, LTC2497_SGL, "CH15"),
 169         LTC2497_CHAN_DIFF(0, LTC2497_DIFF),
 170         LTC2497_CHAN_DIFF(1, LTC2497_DIFF),
 171         LTC2497_CHAN_DIFF(2, LTC2497_DIFF),
 172         LTC2497_CHAN_DIFF(3, LTC2497_DIFF),
 173         LTC2497_CHAN_DIFF(4, LTC2497_DIFF),
 174         LTC2497_CHAN_DIFF(5, LTC2497_DIFF),
 175         LTC2497_CHAN_DIFF(6, LTC2497_DIFF),
 176         LTC2497_CHAN_DIFF(7, LTC2497_DIFF),
 177         LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN),
 178         LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN),
 179         LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN),
 180         LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN),
 181         LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN),
 182         LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN),
 183         LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN),
 184         LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN),
 185 };
 186
 187 static const struct iio_info ltc2497_info = {
 188         .read_raw = ltc2497_read_raw,
 189 };
 190
 191 static int ltc2497_probe(struct i2c_client *client,
 192                          const struct i2c_device_id *id)
 193 {
 194         struct iio_dev *indio_dev;
 195         struct ltc2497_st *st;
 196         struct iio_map *plat_data;
 197         int ret;
 198
 199         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
 200                                      I2C_FUNC_SMBUS_WRITE_BYTE))
 201                 return -EOPNOTSUPP;
 202
 203         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st));
 204         if (!indio_dev)
 205                 return -ENOMEM;
 206
 207         st = iio_priv(indio_dev);
 208         i2c_set_clientdata(client, indio_dev);
 209         st->client = client;
 210
 211         indio_dev->dev.parent = &client->dev;
 212         indio_dev->name = id->name;
 213         indio_dev->info = &ltc2497_info;
 214         indio_dev->modes = INDIO_DIRECT_MODE;
 215         indio_dev->channels = ltc2497_channel;
 216         indio_dev->num_channels = ARRAY_SIZE(ltc2497_channel);
 217
 218         st->ref = devm_regulator_get(&client->dev, "vref");
 219         if (IS_ERR(st->ref))
 220                 return PTR_ERR(st->ref);
 221
 222         ret = regulator_enable(st->ref);
 223         if (ret < 0)
 224                 return ret;
 225
 226         if (client->dev.platform_data) {
 227                 plat_data = ((struct iio_map *)client->dev.platform_data);
 228                 ret = iio_map_array_register(indio_dev, plat_data);
 229                 if (ret) {
 230                         dev_err(&indio_dev->dev, "iio map err: %d\n", ret);
 231                         goto err_regulator_disable;
 232                 }
 233         }
 234
 235         ret = i2c_smbus_write_byte(st->client, LTC2497_CONFIG_DEFAULT);
 236         if (ret < 0)
 237                 goto err_array_unregister;
 238
 239         st->addr_prev = LTC2497_CONFIG_DEFAULT;
 240         st->time_prev = ktime_get();
 241
 242         ret = iio_device_register(indio_dev);
 243         if (ret < 0)
 244                 goto err_array_unregister;
 245
 246         return 0;
 247
 248 err_array_unregister:
 249         iio_map_array_unregister(indio_dev);
 250
 251 err_regulator_disable:
 252         regulator_disable(st->ref);
 253
 254         return ret;
 255 }
 256
 257 static int ltc2497_remove(struct i2c_client *client)
 258 {
 259         struct iio_dev *indio_dev = i2c_get_clientdata(client);
 260         struct ltc2497_st *st = iio_priv(indio_dev);
 261
 262         iio_map_array_unregister(indio_dev);
 263         iio_device_unregister(indio_dev);
 264         regulator_disable(st->ref);
 265
 266         return 0;
 267 }
 268
 269 static const struct i2c_device_id ltc2497_id[] = {
 270         { "ltc2497", 0 },
 271         { }
 272 };
 273 MODULE_DEVICE_TABLE(i2c, ltc2497_id);
 274
 275 static const struct of_device_id ltc2497_of_match[] = {
 276         { .compatible = "lltc,ltc2497", },
 277         {},
 278 };
 279 MODULE_DEVICE_TABLE(of, ltc2497_of_match);
 280
 281 static struct i2c_driver ltc2497_driver = {
 282         .driver = {
 283                 .name = "ltc2497",
 284                 .of_match_table = of_match_ptr(ltc2497_of_match),
 285         },
 286         .probe = ltc2497_probe,
 287         .remove = ltc2497_remove,
 288         .id_table = ltc2497_id,
 289 };
 290 module_i2c_driver(ltc2497_driver);
 291
 292 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 293 MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
 294 MODULE_LICENSE("GPL v2");