drivers/iio/temperature/maxim_thermocouple.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * maxim_thermocouple.c  - Support for Maxim thermocouple chips
   4  *
   5  * Copyright (C) 2016-2018 Matt Ranostay
   6  * Author: <matt.ranostay@konsulko.com>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/mutex.h>
  12 #include <linux/err.h>
  13 #include <linux/of.h>
  14 #include <linux/of_device.h>
  15 #include <linux/spi/spi.h>
  16 #include <linux/iio/iio.h>
  17 #include <linux/iio/sysfs.h>
  18 #include <linux/iio/trigger.h>
  19 #include <linux/iio/buffer.h>
  20 #include <linux/iio/triggered_buffer.h>
  21 #include <linux/iio/trigger_consumer.h>
  22
  23 #define MAXIM_THERMOCOUPLE_DRV_NAME     "maxim_thermocouple"
  24
  25 enum {
  26         MAX6675,
  27         MAX31855,
  28         MAX31855K,
  29         MAX31855J,
  30         MAX31855N,
  31         MAX31855S,
  32         MAX31855T,
  33         MAX31855E,
  34         MAX31855R,
  35 };
  36
  37 static const char maxim_tc_types[] = {
  38         'K', '?', 'K', 'J', 'N', 'S', 'T', 'E', 'R'
  39 };
  40
  41 static const struct iio_chan_spec max6675_channels[] = {
  42         {       /* thermocouple temperature */
  43                 .type = IIO_TEMP,
  44                 .info_mask_separate =
  45                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
  46                         BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
  47                 .scan_index = 0,
  48                 .scan_type = {
  49                         .sign = 's',
  50                         .realbits = 13,
  51                         .storagebits = 16,
  52                         .shift = 3,
  53                         .endianness = IIO_BE,
  54                 },
  55         },
  56         IIO_CHAN_SOFT_TIMESTAMP(1),
  57 };
  58
  59 static const struct iio_chan_spec max31855_channels[] = {
  60         {       /* thermocouple temperature */
  61                 .type = IIO_TEMP,
  62                 .address = 2,
  63                 .info_mask_separate =
  64                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
  65                         BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
  66                 .scan_index = 0,
  67                 .scan_type = {
  68                         .sign = 's',
  69                         .realbits = 14,
  70                         .storagebits = 16,
  71                         .shift = 2,
  72                         .endianness = IIO_BE,
  73                 },
  74         },
  75         {       /* cold junction temperature */
  76                 .type = IIO_TEMP,
  77                 .address = 0,
  78                 .channel2 = IIO_MOD_TEMP_AMBIENT,
  79                 .modified = 1,
  80                 .info_mask_separate =
  81                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
  82                 .scan_index = 1,
  83                 .scan_type = {
  84                         .sign = 's',
  85                         .realbits = 12,
  86                         .storagebits = 16,
  87                         .shift = 4,
  88                         .endianness = IIO_BE,
  89                 },
  90         },
  91         IIO_CHAN_SOFT_TIMESTAMP(2),
  92 };
  93
  94 static const unsigned long max31855_scan_masks[] = {0x3, 0};
  95
  96 struct maxim_thermocouple_chip {
  97         const struct iio_chan_spec *channels;
  98         const unsigned long *scan_masks;
  99         u8 num_channels;
 100         u8 read_size;
 101
 102         /* bit-check for valid input */
 103         u32 status_bit;
 104 };
 105
 106 static const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = {
 107         [MAX6675] = {
 108                         .channels = max6675_channels,
 109                         .num_channels = ARRAY_SIZE(max6675_channels),
 110                         .read_size = 2,
 111                         .status_bit = BIT(2),
 112                 },
 113         [MAX31855] = {
 114                         .channels = max31855_channels,
 115                         .num_channels = ARRAY_SIZE(max31855_channels),
 116                         .read_size = 4,
 117                         .scan_masks = max31855_scan_masks,
 118                         .status_bit = BIT(16),
 119                 },
 120 };
 121
 122 struct maxim_thermocouple_data {
 123         struct spi_device *spi;
 124         const struct maxim_thermocouple_chip *chip;
 125
 126         u8 buffer[16] ____cacheline_aligned;
 127         char tc_type;
 128 };
 129
 130 static int maxim_thermocouple_read(struct maxim_thermocouple_data *data,
 131                                    struct iio_chan_spec const *chan, int *val)
 132 {
 133         unsigned int storage_bytes = data->chip->read_size;
 134         unsigned int shift = chan->scan_type.shift + (chan->address * 8);
 135         __be16 buf16;
 136         __be32 buf32;
 137         int ret;
 138
 139         switch (storage_bytes) {
 140         case 2:
 141                 ret = spi_read(data->spi, (void *)&buf16, storage_bytes);
 142                 *val = be16_to_cpu(buf16);
 143                 break;
 144         case 4:
 145                 ret = spi_read(data->spi, (void *)&buf32, storage_bytes);
 146                 *val = be32_to_cpu(buf32);
 147                 break;
 148         default:
 149                 ret = -EINVAL;
 150         }
 151
 152         if (ret)
 153                 return ret;
 154
 155         /* check to be sure this is a valid reading */
 156         if (*val & data->chip->status_bit)
 157                 return -EINVAL;
 158
 159         *val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1);
 160
 161         return 0;
 162 }
 163
 164 static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private)
 165 {
 166         struct iio_poll_func *pf = private;
 167         struct iio_dev *indio_dev = pf->indio_dev;
 168         struct maxim_thermocouple_data *data = iio_priv(indio_dev);
 169         int ret;
 170
 171         ret = spi_read(data->spi, data->buffer, data->chip->read_size);
 172         if (!ret) {
 173                 iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
 174                                                    iio_get_time_ns(indio_dev));
 175         }
 176
 177         iio_trigger_notify_done(indio_dev->trig);
 178
 179         return IRQ_HANDLED;
 180 }
 181
 182 static int maxim_thermocouple_read_raw(struct iio_dev *indio_dev,
 183                                        struct iio_chan_spec const *chan,
 184                                        int *val, int *val2, long mask)
 185 {
 186         struct maxim_thermocouple_data *data = iio_priv(indio_dev);
 187         int ret = -EINVAL;
 188
 189         switch (mask) {
 190         case IIO_CHAN_INFO_RAW:
 191                 ret = iio_device_claim_direct_mode(indio_dev);
 192                 if (ret)
 193                         return ret;
 194
 195                 ret = maxim_thermocouple_read(data, chan, val);
 196                 iio_device_release_direct_mode(indio_dev);
 197
 198                 if (!ret)
 199                         return IIO_VAL_INT;
 200
 201                 break;
 202         case IIO_CHAN_INFO_SCALE:
 203                 switch (chan->channel2) {
 204                 case IIO_MOD_TEMP_AMBIENT:
 205                         *val = 62;
 206                         *val2 = 500000; /* 1000 * 0.0625 */
 207                         ret = IIO_VAL_INT_PLUS_MICRO;
 208                         break;
 209                 default:
 210                         *val = 250; /* 1000 * 0.25 */
 211                         ret = IIO_VAL_INT;
 212                 }
 213                 break;
 214         case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
 215                 *val = data->tc_type;
 216                 ret = IIO_VAL_CHAR;
 217                 break;
 218         }
 219
 220         return ret;
 221 }
 222
 223 static const struct iio_info maxim_thermocouple_info = {
 224         .read_raw = maxim_thermocouple_read_raw,
 225 };
 226
 227 static int maxim_thermocouple_probe(struct spi_device *spi)
 228 {
 229         const struct spi_device_id *id = spi_get_device_id(spi);
 230         struct iio_dev *indio_dev;
 231         struct maxim_thermocouple_data *data;
 232         const int chip_type = (id->driver_data == MAX6675) ? MAX6675 : MAX31855;
 233         const struct maxim_thermocouple_chip *chip =
 234                 &maxim_thermocouple_chips[chip_type];
 235         int ret;
 236
 237         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
 238         if (!indio_dev)
 239                 return -ENOMEM;
 240
 241         indio_dev->info = &maxim_thermocouple_info;
 242         indio_dev->name = MAXIM_THERMOCOUPLE_DRV_NAME;
 243         indio_dev->channels = chip->channels;
 244         indio_dev->available_scan_masks = chip->scan_masks;
 245         indio_dev->num_channels = chip->num_channels;
 246         indio_dev->modes = INDIO_DIRECT_MODE;
 247
 248         data = iio_priv(indio_dev);
 249         data->spi = spi;
 250         data->chip = chip;
 251         data->tc_type = maxim_tc_types[id->driver_data];
 252
 253         ret = devm_iio_triggered_buffer_setup(&spi->dev,
 254                                 indio_dev, NULL,
 255                                 maxim_thermocouple_trigger_handler, NULL);
 256         if (ret)
 257                 return ret;
 258
 259         if (id->driver_data == MAX31855)
 260                 dev_warn(&spi->dev, "generic max31855 ID is deprecated\nplease use more specific part type");
 261
 262         return devm_iio_device_register(&spi->dev, indio_dev);
 263 }
 264
 265 static const struct spi_device_id maxim_thermocouple_id[] = {
 266         {"max6675", MAX6675},
 267         {"max31855", MAX31855},
 268         {"max31855k", MAX31855K},
 269         {"max31855j", MAX31855J},
 270         {"max31855n", MAX31855N},
 271         {"max31855s", MAX31855S},
 272         {"max31855t", MAX31855T},
 273         {"max31855e", MAX31855E},
 274         {"max31855r", MAX31855R},
 275         {},
 276 };
 277 MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id);
 278
 279 static const struct of_device_id maxim_thermocouple_of_match[] = {
 280         { .compatible = "maxim,max6675" },
 281         { .compatible = "maxim,max31855" },
 282         { .compatible = "maxim,max31855k" },
 283         { .compatible = "maxim,max31855j" },
 284         { .compatible = "maxim,max31855n" },
 285         { .compatible = "maxim,max31855s" },
 286         { .compatible = "maxim,max31855t" },
 287         { .compatible = "maxim,max31855e" },
 288         { .compatible = "maxim,max31855r" },
 289         { },
 290 };
 291 MODULE_DEVICE_TABLE(of, maxim_thermocouple_of_match);
 292
 293 static struct spi_driver maxim_thermocouple_driver = {
 294         .driver = {
 295                 .name   = MAXIM_THERMOCOUPLE_DRV_NAME,
 296                 .of_match_table = maxim_thermocouple_of_match,
 297         },
 298         .probe          = maxim_thermocouple_probe,
 299         .id_table       = maxim_thermocouple_id,
 300 };
 301 module_spi_driver(maxim_thermocouple_driver);
 302
 303 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
 304 MODULE_DESCRIPTION("Maxim thermocouple sensors");
 305 MODULE_LICENSE("GPL");