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/spi/spi.h>
  14 #include <linux/iio/iio.h>
  15 #include <linux/iio/trigger.h>
  16 #include <linux/iio/buffer.h>
  17 #include <linux/iio/triggered_buffer.h>
  18 #include <linux/iio/trigger_consumer.h>
  19
  20 #define MAXIM_THERMOCOUPLE_DRV_NAME     "maxim_thermocouple"
  21
  22 enum {
  23         MAX6675,
  24         MAX31855,
  25 };
  26
  27 static const struct iio_chan_spec max6675_channels[] = {
  28         {       /* thermocouple temperature */
  29                 .type = IIO_TEMP,
  30                 .info_mask_separate =
  31                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
  32                 .scan_index = 0,
  33                 .scan_type = {
  34                         .sign = 's',
  35                         .realbits = 13,
  36                         .storagebits = 16,
  37                         .shift = 3,
  38                         .endianness = IIO_BE,
  39                 },
  40         },
  41         IIO_CHAN_SOFT_TIMESTAMP(1),
  42 };
  43
  44 static const struct iio_chan_spec max31855_channels[] = {
  45         {       /* thermocouple temperature */
  46                 .type = IIO_TEMP,
  47                 .address = 2,
  48                 .info_mask_separate =
  49                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
  50                 .scan_index = 0,
  51                 .scan_type = {
  52                         .sign = 's',
  53                         .realbits = 14,
  54                         .storagebits = 16,
  55                         .shift = 2,
  56                         .endianness = IIO_BE,
  57                 },
  58         },
  59         {       /* cold junction temperature */
  60                 .type = IIO_TEMP,
  61                 .address = 0,
  62                 .channel2 = IIO_MOD_TEMP_AMBIENT,
  63                 .modified = 1,
  64                 .info_mask_separate =
  65                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
  66                 .scan_index = 1,
  67                 .scan_type = {
  68                         .sign = 's',
  69                         .realbits = 12,
  70                         .storagebits = 16,
  71                         .shift = 4,
  72                         .endianness = IIO_BE,
  73                 },
  74         },
  75         IIO_CHAN_SOFT_TIMESTAMP(2),
  76 };
  77
  78 static const unsigned long max31855_scan_masks[] = {0x3, 0};
  79
  80 struct maxim_thermocouple_chip {
  81         const struct iio_chan_spec *channels;
  82         const unsigned long *scan_masks;
  83         u8 num_channels;
  84         u8 read_size;
  85
  86         /* bit-check for valid input */
  87         u32 status_bit;
  88 };
  89
  90 static const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = {
  91         [MAX6675] = {
  92                         .channels = max6675_channels,
  93                         .num_channels = ARRAY_SIZE(max6675_channels),
  94                         .read_size = 2,
  95                         .status_bit = BIT(2),
  96                 },
  97         [MAX31855] = {
  98                         .channels = max31855_channels,
  99                         .num_channels = ARRAY_SIZE(max31855_channels),
 100                         .read_size = 4,
 101                         .scan_masks = max31855_scan_masks,
 102                         .status_bit = BIT(16),
 103                 },
 104 };
 105
 106 struct maxim_thermocouple_data {
 107         struct spi_device *spi;
 108         const struct maxim_thermocouple_chip *chip;
 109
 110         u8 buffer[16] ____cacheline_aligned;
 111 };
 112
 113 static int maxim_thermocouple_read(struct maxim_thermocouple_data *data,
 114                                    struct iio_chan_spec const *chan, int *val)
 115 {
 116         unsigned int storage_bytes = data->chip->read_size;
 117         unsigned int shift = chan->scan_type.shift + (chan->address * 8);
 118         __be16 buf16;
 119         __be32 buf32;
 120         int ret;
 121
 122         switch (storage_bytes) {
 123         case 2:
 124                 ret = spi_read(data->spi, (void *)&buf16, storage_bytes);
 125                 *val = be16_to_cpu(buf16);
 126                 break;
 127         case 4:
 128                 ret = spi_read(data->spi, (void *)&buf32, storage_bytes);
 129                 *val = be32_to_cpu(buf32);
 130                 break;
 131         default:
 132                 ret = -EINVAL;
 133         }
 134
 135         if (ret)
 136                 return ret;
 137
 138         /* check to be sure this is a valid reading */
 139         if (*val & data->chip->status_bit)
 140                 return -EINVAL;
 141
 142         *val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1);
 143
 144         return 0;
 145 }
 146
 147 static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private)
 148 {
 149         struct iio_poll_func *pf = private;
 150         struct iio_dev *indio_dev = pf->indio_dev;
 151         struct maxim_thermocouple_data *data = iio_priv(indio_dev);
 152         int ret;
 153
 154         ret = spi_read(data->spi, data->buffer, data->chip->read_size);
 155         if (!ret) {
 156                 iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
 157                                                    iio_get_time_ns(indio_dev));
 158         }
 159
 160         iio_trigger_notify_done(indio_dev->trig);
 161
 162         return IRQ_HANDLED;
 163 }
 164
 165 static int maxim_thermocouple_read_raw(struct iio_dev *indio_dev,
 166                                        struct iio_chan_spec const *chan,
 167                                        int *val, int *val2, long mask)
 168 {
 169         struct maxim_thermocouple_data *data = iio_priv(indio_dev);
 170         int ret = -EINVAL;
 171
 172         switch (mask) {
 173         case IIO_CHAN_INFO_RAW:
 174                 ret = iio_device_claim_direct_mode(indio_dev);
 175                 if (ret)
 176                         return ret;
 177
 178                 ret = maxim_thermocouple_read(data, chan, val);
 179                 iio_device_release_direct_mode(indio_dev);
 180
 181                 if (!ret)
 182                         return IIO_VAL_INT;
 183
 184                 break;
 185         case IIO_CHAN_INFO_SCALE:
 186                 switch (chan->channel2) {
 187                 case IIO_MOD_TEMP_AMBIENT:
 188                         *val = 62;
 189                         *val2 = 500000; /* 1000 * 0.0625 */
 190                         ret = IIO_VAL_INT_PLUS_MICRO;
 191                         break;
 192                 default:
 193                         *val = 250; /* 1000 * 0.25 */
 194                         ret = IIO_VAL_INT;
 195                 };
 196                 break;
 197         }
 198
 199         return ret;
 200 }
 201
 202 static const struct iio_info maxim_thermocouple_info = {
 203         .read_raw = maxim_thermocouple_read_raw,
 204 };
 205
 206 static int maxim_thermocouple_probe(struct spi_device *spi)
 207 {
 208         const struct spi_device_id *id = spi_get_device_id(spi);
 209         struct iio_dev *indio_dev;
 210         struct maxim_thermocouple_data *data;
 211         const struct maxim_thermocouple_chip *chip =
 212                         &maxim_thermocouple_chips[id->driver_data];
 213         int ret;
 214
 215         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
 216         if (!indio_dev)
 217                 return -ENOMEM;
 218
 219         indio_dev->info = &maxim_thermocouple_info;
 220         indio_dev->name = MAXIM_THERMOCOUPLE_DRV_NAME;
 221         indio_dev->channels = chip->channels;
 222         indio_dev->available_scan_masks = chip->scan_masks;
 223         indio_dev->num_channels = chip->num_channels;
 224         indio_dev->modes = INDIO_DIRECT_MODE;
 225         indio_dev->dev.parent = &spi->dev;
 226
 227         data = iio_priv(indio_dev);
 228         data->spi = spi;
 229         data->chip = chip;
 230
 231         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 232                                 maxim_thermocouple_trigger_handler, NULL);
 233         if (ret)
 234                 return ret;
 235
 236         ret = iio_device_register(indio_dev);
 237         if (ret)
 238                 goto error_unreg_buffer;
 239
 240         return 0;
 241
 242 error_unreg_buffer:
 243         iio_triggered_buffer_cleanup(indio_dev);
 244
 245         return ret;
 246 }
 247
 248 static int maxim_thermocouple_remove(struct spi_device *spi)
 249 {
 250         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 251
 252         iio_device_unregister(indio_dev);
 253         iio_triggered_buffer_cleanup(indio_dev);
 254
 255         return 0;
 256 }
 257
 258 static const struct spi_device_id maxim_thermocouple_id[] = {
 259         {"max6675", MAX6675},
 260         {"max31855", MAX31855},
 261         {},
 262 };
 263 MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id);
 264
 265 static struct spi_driver maxim_thermocouple_driver = {
 266         .driver = {
 267                 .name   = MAXIM_THERMOCOUPLE_DRV_NAME,
 268         },
 269         .probe          = maxim_thermocouple_probe,
 270         .remove         = maxim_thermocouple_remove,
 271         .id_table       = maxim_thermocouple_id,
 272 };
 273 module_spi_driver(maxim_thermocouple_driver);
 274
 275 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
 276 MODULE_DESCRIPTION("Maxim thermocouple sensors");
 277 MODULE_LICENSE("GPL");