2 * maxim_thermocouple.c - Support for Maxim thermocouple chips
4 * Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
17 #include <linux/module.h>
18 #include <linux/init.h>
19 #include <linux/mutex.h>
20 #include <linux/err.h>
21 #include <linux/spi/spi.h>
22 #include <linux/iio/iio.h>
23 #include <linux/iio/trigger.h>
24 #include <linux/iio/buffer.h>
25 #include <linux/iio/triggered_buffer.h>
26 #include <linux/iio/trigger_consumer.h>
28 #define MAXIM_THERMOCOUPLE_DRV_NAME "maxim_thermocouple"
35 static const struct iio_chan_spec max6675_channels[] = {
36 { /* thermocouple temperature */
39 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
49 IIO_CHAN_SOFT_TIMESTAMP(1),
52 static const struct iio_chan_spec max31855_channels[] = {
53 { /* thermocouple temperature */
57 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
67 { /* cold junction temperature */
70 .channel2 = IIO_MOD_TEMP_AMBIENT,
73 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
83 IIO_CHAN_SOFT_TIMESTAMP(2),
86 static const unsigned long max31855_scan_masks[] = {0x3, 0};
88 struct maxim_thermocouple_chip {
89 const struct iio_chan_spec *channels;
90 const unsigned long *scan_masks;
94 /* bit-check for valid input */
98 static const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = {
100 .channels = max6675_channels,
101 .num_channels = ARRAY_SIZE(max6675_channels),
103 .status_bit = BIT(2),
106 .channels = max31855_channels,
107 .num_channels = ARRAY_SIZE(max31855_channels),
109 .scan_masks = max31855_scan_masks,
110 .status_bit = BIT(16),
114 struct maxim_thermocouple_data {
115 struct spi_device *spi;
116 const struct maxim_thermocouple_chip *chip;
118 u8 buffer[16] ____cacheline_aligned;
121 static int maxim_thermocouple_read(struct maxim_thermocouple_data *data,
122 struct iio_chan_spec const *chan, int *val)
124 unsigned int storage_bytes = data->chip->read_size;
125 unsigned int shift = chan->scan_type.shift + (chan->address * 8);
129 ret = spi_read(data->spi, (void *) &buf, storage_bytes);
133 switch (storage_bytes) {
135 *val = be16_to_cpu(buf);
138 *val = be32_to_cpu(buf);
142 /* check to be sure this is a valid reading */
143 if (*val & data->chip->status_bit)
146 *val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1);
151 static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private)
153 struct iio_poll_func *pf = private;
154 struct iio_dev *indio_dev = pf->indio_dev;
155 struct maxim_thermocouple_data *data = iio_priv(indio_dev);
158 ret = spi_read(data->spi, data->buffer, data->chip->read_size);
160 iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
161 iio_get_time_ns(indio_dev));
164 iio_trigger_notify_done(indio_dev->trig);
169 static int maxim_thermocouple_read_raw(struct iio_dev *indio_dev,
170 struct iio_chan_spec const *chan,
171 int *val, int *val2, long mask)
173 struct maxim_thermocouple_data *data = iio_priv(indio_dev);
177 case IIO_CHAN_INFO_RAW:
178 ret = iio_device_claim_direct_mode(indio_dev);
182 ret = maxim_thermocouple_read(data, chan, val);
183 iio_device_release_direct_mode(indio_dev);
189 case IIO_CHAN_INFO_SCALE:
190 switch (chan->channel2) {
191 case IIO_MOD_TEMP_AMBIENT:
193 *val2 = 500000; /* 1000 * 0.0625 */
194 ret = IIO_VAL_INT_PLUS_MICRO;
197 *val = 250; /* 1000 * 0.25 */
206 static const struct iio_info maxim_thermocouple_info = {
207 .driver_module = THIS_MODULE,
208 .read_raw = maxim_thermocouple_read_raw,
211 static int maxim_thermocouple_probe(struct spi_device *spi)
213 const struct spi_device_id *id = spi_get_device_id(spi);
214 struct iio_dev *indio_dev;
215 struct maxim_thermocouple_data *data;
216 const struct maxim_thermocouple_chip *chip =
217 &maxim_thermocouple_chips[id->driver_data];
220 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
224 indio_dev->info = &maxim_thermocouple_info;
225 indio_dev->name = MAXIM_THERMOCOUPLE_DRV_NAME;
226 indio_dev->channels = chip->channels;
227 indio_dev->available_scan_masks = chip->scan_masks;
228 indio_dev->num_channels = chip->num_channels;
229 indio_dev->modes = INDIO_DIRECT_MODE;
231 data = iio_priv(indio_dev);
235 ret = iio_triggered_buffer_setup(indio_dev, NULL,
236 maxim_thermocouple_trigger_handler, NULL);
240 ret = iio_device_register(indio_dev);
242 goto error_unreg_buffer;
247 iio_triggered_buffer_cleanup(indio_dev);
252 static int maxim_thermocouple_remove(struct spi_device *spi)
254 struct iio_dev *indio_dev = spi_get_drvdata(spi);
256 iio_device_unregister(indio_dev);
257 iio_triggered_buffer_cleanup(indio_dev);
262 static const struct spi_device_id maxim_thermocouple_id[] = {
263 {"max6675", MAX6675},
264 {"max31855", MAX31855},
267 MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id);
269 static struct spi_driver maxim_thermocouple_driver = {
271 .name = MAXIM_THERMOCOUPLE_DRV_NAME,
273 .probe = maxim_thermocouple_probe,
274 .remove = maxim_thermocouple_remove,
275 .id_table = maxim_thermocouple_id,
277 module_spi_driver(maxim_thermocouple_driver);
279 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
280 MODULE_DESCRIPTION("Maxim thermocouple sensors");
281 MODULE_LICENSE("GPL");