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/init.h>
10 #include <linux/mod_devicetable.h>
11 #include <linux/module.h>
12 #include <linux/err.h>
13 #include <linux/spi/spi.h>
14 #include <linux/types.h>
15 #include <linux/iio/iio.h>
16 #include <linux/iio/sysfs.h>
17 #include <linux/iio/trigger.h>
18 #include <linux/iio/buffer.h>
19 #include <linux/iio/triggered_buffer.h>
20 #include <linux/iio/trigger_consumer.h>
21
22 #define MAXIM_THERMOCOUPLE_DRV_NAME "maxim_thermocouple"
23
24 enum {
25 MAX6675,
26 MAX31855,
27 MAX31855K,
28 MAX31855J,
29 MAX31855N,
30 MAX31855S,
31 MAX31855T,
32 MAX31855E,
33 MAX31855R,
34 };
35
36 static const char maxim_tc_types[] = {
37 'K', '?', 'K', 'J', 'N', 'S', 'T', 'E', 'R'
38 };
39
40 static const struct iio_chan_spec max6675_channels[] = {
41 { /* thermocouple temperature */
42 .type = IIO_TEMP,
43 .info_mask_separate =
44 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
45 BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
46 .scan_index = 0,
47 .scan_type = {
48 .sign = 's',
49 .realbits = 13,
50 .storagebits = 16,
51 .shift = 3,
52 .endianness = IIO_BE,
53 },
54 },
55 IIO_CHAN_SOFT_TIMESTAMP(1),
56 };
57
58 static const struct iio_chan_spec max31855_channels[] = {
59 { /* thermocouple temperature */
60 .type = IIO_TEMP,
61 .address = 2,
62 .info_mask_separate =
63 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
64 BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
65 .scan_index = 0,
66 .scan_type = {
67 .sign = 's',
68 .realbits = 14,
69 .storagebits = 16,
70 .shift = 2,
71 .endianness = IIO_BE,
72 },
73 },
74 { /* cold junction temperature */
75 .type = IIO_TEMP,
76 .address = 0,
77 .channel2 = IIO_MOD_TEMP_AMBIENT,
78 .modified = 1,
79 .info_mask_separate =
80 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
81 .scan_index = 1,
82 .scan_type = {
83 .sign = 's',
84 .realbits = 12,
85 .storagebits = 16,
86 .shift = 4,
87 .endianness = IIO_BE,
88 },
89 },
90 IIO_CHAN_SOFT_TIMESTAMP(2),
91 };
92
93 static const unsigned long max31855_scan_masks[] = {0x3, 0};
94
95 struct maxim_thermocouple_chip {
96 const struct iio_chan_spec *channels;
97 const unsigned long *scan_masks;
98 u8 num_channels;
99 u8 read_size;
100
101 /* bit-check for valid input */
102 u32 status_bit;
103 };
104
105 static const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = {
106 [MAX6675] = {
107 .channels = max6675_channels,
108 .num_channels = ARRAY_SIZE(max6675_channels),
109 .read_size = 2,
110 .status_bit = BIT(2),
111 },
112 [MAX31855] = {
113 .channels = max31855_channels,
114 .num_channels = ARRAY_SIZE(max31855_channels),
115 .read_size = 4,
116 .scan_masks = max31855_scan_masks,
117 .status_bit = BIT(16),
118 },
119 };
120
121 struct maxim_thermocouple_data {
122 struct spi_device *spi;
123 const struct maxim_thermocouple_chip *chip;
124 char tc_type;
125 /* Buffer for reading up to 2 hardware channels. */
126 struct {
127 union {
128 __be16 raw16;
129 __be32 raw32;
130 __be16 raw[2];
131 };
132 aligned_s64 timestamp;
133 } buffer __aligned(IIO_DMA_MINALIGN);
134 };
135
maxim_thermocouple_read(struct maxim_thermocouple_data * data,struct iio_chan_spec const * chan,int * val)136 static int maxim_thermocouple_read(struct maxim_thermocouple_data *data,
137 struct iio_chan_spec const *chan, int *val)
138 {
139 unsigned int storage_bytes = data->chip->read_size;
140 unsigned int shift = chan->scan_type.shift + (chan->address * 8);
141 int ret;
142
143 switch (storage_bytes) {
144 case 2:
145 ret = spi_read(data->spi, &data->buffer.raw16, storage_bytes);
146 *val = be16_to_cpu(data->buffer.raw16);
147 break;
148 case 4:
149 ret = spi_read(data->spi, &data->buffer.raw32, storage_bytes);
150 *val = be32_to_cpu(data->buffer.raw32);
151 break;
152 default:
153 ret = -EINVAL;
154 }
155
156 if (ret)
157 return ret;
158
159 /* check to be sure this is a valid reading */
160 if (*val & data->chip->status_bit)
161 return -EINVAL;
162
163 *val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1);
164
165 return 0;
166 }
167
maxim_thermocouple_trigger_handler(int irq,void * private)168 static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private)
169 {
170 struct iio_poll_func *pf = private;
171 struct iio_dev *indio_dev = pf->indio_dev;
172 struct maxim_thermocouple_data *data = iio_priv(indio_dev);
173 int ret;
174
175 ret = spi_read(data->spi, data->buffer.raw, data->chip->read_size);
176 if (!ret) {
177 iio_push_to_buffers_with_ts(indio_dev, &data->buffer,
178 sizeof(data->buffer),
179 iio_get_time_ns(indio_dev));
180 }
181
182 iio_trigger_notify_done(indio_dev->trig);
183
184 return IRQ_HANDLED;
185 }
186
maxim_thermocouple_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)187 static int maxim_thermocouple_read_raw(struct iio_dev *indio_dev,
188 struct iio_chan_spec const *chan,
189 int *val, int *val2, long mask)
190 {
191 struct maxim_thermocouple_data *data = iio_priv(indio_dev);
192 int ret;
193
194 switch (mask) {
195 case IIO_CHAN_INFO_RAW:
196 if (!iio_device_claim_direct(indio_dev))
197 return -EBUSY;
198
199 ret = maxim_thermocouple_read(data, chan, val);
200 iio_device_release_direct(indio_dev);
201 if (ret)
202 return ret;
203
204 return IIO_VAL_INT;
205 case IIO_CHAN_INFO_SCALE:
206 switch (chan->channel2) {
207 case IIO_MOD_TEMP_AMBIENT:
208 *val = 62;
209 *val2 = 500000; /* 1000 * 0.0625 */
210 return IIO_VAL_INT_PLUS_MICRO;
211 default:
212 *val = 250; /* 1000 * 0.25 */
213 return IIO_VAL_INT;
214 }
215 case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
216 *val = data->tc_type;
217 return IIO_VAL_CHAR;
218 default:
219 return -EINVAL;
220 }
221 }
222
223 static const struct iio_info maxim_thermocouple_info = {
224 .read_raw = maxim_thermocouple_read_raw,
225 };
226
maxim_thermocouple_probe(struct spi_device * spi)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");
306