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 {"max31856", MAX31855}, 262 {}, 263 }; 264 MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id); 265 266 static struct spi_driver maxim_thermocouple_driver = { 267 .driver = { 268 .name = MAXIM_THERMOCOUPLE_DRV_NAME, 269 }, 270 .probe = maxim_thermocouple_probe, 271 .remove = maxim_thermocouple_remove, 272 .id_table = maxim_thermocouple_id, 273 }; 274 module_spi_driver(maxim_thermocouple_driver); 275 276 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>"); 277 MODULE_DESCRIPTION("Maxim thermocouple sensors"); 278 MODULE_LICENSE("GPL"); 279