1 /* 2 * maxim_thermocouple.c - Support for Maxim thermocouple chips 3 * 4 * Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com> 5 * 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. 10 * 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. 15 */ 16 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> 27 28 #define MAXIM_THERMOCOUPLE_DRV_NAME "maxim_thermocouple" 29 30 enum { 31 MAX6675, 32 MAX31855, 33 }; 34 35 static const struct iio_chan_spec max6675_channels[] = { 36 { /* thermocouple temperature */ 37 .type = IIO_TEMP, 38 .info_mask_separate = 39 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), 40 .scan_index = 0, 41 .scan_type = { 42 .sign = 's', 43 .realbits = 13, 44 .storagebits = 16, 45 .shift = 3, 46 .endianness = IIO_BE, 47 }, 48 }, 49 IIO_CHAN_SOFT_TIMESTAMP(1), 50 }; 51 52 static const struct iio_chan_spec max31855_channels[] = { 53 { /* thermocouple temperature */ 54 .type = IIO_TEMP, 55 .address = 2, 56 .info_mask_separate = 57 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), 58 .scan_index = 0, 59 .scan_type = { 60 .sign = 's', 61 .realbits = 14, 62 .storagebits = 16, 63 .shift = 2, 64 .endianness = IIO_BE, 65 }, 66 }, 67 { /* cold junction temperature */ 68 .type = IIO_TEMP, 69 .address = 0, 70 .channel2 = IIO_MOD_TEMP_AMBIENT, 71 .modified = 1, 72 .info_mask_separate = 73 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), 74 .scan_index = 1, 75 .scan_type = { 76 .sign = 's', 77 .realbits = 12, 78 .storagebits = 16, 79 .shift = 4, 80 .endianness = IIO_BE, 81 }, 82 }, 83 IIO_CHAN_SOFT_TIMESTAMP(2), 84 }; 85 86 static const unsigned long max31855_scan_masks[] = {0x3, 0}; 87 88 struct maxim_thermocouple_chip { 89 const struct iio_chan_spec *channels; 90 const unsigned long *scan_masks; 91 u8 num_channels; 92 u8 read_size; 93 94 /* bit-check for valid input */ 95 u32 status_bit; 96 }; 97 98 static const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = { 99 [MAX6675] = { 100 .channels = max6675_channels, 101 .num_channels = ARRAY_SIZE(max6675_channels), 102 .read_size = 2, 103 .status_bit = BIT(2), 104 }, 105 [MAX31855] = { 106 .channels = max31855_channels, 107 .num_channels = ARRAY_SIZE(max31855_channels), 108 .read_size = 4, 109 .scan_masks = max31855_scan_masks, 110 .status_bit = BIT(16), 111 }, 112 }; 113 114 struct maxim_thermocouple_data { 115 struct spi_device *spi; 116 const struct maxim_thermocouple_chip *chip; 117 118 u8 buffer[16] ____cacheline_aligned; 119 }; 120 121 static int maxim_thermocouple_read(struct maxim_thermocouple_data *data, 122 struct iio_chan_spec const *chan, int *val) 123 { 124 unsigned int storage_bytes = data->chip->read_size; 125 unsigned int shift = chan->scan_type.shift + (chan->address * 8); 126 unsigned int buf; 127 int ret; 128 129 ret = spi_read(data->spi, (void *) &buf, storage_bytes); 130 if (ret) 131 return ret; 132 133 switch (storage_bytes) { 134 case 2: 135 *val = be16_to_cpu(buf); 136 break; 137 case 4: 138 *val = be32_to_cpu(buf); 139 break; 140 } 141 142 /* check to be sure this is a valid reading */ 143 if (*val & data->chip->status_bit) 144 return -EINVAL; 145 146 *val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1); 147 148 return 0; 149 } 150 151 static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private) 152 { 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); 156 int ret; 157 158 ret = spi_read(data->spi, data->buffer, data->chip->read_size); 159 if (!ret) { 160 iio_push_to_buffers_with_timestamp(indio_dev, data->buffer, 161 iio_get_time_ns(indio_dev)); 162 } 163 164 iio_trigger_notify_done(indio_dev->trig); 165 166 return IRQ_HANDLED; 167 } 168 169 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) 172 { 173 struct maxim_thermocouple_data *data = iio_priv(indio_dev); 174 int ret = -EINVAL; 175 176 switch (mask) { 177 case IIO_CHAN_INFO_RAW: 178 ret = iio_device_claim_direct_mode(indio_dev); 179 if (ret) 180 return ret; 181 182 ret = maxim_thermocouple_read(data, chan, val); 183 iio_device_release_direct_mode(indio_dev); 184 185 if (!ret) 186 return IIO_VAL_INT; 187 188 break; 189 case IIO_CHAN_INFO_SCALE: 190 switch (chan->channel2) { 191 case IIO_MOD_TEMP_AMBIENT: 192 *val = 62; 193 *val2 = 500000; /* 1000 * 0.0625 */ 194 ret = IIO_VAL_INT_PLUS_MICRO; 195 break; 196 default: 197 *val = 250; /* 1000 * 0.25 */ 198 ret = IIO_VAL_INT; 199 }; 200 break; 201 } 202 203 return ret; 204 } 205 206 static const struct iio_info maxim_thermocouple_info = { 207 .driver_module = THIS_MODULE, 208 .read_raw = maxim_thermocouple_read_raw, 209 }; 210 211 static int maxim_thermocouple_probe(struct spi_device *spi) 212 { 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]; 218 int ret; 219 220 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data)); 221 if (!indio_dev) 222 return -ENOMEM; 223 224 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; 230 231 data = iio_priv(indio_dev); 232 data->spi = spi; 233 data->chip = chip; 234 235 ret = iio_triggered_buffer_setup(indio_dev, NULL, 236 maxim_thermocouple_trigger_handler, NULL); 237 if (ret) 238 return ret; 239 240 ret = iio_device_register(indio_dev); 241 if (ret) 242 goto error_unreg_buffer; 243 244 return 0; 245 246 error_unreg_buffer: 247 iio_triggered_buffer_cleanup(indio_dev); 248 249 return ret; 250 } 251 252 static int maxim_thermocouple_remove(struct spi_device *spi) 253 { 254 struct iio_dev *indio_dev = spi_get_drvdata(spi); 255 256 iio_device_unregister(indio_dev); 257 iio_triggered_buffer_cleanup(indio_dev); 258 259 return 0; 260 } 261 262 static const struct spi_device_id maxim_thermocouple_id[] = { 263 {"max6675", MAX6675}, 264 {"max31855", MAX31855}, 265 {}, 266 }; 267 MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id); 268 269 static struct spi_driver maxim_thermocouple_driver = { 270 .driver = { 271 .name = MAXIM_THERMOCOUPLE_DRV_NAME, 272 }, 273 .probe = maxim_thermocouple_probe, 274 .remove = maxim_thermocouple_remove, 275 .id_table = maxim_thermocouple_id, 276 }; 277 module_spi_driver(maxim_thermocouple_driver); 278 279 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>"); 280 MODULE_DESCRIPTION("Maxim thermocouple sensors"); 281 MODULE_LICENSE("GPL"); 282