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- // SPDX-License-Identifier: GPL-2.0
- /* max31856.c
- *
- * Maxim MAX31856 thermocouple sensor driver
- *
- * Copyright (C) 2018-2019 Rockwell Collins
- */
- #include <linux/ctype.h>
- #include <linux/mod_devicetable.h>
- #include <linux/module.h>
- #include <linux/init.h>
- #include <linux/err.h>
- #include <linux/property.h>
- #include <linux/spi/spi.h>
- #include <linux/iio/iio.h>
- #include <linux/iio/sysfs.h>
- #include <linux/util_macros.h>
- #include <asm/unaligned.h>
- #include <dt-bindings/iio/temperature/thermocouple.h>
- /*
- * The MSB of the register value determines whether the following byte will
- * be written or read. If it is 0, one or more byte reads will follow.
- */
- #define MAX31856_RD_WR_BIT BIT(7)
- #define MAX31856_CR0_AUTOCONVERT BIT(7)
- #define MAX31856_CR0_1SHOT BIT(6)
- #define MAX31856_CR0_OCFAULT BIT(4)
- #define MAX31856_CR0_OCFAULT_MASK GENMASK(5, 4)
- #define MAX31856_CR0_FILTER_50HZ BIT(0)
- #define MAX31856_AVERAGING_MASK GENMASK(6, 4)
- #define MAX31856_AVERAGING_SHIFT 4
- #define MAX31856_TC_TYPE_MASK GENMASK(3, 0)
- #define MAX31856_FAULT_OVUV BIT(1)
- #define MAX31856_FAULT_OPEN BIT(0)
- /* The MAX31856 registers */
- #define MAX31856_CR0_REG 0x00
- #define MAX31856_CR1_REG 0x01
- #define MAX31856_MASK_REG 0x02
- #define MAX31856_CJHF_REG 0x03
- #define MAX31856_CJLF_REG 0x04
- #define MAX31856_LTHFTH_REG 0x05
- #define MAX31856_LTHFTL_REG 0x06
- #define MAX31856_LTLFTH_REG 0x07
- #define MAX31856_LTLFTL_REG 0x08
- #define MAX31856_CJTO_REG 0x09
- #define MAX31856_CJTH_REG 0x0A
- #define MAX31856_CJTL_REG 0x0B
- #define MAX31856_LTCBH_REG 0x0C
- #define MAX31856_LTCBM_REG 0x0D
- #define MAX31856_LTCBL_REG 0x0E
- #define MAX31856_SR_REG 0x0F
- static const struct iio_chan_spec max31856_channels[] = {
- { /* Thermocouple Temperature */
- .type = IIO_TEMP,
- .info_mask_separate =
- BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
- BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
- .info_mask_shared_by_type =
- BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO)
- },
- { /* Cold Junction Temperature */
- .type = IIO_TEMP,
- .channel2 = IIO_MOD_TEMP_AMBIENT,
- .modified = 1,
- .info_mask_separate =
- BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
- .info_mask_shared_by_type =
- BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO)
- },
- };
- struct max31856_data {
- struct spi_device *spi;
- u32 thermocouple_type;
- bool filter_50hz;
- int averaging;
- };
- static const char max31856_tc_types[] = {
- 'B', 'E', 'J', 'K', 'N', 'R', 'S', 'T'
- };
- static int max31856_read(struct max31856_data *data, u8 reg,
- u8 val[], unsigned int read_size)
- {
- return spi_write_then_read(data->spi, ®, 1, val, read_size);
- }
- static int max31856_write(struct max31856_data *data, u8 reg,
- unsigned int val)
- {
- u8 buf[2];
- buf[0] = reg | (MAX31856_RD_WR_BIT);
- buf[1] = val;
- return spi_write(data->spi, buf, 2);
- }
- static int max31856_init(struct max31856_data *data)
- {
- int ret;
- u8 reg_cr0_val, reg_cr1_val;
- /* Start by changing to Off mode before making changes as
- * some settings are recommended to be set only when the device
- * is off
- */
- ret = max31856_read(data, MAX31856_CR0_REG, ®_cr0_val, 1);
- if (ret)
- return ret;
- reg_cr0_val &= ~MAX31856_CR0_AUTOCONVERT;
- ret = max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
- if (ret)
- return ret;
- /* Set thermocouple type based on dts property */
- ret = max31856_read(data, MAX31856_CR1_REG, ®_cr1_val, 1);
- if (ret)
- return ret;
- reg_cr1_val &= ~MAX31856_TC_TYPE_MASK;
- reg_cr1_val |= data->thermocouple_type;
- reg_cr1_val &= ~MAX31856_AVERAGING_MASK;
- reg_cr1_val |= data->averaging << MAX31856_AVERAGING_SHIFT;
- ret = max31856_write(data, MAX31856_CR1_REG, reg_cr1_val);
- if (ret)
- return ret;
- /*
- * Enable Open circuit fault detection
- * Read datasheet for more information: Table 4.
- * Value 01 means : Enabled (Once every 16 conversions)
- */
- reg_cr0_val &= ~MAX31856_CR0_OCFAULT_MASK;
- reg_cr0_val |= MAX31856_CR0_OCFAULT;
- /* Set Auto Conversion Mode */
- reg_cr0_val &= ~MAX31856_CR0_1SHOT;
- reg_cr0_val |= MAX31856_CR0_AUTOCONVERT;
- if (data->filter_50hz)
- reg_cr0_val |= MAX31856_CR0_FILTER_50HZ;
- else
- reg_cr0_val &= ~MAX31856_CR0_FILTER_50HZ;
- return max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
- }
- static int max31856_thermocouple_read(struct max31856_data *data,
- struct iio_chan_spec const *chan,
- int *val)
- {
- int ret, offset_cjto;
- u8 reg_val[3];
- switch (chan->channel2) {
- case IIO_NO_MOD:
- /*
- * Multibyte Read
- * MAX31856_LTCBH_REG, MAX31856_LTCBM_REG, MAX31856_LTCBL_REG
- */
- ret = max31856_read(data, MAX31856_LTCBH_REG, reg_val, 3);
- if (ret)
- return ret;
- /* Skip last 5 dead bits of LTCBL */
- *val = get_unaligned_be24(®_val[0]) >> 5;
- /* Check 7th bit of LTCBH reg. value for sign*/
- if (reg_val[0] & 0x80)
- *val -= 0x80000;
- break;
- case IIO_MOD_TEMP_AMBIENT:
- /*
- * Multibyte Read
- * MAX31856_CJTO_REG, MAX31856_CJTH_REG, MAX31856_CJTL_REG
- */
- ret = max31856_read(data, MAX31856_CJTO_REG, reg_val, 3);
- if (ret)
- return ret;
- /* Get Cold Junction Temp. offset register value */
- offset_cjto = reg_val[0];
- /* Get CJTH and CJTL value and skip last 2 dead bits of CJTL */
- *val = get_unaligned_be16(®_val[1]) >> 2;
- /* As per datasheet add offset into CJTH and CJTL */
- *val += offset_cjto;
- /* Check 7th bit of CJTH reg. value for sign */
- if (reg_val[1] & 0x80)
- *val -= 0x4000;
- break;
- default:
- return -EINVAL;
- }
- ret = max31856_read(data, MAX31856_SR_REG, reg_val, 1);
- if (ret)
- return ret;
- /* Check for over/under voltage or open circuit fault */
- if (reg_val[0] & (MAX31856_FAULT_OVUV | MAX31856_FAULT_OPEN))
- return -EIO;
- return ret;
- }
- static int max31856_read_raw(struct iio_dev *indio_dev,
- struct iio_chan_spec const *chan,
- int *val, int *val2, long mask)
- {
- struct max31856_data *data = iio_priv(indio_dev);
- int ret;
- switch (mask) {
- case IIO_CHAN_INFO_RAW:
- ret = max31856_thermocouple_read(data, chan, val);
- if (ret)
- return ret;
- return IIO_VAL_INT;
- case IIO_CHAN_INFO_SCALE:
- switch (chan->channel2) {
- case IIO_MOD_TEMP_AMBIENT:
- /* Cold junction Temp. Data resolution is 0.015625 */
- *val = 15;
- *val2 = 625000; /* 1000 * 0.015625 */
- ret = IIO_VAL_INT_PLUS_MICRO;
- break;
- default:
- /* Thermocouple Temp. Data resolution is 0.0078125 */
- *val = 7;
- *val2 = 812500; /* 1000 * 0.0078125) */
- return IIO_VAL_INT_PLUS_MICRO;
- }
- break;
- case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
- *val = 1 << data->averaging;
- return IIO_VAL_INT;
- case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
- *val = max31856_tc_types[data->thermocouple_type];
- return IIO_VAL_CHAR;
- default:
- ret = -EINVAL;
- break;
- }
- return ret;
- }
- static int max31856_write_raw_get_fmt(struct iio_dev *indio_dev,
- struct iio_chan_spec const *chan,
- long mask)
- {
- switch (mask) {
- case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
- return IIO_VAL_CHAR;
- default:
- return IIO_VAL_INT;
- }
- }
- static int max31856_write_raw(struct iio_dev *indio_dev,
- struct iio_chan_spec const *chan,
- int val, int val2, long mask)
- {
- struct max31856_data *data = iio_priv(indio_dev);
- int msb;
- switch (mask) {
- case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
- if (val > 16 || val < 1)
- return -EINVAL;
- msb = fls(val) - 1;
- /* Round up to next 2pow if needed */
- if (BIT(msb) < val)
- msb++;
- data->averaging = msb;
- max31856_init(data);
- break;
- case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
- {
- int tc_type = -1;
- int i;
- for (i = 0; i < ARRAY_SIZE(max31856_tc_types); i++) {
- if (max31856_tc_types[i] == toupper(val)) {
- tc_type = i;
- break;
- }
- }
- if (tc_type < 0)
- return -EINVAL;
- data->thermocouple_type = tc_type;
- max31856_init(data);
- break;
- }
- default:
- return -EINVAL;
- }
- return 0;
- }
- static ssize_t show_fault(struct device *dev, u8 faultbit, char *buf)
- {
- struct iio_dev *indio_dev = dev_to_iio_dev(dev);
- struct max31856_data *data = iio_priv(indio_dev);
- u8 reg_val;
- int ret;
- bool fault;
- ret = max31856_read(data, MAX31856_SR_REG, ®_val, 1);
- if (ret)
- return ret;
- fault = reg_val & faultbit;
- return sysfs_emit(buf, "%d\n", fault);
- }
- static ssize_t show_fault_ovuv(struct device *dev,
- struct device_attribute *attr,
- char *buf)
- {
- return show_fault(dev, MAX31856_FAULT_OVUV, buf);
- }
- static ssize_t show_fault_oc(struct device *dev,
- struct device_attribute *attr,
- char *buf)
- {
- return show_fault(dev, MAX31856_FAULT_OPEN, buf);
- }
- static ssize_t show_filter(struct device *dev,
- struct device_attribute *attr,
- char *buf)
- {
- struct iio_dev *indio_dev = dev_to_iio_dev(dev);
- struct max31856_data *data = iio_priv(indio_dev);
- return sysfs_emit(buf, "%d\n", data->filter_50hz ? 50 : 60);
- }
- static ssize_t set_filter(struct device *dev,
- struct device_attribute *attr,
- const char *buf,
- size_t len)
- {
- struct iio_dev *indio_dev = dev_to_iio_dev(dev);
- struct max31856_data *data = iio_priv(indio_dev);
- unsigned int freq;
- int ret;
- ret = kstrtouint(buf, 10, &freq);
- if (ret)
- return ret;
- switch (freq) {
- case 50:
- data->filter_50hz = true;
- break;
- case 60:
- data->filter_50hz = false;
- break;
- default:
- return -EINVAL;
- }
- max31856_init(data);
- return len;
- }
- static IIO_DEVICE_ATTR(fault_ovuv, 0444, show_fault_ovuv, NULL, 0);
- static IIO_DEVICE_ATTR(fault_oc, 0444, show_fault_oc, NULL, 0);
- static IIO_DEVICE_ATTR(in_temp_filter_notch_center_frequency, 0644,
- show_filter, set_filter, 0);
- static struct attribute *max31856_attributes[] = {
- &iio_dev_attr_fault_ovuv.dev_attr.attr,
- &iio_dev_attr_fault_oc.dev_attr.attr,
- &iio_dev_attr_in_temp_filter_notch_center_frequency.dev_attr.attr,
- NULL,
- };
- static const struct attribute_group max31856_group = {
- .attrs = max31856_attributes,
- };
- static const struct iio_info max31856_info = {
- .read_raw = max31856_read_raw,
- .write_raw = max31856_write_raw,
- .write_raw_get_fmt = max31856_write_raw_get_fmt,
- .attrs = &max31856_group,
- };
- static int max31856_probe(struct spi_device *spi)
- {
- const struct spi_device_id *id = spi_get_device_id(spi);
- struct iio_dev *indio_dev;
- struct max31856_data *data;
- int ret;
- indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
- if (!indio_dev)
- return -ENOMEM;
- data = iio_priv(indio_dev);
- data->spi = spi;
- data->filter_50hz = false;
- spi_set_drvdata(spi, indio_dev);
- indio_dev->info = &max31856_info;
- indio_dev->name = id->name;
- indio_dev->modes = INDIO_DIRECT_MODE;
- indio_dev->channels = max31856_channels;
- indio_dev->num_channels = ARRAY_SIZE(max31856_channels);
- ret = device_property_read_u32(&spi->dev, "thermocouple-type", &data->thermocouple_type);
- if (ret) {
- dev_info(&spi->dev,
- "Could not read thermocouple type DT property, configuring as a K-Type\n");
- data->thermocouple_type = THERMOCOUPLE_TYPE_K;
- }
- /*
- * no need to translate values as the supported types
- * have the same value as the #defines
- */
- switch (data->thermocouple_type) {
- case THERMOCOUPLE_TYPE_B:
- case THERMOCOUPLE_TYPE_E:
- case THERMOCOUPLE_TYPE_J:
- case THERMOCOUPLE_TYPE_K:
- case THERMOCOUPLE_TYPE_N:
- case THERMOCOUPLE_TYPE_R:
- case THERMOCOUPLE_TYPE_S:
- case THERMOCOUPLE_TYPE_T:
- break;
- default:
- dev_err(&spi->dev,
- "error: thermocouple-type %u not supported by max31856\n"
- , data->thermocouple_type);
- return -EINVAL;
- }
- ret = max31856_init(data);
- if (ret) {
- dev_err(&spi->dev, "error: Failed to configure max31856\n");
- return ret;
- }
- return devm_iio_device_register(&spi->dev, indio_dev);
- }
- static const struct spi_device_id max31856_id[] = {
- { "max31856", 0 },
- { }
- };
- MODULE_DEVICE_TABLE(spi, max31856_id);
- static const struct of_device_id max31856_of_match[] = {
- { .compatible = "maxim,max31856" },
- { }
- };
- MODULE_DEVICE_TABLE(of, max31856_of_match);
- static struct spi_driver max31856_driver = {
- .driver = {
- .name = "max31856",
- .of_match_table = max31856_of_match,
- },
- .probe = max31856_probe,
- .id_table = max31856_id,
- };
- module_spi_driver(max31856_driver);
- MODULE_AUTHOR("Paresh Chaudhary <[email protected]>");
- MODULE_AUTHOR("Patrick Havelange <[email protected]>");
- MODULE_DESCRIPTION("Maxim MAX31856 thermocouple sensor driver");
- MODULE_LICENSE("GPL");
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