diff options
Diffstat (limited to 'drivers/iio/temperature/max31856.c')
| -rw-r--r-- | drivers/iio/temperature/max31856.c | 489 |
1 files changed, 489 insertions, 0 deletions
diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c new file mode 100644 index 000000000..8307aae2c --- /dev/null +++ b/drivers/iio/temperature/max31856.c @@ -0,0 +1,489 @@ +// 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 <paresh.chaudhary@rockwellcollins.com>"); +MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com>"); +MODULE_DESCRIPTION("Maxim MAX31856 thermocouple sensor driver"); +MODULE_LICENSE("GPL"); |