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Diffstat (limited to 'drivers/iio/temperature/max31856.c')
-rw-r--r--drivers/iio/temperature/max31856.c489
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..1954322e4
--- /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/module.h>
+#include <linux/init.h>
+#include <linux/err.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, &reg, 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, &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, &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(&reg_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(&reg_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, &reg_val, 1);
+ if (ret)
+ return ret;
+
+ fault = reg_val & faultbit;
+
+ return sprintf(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 sprintf(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 = of_property_read_u32(spi->dev.of_node, "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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-07 15:41:03 +0000