From: Paresh Chaudhary <paresh.chaudhary@xxxxxxxxxxxxxxxxxxx> This patch adds support for Maxim MAX31856 thermocouple temperature sensor support. More information can be found in: https://www.maximintegrated.com/en/ds/MAX31856.pdf NOTE: Driver support only Comparator Mode. Signed-off-by: Paresh Chaudhary <paresh.chaudhary@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Matt Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Patrick Havelange <patrick.havelange@xxxxxxxxxxxxx> --- Changes v1 -> v2 [Peter 1. Fixed all space & 'return' related comments 2. Removed 'sysfs_create_group' api because iio_device_register function is handling sysfs entry 3. Return -EIO if there is any fault 4. Added check for 'read_size' before spi read call 5. Removed license text from the source file 6. Added .o file in alphabetic order 7. Used #defines instead of magic bits v2 -> v3 [Jonathan 1. Used bool for fault_oc and fault_ovuv 2. Changed 'max31856_read' function and use byte array to store registers value. 3. Used 'GENMASK' where required 4. Changed logic 'max31856_thermocouple_read' function. Used array to read registers value. 5. Used 'devm_iio_device_register' and removed 'max31856_remove'. 6. Fixed other cosmetic changes. 7. Added 'sysfs-bus-iio-temperature-max31856' file and updated 'MAINTAINERS' file. v3 -> v4 [Jonathan 1. Removed unwanted logic 2. Updated code to handle return value of max31856_read call 3. Added devicetree id table 4. Removed one-shot support from driver as this support was not implemented with correct design. v4 -> v5 [Patrick 1. Rename thermocouple type to maxim,thermocouple-type for DT entry 2. Don't cache values from the Fault Status Register 3. Simplify a bit max31856_init() 4. Use IIO_NO_MOD in switch case + default error case 5. Use dev_*() instead of pr_*() 6. Fix missing space in comments 7. Removed iio_info.driver_module assignment as no longer present 8. Don't keep read/write buffer into the internal driver struct 9. Updated kernel version, add missing space in documentation 10. Updated (c) year 11. Removed linux/init.h #include 12. More use of BIT() macro 13. Removed iio_chan_spec.address assignment as not used 14. In max31856_thermocouple_read(), same switch case order as channels definition 15. Refactor show_fault_*() functions 16. Use u8 as register type in max31856_{read,write}() v5 -> v6 [Patrick 1. Use generic thermocouple-type property 2. Fix doc for fault_ovuv entry 3. Add check for supported thermocouple-types in probe() v6 -> v7 [Patrick 1. None --- .../sysfs-bus-iio-temperature-max31856 | 24 ++ drivers/iio/temperature/Kconfig | 10 + drivers/iio/temperature/Makefile | 1 + drivers/iio/temperature/max31856.c | 353 ++++++++++++++++++ 4 files changed, 388 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856 create mode 100644 drivers/iio/temperature/max31856.c diff --git a/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856 b/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856 new file mode 100644 index 000000000000..3b3509a3ef2f --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856 @@ -0,0 +1,24 @@ +What: /sys/bus/iio/devices/iio:deviceX/fault_oc +KernelVersion: 5.1 +Contact: linux-iio@xxxxxxxxxxxxxxx +Description: + Open-circuit fault. The detection of open-circuit faults, + such as those caused by broken thermocouple wires. + Reading returns either '1' or '0'. + '1' = An open circuit such as broken thermocouple wires + has been detected. + '0' = No open circuit or broken thermocouple wires are detected + +What: /sys/bus/iio/devices/iio:deviceX/fault_ovuv +KernelVersion: 5.1 +Contact: linux-iio@xxxxxxxxxxxxxxx +Description: + Overvoltage or Undervoltage Input Fault. The internal circuitry + is protected from excessive voltages applied to the thermocouple + cables by integrated MOSFETs at the T+ and T- inputs, and the + BIAS output. These MOSFETs turn off when the input voltage is + negative or greater than VDD. + Reading returns either '1' or '0'. + '1' = The input voltage is negative or greater than VDD. + '0' = The input voltage is positive and less than VDD (normal + state). diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig index 82e4a62745e2..c66eeb23615b 100644 --- a/drivers/iio/temperature/Kconfig +++ b/drivers/iio/temperature/Kconfig @@ -97,4 +97,14 @@ config TSYS02D This driver can also be built as a module. If so, the module will be called tsys02d. +config MAX31856 + tristate "MAX31856 thermocouple sensor" + depends on SPI + help + If you say yes here you get support for MAX31856 + thermocouple sensor chip connected via SPI. + + This driver can also be built as a module. If so, the module + will be called max31856. + endmenu diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile index 34a31db0bb63..baca4776ca0d 100644 --- a/drivers/iio/temperature/Makefile +++ b/drivers/iio/temperature/Makefile @@ -5,6 +5,7 @@ obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o +obj-$(CONFIG_MAX31856) += max31856.o obj-$(CONFIG_MLX90614) += mlx90614.o obj-$(CONFIG_MLX90632) += mlx90632.o obj-$(CONFIG_TMP006) += tmp006.o diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c new file mode 100644 index 000000000000..6b67d6b95cf9 --- /dev/null +++ b/drivers/iio/temperature/max31856.c @@ -0,0 +1,353 @@ +// SPDX-License-Identifier: GPL-2.0 +/* max31856.c + * + * Maxim MAX31856 thermocouple sensor driver + * + * Copyright (C) 2018-2019 Rockwell Collins + */ + +#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 <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_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), + }, + { /* 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), + }, +}; + +struct max31856_data { + struct spi_device *spi; + u32 thermocouple_type; +}; + +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; + 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; + + 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 = (reg_val[0] << 16 | reg_val[1] << 8 | reg_val[2]) >> 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 = (reg_val[1] << 8 | reg_val[2]) >> 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; + } + + return ret; +} + +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 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 IIO_DEVICE_ATTR(fault_ovuv, 0444, show_fault_ovuv, NULL, 0); +static IIO_DEVICE_ATTR(fault_oc, 0444, show_fault_oc, NULL, 0); + +static struct attribute *max31856_attributes[] = { + &iio_dev_attr_fault_ovuv.dev_attr.attr, + &iio_dev_attr_fault_oc.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, + .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; + + 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@xxxxxxxxxxxxxxxxxxx>"); +MODULE_AUTHOR("Patrick Havelange <patrick.havelange@xxxxxxxxxxxxx>"); +MODULE_DESCRIPTION("Maxim MAX31856 thermocouple sensor driver"); +MODULE_LICENSE("GPL"); -- 2.19.1
