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> --- 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. --- .../ABI/testing/sysfs-bus-iio-temperature-max31856 | 23 ++ MAINTAINERS | 7 + drivers/iio/temperature/Kconfig | 10 + drivers/iio/temperature/Makefile | 1 + drivers/iio/temperature/max31856.c | 359 +++++++++++++++++++++ 5 files changed, 400 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 0000000..d3238b8 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856 @@ -0,0 +1,23 @@ +What: /sys/bus/iio/devices/iio:deviceX/fault_oc +KernelVersion: 4.19 +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: 4.19 +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(default). diff --git a/MAINTAINERS b/MAINTAINERS index f642044..3cfa518 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -7157,6 +7157,13 @@ F: drivers/staging/iio/ F: include/linux/iio/ F: tools/iio/ +MAX31856 IIO DRIVER +M: Matthew Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx> +L: linux-iio@xxxxxxxxxxxxxxx +S: Maintained +F: drivers/iio/temperature/max31856.c +F: Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856 + IIO UNIT CONVERTER M: Peter Rosin <peda@xxxxxxxxxx> L: linux-iio@xxxxxxxxxxxxxxx diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig index 82e4a62..c66eeb2 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 34a31db..baca477 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 0000000..8ba1b34 --- /dev/null +++ b/drivers/iio/temperature/max31856.c @@ -0,0 +1,359 @@ +// SPDX-License-Identifier: GPL-2.0 +/* max31856.c + * + * Maxim MAX31856 thermocouple sensor driver + * + * Copyright (C) 2018 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> + +#define MAX31856_RD_WR_BIT_POS 7 +#define MAX31856_CR0_AUTOCONVERT 0x80 +#define MAX31856_CR0_1SHOT 0x40 +#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 0x02 +#define MAX31856_FAULT_OPEN 0x01 + +/* 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, + .address = 2, + .info_mask_separate = + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + }, + { /* Cold Junction Temperature */ + .type = IIO_TEMP, + .channel2 = IIO_MOD_TEMP_AMBIENT, + .address = 0, + .modified = 1, + .info_mask_separate = + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + }, +}; + +struct max31856_data { + struct spi_device *spi; + bool one_shot; + u32 thermocouple_type; + bool fault_ovuv; + bool fault_oc; + u8 buf[3] ____cacheline_aligned; +}; + +static int max31856_read(struct max31856_data *data, unsigned int reg, + u8 val[], int read_size) +{ + int ret; + u8 *buf = data->buf; + + /* + * Make sure top bit is not set, + * The MSB(A7) of this byte determines whether the following byte will + * be written or read. If A7 is 0, one or more byte reads will follow + * the address byte + */ + + reg &= ~(1 << MAX31856_RD_WR_BIT_POS); + + buf[0] = reg; + buf[1] = 0x00; + buf[2] = 0x00; + + if (read_size > 3) { + pr_err("error: Unsupported read_size = %d by %s\n", + read_size, __func__); + return -EINVAL; + } + + ret = spi_write_then_read(data->spi, buf, 1, buf, read_size); + if (ret < 0) + return ret; + + switch (read_size) { + case 1 ... 3: + memcpy(val, buf, read_size); + return 0; + default: + return -EINVAL; + } +} + +static int max31856_write(struct max31856_data *data, unsigned int reg, + unsigned int val) +{ + u8 *buf = data->buf; + + /* + * Make sure top bit is set, + * The MSB(A7) of this byte determines whether the following byte will + * be written or read. If A7 is 1, one or more byte writes will follow + * the address byte + */ + + buf[0] = reg | (1 << MAX31856_RD_WR_BIT_POS); + buf[1] = val; + + return spi_write(data->spi, buf, 2); +} + +static int max31856_init(struct max31856_data *data) +{ + int ret; + u8 reg_val[1]; + + /* + * Enable Open circuit fault detection [01] + * Read datasheet for more information: Table 4. + * BITS [5:4] | Fault Test + * --------------------------- + * 00 | Disabled + * --------------------------- + * 01 | Enabled (Once every 16 seconds) + * --------------------------- + * 10 | Enabled (Once every 16 seconds) + * --------------------------- + * 11 | Enabled (Once every 16 seconds) + */ + ret = max31856_read(data, MAX31856_CR0_REG, reg_val, 1); + if (ret) + return ret; + reg_val[0] &= ~MAX31856_CR0_OCFAULT_MASK; + reg_val[0] |= MAX31856_CR0_OCFAULT; + ret = max31856_write(data, MAX31856_CR0_REG, reg_val[0]); + if (ret) + return ret; + + /* Set thermocouple type based on dts property */ + ret = max31856_read(data, MAX31856_CR1_REG, reg_val, 1); + if (ret) + return ret; + + reg_val[0] &= ~MAX31856_TC_TYPE_MASK; + reg_val[0] |= data->thermocouple_type; + ret = max31856_write(data, MAX31856_CR1_REG, reg_val[0]); + if (ret) + return ret; + + /* Set Conversion Mode (Auto or Oneshot) based on dts property */ + ret = max31856_read(data, MAX31856_CR0_REG, reg_val, 1); + if (ret) + return ret; + if (data->one_shot) { + reg_val[0] &= ~MAX31856_CR0_AUTOCONVERT; + reg_val[0] |= MAX31856_CR0_1SHOT; + } else { + reg_val[0] |= MAX31856_CR0_AUTOCONVERT; + reg_val[0] &= ~MAX31856_CR0_1SHOT; + } + + return max31856_write(data, MAX31856_CR0_REG, reg_val[0]); +} + +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_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: + /* + * Multibyte Read + * MAX31856_LTCBH_REG, MAX31856_LTCBM_REG, MAX31856_LTCBL_REG + */ + ret = max31856_read(data, MAX31856_LTCBH_REG, reg_val, 3); + /* 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; + } + + ret = max31856_read(data, MAX31856_SR_REG, reg_val, 1); + /* Check for over voltage/under voltage fault */ + data->fault_ovuv = (reg_val[0] & MAX31856_FAULT_OVUV) ? true : false; + /* Check for open circuit fault */ + data->fault_oc = (reg_val[0] & MAX31856_FAULT_OPEN) ? true : false; + if (data->fault_oc || data->fault_ovuv) + 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_ovuv(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->fault_ovuv); +} + +static ssize_t show_fault_oc(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->fault_oc); +} + +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 = { + .driver_module = THIS_MODULE, + .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); + + data->one_shot = of_property_read_bool(spi->dev.of_node, "one-shot"); + + ret = of_property_read_u32(spi->dev.of_node, "type", + &data->thermocouple_type); + + if (ret) { + pr_info("Could not read thermocouple type DT property, Configuring as a K-Type\n"); + data->thermocouple_type = 0x03; /* K-Type */ + } + + ret = max31856_init(data); + if (ret) { + pr_err("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 struct spi_driver max31856_driver = { + .driver = { + .name = "max31856", + .owner = THIS_MODULE, + }, + .probe = max31856_probe, + .id_table = max31856_id, +}; +module_spi_driver(max31856_driver); + +MODULE_AUTHOR("Paresh Chaudhary <paresh.chaudhary@xxxxxxxxxxxxxxxxxxx>"); +MODULE_DESCRIPTION("Maxim MAX31856 thermocouple sensor driver"); +MODULE_LICENSE("GPL"); -- 1.9.1
