This patch adds support for Maxim MAX31865 RTD temperature sensor support. More information can be found in: https://datasheets.maximintegrated.com/en/ds/MAX31865.pdf Signed-off-by: Navin Sankar Velliangiri <navin@xxxxxxxxxxx> Note: Changes in v2: -> removed unnecessary header #include <linux/util_macros.h> -> implemented mutex to protect the device state -> Added __cacheline_aligned buffer to hold the raw temperature data -> implemented separate function to enable_bias() & disable_bias() -> call max31865_init() func when updating the filter -> Added ABI documentation for reference & testing -> dropped spi_set_drvdata() --- .../sysfs-bus-iio-temperature-max31865 | 25 ++ drivers/iio/temperature/Kconfig | 10 + drivers/iio/temperature/Makefile | 1 + drivers/iio/temperature/max31865.c | 347 ++++++++++++++++++ 4 files changed, 383 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-temperature-max31865 create mode 100644 drivers/iio/temperature/max31865.c diff --git a/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31865 b/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31865 new file mode 100644 index 000000000000..7ca1e09b73f5 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31865 @@ -0,0 +1,25 @@ +What: /sys/bus/iio/devices/iio:deviceX/fault_ovuv +KernelVersion: 5.11 +Contact: linux-iio@xxxxxxxxxxxxxxx +Description: + Overvoltage or Undervoltage Input fault. The internal circuitry + is protected from excessive voltages applied to the thermocouple + cables at FORCE+, FORCE2, RTDIN+ & RTDIN-. This circuitry 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). + === ======================================================= + +What: /sys/bus/iio/devices/iio:deviceX/in_temp_filter_notch_frequency +KernelVersion: 5.11 +Contact: linux-iio@xxxxxxxxxxxxxxx +Description: + Notch frequency in Hz for a noise rejection filter. Used i.e for + line noise rejection. + + Valid notch filter values are 50 Hz and 60 Hz. diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig index 4df60082c1fa..c9412abca069 100644 --- a/drivers/iio/temperature/Kconfig +++ b/drivers/iio/temperature/Kconfig @@ -128,4 +128,14 @@ config MAX31856 This driver can also be built as a module. If so, the module will be called max31856. +config MAX31865 + tristate "MAX31865 RTD to Digital converter" + depends on SPI + help + If you say yes here you get support for MAX31865 + thermocouple sensor chip connected via SPI. + + This driver can also be build as a module. If so, the module + will be called max31865. + endmenu diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile index 90c113115422..a8f3187258dc 100644 --- a/drivers/iio/temperature/Makefile +++ b/drivers/iio/temperature/Makefile @@ -8,6 +8,7 @@ obj-$(CONFIG_LTC2983) += ltc2983.o obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o obj-$(CONFIG_MAX31856) += max31856.o +obj-$(CONFIG_MAX31865) += max31865.o obj-$(CONFIG_MLX90614) += mlx90614.o obj-$(CONFIG_MLX90632) += mlx90632.o obj-$(CONFIG_TMP006) += tmp006.o diff --git a/drivers/iio/temperature/max31865.c b/drivers/iio/temperature/max31865.c new file mode 100644 index 000000000000..9a6ee251bb3e --- /dev/null +++ b/drivers/iio/temperature/max31865.c @@ -0,0 +1,347 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* + * Copyright (c) Linumiz 2021 + * + * max31865.c - Maxim MAX31865 RTD-to-Digital Converter sensor driver + * + * Author: Navin Sankar Velliangiri <navin@xxxxxxxxxxx> + */ + +#include <linux/ctype.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> +#include <linux/spi/spi.h> +#include <asm/unaligned.h> + +/* + * The MSB of the register value determines whether the following byte will + * be written or read. If it is 0, read will follow and if it is 1, write + * will follow. + */ +#define MAX31865_RD_WR_BIT BIT(7) + +#define MAX31865_CFG_VBIAS BIT(7) +#define MAX31865_CFG_1SHOT BIT(5) +#define MAX31865_3WIRE_RTD BIT(4) +#define MAX31865_FAULT_STATUS_CLEAR BIT(1) +#define MAX31865_FILTER_50HZ BIT(0) + +/* The MAX31865 registers */ +#define MAX31865_CFG_REG 0x00 +#define MAX31865_RTD_MSB 0x01 +#define MAX31865_FAULT_STATUS 0x07 + +#define MAX31865_FAULT_OVUV BIT(2) + +static const struct iio_chan_spec max31865_channels[] = { + { /* RTD Temperature */ + .type = IIO_TEMP, + .info_mask_separate = + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) + }, +}; + +struct max31865_data { + struct spi_device *spi; + struct mutex lock; + u8 buf[2] ____cacheline_aligned; + bool filter_50hz; + bool three_wire; +}; + +static int max31865_read(struct max31865_data *data, u8 reg, + unsigned int read_size) +{ + return spi_write_then_read(data->spi, ®, 1, data->buf, read_size); +} + +static int max31865_write(struct max31865_data *data, size_t len) +{ + return spi_write(data->spi, data->buf, len); +} + +static int enable_bias(struct max31865_data *data) +{ + u8 cfg; + int ret; + + ret = max31865_read(data, MAX31865_CFG_REG, 1); + if (ret) + return ret; + + cfg = data->buf[0]; + + data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT; + data->buf[1] = cfg | MAX31865_CFG_VBIAS; + + return max31865_write(data, 2); +} + +static int disable_bias(struct max31865_data *data) +{ + u8 cfg; + int ret; + + ret = max31865_read(data, MAX31865_CFG_REG, 1); + if (ret) + return ret; + + cfg = data->buf[0]; + cfg &= ~MAX31865_CFG_VBIAS; + + data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT; + data->buf[1] = cfg; + + return max31865_write(data, 2); +} + +static int max31865_rtd_read(struct max31865_data *data, int *val) +{ + u8 reg; + int ret; + + /* Enable BIAS to start the conversion */ + ret = enable_bias(data); + if (ret) + return ret; + + /* wait 10.5ms before initiating the conversion */ + msleep(11); + + ret = max31865_read(data, MAX31865_CFG_REG, 1); + if (ret) + return ret; + + reg = data->buf[0]; + reg |= MAX31865_CFG_1SHOT | MAX31865_FAULT_STATUS_CLEAR; + data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT; + data->buf[1] = reg; + + ret = max31865_write(data, 2); + if (ret) + return ret; + + if (data->filter_50hz) { + /* 50Hz filter mode requires 62.5ms to complete */ + msleep(63); + } else { + /* 60Hz filter mode requires 52ms to complete */ + msleep(52); + } + + ret = max31865_read(data, MAX31865_RTD_MSB, 2); + if (ret) + return ret; + + *val = (data->buf[0] << 8 | data->buf[1]) >> 1; + + return disable_bias(data); +} + +static int max31865_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct max31865_data *data = iio_priv(indio_dev); + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&data->lock); + ret = max31865_rtd_read(data, val); + mutex_unlock(&data->lock); + if (ret) + return ret; + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + /* Temp. Data resolution is 0.03125 degree centigrade */ + *val = 31; + *val2 = 250000; /* 1000 * 0.03125 */ + return IIO_VAL_INT_PLUS_MICRO; + default: + return -EINVAL; + } +} + +static int max31865_init(struct max31865_data *data) +{ + u8 cfg; + int ret; + + ret = max31865_read(data, MAX31865_CFG_REG, 1); + if (ret) + return ret; + + cfg = data->buf[0]; + + if (data->three_wire) + /* 3-wire RTD connection */ + cfg |= MAX31865_3WIRE_RTD; + + if (data->filter_50hz) + /* 50Hz noise rejection filter */ + cfg |= MAX31865_FILTER_50HZ; + + data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT; + data->buf[1] = cfg; + + return max31865_write(data, 2); +} + +static ssize_t show_fault(struct device *dev, u8 faultbit, char *buf) +{ + int ret; + bool fault; + struct iio_dev *indio_dev = dev_to_iio_dev(dev); + struct max31865_data *data = iio_priv(indio_dev); + + ret = max31865_read(data, MAX31865_FAULT_STATUS, 1); + if (ret) + return ret; + + fault = data->buf[0] & 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, MAX31865_FAULT_OVUV, 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 max31865_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 max31865_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; + } + + mutex_lock(&data->lock); + ret = max31865_init(data); + mutex_unlock(&data->lock); + if (ret) + return ret; + + return len; +} + +static IIO_DEVICE_ATTR(fault_ovuv, 0444, show_fault_ovuv, NULL, 0); +static IIO_DEVICE_ATTR(in_temp_filter_notch_frequency, 0644, + show_filter, set_filter, 0); + +static struct attribute *max31865_attributes[] = { + &iio_dev_attr_fault_ovuv.dev_attr.attr, + &iio_dev_attr_in_temp_filter_notch_frequency.dev_attr.attr, + NULL, +}; + +static const struct attribute_group max31865_group = { + .attrs = max31865_attributes, +}; + +static const struct iio_info max31865_info = { + .read_raw = max31865_read_raw, + .attrs = &max31865_group, +}; + +static int max31865_probe(struct spi_device *spi) +{ + const struct spi_device_id *id = spi_get_device_id(spi); + struct iio_dev *indio_dev; + struct max31865_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; + mutex_init(&data->lock); + + indio_dev->info = &max31865_info; + indio_dev->name = id->name; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = max31865_channels; + indio_dev->num_channels = ARRAY_SIZE(max31865_channels); + + if (of_property_read_bool(spi->dev.of_node, "maxim,3-wire")) { + /* select 3 wire */ + data->three_wire = 1; + } else { + /* select 2 or 4 wire */ + data->three_wire = 0; + } + + mutex_lock(&data->lock); + ret = max31865_init(data); + mutex_unlock(&data->lock); + if (ret) { + dev_err(&spi->dev, "error: Failed to configure max31865\n"); + return ret; + } + + return devm_iio_device_register(&spi->dev, indio_dev); +} + +static const struct spi_device_id max31865_id[] = { + { "max31865", 0 }, + { } +}; +MODULE_DEVICE_TABLE(spi, max31865_id); + +static const struct of_device_id max31865_of_match[] = { + { .compatible = "maxim,max31865" }, + { } +}; +MODULE_DEVICE_TABLE(of, max31865_of_match); + +static struct spi_driver max31865_driver = { + .driver = { + .name = "max31865", + .of_match_table = max31865_of_match, + }, + .probe = max31865_probe, + .id_table = max31865_id, +}; +module_spi_driver(max31865_driver); + +MODULE_AUTHOR("Navin Sankar Velliangiri <navin@xxxxxxxxxxx>"); +MODULE_DESCRIPTION("Maxim MAX31865 RTD-to-Digital Converter sensor driver"); +MODULE_LICENSE("GPL v2"); -- 2.32.0
