iio: temperature: Add MAX31865 RTD Support
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@linumiz.com> Link: https://lore.kernel.org/r/20210824050123.71289-1-navin@linumiz.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Navin Sankar Velliangiri
Jonathan Cameron
parent
b0fc3f1dbe
commit
e112dc4e18
20
Documentation/ABI/testing/sysfs-bus-iio-temperature-max31865
Normal file
20
Documentation/ABI/testing/sysfs-bus-iio-temperature-max31865
Normal file
@ -0,0 +1,20 @@
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What: /sys/bus/iio/devices/iio:deviceX/fault_ovuv
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KernelVersion: 5.11
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Contact: linux-iio@vger.kernel.org
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Description:
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Overvoltage or Undervoltage Input fault. The internal circuitry
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is protected from excessive voltages applied to the thermocouple
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cables at FORCE+, FORCE2, RTDIN+ & RTDIN-. This circuitry turn
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off when the input voltage is negative or greater than VDD.
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Reading returns '1' if input voltage is negative or greater
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than VDD, otherwise '0'.
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What: /sys/bus/iio/devices/iio:deviceX/in_filter_notch_center_frequency
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KernelVersion: 5.11
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Contact: linux-iio@vger.kernel.org
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Description:
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Notch frequency in Hz for a noise rejection filter. Used i.e for
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line noise rejection.
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Valid notch filter values are 50 Hz and 60 Hz.
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@ -138,4 +138,14 @@ config MAX31856
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This driver can also be built as a module. If so, the module
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will be called max31856.
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config MAX31865
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tristate "MAX31865 RTD to Digital converter"
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depends on SPI
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help
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If you say yes here you get support for MAX31865
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thermocouple sensor chip connected via SPI.
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This driver can also be build as a module. If so, the module
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will be called max31865.
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endmenu
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@ -8,6 +8,7 @@ obj-$(CONFIG_LTC2983) += ltc2983.o
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obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o
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obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
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obj-$(CONFIG_MAX31856) += max31856.o
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obj-$(CONFIG_MAX31865) += max31865.o
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obj-$(CONFIG_MLX90614) += mlx90614.o
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obj-$(CONFIG_MLX90632) += mlx90632.o
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obj-$(CONFIG_TMP006) += tmp006.o
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349
drivers/iio/temperature/max31865.c
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349
drivers/iio/temperature/max31865.c
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@ -0,0 +1,349 @@
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) Linumiz 2021
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*
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* max31865.c - Maxim MAX31865 RTD-to-Digital Converter sensor driver
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*
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* Author: Navin Sankar Velliangiri <navin@linumiz.com>
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*/
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#include <linux/ctype.h>
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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#include <linux/spi/spi.h>
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#include <asm/unaligned.h>
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/*
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* The MSB of the register value determines whether the following byte will
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* be written or read. If it is 0, read will follow and if it is 1, write
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* will follow.
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*/
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#define MAX31865_RD_WR_BIT BIT(7)
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#define MAX31865_CFG_VBIAS BIT(7)
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#define MAX31865_CFG_1SHOT BIT(5)
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#define MAX31865_3WIRE_RTD BIT(4)
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#define MAX31865_FAULT_STATUS_CLEAR BIT(1)
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#define MAX31865_FILTER_50HZ BIT(0)
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/* The MAX31865 registers */
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#define MAX31865_CFG_REG 0x00
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#define MAX31865_RTD_MSB 0x01
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#define MAX31865_FAULT_STATUS 0x07
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#define MAX31865_FAULT_OVUV BIT(2)
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static const char max31865_show_samp_freq[] = "50 60";
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static const struct iio_chan_spec max31865_channels[] = {
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{ /* RTD Temperature */
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.type = IIO_TEMP,
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.info_mask_separate =
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BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE)
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},
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};
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struct max31865_data {
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struct spi_device *spi;
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struct mutex lock;
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bool filter_50hz;
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bool three_wire;
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u8 buf[2] ____cacheline_aligned;
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};
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static int max31865_read(struct max31865_data *data, u8 reg,
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unsigned int read_size)
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{
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return spi_write_then_read(data->spi, ®, 1, data->buf, read_size);
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}
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static int max31865_write(struct max31865_data *data, size_t len)
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{
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return spi_write(data->spi, data->buf, len);
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}
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static int enable_bias(struct max31865_data *data)
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{
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u8 cfg;
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int ret;
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ret = max31865_read(data, MAX31865_CFG_REG, 1);
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if (ret)
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return ret;
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cfg = data->buf[0];
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data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT;
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data->buf[1] = cfg | MAX31865_CFG_VBIAS;
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return max31865_write(data, 2);
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}
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static int disable_bias(struct max31865_data *data)
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{
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u8 cfg;
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int ret;
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ret = max31865_read(data, MAX31865_CFG_REG, 1);
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if (ret)
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return ret;
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cfg = data->buf[0];
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cfg &= ~MAX31865_CFG_VBIAS;
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data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT;
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data->buf[1] = cfg;
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return max31865_write(data, 2);
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}
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static int max31865_rtd_read(struct max31865_data *data, int *val)
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{
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u8 reg;
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int ret;
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/* Enable BIAS to start the conversion */
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ret = enable_bias(data);
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if (ret)
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return ret;
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/* wait 10.5ms before initiating the conversion */
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msleep(11);
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ret = max31865_read(data, MAX31865_CFG_REG, 1);
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if (ret)
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return ret;
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reg = data->buf[0];
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reg |= MAX31865_CFG_1SHOT | MAX31865_FAULT_STATUS_CLEAR;
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data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT;
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data->buf[1] = reg;
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ret = max31865_write(data, 2);
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if (ret)
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return ret;
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if (data->filter_50hz) {
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/* 50Hz filter mode requires 62.5ms to complete */
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msleep(63);
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} else {
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/* 60Hz filter mode requires 52ms to complete */
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msleep(52);
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}
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ret = max31865_read(data, MAX31865_RTD_MSB, 2);
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if (ret)
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return ret;
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*val = get_unaligned_be16(&data->buf) >> 1;
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return disable_bias(data);
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}
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static int max31865_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int *val, int *val2, long mask)
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{
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struct max31865_data *data = iio_priv(indio_dev);
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int ret;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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mutex_lock(&data->lock);
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ret = max31865_rtd_read(data, val);
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mutex_unlock(&data->lock);
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if (ret)
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return ret;
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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/* Temp. Data resolution is 0.03125 degree centigrade */
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*val = 31;
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*val2 = 250000; /* 1000 * 0.03125 */
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return IIO_VAL_INT_PLUS_MICRO;
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default:
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return -EINVAL;
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}
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}
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static int max31865_init(struct max31865_data *data)
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{
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u8 cfg;
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int ret;
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ret = max31865_read(data, MAX31865_CFG_REG, 1);
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if (ret)
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return ret;
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cfg = data->buf[0];
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if (data->three_wire)
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/* 3-wire RTD connection */
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cfg |= MAX31865_3WIRE_RTD;
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if (data->filter_50hz)
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/* 50Hz noise rejection filter */
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cfg |= MAX31865_FILTER_50HZ;
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data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT;
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data->buf[1] = cfg;
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return max31865_write(data, 2);
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}
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static ssize_t show_fault(struct device *dev, u8 faultbit, char *buf)
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{
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int ret;
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bool fault;
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struct iio_dev *indio_dev = dev_to_iio_dev(dev);
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struct max31865_data *data = iio_priv(indio_dev);
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ret = max31865_read(data, MAX31865_FAULT_STATUS, 1);
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if (ret)
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return ret;
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fault = data->buf[0] & faultbit;
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return sprintf(buf, "%d\n", fault);
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}
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static ssize_t show_fault_ovuv(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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return show_fault(dev, MAX31865_FAULT_OVUV, buf);
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}
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static ssize_t show_filter(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct iio_dev *indio_dev = dev_to_iio_dev(dev);
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struct max31865_data *data = iio_priv(indio_dev);
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return sprintf(buf, "%d\n", data->filter_50hz ? 50 : 60);
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}
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static ssize_t set_filter(struct device *dev,
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struct device_attribute *attr,
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const char *buf,
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size_t len)
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{
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struct iio_dev *indio_dev = dev_to_iio_dev(dev);
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struct max31865_data *data = iio_priv(indio_dev);
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unsigned int freq;
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int ret;
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ret = kstrtouint(buf, 10, &freq);
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if (ret)
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return ret;
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switch (freq) {
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case 50:
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data->filter_50hz = true;
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break;
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case 60:
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data->filter_50hz = false;
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break;
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default:
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return -EINVAL;
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}
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mutex_lock(&data->lock);
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ret = max31865_init(data);
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mutex_unlock(&data->lock);
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if (ret)
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return ret;
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return len;
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}
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static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(max31865_show_samp_freq);
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static IIO_DEVICE_ATTR(fault_ovuv, 0444, show_fault_ovuv, NULL, 0);
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static IIO_DEVICE_ATTR(in_filter_notch_center_frequency, 0644,
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show_filter, set_filter, 0);
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static struct attribute *max31865_attributes[] = {
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&iio_dev_attr_fault_ovuv.dev_attr.attr,
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&iio_const_attr_sampling_frequency_available.dev_attr.attr,
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&iio_dev_attr_in_filter_notch_center_frequency.dev_attr.attr,
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NULL,
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};
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static const struct attribute_group max31865_group = {
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.attrs = max31865_attributes,
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};
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static const struct iio_info max31865_info = {
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.read_raw = max31865_read_raw,
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.attrs = &max31865_group,
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};
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static int max31865_probe(struct spi_device *spi)
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{
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const struct spi_device_id *id = spi_get_device_id(spi);
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struct iio_dev *indio_dev;
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struct max31865_data *data;
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int ret;
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indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
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if (!indio_dev)
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return -ENOMEM;
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data = iio_priv(indio_dev);
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data->spi = spi;
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data->filter_50hz = false;
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mutex_init(&data->lock);
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indio_dev->info = &max31865_info;
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indio_dev->name = id->name;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = max31865_channels;
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indio_dev->num_channels = ARRAY_SIZE(max31865_channels);
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if (of_property_read_bool(spi->dev.of_node, "maxim,3-wire")) {
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/* select 3 wire */
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data->three_wire = 1;
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} else {
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/* select 2 or 4 wire */
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data->three_wire = 0;
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}
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ret = max31865_init(data);
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if (ret) {
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dev_err(&spi->dev, "error: Failed to configure max31865\n");
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return ret;
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}
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return devm_iio_device_register(&spi->dev, indio_dev);
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}
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static const struct spi_device_id max31865_id[] = {
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{ "max31865", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(spi, max31865_id);
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static const struct of_device_id max31865_of_match[] = {
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{ .compatible = "maxim,max31865" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, max31865_of_match);
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static struct spi_driver max31865_driver = {
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.driver = {
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.name = "max31865",
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.of_match_table = max31865_of_match,
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},
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.probe = max31865_probe,
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.id_table = max31865_id,
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};
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module_spi_driver(max31865_driver);
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MODULE_AUTHOR("Navin Sankar Velliangiri <navin@linumiz.com>");
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MODULE_DESCRIPTION("Maxim MAX31865 RTD-to-Digital Converter sensor driver");
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MODULE_LICENSE("GPL v2");
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