On Sun, Aug 1, 2021 at 7:06 AM Navin Sankar Velliangiri <navin@xxxxxxxxxxx> wrote: > > 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); There aren't any changes for race-conditions here. There is no userspace access to the device yet (before devm_iio_device_register() is being called). So, the locking can be removed [here] in probe(). > + 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 >
