> From: Paresh Chaudhary <paresh.chaudhary@xxxxxxxxxxxxxxxxxxx> > > This patch adds support for Maxim MAX31856 thermocouple > temperature sensor support. some comments below > 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> > --- > > We assumed this should be applied and patch checked against the iio testing > branch found in the staging repo. > (git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git) > > --- > > MAINTAINERS | 5 + > drivers/iio/temperature/Kconfig | 10 + > drivers/iio/temperature/Makefile | 1 + > drivers/iio/temperature/max31856.c | 374 +++++++++++++++++++++++++++++++++++++ > 4 files changed, 390 insertions(+) > create mode 100644 drivers/iio/temperature/max31856.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index f642044..dd9a83d 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -7157,6 +7157,11 @@ F: drivers/staging/iio/ > F: include/linux/iio/ > F: tools/iio/ > > +MAX31856 IIO DRIVER > +M: Matthew Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx> > +S: Maintained > +F: drivers/iio/temperature/max31856.c > + > 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..38cf178 100644 > --- a/drivers/iio/temperature/Makefile > +++ b/drivers/iio/temperature/Makefile > @@ -11,3 +11,4 @@ obj-$(CONFIG_TMP006) += tmp006.o > obj-$(CONFIG_TMP007) += tmp007.o > obj-$(CONFIG_TSYS01) += tsys01.o > obj-$(CONFIG_TSYS02D) += tsys02d.o > +obj-$(CONFIG_MAX31856) += max31856.o alphabethic order please > diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c > new file mode 100644 > index 0000000..eb5a03c > --- /dev/null > +++ b/drivers/iio/temperature/max31856.c > @@ -0,0 +1,374 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* max31856.c > + * > + * Maxim MAX31856 thermocouple sensor driver > + * > + * Copyright (C) 2018 Rockwell Collins > + * license text can be skipped thanks to SPDX line > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + */ > + > +#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_READ_MODE 0x7F > +#define MAX31856_WRITE_MODE 0x80 > + > +/* 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; > + int fault_ovuv; > + int fault_oc; > + u8 buf[3] ____cacheline_aligned; > +}; > + > +static int max31856_read(struct max31856_data *data, unsigned int reg, > + s32 *val, int read_size) > +{ > + int ret = 0; no need to initialize ret, will be overwritten anyways > + 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 maybe use a full stop (.) after read / before If for readability > + * address byte > + */ > + > + reg &= MAX31856_READ_MODE; > + > + buf[0] = reg; > + buf[1] = 0x00; > + buf[2] = 0x00; > + > + ret = spi_write_then_read(data->spi, buf, 1, buf, read_size); > + if (ret < 0) > + return ret; > + > + switch (read_size) { > + case 1: > + *val = buf[0]; > + break; just return directly: return 0; > + case 2: > + *val = (buf[0] << 8) | buf[1]; > + break; > + case 3: > + *val = (buf[0] << 16) | (buf[1] << 8) | buf[2]; > + break; > + default: > + ret = -1; return -EINVAL shouldn't the read_size be checked before to avoid overflowing buf? > + } > + > + return ret; > +} > + > +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 . before If > + * the address byte > + */ > + > + reg |= MAX31856_WRITE_MODE; > + > + buf[0] = reg; > + buf[1] = val; > + > + return spi_write(data->spi, buf, 2); > +} > + > +static int max31856_init(struct max31856_data *data) > +{ > + int ret = 0; > + s32 reg_val; > + > + /* 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) maybe a space after Enabled? > + * --------------------------- > + * 10 | Enabled(Once every 16 seconds) > + * --------------------------- > + * 11 | Enabled(Once every 16 seconds) > + */ > + ret = max31856_read(data, MAX31856_CR0_REG, ®_val, 1); > + if (ret) > + return ret; > + reg_val &= ~BIT(5); use #defines for these magic bits and masks in here > + reg_val |= BIT(4); > + ret = max31856_write(data, MAX31856_CR0_REG, reg_val); > + if (ret) > + return ret; > + > + /* Set thermocouple type based on dts property */ > + ret = max31856_read(data, MAX31856_CR1_REG, ®_val, 1); > + if (ret) > + return ret; > + > + reg_val &= 0x00F0; > + reg_val |= (data->thermocouple_type & 0x0F); > + ret = max31856_write(data, MAX31856_CR1_REG, reg_val); > + if (ret) > + return ret; > + > + /* Set Conversion Mode (Auto or Oneshot) based on dts property */ > + ret = max31856_read(data, MAX31856_CR0_REG, ®_val, 1); > + if (ret) > + return ret; > + if (data->one_shot) { > + reg_val &= ~BIT(7); > + reg_val |= BIT(6); > + } else { > + reg_val |= BIT(7); > + reg_val &= ~BIT(6); > + } > + ret = max31856_write(data, MAX31856_CR0_REG, reg_val); just return max31856_write(...); > + > + return ret; > +} > + > +static int max31856_thermocouple_read(struct max31856_data *data, > + struct iio_chan_spec const *chan, > + int *val) > +{ > + int ret = 0, temp, offset_cjto; > + > + switch (chan->channel2) { > + case IIO_MOD_TEMP_AMBIENT: > + /* Read register from 0x09-0x0B */ > + ret = max31856_read(data, MAX31856_CJTO_REG, val, 3); > + /* Get Cold Junction Temp. offset register value */ > + offset_cjto = *val >> 16; > + /* Mask last 2 bytes to get CJTH and CJTL reg. value */ > + *val &= 0x0000FFFF; > + temp = *val; > + /* last 2 bits unused in CJTL reg*/ > + *val >>= 2; > + /* As per datasheet add offset into CJTH and CJTL */ > + *val += offset_cjto; > + /* Check 15th bit for sign */ > + if (temp & 0x8000) > + *val -= 0x4000; > + break; > + default: > + ret = max31856_read(data, MAX31856_LTCBH_REG, val, 3); > + temp = *val; > + *val >>= 5; > + /* Check 23th bit for sign */ > + if (temp & 0x800000) > + *val -= 0x80000; > + } > + > + ret = max31856_read(data, MAX31856_SR_REG, &temp, 1); > + /*Check for over voltage/under voltage fault */ space before Check > + data->fault_ovuv = (temp & BIT(1)) ? 1 : 0; > + /* Check for open circuit fault */ > + data->fault_oc = (temp & BIT(0)) ? 1 : 0; what to do with these error conditions, maybe 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 = -EINVAL; no need to initialize ret > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + ret = max31856_thermocouple_read(data, chan, val); > + if (ret) > + return ret; > + else > + return IIO_VAL_INT; > + break; why not just. 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) */ > + ret = IIO_VAL_INT_PLUS_MICRO; just return IIO_VAL_INT_PLUS_MICRO; > + }; no semicolon after } > + break; > + } > + > + return ret; > +} > + > +static const struct iio_info max31856_info = { > + .driver_module = THIS_MODULE, > + .read_raw = max31856_read_raw, > +}; > + > +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 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; > + } > + > + ret = iio_device_register(indio_dev); > + > + data->fault_ovuv = 0; > + data->fault_oc = 0; not needed to initialize; why after _register(), racy? > + ret = sysfs_create_group(&indio_dev->dev.kobj, &max31856_group); should not be needed and overwrites ret of _register() > + > + return ret; > +} > + > +static int max31856_remove(struct spi_device *spi) > +{ > + struct iio_dev *indio_dev = spi_get_drvdata(spi); > + > + sysfs_remove_group(&indio_dev->dev.kobj, &max31856_group); > + iio_device_unregister(indio_dev); > + > + return 0; > +} > + > +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, > + .remove = max31856_remove, > + .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"); > -- Peter Meerwald-Stadler Mobile: +43 664 24 44 418
