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> --- 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 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 + * + * 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; + 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 &= 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; + 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 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 + * 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) + * --------------------------- + * 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); + 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); + + 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 */ + data->fault_ovuv = (temp & BIT(1)) ? 1 : 0; + /* Check for open circuit fault */ + data->fault_oc = (temp & BIT(0)) ? 1 : 0; + + 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; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + ret = max31856_thermocouple_read(data, chan, val); + if (ret) + return ret; + else + return IIO_VAL_INT; + break; + 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; + }; + 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; + ret = sysfs_create_group(&indio_dev->dev.kobj, &max31856_group); + + 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"); -- 1.9.1
