This patch introduces common thermocouple types used by various
temperature sensors.
Signed-off-by: Patrick Havelange <[email protected]>
---
Changes v6
- Add this file
---
.../dt-bindings/iio/temperature/thermocouple.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
create mode 100644 include/dt-bindings/iio/temperature/thermocouple.h
diff --git a/include/dt-bindings/iio/temperature/thermocouple.h b/include/dt-bindings/iio/temperature/thermocouple.h
new file mode 100644
index 000000000000..ce037f5238ac
--- /dev/null
+++ b/include/dt-bindings/iio/temperature/thermocouple.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _DT_BINDINGS_TEMPERATURE_THERMOCOUPLE_H
+#define _DT_BINDINGS_TEMPERATURE_THERMOCOUPLE_H
+
+
+#define THERMOCOUPLE_TYPE_B 0x00
+#define THERMOCOUPLE_TYPE_E 0x01
+#define THERMOCOUPLE_TYPE_J 0x02
+#define THERMOCOUPLE_TYPE_K 0x03
+#define THERMOCOUPLE_TYPE_N 0x04
+#define THERMOCOUPLE_TYPE_R 0x05
+#define THERMOCOUPLE_TYPE_S 0x06
+#define THERMOCOUPLE_TYPE_T 0x07
+
+#endif /* _DT_BINDINGS_TEMPERATURE_THERMOCOUPLE_H */
--
2.19.1
This explains the new generic property "thermocouple-type" that
can be used with temperature sensors.
Signed-off-by: Patrick Havelange <[email protected]>
---
Changes v6
- Add this file
---
.../bindings/iio/temperature/temperature-bindings.txt | 11 +++++++++++
1 file changed, 11 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt
diff --git a/Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt b/Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt
new file mode 100644
index 000000000000..69a6441d8083
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt
@@ -0,0 +1,11 @@
+If the temperature sensor device can be configured to use some specific
+thermocouple type, you can use the defined types provided in the file
+"include/dt-bindings/iio/temperature/thermocouple.h".
+
+Optional property:
+thermocouple-type: The type of the thermocouple used by the device.
+
+For example:
+ device {
+ thermocouple-type = <THERMOCOUPLE_TYPE_K> ;
+ };
--
2.19.1
From: Paresh Chaudhary <[email protected]>
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 <[email protected]>
Signed-off-by: Matt Weber <[email protected]>
Signed-off-by: Patrick Havelange <[email protected]>
---
Changes
v1 -> v2
[Peter
1. Fixed all space & 'return' related comments
2. Removed 'sysfs_create_group' api because
iio_device_register function is handling sysfs entry
3. Return -EIO if there is any fault
4. Added check for 'read_size' before spi read call
5. Removed license text from the source file
6. Added .o file in alphabetic order
7. Used #defines instead of magic bits
v2 -> v3
[Jonathan
1. Used bool for fault_oc and fault_ovuv
2. Changed 'max31856_read' function and use byte array to
store registers value.
3. Used 'GENMASK' where required
4. Changed logic 'max31856_thermocouple_read' function. Used
array to read registers value.
5. Used 'devm_iio_device_register' and removed 'max31856_remove'.
6. Fixed other cosmetic changes.
7. Added 'sysfs-bus-iio-temperature-max31856' file and updated
'MAINTAINERS' file.
v3 -> v4
[Jonathan
1. Removed unwanted logic
2. Updated code to handle return value of max31856_read call
3. Added devicetree id table
4. Removed one-shot support from driver as this support was not
implemented with correct design.
v4 -> v5
[Patrick
1. Rename thermocouple type to maxim,thermocouple-type for DT entry
2. Don't cache values from the Fault Status Register
3. Simplify a bit max31856_init()
4. Use IIO_NO_MOD in switch case + default error case
5. Use dev_*() instead of pr_*()
6. Fix missing space in comments
7. Removed iio_info.driver_module assignment as no longer present
8. Don't keep read/write buffer into the internal driver struct
9. Updated kernel version, add missing space in documentation
10. Updated (c) year
11. Removed linux/init.h #include
12. More use of BIT() macro
13. Removed iio_chan_spec.address assignment as not used
14. In max31856_thermocouple_read(), same switch case order as
channels definition
15. Refactor show_fault_*() functions
16. Use u8 as register type in max31856_{read,write}()
v5 -> v6
[Patrick
1. Use generic thermocouple-type property
2. Fix doc for fault_ovuv entry
3. Add check for supported thermocouple-types in probe()
---
.../sysfs-bus-iio-temperature-max31856 | 24 ++
drivers/iio/temperature/Kconfig | 10 +
drivers/iio/temperature/Makefile | 1 +
drivers/iio/temperature/max31856.c | 353 ++++++++++++++++++
4 files changed, 388 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856
create mode 100644 drivers/iio/temperature/max31856.c
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856 b/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856
new file mode 100644
index 000000000000..3b3509a3ef2f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856
@@ -0,0 +1,24 @@
+What: /sys/bus/iio/devices/iio:deviceX/fault_oc
+KernelVersion: 5.1
+Contact: [email protected]
+Description:
+ Open-circuit fault. The detection of open-circuit faults,
+ such as those caused by broken thermocouple wires.
+ Reading returns either '1' or '0'.
+ '1' = An open circuit such as broken thermocouple wires
+ has been detected.
+ '0' = No open circuit or broken thermocouple wires are detected
+
+What: /sys/bus/iio/devices/iio:deviceX/fault_ovuv
+KernelVersion: 5.1
+Contact: [email protected]
+Description:
+ Overvoltage or Undervoltage Input Fault. The internal circuitry
+ is protected from excessive voltages applied to the thermocouple
+ cables by integrated MOSFETs at the T+ and T- inputs, and the
+ BIAS output. These MOSFETs 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).
diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
index 82e4a62745e2..c66eeb23615b 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 34a31db0bb63..baca4776ca0d 100644
--- a/drivers/iio/temperature/Makefile
+++ b/drivers/iio/temperature/Makefile
@@ -5,6 +5,7 @@
obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o
obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
+obj-$(CONFIG_MAX31856) += max31856.o
obj-$(CONFIG_MLX90614) += mlx90614.o
obj-$(CONFIG_MLX90632) += mlx90632.o
obj-$(CONFIG_TMP006) += tmp006.o
diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c
new file mode 100644
index 000000000000..6b67d6b95cf9
--- /dev/null
+++ b/drivers/iio/temperature/max31856.c
@@ -0,0 +1,353 @@
+// SPDX-License-Identifier: GPL-2.0
+/* max31856.c
+ *
+ * Maxim MAX31856 thermocouple sensor driver
+ *
+ * Copyright (C) 2018-2019 Rockwell Collins
+ */
+
+#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>
+#include <dt-bindings/iio/temperature/thermocouple.h>
+/*
+ * The MSB of the register value determines whether the following byte will
+ * be written or read. If it is 0, one or more byte reads will follow.
+ */
+#define MAX31856_RD_WR_BIT BIT(7)
+
+#define MAX31856_CR0_AUTOCONVERT BIT(7)
+#define MAX31856_CR0_1SHOT BIT(6)
+#define MAX31856_CR0_OCFAULT BIT(4)
+#define MAX31856_CR0_OCFAULT_MASK GENMASK(5, 4)
+#define MAX31856_TC_TYPE_MASK GENMASK(3, 0)
+#define MAX31856_FAULT_OVUV BIT(1)
+#define MAX31856_FAULT_OPEN BIT(0)
+
+/* 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,
+ .info_mask_separate =
+ BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+ },
+ { /* Cold Junction Temperature */
+ .type = IIO_TEMP,
+ .channel2 = IIO_MOD_TEMP_AMBIENT,
+ .modified = 1,
+ .info_mask_separate =
+ BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+ },
+};
+
+struct max31856_data {
+ struct spi_device *spi;
+ u32 thermocouple_type;
+};
+
+static int max31856_read(struct max31856_data *data, u8 reg,
+ u8 val[], unsigned int read_size)
+{
+ return spi_write_then_read(data->spi, ®, 1, val, read_size);
+}
+
+static int max31856_write(struct max31856_data *data, u8 reg,
+ unsigned int val)
+{
+ u8 buf[2];
+
+ buf[0] = reg | (MAX31856_RD_WR_BIT);
+ buf[1] = val;
+
+ return spi_write(data->spi, buf, 2);
+}
+
+static int max31856_init(struct max31856_data *data)
+{
+ int ret;
+ u8 reg_cr0_val, reg_cr1_val;
+
+ /* Start by changing to Off mode before making changes as
+ * some settings are recommended to be set only when the device
+ * is off
+ */
+ ret = max31856_read(data, MAX31856_CR0_REG, ®_cr0_val, 1);
+ if (ret)
+ return ret;
+
+ reg_cr0_val &= ~MAX31856_CR0_AUTOCONVERT;
+ ret = max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
+ if (ret)
+ return ret;
+
+ /* Set thermocouple type based on dts property */
+ ret = max31856_read(data, MAX31856_CR1_REG, ®_cr1_val, 1);
+ if (ret)
+ return ret;
+
+ reg_cr1_val &= ~MAX31856_TC_TYPE_MASK;
+ reg_cr1_val |= data->thermocouple_type;
+ ret = max31856_write(data, MAX31856_CR1_REG, reg_cr1_val);
+ if (ret)
+ return ret;
+
+ /*
+ * Enable Open circuit fault detection
+ * Read datasheet for more information: Table 4.
+ * Value 01 means : Enabled (Once every 16 conversions)
+ */
+ reg_cr0_val &= ~MAX31856_CR0_OCFAULT_MASK;
+ reg_cr0_val |= MAX31856_CR0_OCFAULT;
+
+ /* Set Auto Conversion Mode */
+ reg_cr0_val &= ~MAX31856_CR0_1SHOT;
+ reg_cr0_val |= MAX31856_CR0_AUTOCONVERT;
+
+ return max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
+}
+
+static int max31856_thermocouple_read(struct max31856_data *data,
+ struct iio_chan_spec const *chan,
+ int *val)
+{
+ int ret, offset_cjto;
+ u8 reg_val[3];
+
+ switch (chan->channel2) {
+ case IIO_NO_MOD:
+ /*
+ * Multibyte Read
+ * MAX31856_LTCBH_REG, MAX31856_LTCBM_REG, MAX31856_LTCBL_REG
+ */
+ ret = max31856_read(data, MAX31856_LTCBH_REG, reg_val, 3);
+ if (ret)
+ return ret;
+ /* Skip last 5 dead bits of LTCBL */
+ *val = (reg_val[0] << 16 | reg_val[1] << 8 | reg_val[2]) >> 5;
+ /* Check 7th bit of LTCBH reg. value for sign*/
+ if (reg_val[0] & 0x80)
+ *val -= 0x80000;
+ break;
+
+ case IIO_MOD_TEMP_AMBIENT:
+ /*
+ * Multibyte Read
+ * MAX31856_CJTO_REG, MAX31856_CJTH_REG, MAX31856_CJTL_REG
+ */
+ ret = max31856_read(data, MAX31856_CJTO_REG, reg_val, 3);
+ if (ret)
+ return ret;
+ /* Get Cold Junction Temp. offset register value */
+ offset_cjto = reg_val[0];
+ /* Get CJTH and CJTL value and skip last 2 dead bits of CJTL */
+ *val = (reg_val[1] << 8 | reg_val[2]) >> 2;
+ /* As per datasheet add offset into CJTH and CJTL */
+ *val += offset_cjto;
+ /* Check 7th bit of CJTH reg. value for sign */
+ if (reg_val[1] & 0x80)
+ *val -= 0x4000;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ ret = max31856_read(data, MAX31856_SR_REG, reg_val, 1);
+ if (ret)
+ return ret;
+ /* Check for over/under voltage or open circuit fault */
+ if (reg_val[0] & (MAX31856_FAULT_OVUV | MAX31856_FAULT_OPEN))
+ 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;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ 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) */
+ return IIO_VAL_INT_PLUS_MICRO;
+ }
+ break;
+ }
+
+ return ret;
+}
+
+static ssize_t show_fault(struct device *dev, u8 faultbit, char *buf)
+{
+ struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+ struct max31856_data *data = iio_priv(indio_dev);
+ u8 reg_val;
+ int ret;
+ bool fault;
+
+ ret = max31856_read(data, MAX31856_SR_REG, ®_val, 1);
+ if (ret)
+ return ret;
+
+ fault = reg_val & 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, MAX31856_FAULT_OVUV, buf);
+}
+
+static ssize_t show_fault_oc(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return show_fault(dev, MAX31856_FAULT_OPEN, buf);
+}
+
+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 const struct iio_info max31856_info = {
+ .read_raw = max31856_read_raw,
+ .attrs = &max31856_group,
+};
+
+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);
+
+ ret = of_property_read_u32(spi->dev.of_node, "thermocouple-type",
+ &data->thermocouple_type);
+
+ if (ret) {
+ dev_info(&spi->dev,
+ "Could not read thermocouple type DT property, configuring as a K-Type\n");
+ data->thermocouple_type = THERMOCOUPLE_TYPE_K;
+ }
+
+ /*
+ * no need to translate values as the supported types
+ * have the same value as the #defines
+ */
+ switch (data->thermocouple_type) {
+ case THERMOCOUPLE_TYPE_B:
+ case THERMOCOUPLE_TYPE_E:
+ case THERMOCOUPLE_TYPE_J:
+ case THERMOCOUPLE_TYPE_K:
+ case THERMOCOUPLE_TYPE_N:
+ case THERMOCOUPLE_TYPE_R:
+ case THERMOCOUPLE_TYPE_S:
+ case THERMOCOUPLE_TYPE_T:
+ break;
+ default:
+ dev_err(&spi->dev,
+ "error: thermocouple-type %u not supported by max31856\n"
+ , data->thermocouple_type);
+ return -EINVAL;
+ }
+
+ ret = max31856_init(data);
+ if (ret) {
+ dev_err(&spi->dev, "error: Failed to configure max31856\n");
+ return ret;
+ }
+
+ return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct spi_device_id max31856_id[] = {
+ { "max31856", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(spi, max31856_id);
+
+static const struct of_device_id max31856_of_match[] = {
+ { .compatible = "maxim,max31856" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, max31856_of_match);
+
+static struct spi_driver max31856_driver = {
+ .driver = {
+ .name = "max31856",
+ .of_match_table = max31856_of_match,
+ },
+ .probe = max31856_probe,
+ .id_table = max31856_id,
+};
+module_spi_driver(max31856_driver);
+
+MODULE_AUTHOR("Paresh Chaudhary <[email protected]>");
+MODULE_AUTHOR("Patrick Havelange <[email protected]>");
+MODULE_DESCRIPTION("Maxim MAX31856 thermocouple sensor driver");
+MODULE_LICENSE("GPL");
--
2.19.1
From: Paresh Chaudhary <[email protected]>
This patch added device tree binding info for MAX31856 driver.
Signed-off-by: Paresh Chaudhary <[email protected]>
Signed-off-by: Matt Weber <[email protected]>
Signed-off-by: Patrick Havelange <[email protected]>
---
Changes
v1 -> v2
[Matt
- Removed comment block and added possibilities of
thermocouple type in device tree binding doc.
v2 -> v3
- Rebased
v3 -> v4
- Removed one-shot property related information.
- Used standard name 'temp-sensor'
v4 -> v5
[Patrick
- Rename thermocouple type to maxim,thermocouple-type for DT entry
v5 -> v6
[Patrick
- use generic thermocouple-type for DT entry
---
.../bindings/iio/temperature/max31856.txt | 24 +++++++++++++++++++
1 file changed, 24 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/temperature/max31856.txt
diff --git a/Documentation/devicetree/bindings/iio/temperature/max31856.txt b/Documentation/devicetree/bindings/iio/temperature/max31856.txt
new file mode 100644
index 000000000000..06ab43bb4de8
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/temperature/max31856.txt
@@ -0,0 +1,24 @@
+Maxim MAX31856 thermocouple support
+
+https://datasheets.maximintegrated.com/en/ds/MAX31856.pdf
+
+Optional property:
+ - thermocouple-type: Type of thermocouple (THERMOCOUPLE_TYPE_K if
+ omitted). Supported types are B, E, J, K, N, R, S, T.
+
+Required properties:
+ - compatible: must be "maxim,max31856"
+ - reg: SPI chip select number for the device
+ - spi-max-frequency: As per datasheet max. supported freq is 5000000
+ - spi-cpha: must be defined for max31856 to enable SPI mode 1
+
+ Refer to spi/spi-bus.txt for generic SPI slave bindings.
+
+ Example:
+ temp-sensor@0 {
+ compatible = "maxim,max31856";
+ reg = <0>;
+ spi-max-frequency = <5000000>;
+ spi-cpha;
+ thermocouple-type = <THERMOCOUPLE_TYPE_K>;
+ };
--
2.19.1
On Thu, 7 Mar 2019 11:34:07 +0100
Patrick Havelange <[email protected]> wrote:
> This explains the new generic property "thermocouple-type" that
> can be used with temperature sensors.
>
> Signed-off-by: Patrick Havelange <[email protected]>
I'm happy with this, but want to allow time for Rob and other
devicetree types to have a look at it as well.
Give me a poke if this is looking unloved in a week or so.
Thanks,
Jonathan
> ---
> Changes v6
> - Add this file
> ---
> .../bindings/iio/temperature/temperature-bindings.txt | 11 +++++++++++
> 1 file changed, 11 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt
>
> diff --git a/Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt b/Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt
> new file mode 100644
> index 000000000000..69a6441d8083
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt
> @@ -0,0 +1,11 @@
> +If the temperature sensor device can be configured to use some specific
> +thermocouple type, you can use the defined types provided in the file
> +"include/dt-bindings/iio/temperature/thermocouple.h".
> +
> +Optional property:
> +thermocouple-type: The type of the thermocouple used by the device.
> +
> +For example:
> + device {
> + thermocouple-type = <THERMOCOUPLE_TYPE_K> ;
> + };
On Thu, 7 Mar 2019 11:34:09 +0100
Patrick Havelange <[email protected]> wrote:
> From: Paresh Chaudhary <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Matt Weber <[email protected]>
> Signed-off-by: Patrick Havelange <[email protected]>
Looks good to me. I'll just wait on the DT parts getting reviewed.
Thanks,
Jonathan
> ---
> Changes
> v1 -> v2
> [Peter
> 1. Fixed all space & 'return' related comments
> 2. Removed 'sysfs_create_group' api because
> iio_device_register function is handling sysfs entry
> 3. Return -EIO if there is any fault
> 4. Added check for 'read_size' before spi read call
> 5. Removed license text from the source file
> 6. Added .o file in alphabetic order
> 7. Used #defines instead of magic bits
>
> v2 -> v3
> [Jonathan
> 1. Used bool for fault_oc and fault_ovuv
> 2. Changed 'max31856_read' function and use byte array to
> store registers value.
> 3. Used 'GENMASK' where required
> 4. Changed logic 'max31856_thermocouple_read' function. Used
> array to read registers value.
> 5. Used 'devm_iio_device_register' and removed 'max31856_remove'.
> 6. Fixed other cosmetic changes.
> 7. Added 'sysfs-bus-iio-temperature-max31856' file and updated
> 'MAINTAINERS' file.
>
> v3 -> v4
> [Jonathan
> 1. Removed unwanted logic
> 2. Updated code to handle return value of max31856_read call
> 3. Added devicetree id table
> 4. Removed one-shot support from driver as this support was not
> implemented with correct design.
>
> v4 -> v5
> [Patrick
> 1. Rename thermocouple type to maxim,thermocouple-type for DT entry
> 2. Don't cache values from the Fault Status Register
> 3. Simplify a bit max31856_init()
> 4. Use IIO_NO_MOD in switch case + default error case
> 5. Use dev_*() instead of pr_*()
> 6. Fix missing space in comments
> 7. Removed iio_info.driver_module assignment as no longer present
> 8. Don't keep read/write buffer into the internal driver struct
> 9. Updated kernel version, add missing space in documentation
> 10. Updated (c) year
> 11. Removed linux/init.h #include
> 12. More use of BIT() macro
> 13. Removed iio_chan_spec.address assignment as not used
> 14. In max31856_thermocouple_read(), same switch case order as
> channels definition
> 15. Refactor show_fault_*() functions
> 16. Use u8 as register type in max31856_{read,write}()
>
> v5 -> v6
> [Patrick
> 1. Use generic thermocouple-type property
> 2. Fix doc for fault_ovuv entry
> 3. Add check for supported thermocouple-types in probe()
> ---
> .../sysfs-bus-iio-temperature-max31856 | 24 ++
> drivers/iio/temperature/Kconfig | 10 +
> drivers/iio/temperature/Makefile | 1 +
> drivers/iio/temperature/max31856.c | 353 ++++++++++++++++++
> 4 files changed, 388 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856
> create mode 100644 drivers/iio/temperature/max31856.c
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856 b/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856
> new file mode 100644
> index 000000000000..3b3509a3ef2f
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-temperature-max31856
> @@ -0,0 +1,24 @@
> +What: /sys/bus/iio/devices/iio:deviceX/fault_oc
> +KernelVersion: 5.1
> +Contact: [email protected]
> +Description:
> + Open-circuit fault. The detection of open-circuit faults,
> + such as those caused by broken thermocouple wires.
> + Reading returns either '1' or '0'.
> + '1' = An open circuit such as broken thermocouple wires
> + has been detected.
> + '0' = No open circuit or broken thermocouple wires are detected
> +
> +What: /sys/bus/iio/devices/iio:deviceX/fault_ovuv
> +KernelVersion: 5.1
> +Contact: [email protected]
> +Description:
> + Overvoltage or Undervoltage Input Fault. The internal circuitry
> + is protected from excessive voltages applied to the thermocouple
> + cables by integrated MOSFETs at the T+ and T- inputs, and the
> + BIAS output. These MOSFETs 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).
> diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
> index 82e4a62745e2..c66eeb23615b 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 34a31db0bb63..baca4776ca0d 100644
> --- a/drivers/iio/temperature/Makefile
> +++ b/drivers/iio/temperature/Makefile
> @@ -5,6 +5,7 @@
>
> obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o
> obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
> +obj-$(CONFIG_MAX31856) += max31856.o
> obj-$(CONFIG_MLX90614) += mlx90614.o
> obj-$(CONFIG_MLX90632) += mlx90632.o
> obj-$(CONFIG_TMP006) += tmp006.o
> diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c
> new file mode 100644
> index 000000000000..6b67d6b95cf9
> --- /dev/null
> +++ b/drivers/iio/temperature/max31856.c
> @@ -0,0 +1,353 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* max31856.c
> + *
> + * Maxim MAX31856 thermocouple sensor driver
> + *
> + * Copyright (C) 2018-2019 Rockwell Collins
> + */
> +
> +#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>
> +#include <dt-bindings/iio/temperature/thermocouple.h>
> +/*
> + * The MSB of the register value determines whether the following byte will
> + * be written or read. If it is 0, one or more byte reads will follow.
> + */
> +#define MAX31856_RD_WR_BIT BIT(7)
> +
> +#define MAX31856_CR0_AUTOCONVERT BIT(7)
> +#define MAX31856_CR0_1SHOT BIT(6)
> +#define MAX31856_CR0_OCFAULT BIT(4)
> +#define MAX31856_CR0_OCFAULT_MASK GENMASK(5, 4)
> +#define MAX31856_TC_TYPE_MASK GENMASK(3, 0)
> +#define MAX31856_FAULT_OVUV BIT(1)
> +#define MAX31856_FAULT_OPEN BIT(0)
> +
> +/* 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,
> + .info_mask_separate =
> + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> + },
> + { /* Cold Junction Temperature */
> + .type = IIO_TEMP,
> + .channel2 = IIO_MOD_TEMP_AMBIENT,
> + .modified = 1,
> + .info_mask_separate =
> + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> + },
> +};
> +
> +struct max31856_data {
> + struct spi_device *spi;
> + u32 thermocouple_type;
> +};
> +
> +static int max31856_read(struct max31856_data *data, u8 reg,
> + u8 val[], unsigned int read_size)
> +{
> + return spi_write_then_read(data->spi, ®, 1, val, read_size);
> +}
> +
> +static int max31856_write(struct max31856_data *data, u8 reg,
> + unsigned int val)
> +{
> + u8 buf[2];
> +
> + buf[0] = reg | (MAX31856_RD_WR_BIT);
> + buf[1] = val;
> +
> + return spi_write(data->spi, buf, 2);
> +}
> +
> +static int max31856_init(struct max31856_data *data)
> +{
> + int ret;
> + u8 reg_cr0_val, reg_cr1_val;
> +
> + /* Start by changing to Off mode before making changes as
> + * some settings are recommended to be set only when the device
> + * is off
> + */
> + ret = max31856_read(data, MAX31856_CR0_REG, ®_cr0_val, 1);
> + if (ret)
> + return ret;
> +
> + reg_cr0_val &= ~MAX31856_CR0_AUTOCONVERT;
> + ret = max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
> + if (ret)
> + return ret;
> +
> + /* Set thermocouple type based on dts property */
> + ret = max31856_read(data, MAX31856_CR1_REG, ®_cr1_val, 1);
> + if (ret)
> + return ret;
> +
> + reg_cr1_val &= ~MAX31856_TC_TYPE_MASK;
> + reg_cr1_val |= data->thermocouple_type;
> + ret = max31856_write(data, MAX31856_CR1_REG, reg_cr1_val);
> + if (ret)
> + return ret;
> +
> + /*
> + * Enable Open circuit fault detection
> + * Read datasheet for more information: Table 4.
> + * Value 01 means : Enabled (Once every 16 conversions)
> + */
> + reg_cr0_val &= ~MAX31856_CR0_OCFAULT_MASK;
> + reg_cr0_val |= MAX31856_CR0_OCFAULT;
> +
> + /* Set Auto Conversion Mode */
> + reg_cr0_val &= ~MAX31856_CR0_1SHOT;
> + reg_cr0_val |= MAX31856_CR0_AUTOCONVERT;
> +
> + return max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
> +}
> +
> +static int max31856_thermocouple_read(struct max31856_data *data,
> + struct iio_chan_spec const *chan,
> + int *val)
> +{
> + int ret, offset_cjto;
> + u8 reg_val[3];
> +
> + switch (chan->channel2) {
> + case IIO_NO_MOD:
> + /*
> + * Multibyte Read
> + * MAX31856_LTCBH_REG, MAX31856_LTCBM_REG, MAX31856_LTCBL_REG
> + */
> + ret = max31856_read(data, MAX31856_LTCBH_REG, reg_val, 3);
> + if (ret)
> + return ret;
> + /* Skip last 5 dead bits of LTCBL */
> + *val = (reg_val[0] << 16 | reg_val[1] << 8 | reg_val[2]) >> 5;
> + /* Check 7th bit of LTCBH reg. value for sign*/
> + if (reg_val[0] & 0x80)
> + *val -= 0x80000;
> + break;
> +
> + case IIO_MOD_TEMP_AMBIENT:
> + /*
> + * Multibyte Read
> + * MAX31856_CJTO_REG, MAX31856_CJTH_REG, MAX31856_CJTL_REG
> + */
> + ret = max31856_read(data, MAX31856_CJTO_REG, reg_val, 3);
> + if (ret)
> + return ret;
> + /* Get Cold Junction Temp. offset register value */
> + offset_cjto = reg_val[0];
> + /* Get CJTH and CJTL value and skip last 2 dead bits of CJTL */
> + *val = (reg_val[1] << 8 | reg_val[2]) >> 2;
> + /* As per datasheet add offset into CJTH and CJTL */
> + *val += offset_cjto;
> + /* Check 7th bit of CJTH reg. value for sign */
> + if (reg_val[1] & 0x80)
> + *val -= 0x4000;
> + break;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + ret = max31856_read(data, MAX31856_SR_REG, reg_val, 1);
> + if (ret)
> + return ret;
> + /* Check for over/under voltage or open circuit fault */
> + if (reg_val[0] & (MAX31856_FAULT_OVUV | MAX31856_FAULT_OPEN))
> + 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;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + 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) */
> + return IIO_VAL_INT_PLUS_MICRO;
> + }
> + break;
> + }
> +
> + return ret;
> +}
> +
> +static ssize_t show_fault(struct device *dev, u8 faultbit, char *buf)
> +{
> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> + struct max31856_data *data = iio_priv(indio_dev);
> + u8 reg_val;
> + int ret;
> + bool fault;
> +
> + ret = max31856_read(data, MAX31856_SR_REG, ®_val, 1);
> + if (ret)
> + return ret;
> +
> + fault = reg_val & 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, MAX31856_FAULT_OVUV, buf);
> +}
> +
> +static ssize_t show_fault_oc(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + return show_fault(dev, MAX31856_FAULT_OPEN, buf);
> +}
> +
> +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 const struct iio_info max31856_info = {
> + .read_raw = max31856_read_raw,
> + .attrs = &max31856_group,
> +};
> +
> +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);
> +
> + ret = of_property_read_u32(spi->dev.of_node, "thermocouple-type",
> + &data->thermocouple_type);
> +
> + if (ret) {
> + dev_info(&spi->dev,
> + "Could not read thermocouple type DT property, configuring as a K-Type\n");
> + data->thermocouple_type = THERMOCOUPLE_TYPE_K;
> + }
> +
> + /*
> + * no need to translate values as the supported types
> + * have the same value as the #defines
> + */
> + switch (data->thermocouple_type) {
> + case THERMOCOUPLE_TYPE_B:
> + case THERMOCOUPLE_TYPE_E:
> + case THERMOCOUPLE_TYPE_J:
> + case THERMOCOUPLE_TYPE_K:
> + case THERMOCOUPLE_TYPE_N:
> + case THERMOCOUPLE_TYPE_R:
> + case THERMOCOUPLE_TYPE_S:
> + case THERMOCOUPLE_TYPE_T:
> + break;
> + default:
> + dev_err(&spi->dev,
> + "error: thermocouple-type %u not supported by max31856\n"
> + , data->thermocouple_type);
> + return -EINVAL;
> + }
> +
> + ret = max31856_init(data);
> + if (ret) {
> + dev_err(&spi->dev, "error: Failed to configure max31856\n");
> + return ret;
> + }
> +
> + return devm_iio_device_register(&spi->dev, indio_dev);
> +}
> +
> +static const struct spi_device_id max31856_id[] = {
> + { "max31856", 0 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(spi, max31856_id);
> +
> +static const struct of_device_id max31856_of_match[] = {
> + { .compatible = "maxim,max31856" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, max31856_of_match);
> +
> +static struct spi_driver max31856_driver = {
> + .driver = {
> + .name = "max31856",
> + .of_match_table = max31856_of_match,
> + },
> + .probe = max31856_probe,
> + .id_table = max31856_id,
> +};
> +module_spi_driver(max31856_driver);
> +
> +MODULE_AUTHOR("Paresh Chaudhary <[email protected]>");
> +MODULE_AUTHOR("Patrick Havelange <[email protected]>");
> +MODULE_DESCRIPTION("Maxim MAX31856 thermocouple sensor driver");
> +MODULE_LICENSE("GPL");
On Thu, Mar 07, 2019 at 11:34:07AM +0100, Patrick Havelange wrote:
> This explains the new generic property "thermocouple-type" that
> can be used with temperature sensors.
>
> Signed-off-by: Patrick Havelange <[email protected]>
> ---
> Changes v6
> - Add this file
> ---
> .../bindings/iio/temperature/temperature-bindings.txt | 11 +++++++++++
> 1 file changed, 11 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt
>
> diff --git a/Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt b/Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt
> new file mode 100644
> index 000000000000..69a6441d8083
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/temperature/temperature-bindings.txt
> @@ -0,0 +1,11 @@
> +If the temperature sensor device can be configured to use some specific
> +thermocouple type, you can use the defined types provided in the file
> +"include/dt-bindings/iio/temperature/thermocouple.h".
You can include patch 1 in this patch.
> +
> +Optional property:
Optional or not is really up to the specific device.
> +thermocouple-type: The type of the thermocouple used by the device.
What's the type? "A single cell" presumably.
> +
> +For example:
As this is example is incomplete, I'd drop this.
> + device {
> + thermocouple-type = <THERMOCOUPLE_TYPE_K> ;
> + };
> --
> 2.19.1
>
On Thu, 7 Mar 2019 11:34:08 +0100, Patrick Havelange wrote:
> From: Paresh Chaudhary <[email protected]>
>
> This patch added device tree binding info for MAX31856 driver.
>
> Signed-off-by: Paresh Chaudhary <[email protected]>
> Signed-off-by: Matt Weber <[email protected]>
> Signed-off-by: Patrick Havelange <[email protected]>
> ---
> Changes
> v1 -> v2
> [Matt
> - Removed comment block and added possibilities of
> thermocouple type in device tree binding doc.
>
> v2 -> v3
> - Rebased
>
> v3 -> v4
> - Removed one-shot property related information.
> - Used standard name 'temp-sensor'
>
> v4 -> v5
> [Patrick
> - Rename thermocouple type to maxim,thermocouple-type for DT entry
>
> v5 -> v6
> [Patrick
> - use generic thermocouple-type for DT entry
> ---
> .../bindings/iio/temperature/max31856.txt | 24 +++++++++++++++++++
> 1 file changed, 24 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/temperature/max31856.txt
>
Reviewed-by: Rob Herring <[email protected]>