Skip to contentSkip to conversation

Add support for the MCP9600 thermocouple EMF converter

PATCH Superseded Andrew Hepp 3 participants 5 messages Mar 5, 2023 – Mar 12, 2023

Subsystems (2)
Device tree bindings IIO

v5 of 7 Superseded Latest is v7 →

lore
Share & tools
lore

Andrew Hepp

author
#0 lore raw

v5 cover Add support for the MCP9600 thermocouple EMF converter

Add support for the MCP9600 thermocouple EMF converter.

Andrew Hepp (2):
dt-bindings: iio: Add MCP9600 thermocouple EMF converter
iio: temperature: Add MCP9600 thermocouple EMF converter

 .../iio/temperature/microchip,mcp9600.yaml    |  70 +++++++++
 drivers/iio/temperature/Kconfig               |  10 ++
 drivers/iio/temperature/Makefile              |   1 +
 drivers/iio/temperature/mcp9600.c             | 146 ++++++++++++++++++
 4 files changed, 227 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/temperature/microchip,mcp9600.yaml
 create mode 100644 drivers/iio/temperature/mcp9600.c
Signature · 1 line
2.30.2
author
#1 lore raw

PATCH v5 1/2 dt-bindings: iio: Add MCP9600 thermocouple EMF converter

Add support for the MCP9600 thermocouple EMF converter.

Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/MCP960X-Data-Sheet-20005426.pdf

Signed-off-by Andrew Hepp <[email protected]>

---
Changes for v5:
- remove "bindings" from subject
- change unevaluatedProperties to additionalProperties Changes for v4:
- use descriptive names for open/short circuit interrupts
- remove vdd regulator description
- remove unused import
- use generic sensor name in example
- don't use literal style for doc description Changes for v3:
- Added dt-bindings

---
 .../iio/temperature/microchip,mcp9600.yaml    | 70 +++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/temperature/microchip,mcp9600.yaml
Documentation/devicetree/bindings/iio/temperature/microchip,mcp9600.yaml new file +70 -0
new file mode 100644
index 000000000000..d2cafa38a544
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/temperature/microchip,mcp9600.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip MCP9600 thermocouple EMF converter
+
+maintainers:
+  - Andrew Hepp <[email protected]>
+
+description:
+  https://ww1.microchip.com/downloads/en/DeviceDoc/MCP960X-Data-Sheet-20005426.pdf
+
+properties:
+  compatible:
+    const: microchip,mcp9600
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    minItems: 1
+    maxItems: 6
+
+  interrupt-names:
+    minItems: 1
+    maxItems: 6
+    items:
+      enum:
+        - open-circuit
+        - short-circuit
+        - alert1
+        - alert2
+        - alert3
+        - alert4
+
+  thermocouple-type:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Type of thermocouple (THERMOCOUPLE_TYPE_K if omitted).
+      Use defines in dt-bindings/iio/temperature/thermocouple.h.
+      Supported types are B, E, J, K, N, R, S, T.
+
+  vdd-supply: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/iio/temperature/thermocouple.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        temperature-sensor@60 {
+            compatible = "microchip,mcp9600";
+            reg = <0x60>;
+            interrupt-parent = <&gpio>;
+            interrupts = <25 IRQ_TYPE_EDGE_RISING>;
+            interrupt-names = "open-circuit";
+            thermocouple-type = <THERMOCOUPLE_TYPE_K>;
+            vdd-supply = <&vdd>;
+        };
+    };
Signature · 1 line
2.30.2
author
#3 lore raw

PATCH v5 2/2 iio: temperature: Add MCP9600 thermocouple EMF converter

In reply to Andrew Hepp

Add support for the MCP9600 thermocouple EMF converter.

Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/MCP960X-Data-Sheet-20005426.pdf

Signed-off-by Andrew Hepp <[email protected]>

---
Changes for v5:
- remove "driver" from subject
Changes for v4:
- none
Changes for v3:
- none
Changes for v2:
- remove unused sysfs include
- remove unused scan fields from channel
- warn rather than fail when probing unknown device
- register device through devm
- clean up style and prints

---
 drivers/iio/temperature/Kconfig   |  10 ++
 drivers/iio/temperature/Makefile  |   1 +
 drivers/iio/temperature/mcp9600.c | 146 ++++++++++++++++++++++++++++++
 3 files changed, 157 insertions(+)
 create mode 100644 drivers/iio/temperature/mcp9600.c
drivers/iio/temperature/Kconfig +10 -0
index ed384f33e0c7..ea2ce364b2e9 100644
@@ -158,4 +158,14 @@ config MAX31865
 	  This driver can also be build as a module. If so, the module
 	  will be called max31865.
 
+config MCP9600
+	tristate "MCP9600 thermocouple EMF converter"
+	depends on I2C
+	help
+	  If you say yes here you get support for MCP9600
+	  thermocouple EMF converter connected via I2C.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called mcp9600.
+
 endmenu
drivers/iio/temperature/Makefile +1 -0
index dfec8c6d3019..9330d4a39598 100644
@@ -10,6 +10,7 @@ obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
 obj-$(CONFIG_MAX30208) += max30208.o
 obj-$(CONFIG_MAX31856) += max31856.o
 obj-$(CONFIG_MAX31865) += max31865.o
+obj-$(CONFIG_MCP9600) += mcp9600.o
 obj-$(CONFIG_MLX90614) += mlx90614.o
 obj-$(CONFIG_MLX90632) += mlx90632.o
 obj-$(CONFIG_TMP006) += tmp006.o
drivers/iio/temperature/mcp9600.c new file +146 -0

146 lines not on this page · raw message

Signature · 1 line
2.30.2
maintainer
#4 lore raw

Re: [PATCH v5 2/2] iio: temperature: Add MCP9600 thermocouple EMF converter

Quoted 4 lines · On Sun, 5 Mar 2023 13:36:04 -0800 Andrew Hepp <[email protected]> wrote:

Add support for the MCP9600 thermocouple EMF converter.

Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/MCP960X-Data-Sheet-20005426.pdf

Signed-off-by Andrew Hepp <[email protected]>

Hi Andrew,

One minor improvement suggested inline.

If you can test with
i2c_smbus_read_word_swapped() as suggested (I'm never sure when we need the swapped form) that would be great.

If we had been later in the cycle I'd have taken this anyway and suggested that change as a follow up patch, but we have lots of time, so no rush.

Thanks,

Jonathan

drivers/iio/temperature/mcp9600.c line 56

Quoted 9 lines
drivers/iio/temperature/mcp9600.c new file +9 -0
+static int mcp9600_read(struct mcp9600_data *data,
+			struct iio_chan_spec const *chan, int *val)
+{
+	__be16 buf;
+	int ret;
+
+	mutex_lock(&data->read_lock);
+	ret = i2c_smbus_read_i2c_block_data(data->client, chan->address, 2,
+					    (u8 *)&buf);

Rare to see this call, so I went looking in the datasheet
https://www.kernel.org/doc/html/v5.5/i2c/smbus-protocol.html gives the structure of this command as
S Addr Wr [A] Comm [A]
S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P

which matches the datasheet. However for two bytes it's also the same as...

S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P which is the more common

i2c_smbus_read_word_data() which has a defined endian type and which I think is the wrong one here.

Given that's a common situation we also have i2c_smbus_read_word_swapped() which is same thing but for data the opposite way around and will avoid the need for an explicit endian swap.

Jonathan

Quoted 9 lines
drivers/iio/temperature/mcp9600.c new file +9 -0
+	mutex_unlock(&data->read_lock);
+
+	if (ret < 0)
+		return ret;
+	*val = be16_to_cpu(buf);
+
+	return 0;
+}
+