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[PATCH v5 3/5] iio: mcp9600: Recognize chip id for mcp9601

Ben Collins posted 5 patches 1 month, 2 weeks ago
There is a newer version of this series
[PATCH v5 3/5] iio: mcp9600: Recognize chip id for mcp9601
Posted by Ben Collins 1 month, 2 weeks ago 
From: Ben Collins <bcollins@watter.com>

The current driver works with mcp9601, but emits a warning because it
does not recognize the chip id.

MCP9601 is a superset of MCP9600. The drivers works without changes
on this chipset.

However, the 9601 chip supports open/closed-circuit detection if wired
properly, so we'll need to be able to differentiate between them.

Signed-off-by: Ben Collins <bcollins@watter.com>
---
 drivers/iio/temperature/Kconfig   |  8 +++--
 drivers/iio/temperature/mcp9600.c | 55 +++++++++++++++++++++++++------
 2 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
index 1244d8e17d504..9328b2250aced 100644
--- a/drivers/iio/temperature/Kconfig
+++ b/drivers/iio/temperature/Kconfig
@@ -173,11 +173,13 @@ config MAX31865
 	  will be called max31865.
 
 config MCP9600
-	tristate "MCP9600 thermocouple EMF converter"
+	tristate "MCP9600 and similar thermocouple EMF converters"
 	depends on I2C
 	help
-	  If you say yes here you get support for MCP9600
-	  thermocouple EMF converter connected via I2C.
+	  If you say yes here you get support for...
+	  - MCP9600
+	  - MCP9601
+	  ...thermocouple EMF converters connected via I2C.
 
 	  This driver can also be built as a module. If so, the module
 	  will be called mcp9600.
diff --git a/drivers/iio/temperature/mcp9600.c b/drivers/iio/temperature/mcp9600.c
index 40906bb200ec9..54de38a39292e 100644
--- a/drivers/iio/temperature/mcp9600.c
+++ b/drivers/iio/temperature/mcp9600.c
@@ -42,6 +42,7 @@
 
 /* MCP9600 device id value */
 #define MCP9600_DEVICE_ID_MCP9600	0x40
+#define MCP9600_DEVICE_ID_MCP9601	0x41
 
 #define MCP9600_ALERT_COUNT		4
 
@@ -123,6 +124,11 @@ static const struct iio_chan_spec mcp9600_channels[][2] = {
 	MCP9600_CHANNELS(2, 0, 2, 0), /* Alerts: 1 2 3 4 */
 };
 
+struct mcp_chip_info {
+	u8 chip_id;
+	const char *chip_name;
+};
+
 struct mcp9600_data {
 	struct i2c_client *client;
 };
@@ -416,16 +422,33 @@ static int mcp9600_probe_alerts(struct iio_dev *indio_dev)
 
 static int mcp9600_probe(struct i2c_client *client)
 {
+	const struct mcp_chip_info *chip_info = i2c_get_match_data(client);
 	struct iio_dev *indio_dev;
 	struct mcp9600_data *data;
-	int ret, ch_sel;
+	int ch_sel, dev_id, ret;
+
+	if (chip_info == NULL)
+		return dev_err_probe(&client->dev, -EINVAL,
+                                     "No chip-info found for device\n");
+
+	dev_id = i2c_smbus_read_byte_data(client, MCP9600_DEVICE_ID);
+	if (dev_id < 0)
+		return dev_err_probe(&client->dev, dev_id,
+				     "Failed to read device ID\n");
+
+	switch (dev_id) {
+	case MCP9600_DEVICE_ID_MCP9600:
+	case MCP9600_DEVICE_ID_MCP9601:
+		if (dev_id != chip_info->chip_id)
+			dev_warn(&client->dev,
+				 "Expected id %02x, but device responded with %02x\n",
+				 chip_info->chip_id, dev_id);
+		break;
 
-	ret = i2c_smbus_read_byte_data(client, MCP9600_DEVICE_ID);
-	if (ret < 0)
-		return dev_err_probe(&client->dev, ret, "Failed to read device ID\n");
-	if (ret != MCP9600_DEVICE_ID_MCP9600)
-		dev_warn(&client->dev, "Expected ID %x, got %x\n",
-				MCP9600_DEVICE_ID_MCP9600, ret);
+	default:
+		dev_warn(&client->dev, "Unknown id %x, using %x\n", dev_id,
+			 chip_info->chip_id);
+	}
 
 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
@@ -439,7 +462,7 @@ static int mcp9600_probe(struct i2c_client *client)
 		return ch_sel;
 
 	indio_dev->info = &mcp9600_info;
-	indio_dev->name = "mcp9600";
+	indio_dev->name = chip_info->chip_name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = mcp9600_channels[ch_sel];
 	indio_dev->num_channels = ARRAY_SIZE(mcp9600_channels[ch_sel]);
@@ -447,14 +470,26 @@ static int mcp9600_probe(struct i2c_client *client)
 	return devm_iio_device_register(&client->dev, indio_dev);
 }
 
+static const struct mcp_chip_info mcp9600_chip_info = {
+	.chip_id   = MCP9600_DEVICE_ID_MCP9600,
+	.chip_name = "mcp9600",
+};
+
+static const struct mcp_chip_info mcp9601_chip_info = {
+	.chip_id   = MCP9600_DEVICE_ID_MCP9601,
+	.chip_name = "mcp9601",
+};
+
 static const struct i2c_device_id mcp9600_id[] = {
-	{ "mcp9600" },
+	{ "mcp9600", .driver_data = (kernel_ulong_t)&mcp9600_chip_info },
+	{ "mcp9601", .driver_data = (kernel_ulong_t)&mcp9601_chip_info },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, mcp9600_id);
 
 static const struct of_device_id mcp9600_of_match[] = {
-	{ .compatible = "microchip,mcp9600" },
+	{ .compatible = "microchip,mcp9600", .data = &mcp9600_chip_info },
+	{ .compatible = "microchip,mcp9601", .data = &mcp9601_chip_info },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, mcp9600_of_match);
-- 
2.39.5
Re: [PATCH v5 3/5] iio: mcp9600: Recognize chip id for mcp9601
Posted by Jonathan Cameron 1 month, 2 weeks ago 
On Sun, 17 Aug 2025 23:59:51 -0400
Ben Collins <bcollins@kernel.org> wrote:

> From: Ben Collins <bcollins@watter.com>
> 
> The current driver works with mcp9601, but emits a warning because it
> does not recognize the chip id.
> 
> MCP9601 is a superset of MCP9600. The drivers works without changes
> on this chipset.
> 
> However, the 9601 chip supports open/closed-circuit detection if wired
> properly, so we'll need to be able to differentiate between them.
> 
> Signed-off-by: Ben Collins <bcollins@watter.com>

Hi Ben

One minor thing inline that need fixing up.

> diff --git a/drivers/iio/temperature/mcp9600.c b/drivers/iio/temperature/mcp9600.c
> index 40906bb200ec9..54de38a39292e 100644
> --- a/drivers/iio/temperature/mcp9600.c
> +++ b/drivers/iio/temperature/mcp9600.c
> @@ -42,6 +42,7 @@

> @@ -416,16 +422,33 @@ static int mcp9600_probe_alerts(struct iio_dev *indio_dev)
>  
>  static int mcp9600_probe(struct i2c_client *client)
>  {
> +	const struct mcp_chip_info *chip_info = i2c_get_match_data(client);
>  	struct iio_dev *indio_dev;
>  	struct mcp9600_data *data;
> -	int ret, ch_sel;
> +	int ch_sel, dev_id, ret;
> +
> +	if (chip_info == NULL)
> +		return dev_err_probe(&client->dev, -EINVAL,
> +                                     "No chip-info found for device\n");

This line seems to be indented with spaces, not tabs then spaces which
is the coding style. I only noticed because of the shift seen in this reply.



> +
> +	dev_id = i2c_smbus_read_byte_data(client, MCP9600_DEVICE_ID);
> +	if (dev_id < 0)
> +		return dev_err_probe(&client->dev, dev_id,
> +				     "Failed to read device ID\n");
> +
> +	switch (dev_id) {
> +	case MCP9600_DEVICE_ID_MCP9600:
> +	case MCP9600_DEVICE_ID_MCP9601:
> +		if (dev_id != chip_info->chip_id)
> +			dev_warn(&client->dev,
> +				 "Expected id %02x, but device responded with %02x\n",
> +				 chip_info->chip_id, dev_id);
> +		break;
>  
> -	ret = i2c_smbus_read_byte_data(client, MCP9600_DEVICE_ID);
> -	if (ret < 0)
> -		return dev_err_probe(&client->dev, ret, "Failed to read device ID\n");
> -	if (ret != MCP9600_DEVICE_ID_MCP9600)
> -		dev_warn(&client->dev, "Expected ID %x, got %x\n",
> -				MCP9600_DEVICE_ID_MCP9600, ret);
> +	default:
> +		dev_warn(&client->dev, "Unknown id %x, using %x\n", dev_id,
> +			 chip_info->chip_id);
> +	}

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