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Message-ID: <20250816111125.65fcbb09@jic23-huawei>
Date: Sat, 16 Aug 2025 11:11:25 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Ben Collins <bcollins@...ter.com>
Cc: David Lechner <dlechner@...libre.com>, Nuno Sá
<nuno.sa@...log.com>, Andy Shevchenko <andy@...nel.org>,
linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] iio: mcp9600: Add support for thermocouple-type
On Fri, 15 Aug 2025 16:46:06 +0000
Ben Collins <bcollins@...ter.com> wrote:
> dt-bindings documentation for this driver claims to support
> thermocouple-type, but the driver does not actually make use of
> the property.
>
> Implement usage of the property to configure the chip for the
> selected thermocouple-type.
>
> Signed-off-by: Ben Collins <bcollins@...ter.com>
Hi Ben,
Just one trivial thing inline.
Thanks
Jonathan
> ---
> drivers/iio/temperature/mcp9600.c | 69 +++++++++++++++++++++++++++++++
> 1 file changed, 69 insertions(+)
>
> diff --git a/drivers/iio/temperature/mcp9600.c b/drivers/iio/temperature/mcp9600.c
> index c18ae17b6d82f..361572a241f06 100644
> --- a/drivers/iio/temperature/mcp9600.c
> +++ b/drivers/iio/temperature/mcp9600.c
> @@ -22,11 +22,15 @@
> #include <linux/iio/events.h>
> #include <linux/iio/iio.h>
>
> +#include <dt-bindings/iio/temperature/thermocouple.h>
> +
> /* MCP9600 registers */
> #define MCP9600_HOT_JUNCTION 0x00
> #define MCP9600_COLD_JUNCTION 0x02
> #define MCP9600_STATUS 0x04
> #define MCP9600_STATUS_ALERT(x) BIT(x)
> +#define MCP9600_SENSOR_CFG 0x05
> +#define MCP9600_SENSOR_TYPE_MASK GENMASK(6, 4)
> #define MCP9600_ALERT_CFG1 0x08
> #define MCP9600_ALERT_CFG(x) (MCP9600_ALERT_CFG1 + (x - 1))
> #define MCP9600_ALERT_CFG_ENABLE BIT(0)
> @@ -66,6 +70,30 @@ static const char * const mcp9600_alert_name[MCP9600_ALERT_COUNT] = {
> [MCP9600_ALERT4] = "alert4",
> };
>
> +/* Map between dt-bindings enum and the chip's type value */
> +static const unsigned int mcp9600_type_map[] = {
> + [THERMOCOUPLE_TYPE_K] = 0,
> + [THERMOCOUPLE_TYPE_J] = 1,
> + [THERMOCOUPLE_TYPE_T] = 2,
> + [THERMOCOUPLE_TYPE_N] = 3,
> + [THERMOCOUPLE_TYPE_S] = 4,
> + [THERMOCOUPLE_TYPE_E] = 5,
> + [THERMOCOUPLE_TYPE_B] = 6,
> + [THERMOCOUPLE_TYPE_R] = 7,
> +};
> +
> +/* Map thermocouple type to a char for for iio info in sysfs */
> +static const int mcp9600_tc_types[] = {
> + [THERMOCOUPLE_TYPE_K] = 'K',
> + [THERMOCOUPLE_TYPE_J] = 'J',
> + [THERMOCOUPLE_TYPE_T] = 'T',
> + [THERMOCOUPLE_TYPE_N] = 'N',
> + [THERMOCOUPLE_TYPE_S] = 'S',
> + [THERMOCOUPLE_TYPE_E] = 'E',
> + [THERMOCOUPLE_TYPE_B] = 'B',
> + [THERMOCOUPLE_TYPE_R] = 'R',
> +};
> +
> static const struct iio_event_spec mcp9600_events[] = {
> {
> .type = IIO_EV_TYPE_THRESH,
> @@ -89,6 +117,7 @@ static const struct iio_event_spec mcp9600_events[] = {
> .type = IIO_TEMP, \
> .address = MCP9600_HOT_JUNCTION, \
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> + BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE) | \
> BIT(IIO_CHAN_INFO_SCALE), \
> .event_spec = &mcp9600_events[hj_ev_spec_off], \
> .num_event_specs = hj_num_ev, \
> @@ -131,6 +160,7 @@ struct mcp_chip_info {
>
> struct mcp9600_data {
> struct i2c_client *client;
> + u32 thermocouple_type;
> };
>
> static int mcp9600_read(struct mcp9600_data *data,
> @@ -165,11 +195,32 @@ static int mcp9600_read_raw(struct iio_dev *indio_dev,
> *val = 62;
> *val2 = 500000;
> return IIO_VAL_INT_PLUS_MICRO;
> + case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
> + *val = mcp9600_tc_types[data->thermocouple_type];
> + return IIO_VAL_CHAR;
> default:
> return -EINVAL;
> }
> }
>
> +static int mcp9600_config(struct mcp9600_data *data)
> +{
> + struct i2c_client *client = data->client;
> + int ret;
> + u8 cfg;
> +
> + cfg = FIELD_PREP(MCP9600_SENSOR_TYPE_MASK,
> + mcp9600_type_map[data->thermocouple_type]);
> +
> + ret = i2c_smbus_write_byte_data(client, MCP9600_SENSOR_CFG, cfg);
> + if (ret < 0) {
> + dev_err(&client->dev, "Failed to set sensor configuration\n");
Only called from probe so use return dev_err_probe() here
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> static int mcp9600_get_alert_index(int channel2, enum iio_event_direction dir)
> {
> if (channel2 == IIO_MOD_TEMP_AMBIENT) {
> @@ -453,6 +504,24 @@ static int mcp9600_probe(struct i2c_client *client)
> data = iio_priv(indio_dev);
> data->client = client;
>
> + /* Accept type from dt with default of Type-K. */
> + data->thermocouple_type = THERMOCOUPLE_TYPE_K;
> + ret = device_property_read_u32(&client->dev, "thermocouple-type",
> + &data->thermocouple_type);
> + if (ret < 0 && ret != -EINVAL)
> + return dev_err_probe(&client->dev, ret,
> + "Error reading thermocouple-type property\n");
> +
> + if (data->thermocouple_type >= ARRAY_SIZE(mcp9600_type_map))
> + return dev_err_probe(&client->dev, -EINVAL,
> + "Invalid thermocouple-type property %u.\n",
> + data->thermocouple_type);
> +
> + /* Set initial config. */
> + ret = mcp9600_config(data);
> + if (ret < 0)
> + return ret;
> +
> ch_sel = mcp9600_probe_alerts(indio_dev);
> if (ch_sel < 0)
> return ch_sel;
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