iio: mcp9600: Add support for thermocouple-type

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@watter.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250822-upstream-changes-v8-5-40bb1739e3e2@watter.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/temperature/mcp9600.c b/drivers/iio/temperature/mcp9600.c
index 51ed780ea72fa552884cf170def1450ce017b197..aa42c2b1a369edbd36e0d6d6d1738ed0069fd990 100644 (file)
--- 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 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,
@@ -90,14 +118,34 @@ struct mcp_chip_info {
 
 struct mcp9600_data {
        struct i2c_client *client;
+       u32 thermocouple_type;
 };
 
+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");
+               return ret;
+       }
+
+       return 0;
+}
+
 #define MCP9600_CHANNELS(hj_num_ev, hj_ev_spec_off, cj_num_ev, cj_ev_spec_off) \
        {                                                                      \
                {                                                              \
                        .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,                          \
@@ -165,6 +213,9 @@ 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;
        }
@@ -426,7 +477,7 @@ static int mcp9600_probe(struct i2c_client *client)
        const struct mcp_chip_info *chip_info;
        struct iio_dev *indio_dev;
        struct mcp9600_data *data;
-       int ch_sel, dev_id;
+       int ch_sel, dev_id, ret;
 
        chip_info = i2c_get_match_data(client);
        if (!chip_info)
@@ -458,6 +509,24 @@ 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(dev, "thermocouple-type",
+                                      &data->thermocouple_type);
+       if (ret && ret != -EINVAL)
+               return dev_err_probe(dev, ret,
+                                    "Error reading thermocouple-type property\n");
+
+       if (data->thermocouple_type >= ARRAY_SIZE(mcp9600_type_map))
+               return dev_err_probe(dev, -EINVAL,
+                                    "Invalid thermocouple-type property %u.\n",
+                                    data->thermocouple_type);
+
+       /* Set initial config. */
+       ret = mcp9600_config(data);
+       if (ret)
+               return ret;
+
        ch_sel = mcp9600_probe_alerts(indio_dev);
        if (ch_sel < 0)
                return ch_sel;