]> git.ipfire.org Git - thirdparty/kernel/stable.git/commitdiff
iio: adc: ad4170-4: Add support for weigh scale, thermocouple, and RTD sens
authorMarcelo Schmitt <marcelo.schmitt@analog.com>
Mon, 7 Jul 2025 13:54:29 +0000 (10:54 -0300)
committerJonathan Cameron <Jonathan.Cameron@huawei.com>
Mon, 14 Jul 2025 18:20:53 +0000 (19:20 +0100)
The AD4170-4 design provides features to aid interfacing with weigh scales,
thermocouples, and RTD sensors, which are set up with additional circuitry
for proper sensor operation. A key characteristic of those sensors is that
the circuit they are in must be excited with a single, a pair, or two pairs
of signals. The external circuit can be excited either by a voltage supply
or by AD4170-4 excitation signals. The sensor can then be read through a
different pair of lines that are connected to the AD4170-4 ADC.

Extend the ad4170-4 driver to handle external circuit sensors.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Link: https://patch.msgid.link/52686943040ecad34cc89833d4d5d37f1a51f412.1751895245.git.marcelo.schmitt@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
drivers/iio/adc/ad4170-4.c

index 2a20868a1db7cb8e27535a159100b078eaa0974c..6cd84d6fb08b1c84dda0aabf0dfd867449abef34 100644 (file)
@@ -69,6 +69,8 @@
 #define AD4170_FILTER_FS_REG(x)                                (0xC7 + 14 * (x))
 #define AD4170_OFFSET_REG(x)                           (0xCA + 14 * (x))
 #define AD4170_GAIN_REG(x)                             (0xCD + 14 * (x))
+#define AD4170_V_BIAS_REG                              0x135
+#define AD4170_CURRENT_SRC_REG(x)                      (0x139 + 2 * (x))
 #define AD4170_GPIO_MODE_REG                           0x191
 #define AD4170_GPIO_OUTPUT_REG                         0x193
 #define AD4170_GPIO_INPUT_REG                          0x195
 #define AD4170_CHAN_MAP_AINP_MSK                       GENMASK(12, 8)
 #define AD4170_CHAN_MAP_AINM_MSK                       GENMASK(4, 0)
 
+/* AD4170_MISC_REG */
+#define AD4170_MISC_CHOP_IEXC_MSK                      GENMASK(15, 14)
+#define AD4170_MISC_CHOP_ADC_MSK                       GENMASK(9, 8)
+
 /* AD4170_AFE_REG */
 #define AD4170_AFE_REF_BUF_M_MSK                       GENMASK(11, 10)
 #define AD4170_AFE_REF_BUF_P_MSK                       GENMASK(9, 8)
 /* AD4170_FILTER_REG */
 #define AD4170_FILTER_FILTER_TYPE_MSK                  GENMASK(3, 0)
 
+/* AD4170_CURRENT_SRC_REG */
+#define AD4170_CURRENT_SRC_I_OUT_PIN_MSK               GENMASK(12, 8)
+#define AD4170_CURRENT_SRC_I_OUT_VAL_MSK               GENMASK(2, 0)
+
 /* AD4170_GPIO_MODE_REG */
 #define AD4170_GPIO_MODE_GPIO0_MSK                     GENMASK(1, 0)
 #define AD4170_GPIO_MODE_GPIO1_MSK                     GENMASK(3, 2)
 #define AD4170_GPIO_MODE_GPIO2_MSK                     GENMASK(5, 4)
 #define AD4170_GPIO_MODE_GPIO3_MSK                     GENMASK(7, 6)
 
+/* AD4170_GPIO_OUTPUT_REG */
+#define AD4170_GPIO_OUTPUT_GPIO_MSK(x)                 BIT(x)
+
 /* AD4170 register constants */
 
 /* AD4170_CLOCK_CTRL_REG constants */
 #define AD4170_CHAN_MAP_REFIN2_N               28
 #define AD4170_CHAN_MAP_REFOUT                 29
 
+/* AD4170_MISC_REG constants */
+#define AD4170_MISC_CHOP_IEXC_PAIR1                    0x1
+#define AD4170_MISC_CHOP_IEXC_PAIR2                    0x2
+#define AD4170_MISC_CHOP_IEXC_BOTH                     0x3
+
 /* AD4170_PIN_MUXING_REG constants */
 #define AD4170_PIN_MUXING_DIG_AUX1_DISABLED            0x0
 #define AD4170_PIN_MUXING_DIG_AUX1_RDY                 0x1
 #define AD4170_FILTER_FILTER_TYPE_SINC5                        0x4
 #define AD4170_FILTER_FILTER_TYPE_SINC3                        0x6
 
+/* AD4170_CURRENT_SRC_REG constants */
+#define AD4170_CURRENT_SRC_I_OUT_PIN_AIN(x)            (x)
+#define AD4170_CURRENT_SRC_I_OUT_PIN_GPIO(x)           ((x) + 17)
+
 /* AD4170_GPIO_MODE_REG constants */
 #define AD4170_GPIO_MODE_GPIO_INPUT                    1
 #define AD4170_GPIO_MODE_GPIO_OUTPUT                   2
 #define AD4170_INVALID_SETUP                           9
 #define AD4170_SPI_INST_PHASE_LEN                      2
 #define AD4170_SPI_MAX_XFER_LEN                                6
+#define AD4170_NUM_CURRENT_SRC                         4
 #define AD4170_DEFAULT_SAMP_RATE                       (125 * HZ_PER_KHZ)
 
 #define AD4170_INT_REF_2_5V                            2500000
 
 #define AD4170_ADC_CTRL_CONT_READ_EXIT                 0xA5
 
+/* Analog pin functions  */
+#define AD4170_PIN_UNASSIGNED                          0x00
+#define AD4170_PIN_ANALOG_IN                           0x01
+#define AD4170_PIN_CURRENT_OUT                         0x02
+#define AD4170_PIN_VBIAS                               0x04
+
 /* GPIO pin functions  */
 #define AD4170_GPIO_UNASSIGNED                         0x00
+#define AD4170_GPIO_AC_EXCITATION                      0x02
+#define AD4170_GPIO_OUTPUT                             0x04
+
+/* Current source */
+#define AD4170_CURRENT_SRC_DISABLED                    0xFF
 
 static const unsigned int ad4170_reg_size[] = {
        [AD4170_CONFIG_A_REG] = 1,
@@ -232,6 +266,8 @@ static const unsigned int ad4170_reg_size[] = {
        [AD4170_OFFSET_REG(5) ... AD4170_GAIN_REG(5)] = 3,
        [AD4170_OFFSET_REG(6) ... AD4170_GAIN_REG(6)] = 3,
        [AD4170_OFFSET_REG(7) ... AD4170_GAIN_REG(7)] = 3,
+       [AD4170_V_BIAS_REG] = 2,
+       [AD4170_CURRENT_SRC_REG(0) ... AD4170_CURRENT_SRC_REG(3)] = 2,
        [AD4170_GPIO_MODE_REG] = 2,
        [AD4170_GPIO_OUTPUT_REG] = 2,
        [AD4170_GPIO_INPUT_REG] = 2,
@@ -301,8 +337,39 @@ static const unsigned int ad4170_sinc5_filt_fs_tbl[] = {
        1, 2, 4, 8, 12, 16, 20, 40, 48, 80, 100, 256,
 };
 
+static const unsigned int ad4170_iout_pin_tbl[] = {
+       AD4170_CURRENT_SRC_I_OUT_PIN_AIN(0),
+       AD4170_CURRENT_SRC_I_OUT_PIN_AIN(1),
+       AD4170_CURRENT_SRC_I_OUT_PIN_AIN(2),
+       AD4170_CURRENT_SRC_I_OUT_PIN_AIN(3),
+       AD4170_CURRENT_SRC_I_OUT_PIN_AIN(4),
+       AD4170_CURRENT_SRC_I_OUT_PIN_AIN(5),
+       AD4170_CURRENT_SRC_I_OUT_PIN_AIN(6),
+       AD4170_CURRENT_SRC_I_OUT_PIN_AIN(7),
+       AD4170_CURRENT_SRC_I_OUT_PIN_AIN(8),
+       AD4170_CURRENT_SRC_I_OUT_PIN_GPIO(0),
+       AD4170_CURRENT_SRC_I_OUT_PIN_GPIO(1),
+       AD4170_CURRENT_SRC_I_OUT_PIN_GPIO(2),
+       AD4170_CURRENT_SRC_I_OUT_PIN_GPIO(3),
+};
+
+static const unsigned int ad4170_iout_current_ua_tbl[] = {
+       0, 10, 50, 100, 250, 500, 1000, 1500,
+};
+
 enum ad4170_sensor_enum {
        AD4170_ADC_SENSOR = 0,
+       AD4170_WEIGH_SCALE_SENSOR = 1,
+       AD4170_RTD_SENSOR = 2,
+       AD4170_THERMOCOUPLE_SENSOR = 3,
+};
+
+/* maps adi,sensor-type property value to enum */
+static const char * const ad4170_sensor_type[] = {
+       [AD4170_ADC_SENSOR] = "adc",
+       [AD4170_WEIGH_SCALE_SENSOR] = "weighscale",
+       [AD4170_RTD_SENSOR] = "rtd",
+       [AD4170_THERMOCOUPLE_SENSOR] = "thermocouple",
 };
 
 struct ad4170_chip_info {
@@ -387,6 +454,7 @@ struct ad4170_state {
        unsigned int clock_ctrl;
        unsigned int pins_fn[AD4170_NUM_ANALOG_PINS];
        int gpio_fn[AD4170_NUM_GPIO_PINS];
+       unsigned int cur_src_pins[AD4170_NUM_CURRENT_SRC];
        struct gpio_chip gpiochip;
        /*
         * DMA (thus cache coherency maintenance) requires the transfer buffers
@@ -909,6 +977,19 @@ static int ad4170_get_ain_voltage_uv(struct ad4170_state *st, int ain_n,
        int v_diff;
 
        *ain_voltage = 0;
+       /*
+        * The voltage bias (vbias) sets the common-mode voltage of the channel
+        * to (AVDD + AVSS)/2. If provided, AVSS supply provides the magnitude
+        * (absolute value) of the negative voltage supplied to the AVSS pin.
+        * So, we do AVDD - AVSS to compute the DC voltage generated by the bias
+        * voltage generator.
+        */
+       if (st->pins_fn[ain_n] & AD4170_PIN_VBIAS) {
+               int v_diff = st->vrefs_uv[AD4170_AVDD_SUP] - st->vrefs_uv[AD4170_AVSS_SUP];
+               *ain_voltage = v_diff / 2;
+               return 0;
+       }
+
        if (ain_n <= AD4170_CHAN_MAP_TEMP_SENSOR)
                return 0;
 
@@ -963,6 +1044,19 @@ static int ad4170_get_ain_voltage_uv(struct ad4170_state *st, int ain_n,
        }
 }
 
+static int ad4170_validate_analog_input(struct ad4170_state *st, int pin)
+{
+       if (pin <= AD4170_MAX_ANALOG_PINS) {
+               if (st->pins_fn[pin] & AD4170_PIN_CURRENT_OUT)
+                       return dev_err_probe(&st->spi->dev, -EINVAL,
+                                            "Pin %d already used with fn %u.\n",
+                                            pin, st->pins_fn[pin]);
+
+               st->pins_fn[pin] |= AD4170_PIN_ANALOG_IN;
+       }
+       return 0;
+}
+
 static int ad4170_validate_channel_input(struct ad4170_state *st, int pin, bool com)
 {
        /* Check common-mode input pin is mapped to a special input. */
@@ -977,7 +1071,7 @@ static int ad4170_validate_channel_input(struct ad4170_state *st, int pin, bool
                                     "Invalid analog input pin number. %d\n",
                                     pin);
 
-       return 0;
+       return ad4170_validate_analog_input(st, pin);
 }
 
 /*
@@ -1719,6 +1813,371 @@ static int ad4170_gpio_init(struct iio_dev *indio_dev)
        return devm_gpiochip_add_data(&st->spi->dev, &st->gpiochip, indio_dev);
 }
 
+static int ad4170_validate_excitation_pin(struct ad4170_state *st, u32 pin)
+{
+       struct device *dev = &st->spi->dev;
+       unsigned int i;
+
+       /* Check the pin number is valid */
+       for (i = 0; i < ARRAY_SIZE(ad4170_iout_pin_tbl); i++)
+               if (ad4170_iout_pin_tbl[i] == pin)
+                       break;
+
+       if (i == ARRAY_SIZE(ad4170_iout_pin_tbl))
+               return dev_err_probe(dev, -EINVAL,
+                                    "Invalid excitation pin: %u\n",
+                                    pin);
+
+       /* Check the pin is available */
+       if (pin <= AD4170_MAX_ANALOG_PINS) {
+               if (st->pins_fn[pin] != AD4170_PIN_UNASSIGNED)
+                       return dev_err_probe(dev, -EINVAL,
+                                            "Pin %u already used with fn %u\n",
+                                            pin, st->pins_fn[pin]);
+
+               st->pins_fn[pin] |= AD4170_PIN_CURRENT_OUT;
+       } else {
+               unsigned int gpio = pin - AD4170_CURRENT_SRC_I_OUT_PIN_GPIO(0);
+
+               if (st->gpio_fn[gpio] != AD4170_GPIO_UNASSIGNED)
+                       return dev_err_probe(dev, -EINVAL,
+                                            "GPIO %u already used with fn %u\n",
+                                            gpio, st->gpio_fn[gpio]);
+
+               st->gpio_fn[gpio] |= AD4170_GPIO_AC_EXCITATION;
+       }
+
+       return 0;
+}
+
+static int ad4170_validate_excitation_pins(struct ad4170_state *st,
+                                          u32 *exc_pins, int num_exc_pins)
+{
+       unsigned int i;
+       int ret;
+
+       for (i = 0; i < num_exc_pins; i++) {
+               ret = ad4170_validate_excitation_pin(st, exc_pins[i]);
+               if (ret)
+                       return ret;
+       }
+       return 0;
+}
+
+static const char *const ad4170_i_out_pin_dt_props[] = {
+       "adi,excitation-pin-0",
+       "adi,excitation-pin-1",
+       "adi,excitation-pin-2",
+       "adi,excitation-pin-3",
+};
+
+static const char *const ad4170_i_out_val_dt_props[] = {
+       "adi,excitation-current-0-microamp",
+       "adi,excitation-current-1-microamp",
+       "adi,excitation-current-2-microamp",
+       "adi,excitation-current-3-microamp",
+};
+
+/*
+ * Parses firmware data describing output current source setup. There are 4
+ * excitation currents (IOUT0 to IOUT3) that can be configured independently.
+ * Excitation currents are added if they are output on the same pin.
+ */
+static int ad4170_parse_exc_current(struct ad4170_state *st,
+                                   struct fwnode_handle *child,
+                                   unsigned int *exc_pins,
+                                   unsigned int *exc_curs,
+                                   unsigned int *num_exc_pins)
+{
+       struct device *dev = &st->spi->dev;
+       unsigned int num_pins, i, j;
+       u32 pin, val;
+       int ret;
+
+       num_pins = 0;
+       for (i = 0; i < AD4170_NUM_CURRENT_SRC; i++) {
+               /* Parse excitation current output pin properties. */
+               pin = AD4170_CURRENT_SRC_I_OUT_PIN_AIN(0);
+               ret = fwnode_property_read_u32(child, ad4170_i_out_pin_dt_props[i],
+                                              &pin);
+               if (ret)
+                       continue;
+
+               exc_pins[num_pins] = pin;
+
+               /* Parse excitation current value properties. */
+               val = ad4170_iout_current_ua_tbl[0];
+               fwnode_property_read_u32(child,
+                                        ad4170_i_out_val_dt_props[i], &val);
+
+               for (j = 0; j < ARRAY_SIZE(ad4170_iout_current_ua_tbl); j++)
+                       if (ad4170_iout_current_ua_tbl[j] == val)
+                               break;
+
+               if (j == ARRAY_SIZE(ad4170_iout_current_ua_tbl))
+                       return dev_err_probe(dev, -EINVAL, "Invalid %s: %uuA\n",
+                                            ad4170_i_out_val_dt_props[i], val);
+
+               exc_curs[num_pins] = j;
+               num_pins++;
+       }
+       *num_exc_pins = num_pins;
+
+       return 0;
+}
+
+static int ad4170_setup_current_src(struct ad4170_state *st,
+                                   struct fwnode_handle *child,
+                                   struct ad4170_setup *setup, u32 *exc_pins,
+                                   unsigned int *exc_curs, int num_exc_pins,
+                                   bool ac_excited)
+{
+       unsigned int exc_cur_pair, i, j;
+       int ret;
+
+       for (i = 0; i < num_exc_pins; i++) {
+               unsigned int exc_cur = exc_curs[i];
+               unsigned int pin = exc_pins[i];
+               unsigned int current_src = 0;
+
+               for (j = 0; j < AD4170_NUM_CURRENT_SRC; j++)
+                       if (st->cur_src_pins[j] == AD4170_CURRENT_SRC_DISABLED)
+                               break;
+
+               if (j == AD4170_NUM_CURRENT_SRC)
+                       return dev_err_probe(&st->spi->dev, -EINVAL,
+                                            "Too many excitation current sources\n");
+
+               current_src |= FIELD_PREP(AD4170_CURRENT_SRC_I_OUT_PIN_MSK, pin);
+               current_src |= FIELD_PREP(AD4170_CURRENT_SRC_I_OUT_VAL_MSK, exc_cur);
+               st->cur_src_pins[j] = pin;
+               ret = regmap_write(st->regmap, AD4170_CURRENT_SRC_REG(j),
+                                  current_src);
+               if (ret)
+                       return ret;
+       }
+
+       if (!ac_excited)
+               return 0;
+
+       if (num_exc_pins < 2)
+               return dev_err_probe(&st->spi->dev, -EINVAL,
+                       "Current chopping requested but only one pin provided: %u\n",
+                       exc_pins[0]);
+
+       /*
+        * Two use cases to handle here:
+        * - 2 pairs of excitation currents;
+        * - 1 pair of excitation currents.
+        */
+       if (num_exc_pins == 4) {
+               for (i = 0; i < AD4170_NUM_CURRENT_SRC; i++)
+                       if (st->cur_src_pins[i] != exc_pins[i])
+                               return dev_err_probe(&st->spi->dev, -EINVAL,
+                                                    "Unable to use 4 exc pins\n");
+       } else {
+               /*
+                * Excitation current chopping is configured in pairs. Current
+                * sources IOUT0 and IOUT1 form pair 1, IOUT2 and IOUT3 make up
+                * pair 2. So, if current chopping was requested, check if the
+                * first end of the first pair of excitation currents is
+                * available. Try the next pair if IOUT0 has already been
+                * configured for another channel.
+                */
+               i = st->cur_src_pins[0] == exc_pins[0] ? 0 : 2;
+
+               if (st->cur_src_pins[i] != exc_pins[0] ||
+                   st->cur_src_pins[i + 1] != exc_pins[1])
+                       return dev_err_probe(&st->spi->dev, -EINVAL,
+                                            "Failed to setup current chopping\n");
+
+               st->cur_src_pins[i] = exc_pins[0];
+               st->cur_src_pins[i + 1] = exc_pins[1];
+
+               if (i == 0)
+                       exc_cur_pair = AD4170_MISC_CHOP_IEXC_PAIR1;
+               else
+                       exc_cur_pair = AD4170_MISC_CHOP_IEXC_PAIR2;
+       }
+
+       /*
+        * Configure excitation current chopping.
+        * Chop both pairs if using four excitation pins.
+        */
+       setup->misc |= FIELD_PREP(AD4170_MISC_CHOP_IEXC_MSK,
+                                 num_exc_pins == 2 ?
+                                 exc_cur_pair :
+                                 AD4170_MISC_CHOP_IEXC_BOTH);
+
+       return 0;
+}
+
+static int ad4170_setup_bridge(struct ad4170_state *st,
+                              struct fwnode_handle *child,
+                              struct ad4170_setup *setup, u32 *exc_pins,
+                              unsigned int *exc_curs, int num_exc_pins,
+                              bool ac_excited)
+{
+       unsigned long gpio_mask;
+       unsigned int i;
+       int ret;
+
+       /*
+        * If a specific current is provided through
+        * adi,excitation-current-n-microamp, set excitation pins provided
+        * through adi,excitation-pin-n to excite the bridge circuit.
+        */
+       for (i = 0; i < num_exc_pins; i++)
+               if (exc_curs[i] > 0)
+                       return ad4170_setup_current_src(st, child, setup, exc_pins,
+                                                       exc_curs, num_exc_pins,
+                                                       ac_excited);
+
+       /*
+        * Else, use predefined ACX1, ACX1 negated, ACX2, ACX2 negated signals
+        * to AC excite the bridge. Those signals are output on GPIO2, GPIO0,
+        * GPIO3, and GPIO1, respectively. If only two pins are specified for AC
+        * excitation, use ACX1 and ACX2 (GPIO2 and GPIO3).
+        *
+        * Also, to avoid any short-circuit condition when more than one channel
+        * is enabled, set GPIO2 and GPIO0 high, and set GPIO1 and GPIO3 low to
+        * DC excite the bridge whenever a channel without AC excitation is
+        * selected. That is needed because GPIO pins are controlled by the next
+        * highest priority GPIO function when a channel doesn't enable AC
+        * excitation. See datasheet Figure 113 Weigh Scale (AC Excitation) for
+        * the reference circuit diagram.
+        */
+       if (num_exc_pins == 2) {
+               setup->misc |= FIELD_PREP(AD4170_MISC_CHOP_ADC_MSK, 0x3);
+
+               gpio_mask = AD4170_GPIO_MODE_GPIO3_MSK | AD4170_GPIO_MODE_GPIO2_MSK;
+               ret = regmap_update_bits(st->regmap, AD4170_GPIO_MODE_REG, gpio_mask,
+                                        FIELD_PREP(AD4170_GPIO_MODE_GPIO3_MSK,
+                                                   AD4170_GPIO_MODE_GPIO_OUTPUT) |
+                                        FIELD_PREP(AD4170_GPIO_MODE_GPIO2_MSK,
+                                                   AD4170_GPIO_MODE_GPIO_OUTPUT));
+               if (ret)
+                       return ret;
+
+               /*
+                * Set GPIO2 high and GPIO3 low to DC excite the bridge when
+                * a different channel is selected.
+                */
+               gpio_mask = AD4170_GPIO_OUTPUT_GPIO_MSK(3) |
+                           AD4170_GPIO_OUTPUT_GPIO_MSK(2);
+               ret = regmap_update_bits(st->regmap, AD4170_GPIO_OUTPUT_REG, gpio_mask,
+                                        FIELD_PREP(AD4170_GPIO_OUTPUT_GPIO_MSK(3), 0) |
+                                        FIELD_PREP(AD4170_GPIO_OUTPUT_GPIO_MSK(2), 1));
+               if (ret)
+                       return ret;
+
+               st->gpio_fn[3] |= AD4170_GPIO_OUTPUT;
+               st->gpio_fn[2] |= AD4170_GPIO_OUTPUT;
+       } else {
+               setup->misc |= FIELD_PREP(AD4170_MISC_CHOP_ADC_MSK, 0x2);
+
+               gpio_mask = AD4170_GPIO_MODE_GPIO3_MSK | AD4170_GPIO_MODE_GPIO2_MSK |
+                           AD4170_GPIO_MODE_GPIO1_MSK | AD4170_GPIO_MODE_GPIO0_MSK;
+               ret = regmap_update_bits(st->regmap, AD4170_GPIO_MODE_REG, gpio_mask,
+                                        FIELD_PREP(AD4170_GPIO_MODE_GPIO3_MSK,
+                                                   AD4170_GPIO_MODE_GPIO_OUTPUT) |
+                                        FIELD_PREP(AD4170_GPIO_MODE_GPIO2_MSK,
+                                                   AD4170_GPIO_MODE_GPIO_OUTPUT) |
+                                        FIELD_PREP(AD4170_GPIO_MODE_GPIO1_MSK,
+                                                   AD4170_GPIO_MODE_GPIO_OUTPUT) |
+                                        FIELD_PREP(AD4170_GPIO_MODE_GPIO0_MSK,
+                                                   AD4170_GPIO_MODE_GPIO_OUTPUT));
+               if (ret)
+                       return ret;
+
+               /*
+                * Set GPIO2 and GPIO0 high, and set GPIO1 and GPIO3 low to DC
+                * excite the bridge when a different channel is selected.
+                */
+               gpio_mask = AD4170_GPIO_OUTPUT_GPIO_MSK(3) |
+                           AD4170_GPIO_OUTPUT_GPIO_MSK(2) |
+                           AD4170_GPIO_OUTPUT_GPIO_MSK(1) |
+                           AD4170_GPIO_OUTPUT_GPIO_MSK(0);
+               ret = regmap_update_bits(st->regmap, AD4170_GPIO_OUTPUT_REG, gpio_mask,
+                                        FIELD_PREP(AD4170_GPIO_OUTPUT_GPIO_MSK(3), 0) |
+                                        FIELD_PREP(AD4170_GPIO_OUTPUT_GPIO_MSK(2), 1) |
+                                        FIELD_PREP(AD4170_GPIO_OUTPUT_GPIO_MSK(1), 0) |
+                                        FIELD_PREP(AD4170_GPIO_OUTPUT_GPIO_MSK(0), 1));
+               if (ret)
+                       return ret;
+
+               st->gpio_fn[3] |= AD4170_GPIO_OUTPUT;
+               st->gpio_fn[2] |= AD4170_GPIO_OUTPUT;
+               st->gpio_fn[1] |= AD4170_GPIO_OUTPUT;
+               st->gpio_fn[0] |= AD4170_GPIO_OUTPUT;
+       }
+
+       return 0;
+}
+
+static int ad4170_setup_rtd(struct ad4170_state *st,
+                           struct fwnode_handle *child,
+                           struct ad4170_setup *setup, u32 *exc_pins,
+                           unsigned int *exc_curs, int num_exc_pins, bool ac_excited)
+{
+       return ad4170_setup_current_src(st, child, setup, exc_pins,
+                                       exc_curs, num_exc_pins, ac_excited);
+}
+
+static int ad4170_parse_external_sensor(struct ad4170_state *st,
+                                       struct fwnode_handle *child,
+                                       struct ad4170_setup *setup,
+                                       struct iio_chan_spec *chan,
+                                       unsigned int s_type)
+{
+       unsigned int num_exc_pins, reg_val;
+       struct device *dev = &st->spi->dev;
+       u32 pins[2], exc_pins[4], exc_curs[4];
+       bool ac_excited;
+       int ret;
+
+       ret = fwnode_property_read_u32_array(child, "diff-channels", pins,
+                                            ARRAY_SIZE(pins));
+       if (ret)
+               return dev_err_probe(dev, ret,
+                                    "Failed to read sensor diff-channels\n");
+
+       chan->differential = true;
+       chan->channel = pins[0];
+       chan->channel2 = pins[1];
+
+       ret = ad4170_parse_exc_current(st, child, exc_pins, exc_curs, &num_exc_pins);
+       if (ret)
+               return ret;
+
+       /* The external sensor may not need excitation from the ADC chip. */
+       if (num_exc_pins == 0)
+               return 0;
+
+       ret = ad4170_validate_excitation_pins(st, exc_pins, num_exc_pins);
+       if (ret)
+               return ret;
+
+       ac_excited = fwnode_property_read_bool(child, "adi,excitation-ac");
+
+       if (s_type == AD4170_THERMOCOUPLE_SENSOR) {
+               if (st->pins_fn[chan->channel2] & AD4170_PIN_VBIAS) {
+                       reg_val = BIT(chan->channel2);
+                       ret = regmap_write(st->regmap, AD4170_V_BIAS_REG, reg_val);
+                       if (ret)
+                               dev_err_probe(dev, ret, "Failed to set vbias\n");
+               }
+       }
+       if (s_type == AD4170_WEIGH_SCALE_SENSOR)
+               ret = ad4170_setup_bridge(st, child, setup, exc_pins, exc_curs,
+                                         num_exc_pins, ac_excited);
+       else
+               ret = ad4170_setup_rtd(st, child, setup, exc_pins, exc_curs,
+                                      num_exc_pins, ac_excited);
+
+       return ret;
+}
+
 static int ad4170_parse_reference(struct ad4170_state *st,
                                  struct fwnode_handle *child,
                                  struct ad4170_setup *setup)
@@ -1848,12 +2307,26 @@ static int ad4170_parse_channel_node(struct iio_dev *indio_dev,
        if (ret)
                return ret;
 
+       ret = fwnode_property_match_property_string(child, "adi,sensor-type",
+                                                   ad4170_sensor_type,
+                                                   ARRAY_SIZE(ad4170_sensor_type));
+
+       /* Default to conventional ADC channel if sensor type not present */
+       s_type = ret < 0 ? AD4170_ADC_SENSOR : ret;
        switch (s_type) {
        case AD4170_ADC_SENSOR:
                ret = ad4170_parse_adc_channel_type(dev, child, chan);
                if (ret)
                        return ret;
 
+               break;
+       case AD4170_WEIGH_SCALE_SENSOR:
+       case AD4170_THERMOCOUPLE_SENSOR:
+       case AD4170_RTD_SENSOR:
+               ret = ad4170_parse_external_sensor(st, child, setup, chan, s_type);
+               if (ret)
+                       return ret;
+
                break;
        default:
                return -EINVAL;
@@ -2060,10 +2533,13 @@ static int ad4170_clock_select(struct iio_dev *indio_dev)
 
 static int ad4170_parse_firmware(struct iio_dev *indio_dev)
 {
+       unsigned int vbias_pins[AD4170_MAX_ANALOG_PINS];
        struct ad4170_state *st = iio_priv(indio_dev);
        struct device *dev = &st->spi->dev;
+       unsigned int num_vbias_pins;
        int reg_data, ret;
        u32 int_pin_sel;
+       unsigned int i;
 
        ret = ad4170_clock_select(indio_dev);
        if (ret)
@@ -2073,6 +2549,9 @@ static int ad4170_parse_firmware(struct iio_dev *indio_dev)
        if (ret)
                return ret;
 
+       for (i = 0; i < AD4170_NUM_CURRENT_SRC; i++)
+               st->cur_src_pins[i] = AD4170_CURRENT_SRC_DISABLED;
+
        /* On power on, device defaults to using SDO pin for data ready signal */
        int_pin_sel = AD4170_INT_PIN_SDO;
        ret = device_property_match_property_string(dev, "interrupt-names",
@@ -2091,6 +2570,25 @@ static int ad4170_parse_firmware(struct iio_dev *indio_dev)
        if (ret)
                return ret;
 
+       ret = device_property_count_u32(dev, "adi,vbias-pins");
+       if (ret > 0) {
+               if (ret > AD4170_MAX_ANALOG_PINS)
+                       return dev_err_probe(dev, -EINVAL,
+                                            "Too many vbias pins %u\n", ret);
+
+               num_vbias_pins = ret;
+
+               ret = device_property_read_u32_array(dev, "adi,vbias-pins",
+                                                    vbias_pins,
+                                                    num_vbias_pins);
+               if (ret)
+                       return dev_err_probe(dev, ret,
+                                            "Failed to read vbias pins\n");
+
+               for (i = 0; i < num_vbias_pins; i++)
+                       st->pins_fn[vbias_pins[i]] |= AD4170_PIN_VBIAS;
+       }
+
        ret = ad4170_parse_channels(indio_dev);
        if (ret)
                return ret;