[PATCH v3 6/9] iio: adc: ti-ads1262: support excitation currents

[Kurt Borja <kuurtb@gmail.com>]

Support the two IDAC excitation current sources. Each channel can route
its IDAC1/IDAC2 outputs to a pin via the "excitation-channels" property
and select a magnitude via "excitation-current-nanoamp".

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
 drivers/iio/adc/ti-ads1262.c | 101 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 98 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ti-ads1262.c b/drivers/iio/adc/ti-ads1262.c
index e2659941e1af..d5464b4f2bfb 100644
--- a/drivers/iio/adc/ti-ads1262.c
+++ b/drivers/iio/adc/ti-ads1262.c
@@ -98,6 +98,8 @@
 #define     ADS1262_IDACMUX_NO_CONN		0xB
 
 #define ADS1262_IDACMAG_REG			0x0E
+#define   ADS1262_IDACMAG_MAG2_MASK		GENMASK(7, 4)
+#define   ADS1262_IDACMAG_MAG1_MASK		GENMASK(3, 0)
 
 #define ADS1262_REFMUX_REG			0x0F
 #define   ADS1262_REFMUX_RMUXP_MASK		GENMASK(5, 3)
@@ -205,12 +207,15 @@ struct ads1262_chip_info {
 
 struct ads1262_channel {
 	u8 data_rate;
+	u8 idac_mux[2];
+	u8 idac_mag[2];
 	u8 gain;
 	u8 ref_p;
 	u8 ref_n;
 	bool ref_reversal;
 	bool is_resistance;
 	bool input_chop;
+	bool idac_chop;
 	int offset;
 	int scales[6][2];
 	size_t num_scales;
@@ -277,6 +282,25 @@ static const char * const ads1262_ref_sources_neg[] = {
 	NULL
 };
 
+static const u32 ads1262_idac_mags_nA[] = {
+	0, 50000, 100000, 250000, 500000, 750000, 1000000, 1500000, 2000000,
+	2500000, 3000000
+};
+
+static int ads1262_find_one(const int *array, size_t num_elements, int val)
+{
+	int i;
+
+	for (i = 0; i < num_elements; i++) {
+		if (val == array[i])
+			break;
+	}
+	if (i == num_elements)
+		return -EINVAL;
+
+	return i;
+}
+
 static int ads1262_find_two(const int (*array)[2], size_t num_elements, int val,
 			    int val2)
 {
@@ -433,9 +457,11 @@ static int ads1262_channel_enable(struct ads1262 *st,
 	guard(mutex)(&st->chan_lock);
 
 	val = FIELD_PREP(ADS1262_MODE0_INPUT_CHOP_MASK, chan->input_chop) |
+	      FIELD_PREP(ADS1262_MODE0_IDAC_CHOP_MASK, chan->idac_chop) |
 	      FIELD_PREP(ADS1262_MODE0_REFREV_MASK, chan->ref_reversal);
 	ret = regmap_update_bits(st->regmap, ADS1262_MODE0_REG,
 				 ADS1262_MODE0_INPUT_CHOP_MASK |
+				 ADS1262_MODE0_IDAC_CHOP_MASK |
 				 ADS1262_MODE0_REFREV_MASK, val);
 	if (ret)
 		return ret;
@@ -456,6 +482,22 @@ static int ads1262_channel_enable(struct ads1262 *st,
 	if (ret)
 		return ret;
 
+	val = FIELD_PREP(ADS1262_IDACMUX_MUX1_MASK, chan->idac_mux[0]) |
+	      FIELD_PREP(ADS1262_IDACMUX_MUX2_MASK, chan->idac_mux[1]);
+	ret = regmap_update_bits(st->regmap, ADS1262_IDACMUX_REG,
+				 ADS1262_IDACMUX_MUX1_MASK |
+				 ADS1262_IDACMUX_MUX2_MASK, val);
+	if (ret)
+		return ret;
+
+	val = FIELD_PREP(ADS1262_IDACMAG_MAG1_MASK, chan->idac_mag[0]) |
+	      FIELD_PREP(ADS1262_IDACMAG_MAG2_MASK, chan->idac_mag[1]);
+	ret = regmap_update_bits(st->regmap, ADS1262_IDACMAG_REG,
+				 ADS1262_IDACMAG_MAG1_MASK |
+				 ADS1262_IDACMAG_MAG2_MASK, val);
+	if (ret)
+		return ret;
+
 	val = FIELD_PREP(ADS1262_REFMUX_RMUXN_MASK, chan->ref_n) |
 	      FIELD_PREP(ADS1262_REFMUX_RMUXP_MASK, chan->ref_p);
 	return regmap_update_bits(st->regmap, ADS1262_REFMUX_REG,
@@ -490,7 +532,7 @@ static int ads1262_channel_read(struct iio_dev *indio_dev,
 	 * CONTINUOUS mode and briefly starting and stopping conversions to
 	 * achieve the same effect (Section 9.4.1.2).
 	 */
-	if (chan->input_chop)
+	if (chan->input_chop || chan->idac_chop)
 		runmode = ADS1262_RUNMODE_CONTINUOUS;
 	else
 		runmode = ADS1262_RUNMODE_PULSE;
@@ -1070,8 +1112,8 @@ static int ads1262_parse_channel_node(struct ads1262 *st,
 	struct device *dev = &st->spi->dev;
 	const char *sources[2];
 	char name[sizeof("ti,refpN-refnM-resistor-ohms")];
-	u32 pins[2];
-	int ret;
+	u32 pins[2], mags[2];
+	int count, ret;
 
 	if (fwnode_property_present(node, "single-channel")) {
 		ret = fwnode_property_read_u32(node, "single-channel", &pins[0]);
@@ -1150,7 +1192,58 @@ static int ads1262_parse_channel_node(struct ads1262 *st,
 		}
 	}
 
+	if (fwnode_property_present(node, "excitation-channels")) {
+		count = fwnode_property_count_u32(node, "excitation-channels");
+		if (count < 0)
+			return dev_err_probe(dev, count,
+					     "%s: failed to count excitation-channels\n",
+					     fwnode_get_name(node));
+
+		pins[0] = ADS1262_IDACMUX_NO_CONN;
+		pins[1] = ADS1262_IDACMUX_NO_CONN;
+		ret = fwnode_property_read_u32_array(node, "excitation-channels",
+						     pins, min(count, ARRAY_SIZE(pins)));
+		if (ret)
+			return dev_err_probe(dev, ret, "%s: failed to read excitation-channels\n",
+					     fwnode_get_name(node));
+		if (pins[0] > ADS1262_IDACMUX_NO_CONN || pins[1] > ADS1262_IDACMUX_NO_CONN)
+			return dev_err_probe(dev, -EINVAL, "%s: excitation-channels not in range\n",
+					     fwnode_get_name(node));
+		chan->idac_mux[0] = pins[0];
+		chan->idac_mux[1] = pins[1];
+
+		mags[0] = 0;
+		mags[1] = 0;
+		ret = fwnode_property_read_u32_array(node, "excitation-current-nanoamp",
+						     mags, min(count, ARRAY_SIZE(mags)));
+		if (ret == -EOVERFLOW)
+			return dev_err_probe(dev, ret,
+					     "%s: excitation-current-nanoamp size mismatch\n",
+					     fwnode_get_name(node));
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "%s: failed to read excitation-current-nanoamp\n",
+					     fwnode_get_name(node));
+
+		ret = ads1262_find_one(ads1262_idac_mags_nA,
+				       ARRAY_SIZE(ads1262_idac_mags_nA), mags[0]);
+		if (ret < 0)
+			return dev_err_probe(dev, ret,
+					     "%s: invalid excitation-current-nanoamp\n",
+					     fwnode_get_name(node));
+		chan->idac_mag[0] = ret;
+
+		ret = ads1262_find_one(ads1262_idac_mags_nA,
+				       ARRAY_SIZE(ads1262_idac_mags_nA), mags[1]);
+		if (ret < 0)
+			return dev_err_probe(dev, ret,
+					     "%s: invalid excitation-current-nanoamp\n",
+					     fwnode_get_name(node));
+		chan->idac_mag[1] = ret;
+	}
+
 	chan->input_chop = fwnode_property_read_bool(node, "input-chopping");
+	chan->idac_chop = fwnode_property_read_bool(node, "ti,idac-rotation");
 	chan->ref_reversal = fwnode_property_read_bool(node, "ti,reference-reversal");
 
 	return 0;
@@ -1198,6 +1291,8 @@ static int ads1262_parse_channels(struct iio_dev *indio_dev)
 					     fwnode_get_name(node));
 
 		st->channels[reg].data_rate = ADS1262_DR_20_SPS;
+		st->channels[reg].idac_mux[0] = ADS1262_IDACMUX_NO_CONN;
+		st->channels[reg].idac_mux[1] = ADS1262_IDACMUX_NO_CONN;
 
 		specs[reg].scan_index = reg;
 		specs[reg].scan_type = (struct iio_scan_type) {

-- 
2.55.0