[PATCH v4 07/10] 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".

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
 drivers/iio/adc/ti-ads1262.c | 87 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 84 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ti-ads1262.c b/drivers/iio/adc/ti-ads1262.c
index 4d38da092001..04566d00d7cb 100644
--- a/drivers/iio/adc/ti-ads1262.c
+++ b/drivers/iio/adc/ti-ads1262.c
@@ -198,12 +198,15 @@
 struct ads1262_channel {
 	u8 data_rate;
 	u8 filter;
+	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;
 	size_t num_scales;
 	int scales[ADS1262_GAIN_COUNT][2];
 };
@@ -315,6 +318,7 @@ static const struct iio_chan_spec ads1262_monitor_chan_specs[] = {
 static const struct ads1262_channel ads1262_default_channel = {
 	.data_rate = ADS1262_DR_20_SPS,
 	.filter = ADS1262_FILTER_FIR,
+	.idac_mux = { ADS1262_IDACMUX_NO_CONN, ADS1262_IDACMUX_NO_CONN },
 };
 
 static const u32 ads1262_mod_decimator_a[] = {
@@ -373,6 +377,21 @@ static const char * const ads1262_ref_sources_neg[] = {
 	NULL
 };
 
+static const u32 ads1262_idac_mags_nA[] = {
+	0, 50000, 100000, 250000, 500000, 750000, 1000000, 1500000,	/* 0..7 */
+	2000000, 2500000, 3000000					/* 8..10 */
+};
+
+static int ads1262_find_one(const u32 *array, size_t num_elements, u32 val)
+{
+	for (unsigned int i = 0; i < num_elements; i++) {
+		if (val == array[i])
+			return i;
+	}
+
+	return -EINVAL;
+}
+
 static int ads1262_find_two(const int (*array)[2], size_t num_elements, int val,
 			    int val2)
 {
@@ -522,8 +541,10 @@ static int ads1262_channel_enable(struct ads1262 *st,
 
 	ret = regmap_update_bits(st->regmap, ADS1262_MODE0_REG,
 				 ADS1262_MODE0_INPUT_CHOP_MASK |
+				 ADS1262_MODE0_IDAC_CHOP_MASK |
 				 ADS1262_MODE0_REFREV_MASK,
 				 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));
 	if (ret)
 		return ret;
@@ -544,6 +565,22 @@ static int ads1262_channel_enable(struct ads1262 *st,
 	if (ret)
 		return ret;
 
+	ret = regmap_update_bits(st->regmap, ADS1262_IDACMUX_REG,
+				 ADS1262_IDACMUX_MUX1_MASK |
+				 ADS1262_IDACMUX_MUX2_MASK,
+				 FIELD_PREP(ADS1262_IDACMUX_MUX1_MASK, chan->idac_mux[0]) |
+				 FIELD_PREP(ADS1262_IDACMUX_MUX2_MASK, chan->idac_mux[1]));
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(st->regmap, ADS1262_IDACMAG_REG,
+				 ADS1262_IDACMAG_MAG1_MASK |
+				 ADS1262_IDACMAG_MAG2_MASK,
+				 FIELD_PREP(ADS1262_IDACMAG_MAG1_MASK, chan->idac_mag[0]) |
+				 FIELD_PREP(ADS1262_IDACMAG_MAG2_MASK, chan->idac_mag[1]));
+	if (ret)
+		return ret;
+
 	return regmap_update_bits(st->regmap, ADS1262_REFMUX_REG,
 				  ADS1262_REFMUX_RMUXN_MASK |
 				  ADS1262_REFMUX_RMUXP_MASK,
@@ -578,7 +615,7 @@ 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;
@@ -1288,8 +1325,8 @@ 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]);
@@ -1356,7 +1393,51 @@ 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,
+					     "%pfwP: failed to count excitation-channels\n", 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,
+					     "%pfwP: failed to read excitation-channels\n", node);
+		if (pins[0] > ADS1262_IDACMUX_NO_CONN || pins[1] > ADS1262_IDACMUX_NO_CONN)
+			return dev_err_probe(dev, -EINVAL,
+					     "%pfwP: excitation-channels not in range\n", 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)
+			return dev_err_probe(dev, ret,
+					     "%pfwP: failed to read excitation-current-nanoamp\n",
+					     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,
+					     "%pfwP: invalid excitation-current-nanoamp\n", 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,
+					     "%pfwP: invalid excitation-current-nanoamp\n", node);
+		chan->idac_mag[1] = ret;
+	}
+
 	chan->input_chop = fwnode_property_read_bool(node, "input-chopping");
+	chan->idac_chop = fwnode_property_read_bool(node, "excitation-current-chopping");
 	chan->ref_reversal = fwnode_property_read_bool(node, "ti,reference-reversal");
 
 	return 0;

-- 
2.55.0