[PATCH] iio: accel: adis16203: Fix single-axis representation and CALIBBIAS handling

[Gabriel Shahrouzi <gshahrouzi@gmail.com>]

The ADIS16203 is a single-axis 360 degree inclinometer. The previous
driver code incorrectly represented this by defining separate X and Y
inclination channels based on the two different output format registers
(0x0C for 0-360 deg, 0x0E for +/-180 deg). This violated IIO conventions
and misrepresented the hardware's single angle output. The 'Fixme'
comment on the original Y channel definition indicated this known issue.

Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
---
Not sure to put a fixes tag here or not because the driver used to be
spread out across multiple files until it was whittled down to one file
using a common interface for similar devices.
---
 drivers/staging/iio/accel/adis16203.c | 52 ++++++++++++++++-----------
 1 file changed, 31 insertions(+), 21 deletions(-)

diff --git a/drivers/staging/iio/accel/adis16203.c b/drivers/staging/iio/accel/adis16203.c
index c1c73308800c5..73288121bf0bd 100644
--- a/drivers/staging/iio/accel/adis16203.c
+++ b/drivers/staging/iio/accel/adis16203.c
@@ -28,11 +28,11 @@
 /* Output, temperature */
 #define ADIS16203_TEMP_OUT       0x0A
 
-/* Output, x-axis inclination */
-#define ADIS16203_XINCL_OUT      0x0C
+/* Output, 360 deg format */
+#define ADIS16203_INCL_OUT       0x0C
 
-/* Output, y-axis inclination */
-#define ADIS16203_YINCL_OUT      0x0E
+/* Output, +/-180 deg format */
+#define ADIS16203_INCL_180_OUT   0x0E
 
 /* Incline null calibration */
 #define ADIS16203_INCL_NULL      0x18
@@ -128,8 +128,7 @@
 #define ADIS16203_ERROR_ACTIVE          BIT(14)
 
 enum adis16203_scan {
-	 ADIS16203_SCAN_INCLI_X,
-	 ADIS16203_SCAN_INCLI_Y,
+	 ADIS16203_SCAN_INCLI,
 	 ADIS16203_SCAN_SUPPLY,
 	 ADIS16203_SCAN_AUX_ADC,
 	 ADIS16203_SCAN_TEMP,
@@ -137,10 +136,6 @@ enum adis16203_scan {
 
 #define DRIVER_NAME		"adis16203"
 
-static const u8 adis16203_addresses[] = {
-	[ADIS16203_SCAN_INCLI_X] = ADIS16203_INCL_NULL,
-};
-
 static int adis16203_write_raw(struct iio_dev *indio_dev,
 			       struct iio_chan_spec const *chan,
 			       int val,
@@ -148,10 +143,15 @@ static int adis16203_write_raw(struct iio_dev *indio_dev,
 			       long mask)
 {
 	struct adis *st = iio_priv(indio_dev);
-	/* currently only one writable parameter which keeps this simple */
-	u8 addr = adis16203_addresses[chan->scan_index];
 
-	return adis_write_reg_16(st, addr, val & 0x3FFF);
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBBIAS:
+		if (chan->scan_index != ADIS16203_SCAN_INCLI)
+			return -EINVAL;
+		return adis_write_reg_16(st, ADIS16203_INCL_NULL, val & 0x3FFF);
+	default:
+		return -EINVAL;
+	}
 }
 
 static int adis16203_read_raw(struct iio_dev *indio_dev,
@@ -161,7 +161,6 @@ static int adis16203_read_raw(struct iio_dev *indio_dev,
 {
 	struct adis *st = iio_priv(indio_dev);
 	int ret;
-	u8 addr;
 	s16 val16;
 
 	switch (mask) {
@@ -194,8 +193,9 @@ static int adis16203_read_raw(struct iio_dev *indio_dev,
 		*val = 25000 / -470 - 1278; /* 25 C = 1278 */
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_CALIBBIAS:
-		addr = adis16203_addresses[chan->scan_index];
-		ret = adis_read_reg_16(st, addr, &val16);
+		if (chan->scan_index != ADIS16203_SCAN_INCLI)
+			return -EINVAL;
+		ret = adis_read_reg_16(st, ADIS16203_INCL_NULL, &val16);
 		if (ret)
 			return ret;
 		*val = sign_extend32(val16, 13);
@@ -206,13 +206,23 @@ static int adis16203_read_raw(struct iio_dev *indio_dev,
 }
 
 static const struct iio_chan_spec adis16203_channels[] = {
+	{
+		.type = IIO_INCLI,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+					BIT(IIO_CHAN_INFO_SCALE) |
+					BIT(IIO_CHAN_INFO_CALIBBIAS),
+		.address = ADIS16203_INCL_180_OUT,
+		.scan_index = ADIS16203_SCAN_INCLI,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 14,
+			.storagebits = 16,
+			.shift = 0,
+			.endianness = IIO_CPU,
+		},
+	},
 	ADIS_SUPPLY_CHAN(ADIS16203_SUPPLY_OUT, ADIS16203_SCAN_SUPPLY, 0, 12),
 	ADIS_AUX_ADC_CHAN(ADIS16203_AUX_ADC, ADIS16203_SCAN_AUX_ADC, 0, 12),
-	ADIS_INCLI_CHAN(X, ADIS16203_XINCL_OUT, ADIS16203_SCAN_INCLI_X,
-			BIT(IIO_CHAN_INFO_CALIBBIAS), 0, 14),
-	/* Fixme: Not what it appears to be - see data sheet */
-	ADIS_INCLI_CHAN(Y, ADIS16203_YINCL_OUT, ADIS16203_SCAN_INCLI_Y,
-			0, 0, 14),
 	ADIS_TEMP_CHAN(ADIS16203_TEMP_OUT, ADIS16203_SCAN_TEMP, 0, 12),
 	IIO_CHAN_SOFT_TIMESTAMP(5),
 };
-- 
2.43.0