[PATCH v3] iio: light: veml3328: reshape scale array for readability

[Giorgi Tchankvetadze]

From: Giorgi Tchankvetadze <giorgi@xxxxxxxxxxxxxxxxx>

The veml3328_scale_vals array is declared as a flattened [4][8] array,
so accessing a scale value requires calculating the offset of its
(val, val2) pair using gain_inx * 2.

Reshape the array as [4][4][2], with separate dimensions for integration
time, gain and the scale value pair. This removes the manual stride
calculation and makes the relationship between the indexes and values
explicit.

Add named integration-time indexes and use designated initializers for
veml3328_it_times and veml3328_scale_vals so both tables use the same
index definitions.

Suggested-by: David Lechner <dlechner@xxxxxxxxxxxx>
Suggested-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Reviewed-by: Joshua Crofts <joshua.crofts1@xxxxxxxxx>
Signed-off-by: Giorgi Tchankvetadze <giorgi@xxxxxxxxxxxxxxxxx>
---
Changes in v3:
- Add named integration-time indexes as suggested by Jonathan Cameron.
- Use designated initializers for veml3328_it_times and
  veml3328_scale_vals to keep both tables indexed consistently.

Changes in v2:
- Reshape veml3328_scale_vals as [4][4][2], as suggested by
  David Lechner.
- Update read and write paths to access the scale value pair directly.

drivers/iio/light/veml3328.c | 53 ++++++++++++++++++++++++++----------
 1 file changed, 38 insertions(+), 15 deletions(-)

diff --git a/drivers/iio/light/veml3328.c b/drivers/iio/light/veml3328.c
index 7ff1753925c4..df36c48204be 100644
--- a/drivers/iio/light/veml3328.c
+++ b/drivers/iio/light/veml3328.c
@@ -32,6 +32,11 @@
 #define VEML3328_REG_DATA_B		0x07
 #define VEML3328_REG_DATA_IR		0x08
 
+#define VEML3328_CONT_IT_50MSECS	0
+#define VEML3328_CONT_IT_100MSECS	1
+#define VEML3328_CONT_IT_200MSECS	2
+#define VEML3328_CONT_IT_400MSECS	3
+
 #define VEML3328_CONF_IT_MASK		GENMASK(5, 4)
 #define VEML3328_CONF_GAIN_MASK		GENMASK(11, 10)
 
@@ -89,21 +94,40 @@ static const struct iio_chan_spec veml3328_channels[] = {
  * Precomputed scale values (micro units).
  * Formula for calculation: 0.384 * (50000 / IT_us) * (1 / Gain)
  * Gain indexes: 0 (x0.5), 1 (x1), 2 (x2), 3 (x4)
- * IT indexes: 0 (50ms), 1 (100ms), 2 (200ms), 3 (400ms)
  */
-static const int veml3328_scale_vals[4][8] = {
-	{ 0, 768000, 0, 384000, 0, 192000, 0, 96000 },
-	{ 0, 384000, 0, 192000, 0, 96000,  0, 48000 },
-	{ 0, 192000, 0, 96000,  0, 48000,  0, 24000 },
-	{ 0, 96000,  0, 48000,  0, 24000,  0, 12000 },
+static const int veml3328_scale_vals[4][4][2] = {
+	[VEML3328_CONT_IT_50MSECS] = {
+		{ 0, 768000 },
+		{ 0, 384000 },
+		{ 0, 192000 },
+		{ 0, 96000 },
+	},
+	[VEML3328_CONT_IT_100MSECS] = {
+		{ 0, 384000 },
+		{ 0, 192000 },
+		{ 0, 96000 },
+		{ 0, 48000 },
+	},
+	[VEML3328_CONT_IT_200MSECS] = {
+		{ 0, 192000 },
+		{ 0, 96000 },
+		{ 0, 48000 },
+		{ 0, 24000 },
+	},
+	[VEML3328_CONT_IT_400MSECS] = {
+		{ 0, 96000 },
+		{ 0, 48000 },
+		{ 0, 24000 },
+		{ 0, 12000 },
+	},
 };
 
 /* integration times in microseconds */
 static const int veml3328_it_times[][2] = {
-	{ 0, 50 * USEC_PER_MSEC },
-	{ 0, 100 * USEC_PER_MSEC },
-	{ 0, 200 * USEC_PER_MSEC },
-	{ 0, 400 * USEC_PER_MSEC },
+	[VEML3328_CONT_IT_50MSECS] = { 0, 50 * USEC_PER_MSEC },
+	[VEML3328_CONT_IT_100MSECS] = { 0, 100 * USEC_PER_MSEC },
+	[VEML3328_CONT_IT_200MSECS] = { 0, 200 * USEC_PER_MSEC },
+	[VEML3328_CONT_IT_400MSECS] = { 0, 400 * USEC_PER_MSEC },
 };
 
 static int veml3328_power_down(struct veml3328_data *data)
@@ -184,9 +208,8 @@ static int veml3328_read_raw(struct iio_dev *indio_dev,
 		if (it_inx >= ARRAY_SIZE(veml3328_it_times) || gain_inx >= 4)
 			return -EINVAL;
 
-		/* Stride by 2 through the flattened array to match (val, val2) */
-		*val = veml3328_scale_vals[it_inx][gain_inx * 2];
-		*val2 = veml3328_scale_vals[it_inx][gain_inx * 2 + 1];
+		*val = veml3328_scale_vals[it_inx][gain_inx][0];
+		*val2 = veml3328_scale_vals[it_inx][gain_inx][1];
 
 		return IIO_VAL_INT_PLUS_MICRO;
 
@@ -282,8 +305,8 @@ static int veml3328_write_raw(struct iio_dev *indio_dev,
 			return -EINVAL;
 
 		for (i = 0; i < 4; i++) {
-			if (val == veml3328_scale_vals[it_inx][i * 2] &&
-			    val2 == veml3328_scale_vals[it_inx][i * 2 + 1])
+			if (val == veml3328_scale_vals[it_inx][i][0] &&
+			    val2 == veml3328_scale_vals[it_inx][i][1])
 				break;
 		}
 
-- 
2.52.0