[PATCH v2 1/3] iio: light: ltr390: Add configurable gain and resolution

From: Abhash Jha
Date: Sun Jul 28 2024 - 11:20:43 EST

Add support for configuring and reading the gain and resolution
(integration time). Also provide the available values for gain and
resoltion respectively via `read_avail` callback.

Signed-off-by: Abhash Jha <abhashkumarjha123@xxxxxxxxx>
---
drivers/iio/light/ltr390.c | 144 +++++++++++++++++++++++++++++++++----
1 file changed, 130 insertions(+), 14 deletions(-)

diff --git a/drivers/iio/light/ltr390.c b/drivers/iio/light/ltr390.c
index fff1e8990..9f00661c3 100644
--- a/drivers/iio/light/ltr390.c
+++ b/drivers/iio/light/ltr390.c
@@ -25,19 +25,26 @@
#include <linux/regmap.h>

#include <linux/iio/iio.h>
-
+#include <linux/iio/sysfs.h>
#include <asm/unaligned.h>

-#define LTR390_MAIN_CTRL 0x00
-#define LTR390_PART_ID 0x06
-#define LTR390_UVS_DATA 0x10
+#define LTR390_MAIN_CTRL 0x00
+#define LTR390_ALS_UVS_MEAS_RATE 0x04
+#define LTR390_ALS_UVS_GAIN 0x05
+#define LTR390_PART_ID 0x06
+#define LTR390_ALS_DATA 0x0D
+#define LTR390_UVS_DATA 0x10
+#define LTR390_INT_CFG 0x19
+
+#define LTR390_PART_NUMBER_ID 0xb
+#define LTR390_ALS_UVS_GAIN_MASK 0x07
+#define LTR390_ALS_UVS_INT_TIME_MASK 0x70
+#define LTR390_ALS_UVS_INT_TIME(x) FIELD_PREP(LTR390_ALS_UVS_INT_TIME_MASK, x)

#define LTR390_SW_RESET BIT(4)
#define LTR390_UVS_MODE BIT(3)
#define LTR390_SENSOR_ENABLE BIT(1)

-#define LTR390_PART_NUMBER_ID 0xb
-
/*
* At 20-bit resolution (integration time: 400ms) and 18x gain, 2300 counts of
* the sensor are equal to 1 UV Index [Datasheet Page#8].
@@ -60,6 +67,8 @@ struct ltr390_data {
struct i2c_client *client;
/* Protects device from simulataneous reads */
struct mutex lock;
+ int gain;
+ int int_time_us;
};

static const struct regmap_config ltr390_regmap_config = {
@@ -75,8 +84,6 @@ static int ltr390_register_read(struct ltr390_data *data, u8 register_address)
int ret;
u8 recieve_buffer[3];

- guard(mutex)(&data->lock);
-
ret = regmap_bulk_read(data->regmap, register_address, recieve_buffer,
sizeof(recieve_buffer));
if (ret) {
@@ -91,32 +98,135 @@ static int ltr390_read_raw(struct iio_dev *iio_device,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
- int ret;
struct ltr390_data *data = iio_priv(iio_device);
+ int ret;

+ guard(mutex)(&data->lock);
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = ltr390_register_read(data, LTR390_UVS_DATA);
if (ret < 0)
return ret;
+
*val = ret;
return IIO_VAL_INT;
+
case IIO_CHAN_INFO_SCALE:
*val = LTR390_WINDOW_FACTOR;
*val2 = LTR390_COUNTS_PER_UVI;
return IIO_VAL_FRACTIONAL;
+
+ case IIO_CHAN_INFO_INT_TIME:
+ *val = data->int_time_us;
+ return IIO_VAL_INT;
+
default:
return -EINVAL;
}
}

-static const struct iio_info ltr390_info = {
- .read_raw = ltr390_read_raw,
-};
+/* integration time in us */
+static const int ltr390_int_time_map_us[] = {400000, 200000, 100000, 50000, 25000, 12500};
+static const int ltr390_gain_map[] = {1, 3, 6, 9, 18};

static const struct iio_chan_spec ltr390_channel = {
.type = IIO_UVINDEX,
- .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE)
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+ .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
+ .info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) | BIT(IIO_CHAN_INFO_SCALE)
+};
+
+static int ltr390_set_gain(struct ltr390_data *data, int val)
+{
+ int ret, idx;
+
+ for (idx = 0; idx < ARRAY_SIZE(ltr390_gain_map); idx++) {
+ if (ltr390_gain_map[idx] != val)
+ continue;
+
+ guard(mutex)(&data->lock);
+ ret = regmap_update_bits(data->regmap,
+ LTR390_ALS_UVS_GAIN,
+ LTR390_ALS_UVS_GAIN_MASK, idx);
+ if (ret)
+ return ret;
+
+ data->gain = ltr390_gain_map[idx];
+ break;
+ }
+
+ return 0;
+}
+
+static int ltr390_set_int_time(struct ltr390_data *data, int val)
+{
+ int ret, idx;
+
+ for (idx = 0; idx < ARRAY_SIZE(ltr390_int_time_map_us); idx++) {
+ if (ltr390_int_time_map_us[idx] != val)
+ continue;
+
+ guard(mutex)(&data->lock);
+ ret = regmap_update_bits(data->regmap,
+ LTR390_ALS_UVS_MEAS_RATE,
+ LTR390_ALS_UVS_INT_TIME_MASK,
+ LTR390_ALS_UVS_INT_TIME(idx));
+ if (ret)
+ return ret;
+
+ data->int_time_us = ltr390_int_time_map_us[idx];
+ break;
+ }
+
+ return 0;
+}
+
+static int ltr390_read_avail(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+ const int **vals, int *type, int *length, long mask)
+{
+ switch (mask) {
+ case IIO_CHAN_INFO_SCALE:
+ *length = ARRAY_SIZE(ltr390_gain_map);
+ *type = IIO_VAL_INT;
+ *vals = ltr390_gain_map;
+ return IIO_AVAIL_LIST;
+ case IIO_CHAN_INFO_INT_TIME:
+ *length = ARRAY_SIZE(ltr390_int_time_map_us);
+ *type = IIO_VAL_INT;
+ *vals = ltr390_int_time_map_us;
+ return IIO_AVAIL_LIST;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ltr390_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct ltr390_data *data = iio_priv(indio_dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SCALE:
+ if (val2 != 0)
+ return -EINVAL;
+
+ return ltr390_set_gain(data, val);
+
+ case IIO_CHAN_INFO_INT_TIME:
+ if (val2 != 0)
+ return -EINVAL;
+
+ return ltr390_set_int_time(data, val);
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info ltr390_info = {
+ .read_raw = ltr390_read_raw,
+ .write_raw = ltr390_write_raw,
+ .read_avail = ltr390_read_avail,
};

static int ltr390_probe(struct i2c_client *client)
@@ -139,6 +249,11 @@ static int ltr390_probe(struct i2c_client *client)
"regmap initialization failed\n");

data->client = client;
+ /* default value of integration time from pg: 15 of the datasheet */
+ data->int_time_us = 100000;
+ /* default value of gain from pg: 16 of the datasheet */
+ data->gain = 3;
+
mutex_init(&data->lock);

indio_dev->info = &ltr390_info;
@@ -162,7 +277,7 @@ static int ltr390_probe(struct i2c_client *client)
usleep_range(1000, 2000);

ret = regmap_set_bits(data->regmap, LTR390_MAIN_CTRL,
- LTR390_SENSOR_ENABLE | LTR390_UVS_MODE);
+ LTR390_SENSOR_ENABLE | LTR390_UVS_MODE);
if (ret)
return dev_err_probe(dev, ret, "failed to enable the sensor\n");

@@ -189,6 +304,7 @@ static struct i2c_driver ltr390_driver = {
.probe = ltr390_probe,
.id_table = ltr390_id,
};
+
module_i2c_driver(ltr390_driver);

MODULE_AUTHOR("Anshul Dalal <anshulusr@xxxxxxxxx>");
--
2.43.0