iio: light: add support for Broadcom APDS9999

Add Device Tree binding for the Broadcom APDS9999 ambient light and proximity sensor. A separate binding file is used rather than merging with avago,apds9300.yaml because the APDS9999 has an additional vcsel-supply for the VCSEL.

The APDS9999 features individual R, G, B, and IR channels with a green channel that uses optical coating to approximate the human eye spectral response for ALS/lux measurements. Calibrated RGB color sensing is not yet implemented in the driver.

Signed-off-by Jose A. Perez de Azpillaga <[email protected]>

Add IIO driver for Broadcom APDS9999 ambient light sensor.

The APDS9999 is a digital proximity and RGB sensor with ALS capability. The driver implements the ALS/Lux functionality using the green channel, which uses optical coating technology to approximate the human eye spectral response.

Raw IIO_INTENSITY channels are exposed for red, green, blue, and IR so userspace can compute its own weighted lux. Proximity (PS) support is not yet implemented.

Signed-off-by Jose A. Perez de Azpillaga <[email protected]>

drivers/iio/light/apds9999.c new file +8 -0

new file mode 100644
index 000000000000..f2fbd743abe7
 
+
+static const int apds9999_gains[] = {
+	[APDS9999_GAIN_1X]  = 1,
+	[APDS9999_GAIN_3X]  = 3,
+	[APDS9999_GAIN_6X]  = 6,
+	[APDS9999_GAIN_9X]  = 9,
+	[APDS9999_GAIN_18X] = 18,
+};

drivers/iio/light/apds9999.c new file +58 -0

+
+static const int apds9999_itimes_us[APDS9999_RES_NUM] = {
+	[APDS9999_RES_20BIT] = 400 * USEC_PER_MSEC,
+	[APDS9999_RES_19BIT] = 200 * USEC_PER_MSEC,
+	[APDS9999_RES_18BIT] = 100 * USEC_PER_MSEC,
+	[APDS9999_RES_17BIT] =  50 * USEC_PER_MSEC,
+	[APDS9999_RES_16BIT] =  25 * USEC_PER_MSEC,
+	[APDS9999_RES_13BIT] =   3125,
+};
+
+#define APDS9999_RATE_25_MS		0
+#define APDS9999_RATE_50_MS		1
+#define APDS9999_RATE_100_MS		2
+#define APDS9999_RATE_200_MS		3
+#define APDS9999_RATE_500_MS		4
+#define APDS9999_RATE_1000_MS		5
+#define APDS9999_RATE_2000_MS		6
 
 
+static int apds9999_read_channel(struct apds9999_data *data, u8 reg,
+				 u32 *counts)
+{
+	struct i2c_client *client = data->client;
+	u8 buf[3];
+	int ret, tries;
+
+	guard(mutex)(&data->lock);
+
+	/*
+	 * Poll MAIN_STATUS for new data.  Timeout: ~2 integration periods
+	 * plus margin.  Each try sleeps 20 ms.
+	 */
+	tries = max(2, (apds9999_itimes_us[data->als_res] * 2) / 20000);
+
+	while (tries--) {
+		ret = i2c_smbus_read_byte_data(client,
+					       APDS9999_REG_MAIN_STATUS);
+		if (ret < 0)
+			return ret;
+		if (ret & APDS9999_MAIN_STATUS_LS_DATA)
+			break;
+		fsleep(20000);
+	}
+
+	if (tries < 0)
+		return -ETIMEDOUT;
+
+	ret = i2c_smbus_read_i2c_block_data(client, reg, sizeof(buf), buf);
+	if (ret < 0)
+		return ret;
+	if (ret != sizeof(buf))
+		return -EIO;
+
+	*counts = get_unaligned_le24(buf) & GENMASK(19, 0);
+	return 0;
+}
+
+static int apds9999_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)

drivers/iio/light/apds9999.c new file +48 -0

+		if (ret)
+			return ret;
+		*val = (int)counts;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		/*
+		 * Scale (lux per count) = 54 / (gain * integration_time_ms)
+		 *
+		 * The constant 54 is derived from the datasheet table:
+		 *   at gain = 3x, itime = 100 ms -> 0.180 lux/count
+		 *   -> C = 0.180 * 3 * 100 = 54
+		 *
+		 * Expressed as IIO_VAL_INT_PLUS_NANO.
+		 */
+		gain = apds9999_gains[data->als_gain_idx];
+		itime_us = apds9999_itimes_us[data->als_res];
+
+		/* scale_nano = 54 * 1e12 / (gain * itime_us) nano-lux/count */
+		scale_nano = div_u64(54ULL * NSEC_PER_SEC * USEC_PER_MSEC, (u32)(gain * itime_us));
+		*val = (int)(scale_nano / NSEC_PER_SEC);
+		*val2 = (int)(scale_nano % NSEC_PER_SEC);
+		return IIO_VAL_INT_PLUS_NANO;
+
+	case IIO_CHAN_INFO_INT_TIME:
+		*val = 0;
+		*val2 = apds9999_itimes_us[data->als_res];
+		return IIO_VAL_INT_PLUS_MICRO;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info apds9999_info = {
+	.read_raw = apds9999_read_raw,
+};
+
+/*
+ * The green channel uses optical coating to approximate the human eye
+ * spectral response.  IIO_INTENSITY channels provide raw ADC data for
+ * red, green, blue, and IR so userspace can compute weighted lux.
+ */
+static const struct iio_chan_spec apds9999_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),

drivers/iio/light/apds9999.c new file +39 -0

+	},
+	{
+		.type = IIO_INTENSITY,
+		.modified = 1,
+		.channel2 = IIO_MOD_LIGHT_GREEN,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
+		.address = APDS9999_REG_LS_DATA_GREEN_0,
+	},
+	{
+		.type = IIO_INTENSITY,
+		.modified = 1,
+		.channel2 = IIO_MOD_LIGHT_BLUE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
+		.address = APDS9999_REG_LS_DATA_BLUE_0,
+	},
+	{
+		.type = IIO_INTENSITY,
+		.modified = 1,
+		.channel2 = IIO_MOD_LIGHT_IR,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
+		.address = APDS9999_REG_LS_DATA_IR_0,
+	},
+};
+
+static int apds9999_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct apds9999_data *data;
+	struct iio_dev *indio_dev;
+	int ret, part_id;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);

Quoted 11 lines · On Tue, 26 May 2026 09:55:46 +0200 "Jose A. Perez de Azpillaga"…

Add IIO driver for Broadcom APDS9999 ambient light sensor.

The APDS9999 is a digital proximity and RGB sensor with ALS capability. The driver implements the ALS/Lux functionality using the green channel, which uses optical coating technology to approximate the human eye spectral response.

Raw IIO_INTENSITY channels are exposed for red, green, blue, and IR so userspace can compute its own weighted lux. Proximity (PS) support is not yet implemented.

Quoted 1 line

Signed-off-by Jose A. Perez de Azpillaga <[email protected]>

Hi Jose,

A few really minor things inline. Given how minor they are I've applied this series to the testing branch of iio.git with the following tweaks:
(shout if you disagree with any of them!)