1 files changed, 196 insertions, 5 deletions

diff --git a/drivers/iio/light/rohm-bu27008.c b/drivers/iio/light/rohm-bu27008.c
index 6a6d77805091..0f010eff1981 100644
--- a/drivers/iio/light/rohm-bu27008.c
+++ b/drivers/iio/light/rohm-bu27008.c
@@ -130,6 +130,7 @@
  * @BU27008_BLUE:	Blue channel. Via data2 (when used).
  * @BU27008_CLEAR:	Clear channel. Via data2 or data3 (when used).
  * @BU27008_IR:		IR channel. Via data3 (when used).
+ * @BU27008_LUX:	Illuminance channel, computed using RGB and IR.
  * @BU27008_NUM_CHANS:	Number of channel types.
  */
 enum bu27008_chan_type {
@@ -138,6 +139,7 @@ enum bu27008_chan_type {
 	BU27008_BLUE,
 	BU27008_CLEAR,
 	BU27008_IR,
+	BU27008_LUX,
 	BU27008_NUM_CHANS
 };
 
@@ -172,6 +174,8 @@ static const unsigned long bu27008_scan_masks[] = {
 	ALWAYS_SCANNABLE | BIT(BU27008_CLEAR) | BIT(BU27008_IR),
 	/* buffer is R, G, B, IR */
 	ALWAYS_SCANNABLE | BIT(BU27008_BLUE) | BIT(BU27008_IR),
+	/* buffer is R, G, B, IR, LUX */
+	ALWAYS_SCANNABLE | BIT(BU27008_BLUE) | BIT(BU27008_IR) | BIT(BU27008_LUX),
 	0
 };
 
@@ -331,6 +335,19 @@ static const struct iio_chan_spec bu27008_channels[] = {
 	 * Hence we don't advertise available ones either.
 	 */
 	BU27008_CHAN(IR, DATA3, 0),
+	{
+		.type = IIO_LIGHT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.channel = BU27008_LUX,
+		.scan_index = BU27008_LUX,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 64,
+			.storagebits = 64,
+			.endianness = IIO_CPU,
+		},
+	},
 	IIO_CHAN_SOFT_TIMESTAMP(BU27008_NUM_CHANS),
 };
 
@@ -1004,6 +1021,169 @@ static int bu27008_read_one(struct bu27008_data *data, struct iio_dev *idev,
 	return ret;
 }
 
+#define BU27008_LUX_DATA_RED	0
+#define BU27008_LUX_DATA_GREEN	1
+#define BU27008_LUX_DATA_BLUE	2
+#define BU27008_LUX_DATA_IR	3
+#define LUX_DATA_SIZE (BU27008_NUM_HW_CHANS * sizeof(__le16))
+
+static int bu27008_read_lux_chans(struct bu27008_data *data, unsigned int time,
+				  __le16 *chan_data)
+{
+	int ret, chan_sel, tmpret, valid;
+
+	chan_sel = BU27008_BLUE2_IR3 << (ffs(data->cd->chan_sel_mask) - 1);
+
+	ret = regmap_update_bits(data->regmap, data->cd->chan_sel_reg,
+				 data->cd->chan_sel_mask, chan_sel);
+	if (ret)
+		return ret;
+
+	ret = bu27008_meas_set(data, true);
+	if (ret)
+		return ret;
+
+	msleep(time / USEC_PER_MSEC);
+
+	ret = regmap_read_poll_timeout(data->regmap, data->cd->valid_reg,
+				       valid, (valid & BU27008_MASK_VALID),
+				       BU27008_VALID_RESULT_WAIT_QUANTA_US,
+				       BU27008_MAX_VALID_RESULT_WAIT_US);
+	if (ret)
+		goto out;
+
+	ret = regmap_bulk_read(data->regmap, BU27008_REG_DATA0_LO, chan_data,
+			       LUX_DATA_SIZE);
+	if (ret)
+		goto out;
+out:
+	tmpret = bu27008_meas_set(data, false);
+	if (tmpret)
+		dev_warn(data->dev, "Stopping measurement failed\n");
+
+	return ret;
+}
+
+/*
+ * Following equation for computing lux out of register values was given by
+ * ROHM HW colleagues;
+ *
+ * Red = RedData*1024 / Gain * 20 / meas_mode
+ * Green = GreenData* 1024 / Gain * 20 / meas_mode
+ * Blue = BlueData* 1024 / Gain * 20 / meas_mode
+ * IR = IrData* 1024 / Gain * 20 / meas_mode
+ *
+ * where meas_mode is the integration time in mS / 10
+ *
+ * IRratio = (IR > 0.18 * Green) ? 0 : 1
+ *
+ * Lx = max(c1*Red + c2*Green + c3*Blue,0)
+ *
+ * for
+ * IRratio 0: c1 = -0.00002237, c2 = 0.0003219, c3 = -0.000120371
+ * IRratio 1: c1 = -0.00001074, c2 = 0.000305415, c3 = -0.000129367
+ */
+
+/*
+ * The max chan data is 0xffff. When we multiply it by 1024 * 20, we'll get
+ * 0x4FFFB000 which still fits in 32-bit integer. This won't overflow.
+ */
+#define NORM_CHAN_DATA_FOR_LX_CALC(chan, gain, time) (le16_to_cpu(chan) * \
+				   1024 * 20 / (gain) / (time))
+static u64 bu27008_calc_nlux(struct bu27008_data *data, __le16 *lux_data,
+		unsigned int gain, unsigned int gain_ir, unsigned int time)
+{
+	unsigned int red, green, blue, ir;
+	s64 c1, c2, c3, nlux;
+
+	time /= 10000;
+	ir = NORM_CHAN_DATA_FOR_LX_CALC(lux_data[BU27008_LUX_DATA_IR], gain_ir, time);
+	red = NORM_CHAN_DATA_FOR_LX_CALC(lux_data[BU27008_LUX_DATA_RED], gain, time);
+	green = NORM_CHAN_DATA_FOR_LX_CALC(lux_data[BU27008_LUX_DATA_GREEN], gain, time);
+	blue = NORM_CHAN_DATA_FOR_LX_CALC(lux_data[BU27008_LUX_DATA_BLUE], gain, time);
+
+	if ((u64)ir * 100LLU > (u64)green * 18LLU) {
+		c1 = -22370;
+		c2 = 321900;
+		c3 = -120371;
+	} else {
+		c1 = -10740;
+		c2 = 305415;
+		c3 = -129367;
+	}
+	nlux = c1 * red + c2 * green + c3 * blue;
+
+	return max_t(s64, 0, nlux);
+}
+
+static int bu27008_get_time_n_gains(struct bu27008_data *data,
+		unsigned int *gain, unsigned int *gain_ir, unsigned int *time)
+{
+	int ret;
+
+	ret = bu27008_get_gain(data, &data->gts, gain);
+	if (ret < 0)
+		return ret;
+
+	ret = bu27008_get_gain(data, &data->gts_ir, gain_ir);
+	if (ret < 0)
+		return ret;
+
+	ret = bu27008_get_int_time_us(data);
+	if (ret < 0)
+		return ret;
+
+	/* Max integration time is 400000. Fits in signed int. */
+	*time = ret;
+
+	return 0;
+}
+
+struct bu27008_buf {
+	__le16 chan[BU27008_NUM_HW_CHANS];
+	u64 lux __aligned(8);
+	s64 ts __aligned(8);
+};
+
+static int bu27008_buffer_fill_lux(struct bu27008_data *data,
+				   struct bu27008_buf *raw)
+{
+	unsigned int gain, gain_ir, time;
+	int ret;
+
+	ret = bu27008_get_time_n_gains(data, &gain, &gain_ir, &time);
+	if (ret)
+		return ret;
+
+	raw->lux = bu27008_calc_nlux(data, raw->chan, gain, gain_ir, time);
+
+	return 0;
+}
+
+static int bu27008_read_lux(struct bu27008_data *data, struct iio_dev *idev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2)
+{
+	__le16 lux_data[BU27008_NUM_HW_CHANS];
+	unsigned int gain, gain_ir, time;
+	u64 nlux;
+	int ret;
+
+	ret = bu27008_get_time_n_gains(data, &gain, &gain_ir, &time);
+	if (ret)
+		return ret;
+
+	ret = bu27008_read_lux_chans(data, time, lux_data);
+	if (ret)
+		return ret;
+
+	nlux = bu27008_calc_nlux(data, lux_data, gain, gain_ir, time);
+	*val = (int)nlux;
+	*val2 = nlux >> 32LLU;
+
+	return IIO_VAL_INT_64;
+}
+
 static int bu27008_read_raw(struct iio_dev *idev,
 			   struct iio_chan_spec const *chan,
 			   int *val, int *val2, long mask)
@@ -1018,7 +1198,10 @@ static int bu27008_read_raw(struct iio_dev *idev,
 			return -EBUSY;
 
 		mutex_lock(&data->mutex);
-		ret = bu27008_read_one(data, idev, chan, val, val2);
+		if (chan->type == IIO_LIGHT)
+			ret = bu27008_read_lux(data, idev, chan, val, val2);
+		else
+			ret = bu27008_read_one(data, idev, chan, val, val2);
 		mutex_unlock(&data->mutex);
 
 		iio_device_release_direct_mode(idev);
@@ -1026,6 +1209,11 @@ static int bu27008_read_raw(struct iio_dev *idev,
 		return ret;
 
 	case IIO_CHAN_INFO_SCALE:
+		if (chan->type == IIO_LIGHT) {
+			*val = 0;
+			*val2 = 1;
+			return IIO_VAL_INT_PLUS_NANO;
+		}
 		ret = bu27008_get_scale(data, chan->scan_index == BU27008_IR,
 					val, val2);
 		if (ret)
@@ -1236,10 +1424,7 @@ static irqreturn_t bu27008_trigger_handler(int irq, void *p)
 	struct iio_poll_func *pf = p;
 	struct iio_dev *idev = pf->indio_dev;
 	struct bu27008_data *data = iio_priv(idev);
-	struct {
-		__le16 chan[BU27008_NUM_HW_CHANS];
-		s64 ts __aligned(8);
-	} raw;
+	struct bu27008_buf raw;
 	int ret, dummy;
 
 	memset(&raw, 0, sizeof(raw));
@@ -1257,6 +1442,12 @@ static irqreturn_t bu27008_trigger_handler(int irq, void *p)
 	if (ret < 0)
 		goto err_read;
 
+	if (test_bit(BU27008_LUX, idev->active_scan_mask)) {
+		ret = bu27008_buffer_fill_lux(data, &raw);
+		if (ret)
+			goto err_read;
+	}
+
 	iio_push_to_buffers_with_timestamp(idev, &raw, pf->timestamp);
 err_read:
 	iio_trigger_notify_done(idev->trig);