@@ -289,6 +289,20 @@ config JSA1212
To compile this driver as a module, choose M here:
the module will be called jsa1212.
+config ROHM_BU27034
+ tristate "ROHM BU27034 ambient light sensor"
+ depends on I2C
+ select REGMAP_I2C
+ select IIO_GTS_HELPER
+ select IIO_BUFFER
+ select IIO_KFIFO_BUF
+ help
+ Enable support for the ROHM BU27034 ambient light sensor. ROHM BU27034
+ is an ambient light sesnor with 3 channels and 3 photo diodes capable
+ of detecting a very wide range of illuminance.
+ Typical application is adjusting LCD and backlight power of TVs and
+ mobile phones.
+
config RPR0521
tristate "ROHM RPR0521 ALS and proximity sensor driver"
depends on I2C
@@ -38,6 +38,7 @@ obj-$(CONFIG_MAX44009) += max44009.o
obj-$(CONFIG_NOA1305) += noa1305.o
obj-$(CONFIG_OPT3001) += opt3001.o
obj-$(CONFIG_PA12203001) += pa12203001.o
+obj-$(CONFIG_ROHM_BU27034) += rohm-bu27034.o
obj-$(CONFIG_RPR0521) += rpr0521.o
obj-$(CONFIG_SI1133) += si1133.o
obj-$(CONFIG_SI1145) += si1145.o
new file mode 100644
@@ -0,0 +1,1496 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * BU27034 ROHM Ambient Light Sensor
+ *
+ * Copyright (c) 2023, ROHM Semiconductor.
+ * https://fscdn.rohm.com/en/products/databook/datasheet/ic/sensor/light/bu27034nuc-e.pdf
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/units.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/iio-gts-helper.h>
+#include <linux/iio/kfifo_buf.h>
+
+
+#define BU27034_REG_SYSTEM_CONTROL 0x40
+#define BU27034_MASK_SW_RESET BIT(7)
+#define BU27034_MASK_PART_ID GENMASK(5, 0)
+#define BU27034_ID 0x19
+#define BU27034_REG_MODE_CONTROL1 0x41
+#define BU27034_MASK_MEAS_MODE GENMASK(2, 0)
+
+#define BU27034_REG_MODE_CONTROL2 0x42
+#define BU27034_MASK_D01_GAIN GENMASK(7, 3)
+#define BU27034_MASK_D2_GAIN_HI GENMASK(7, 6)
+#define BU27034_MASK_D2_GAIN_LO GENMASK(2, 0)
+
+#define BU27034_REG_MODE_CONTROL3 0x43
+#define BU27034_REG_MODE_CONTROL4 0x44
+#define BU27034_MASK_MEAS_EN BIT(0)
+#define BU27034_MASK_VALID BIT(7)
+#define BU27034_REG_DATA0_LO 0x50
+#define BU27034_REG_DATA1_LO 0x52
+#define BU27034_REG_DATA2_LO 0x54
+#define BU27034_REG_DATA2_HI 0x55
+#define BU27034_REG_MANUFACTURER_ID 0x92
+#define BU27034_REG_MAX BU27034_REG_MANUFACTURER_ID
+
+/*
+ * The BU27034 does not have interrupt to trigger the data read when a
+ * measurement has finished. Hence we poll the VALID bit in a thread. We will
+ * try to wake the thread BU27034_MEAS_WAIT_PREMATURE_MS milliseconds before
+ * the expected sampling time to prevent the drifting.
+ *
+ * If we constantly wake up a bit too late we would eventually skip a sample.
+ * And because the sleep can't wake up _exactly_ at given time this would be
+ * inevitable even if the sensor clock would be perfectly phase-locked to CPU
+ * clock - which we can't say is the case.
+ *
+ * This is still fragile. No matter how big advance do we have, we will still
+ * risk of losing a sample because things can in a rainy-day scenario be
+ * delayed a lot. Yet, more we reserve the time for polling, more we also lose
+ * the performance by spending cycles polling the register. So, selecting this
+ * value is a balancing dance between severity of wasting CPU time and severity
+ * of losing samples.
+ *
+ * In most cases losing the samples is not _that_ crucial because light levels
+ * tend to change slowly.
+ *
+ * Other option that was pointed to me would be always sleeping 1/2 of the
+ * measurement time, checking the VALID bit and just sleeping again if the bit
+ * was not set. That should be pretty tolerant against missing samples due to
+ * the scheduling delays while also not wasting much of cycles for polling.
+ * Downside is that the time-stamps would be very inaccurate as the wake-up
+ * would not really be tied to the sensor toggling the valid bit. This would also
+ * result 'jumps' in the time-stamps when the delay drifted so that wake-up was
+ * performed during the consecutive wake-ups (Or, when sensor and CPU clocks
+ * were very different and scheduling the wake-ups was very close to given
+ * timeout - and when the time-outs were very close to the actual sensor
+ * sampling, Eg. once in a blue moon, two consecutive time-outs would occur
+ * without having a sample ready).
+ */
+#define BU27034_MEAS_WAIT_PREMATURE_MS 5
+#define BU27034_DATA_WAIT_TIME_US 1000
+#define BU27034_TOTAL_DATA_WAIT_TIME_US (BU27034_MEAS_WAIT_PREMATURE_MS * 1000)
+
+#define BU27034_RETRY_LIMIT 18
+
+enum {
+ BU27034_CHAN_ALS,
+ BU27034_CHAN_DATA0,
+ BU27034_CHAN_DATA1,
+ BU27034_CHAN_DATA2,
+ BU27034_NUM_CHANS
+};
+
+static const unsigned long bu27034_scan_masks[] = {
+ BIT(BU27034_CHAN_ALS) | BIT(BU27034_CHAN_DATA0) |
+ BIT(BU27034_CHAN_DATA1) | BIT(BU27034_CHAN_DATA2), 0
+};
+
+/*
+ * Available scales with gain 1x - 4096x, timings 55, 100, 200, 400 mS
+ * Time impacts to gain: 1x, 2x, 4x, 8x.
+ *
+ * => Max total gain is HWGAIN * gain by integration time (8 * 4096) = 32768
+ *
+ * Using NANO precision for scale we must use scale 64x corresponding gain 1x
+ * to avoid precision loss. (32x would result scale 976 562.5(nanos).
+ */
+#define BU27034_SCALE_1X 64
+
+/* See the data sheet for the "Gain Setting" table */
+#define BU27034_GSEL_1X 0x00 /* 00000 */
+#define BU27034_GSEL_4X 0x08 /* 01000 */
+#define BU27034_GSEL_16X 0x0a /* 01010 */
+#define BU27034_GSEL_32X 0x0b /* 01011 */
+#define BU27034_GSEL_64X 0x0c /* 01100 */
+#define BU27034_GSEL_256X 0x18 /* 11000 */
+#define BU27034_GSEL_512X 0x19 /* 11001 */
+#define BU27034_GSEL_1024X 0x1a /* 11010 */
+#define BU27034_GSEL_2048X 0x1b /* 11011 */
+#define BU27034_GSEL_4096X 0x1c /* 11100 */
+
+/* Available gain settings */
+static const struct iio_gain_sel_pair bu27034_gains[] = {
+ GAIN_SCALE_GAIN(1, BU27034_GSEL_1X),
+ GAIN_SCALE_GAIN(4, BU27034_GSEL_4X),
+ GAIN_SCALE_GAIN(16, BU27034_GSEL_16X),
+ GAIN_SCALE_GAIN(32, BU27034_GSEL_32X),
+ GAIN_SCALE_GAIN(64, BU27034_GSEL_64X),
+ GAIN_SCALE_GAIN(256, BU27034_GSEL_256X),
+ GAIN_SCALE_GAIN(512, BU27034_GSEL_512X),
+ GAIN_SCALE_GAIN(1024, BU27034_GSEL_1024X),
+ GAIN_SCALE_GAIN(2048, BU27034_GSEL_2048X),
+ GAIN_SCALE_GAIN(4096, BU27034_GSEL_4096X),
+};
+
+/*
+ * The IC has 5 modes for sampling time. 5 mS mode is exceptional as it limits
+ * the data collection to data0-channel only and cuts the supported range to
+ * 10 bit. It is not supported by the driver.
+ *
+ * "normal" modes are 55, 100, 200 and 400 mS modes - which do have direct
+ * multiplying impact to the register values (similar to gain).
+ *
+ * This means that if meas-mode is changed for example from 400 => 200,
+ * the scale is doubled. Eg, time impact to total gain is x1, x2, x4, x8.
+ */
+#define BU27034_MEAS_MODE_100MS 0
+#define BU27034_MEAS_MODE_55MS 1
+#define BU27034_MEAS_MODE_200MS 2
+#define BU27034_MEAS_MODE_400MS 4
+
+static const struct iio_itime_sel_mul bu27034_itimes[] = {
+ GAIN_SCALE_ITIME_US(400000, BU27034_MEAS_MODE_400MS, 8),
+ GAIN_SCALE_ITIME_US(200000, BU27034_MEAS_MODE_200MS, 4),
+ GAIN_SCALE_ITIME_US(100000, BU27034_MEAS_MODE_100MS, 2),
+ GAIN_SCALE_ITIME_US(55000, BU27034_MEAS_MODE_55MS, 1),
+};
+
+#define BU27034_CHAN_DATA(_name, _ch2) \
+{ \
+ .type = IIO_INTENSITY, \
+ .channel = BU27034_CHAN_##_name, \
+ .channel2 = (_ch2), \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+ BIT(IIO_CHAN_INFO_SCALE), \
+ .info_mask_separate_available = 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), \
+ .address = BU27034_REG_##_name##_LO, \
+ .scan_index = BU27034_CHAN_##_name, \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = 16, \
+ .storagebits = 16, \
+ .endianness = IIO_LE, \
+ }, \
+ .indexed = 1, \
+}
+
+static const struct iio_chan_spec bu27034_channels[] = {
+ {
+ .type = IIO_LIGHT,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE),
+ .channel = BU27034_CHAN_ALS,
+ .scan_index = BU27034_CHAN_ALS,
+ .scan_type = {
+ .sign = 'u',
+ .realbits = 32,
+ .storagebits = 32,
+ .endianness = IIO_CPU,
+ },
+ },
+ /*
+ * The BU27034 DATA0 and DATA1 channels are both on the visible light
+ * area (mostly). The data0 sensitivity peaks at 500nm, DATA1 at 600nm.
+ * These wave lengths are pretty much on the border of colours making
+ * these a poor candidates for R/G/B standardization. Hence they're both
+ * marked as clear channels
+ */
+ BU27034_CHAN_DATA(DATA0, IIO_MOD_LIGHT_CLEAR),
+ BU27034_CHAN_DATA(DATA1, IIO_MOD_LIGHT_CLEAR),
+ BU27034_CHAN_DATA(DATA2, IIO_MOD_LIGHT_IR),
+ IIO_CHAN_SOFT_TIMESTAMP(4),
+};
+
+struct bu27034_data {
+ struct regmap *regmap;
+ struct device *dev;
+ /*
+ * Protect gain and time during scale adjustment and data reading.
+ * Protect measurement enabling/disabling.
+ */
+ struct mutex mutex;
+ struct iio_gts gts;
+ struct task_struct *task;
+ __le16 raw[3];
+ struct {
+ u32 mlux;
+ __le16 channels[3];
+ s64 ts __aligned(8);
+ } scan;
+};
+
+struct bu27034_result {
+ u16 ch0;
+ u16 ch1;
+ u16 ch2;
+};
+
+static const struct regmap_range bu27034_volatile_ranges[] = {
+ {
+ .range_min = BU27034_REG_MODE_CONTROL4,
+ .range_max = BU27034_REG_MODE_CONTROL4,
+ }, {
+ .range_min = BU27034_REG_DATA0_LO,
+ .range_max = BU27034_REG_DATA2_HI,
+ },
+};
+
+static const struct regmap_access_table bu27034_volatile_regs = {
+ .yes_ranges = &bu27034_volatile_ranges[0],
+ .n_yes_ranges = ARRAY_SIZE(bu27034_volatile_ranges),
+};
+
+static const struct regmap_range bu27034_read_only_ranges[] = {
+ {
+ .range_min = BU27034_REG_DATA0_LO,
+ .range_max = BU27034_REG_DATA2_HI,
+ }, {
+ .range_min = BU27034_REG_MANUFACTURER_ID,
+ .range_max = BU27034_REG_MANUFACTURER_ID,
+ }
+};
+
+static const struct regmap_access_table bu27034_ro_regs = {
+ .no_ranges = &bu27034_read_only_ranges[0],
+ .n_no_ranges = ARRAY_SIZE(bu27034_read_only_ranges),
+};
+
+static const struct regmap_config bu27034_regmap = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = BU27034_REG_MAX,
+ .cache_type = REGCACHE_RBTREE,
+ .volatile_table = &bu27034_volatile_regs,
+ .wr_table = &bu27034_ro_regs,
+};
+
+struct bu27034_gain_check {
+ int old_gain;
+ int new_gain;
+ int chan;
+};
+
+static int bu27034_get_gain_sel(struct bu27034_data *data, int chan)
+{
+ int ret, val;
+
+ switch (chan) {
+ case BU27034_CHAN_DATA0:
+ case BU27034_CHAN_DATA1:
+ {
+ int reg[] = {
+ [BU27034_CHAN_DATA0] = BU27034_REG_MODE_CONTROL2,
+ [BU27034_CHAN_DATA1] = BU27034_REG_MODE_CONTROL3,
+ };
+ ret = regmap_read(data->regmap, reg[chan], &val);
+ if (ret)
+ return ret;
+
+ return FIELD_GET(BU27034_MASK_D01_GAIN, val);
+ }
+ case BU27034_CHAN_DATA2:
+ {
+ int d2_lo_bits = fls(BU27034_MASK_D2_GAIN_LO);
+
+ ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL2, &val);
+ if (ret)
+ return ret;
+
+ /*
+ * The data2 channel gain is composed by 5 non continuous bits
+ * [7:6], [2:0]. Thus when we combine the 5-bit 'selector'
+ * from register value we must right shift the high bits by 3.
+ */
+ return FIELD_GET(BU27034_MASK_D2_GAIN_HI, val) << d2_lo_bits |
+ FIELD_GET(BU27034_MASK_D2_GAIN_LO, val);
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static int bu27034_get_gain(struct bu27034_data *data, int chan, int *gain)
+{
+ int ret, sel;
+
+ ret = bu27034_get_gain_sel(data, chan);
+ if (ret < 0)
+ return ret;
+
+ sel = ret;
+
+ ret = iio_gts_find_gain_by_sel(&data->gts, sel);
+ if (ret < 0) {
+ dev_err(data->dev, "chan %u: unknown gain value 0x%x\n", chan,
+ sel);
+
+ return ret;
+ }
+
+ *gain = ret;
+
+ return 0;
+}
+
+static int bu27034_get_int_time(struct bu27034_data *data)
+{
+ int ret, sel;
+
+ ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL1, &sel);
+ if (ret)
+ return ret;
+
+ return iio_gts_find_int_time_by_sel(&data->gts,
+ sel & BU27034_MASK_MEAS_MODE);
+}
+
+static int _bu27034_get_scale(struct bu27034_data *data, int channel, int *val,
+ int *val2)
+{
+ int gain, ret;
+
+ ret = bu27034_get_gain(data, channel, &gain);
+ if (ret)
+ return ret;
+
+ ret = bu27034_get_int_time(data);
+ if (ret < 0)
+ return ret;
+
+ return iio_gts_get_scale(&data->gts, gain, ret, val, val2);
+}
+
+static int bu27034_get_scale(struct bu27034_data *data, int channel, int *val,
+ int *val2)
+{
+ int ret;
+
+ if (channel == BU27034_CHAN_ALS) {
+ *val = 0;
+ *val2 = 1000;
+ return IIO_VAL_INT_PLUS_MICRO;
+ }
+
+ mutex_lock(&data->mutex);
+ ret = _bu27034_get_scale(data, channel, val, val2);
+ mutex_unlock(&data->mutex);
+ if (ret)
+ return ret;
+
+ return IIO_VAL_INT_PLUS_NANO;
+}
+
+/* Caller should hold the lock to protect lux reading */
+static int bu27034_write_gain_sel(struct bu27034_data *data, int chan, int sel)
+{
+ static const int reg[] = {
+ [BU27034_CHAN_DATA0] = BU27034_REG_MODE_CONTROL2,
+ [BU27034_CHAN_DATA1] = BU27034_REG_MODE_CONTROL3,
+ };
+ int mask, val;
+
+ if (chan != BU27034_CHAN_DATA0 && chan != BU27034_CHAN_DATA1)
+ return -EINVAL;
+
+ mask = BU27034_MASK_D01_GAIN;
+ val = FIELD_PREP(mask, sel);
+
+ if (chan == BU27034_CHAN_DATA0) {
+ /*
+ * We keep the same gain for channel 2 as we set for channel 0
+ * We can't allow them to be individually controlled because
+ * setting one will impact also the other. Also, if we don't
+ * always update both gains we may result unsupported bit
+ * combinations.
+ *
+ * This is not nice but this is yet another place where the
+ * user space must be prepared to surprizes. Namely, see chan 2
+ * gain changed when chan 0 gain is changed.
+ *
+ * This is not fatal for most users though. I don't expect the
+ * channel 2 to be used in any generic cases - the intensity
+ * values provided by the sensor for IR area are not openly
+ * documented. Also, channel 2 is not used for visible light.
+ *
+ * So, if there is application which is written to utilize the
+ * channel 2 - then it is probably specifically targeted to this
+ * sensor and knows how to utilize those values. It is safe to
+ * hope such user can also cope with the gain changes.
+ */
+ mask |= BU27034_MASK_D2_GAIN_LO;
+
+ /*
+ * The D2 gain bits are directly the lowest bits of selector.
+ * Just do add those bits to the value
+ */
+ val |= sel & BU27034_MASK_D2_GAIN_LO;
+ }
+
+ return regmap_update_bits(data->regmap, reg[chan], mask, val);
+}
+
+static int bu27034_set_gain(struct bu27034_data *data, int chan, int gain)
+{
+ int ret;
+
+ /*
+ * We don't allow setting channel 2 gain as it messes up the
+ * gain for channel 0 - which shares the high bits
+ */
+ if (chan != BU27034_CHAN_DATA0 && chan != BU27034_CHAN_DATA1)
+ return -EINVAL;
+
+ ret = iio_gts_find_sel_by_gain(&data->gts, gain);
+ if (ret < 0)
+ return ret;
+
+ return bu27034_write_gain_sel(data, chan, ret);
+}
+
+/* Caller should hold the lock to protect data->int_time */
+static int bu27034_set_int_time(struct bu27034_data *data, int time)
+{
+ int ret;
+
+ ret = iio_gts_find_sel_by_int_time(&data->gts, time);
+ if (ret < 0)
+ return ret;
+
+ return regmap_update_bits(data->regmap, BU27034_REG_MODE_CONTROL1,
+ BU27034_MASK_MEAS_MODE, ret);
+}
+
+/*
+ * We try to change the time in such way that the scale is maintained for
+ * given channels by adjusting gain so that it compensates the time change.
+ */
+static int bu27034_try_set_int_time(struct bu27034_data *data, int time_us)
+{
+ struct bu27034_gain_check gains[] = {
+ { .chan = BU27034_CHAN_DATA0 },
+ { .chan = BU27034_CHAN_DATA1 },
+ };
+ int numg = ARRAY_SIZE(gains);
+ int ret, int_time_old, i;
+
+ mutex_lock(&data->mutex);
+ ret = bu27034_get_int_time(data);
+ if (ret < 0)
+ goto unlock_out;
+
+ int_time_old = ret;
+
+ if (!iio_gts_valid_time(&data->gts, time_us)) {
+ dev_err(data->dev, "Unsupported integration time %u\n",
+ time_us);
+ ret = -EINVAL;
+
+ goto unlock_out;
+ }
+
+ if (time_us == int_time_old) {
+ ret = 0;
+ goto unlock_out;
+ }
+
+ for (i = 0; i < numg; i++) {
+ ret = bu27034_get_gain(data, gains[i].chan, &gains[i].old_gain);
+ if (ret)
+ goto unlock_out;
+
+ ret = iio_gts_find_new_gain_by_old_gain_time(&data->gts,
+ gains[i].old_gain,
+ int_time_old, time_us,
+ &gains[i].new_gain);
+ if (ret) {
+ int scale1, scale2;
+ bool ok;
+
+ _bu27034_get_scale(data, gains[i].chan, &scale1, &scale2);
+ dev_dbg(data->dev,
+ "chan %u, can't support time %u with scale %u %u\n",
+ gains[i].chan, time_us, scale1, scale2);
+
+ /*
+ * If caller requests for integration time change and we
+ * can't support the scale - then the caller should be
+ * prepared to 'pick up the pieces and deal with the
+ * fact that the scale changed'.
+ */
+ ret = iio_find_closest_gain_low(&data->gts,
+ gains[i].new_gain, &ok);
+
+ if (!ok) {
+ dev_dbg(data->dev,
+ "optimal gain out of range for chan %u\n",
+ gains[i].chan);
+ }
+ if (ret < 0) {
+ dev_dbg(data->dev,
+ "Total gain increase. Risk of saturation");
+ ret = iio_gts_get_min_gain(&data->gts);
+ if (ret < 0)
+ goto unlock_out;
+ }
+ dev_dbg(data->dev, "chan %u scale changed\n",
+ gains[i].chan);
+ gains[i].new_gain = ret;
+ dev_dbg(data->dev, "chan %u new gain %u\n",
+ gains[i].chan, gains[i].new_gain);
+ }
+ }
+
+ for (i = 0; i < numg; i++) {
+ ret = bu27034_set_gain(data, gains[i].chan, gains[i].new_gain);
+ if (ret)
+ goto unlock_out;
+ }
+
+ ret = bu27034_set_int_time(data, time_us);
+
+unlock_out:
+ mutex_unlock(&data->mutex);
+
+ return ret;
+}
+
+static int bu27034_set_scale(struct bu27034_data *data, int chan,
+ int val, int val2)
+{
+ int ret, time_sel, gain_sel, i;
+ bool found = false;
+
+ if (chan == BU27034_CHAN_DATA2)
+ return -EINVAL;
+
+ if (chan == BU27034_CHAN_ALS) {
+ if (val == 0 && val2 == 1000)
+ return 0;
+
+ return -EINVAL;
+ }
+
+ mutex_lock(&data->mutex);
+ ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL1, &time_sel);
+ if (ret)
+ goto unlock_out;
+
+ ret = iio_gts_find_gain_sel_for_scale_using_time(&data->gts, time_sel,
+ val, val2 * 1000, &gain_sel);
+ if (ret) {
+ /*
+ * Could not support scale with given time. Need to change time.
+ * We still want to maintain the scale for all channels
+ */
+ struct bu27034_gain_check gain;
+ int new_time_sel;
+
+ /*
+ * Populate information for the other channel which should also
+ * maintain the scale. (Due to the HW limitations the chan2
+ * gets the same gain as chan0, so we only need to explicitly
+ * set the chan 0 and 1).
+ */
+ if (chan == BU27034_CHAN_DATA0)
+ gain.chan = BU27034_CHAN_DATA1;
+ else if (chan == BU27034_CHAN_DATA1)
+ gain.chan = BU27034_CHAN_DATA0;
+
+ ret = bu27034_get_gain(data, gain.chan, &gain.old_gain);
+ if (ret)
+ goto unlock_out;
+
+ /*
+ * Iterate through all the times to see if we find one which
+ * can support requested scale for requested channel, while
+ * maintaining the scale for other channels
+ */
+ for (i = 0; i < data->gts.num_itime; i++) {
+ new_time_sel = data->gts.itime_table[i].sel;
+
+ if (new_time_sel == time_sel)
+ continue;
+
+ /* Can we provide requested scale with this time? */
+ ret = iio_gts_find_gain_sel_for_scale_using_time(
+ &data->gts, new_time_sel, val, val2 * 1000,
+ &gain_sel);
+ if (ret)
+ continue;
+
+ /* Can the other channel(s) maintain scale? */
+ ret = iio_gts_find_new_gain_sel_by_old_gain_time(
+ &data->gts, gain.old_gain, time_sel,
+ new_time_sel, &gain.new_gain);
+ if (!ret) {
+ /* Yes - we found suitable time */
+ found = true;
+ break;
+ }
+ }
+ if (!found) {
+ dev_dbg(data->dev,
+ "Can't set scale maintaining other channels\n");
+ ret = -EINVAL;
+
+ goto unlock_out;
+ }
+
+ ret = bu27034_set_gain(data, gain.chan, gain.new_gain);
+ if (ret)
+ goto unlock_out;
+
+ ret = regmap_update_bits(data->regmap, BU27034_REG_MODE_CONTROL1,
+ BU27034_MASK_MEAS_MODE, new_time_sel);
+ if (ret)
+ goto unlock_out;
+ }
+
+ ret = bu27034_write_gain_sel(data, chan, gain_sel);
+unlock_out:
+ mutex_unlock(&data->mutex);
+
+ return ret;
+}
+
+/*
+ * for (D1/D0 < 0.87):
+ * lx = 0.004521097 * D1 - 0.002663996 * D0 +
+ * 0.00012213 * D1 * D1 / D0
+ *
+ * => 115.7400832 * ch1 / gain1 / mt -
+ * 68.1982976 * ch0 / gain0 / mt +
+ * 0.00012213 * 25600 * (ch1 / gain1 / mt) * 25600 *
+ * (ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt)
+ *
+ * A = 0.00012213 * 25600 * (ch1 /gain1 / mt) * 25600 *
+ * (ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt)
+ * => 0.00012213 * 25600 * (ch1 /gain1 / mt) *
+ * (ch1 /gain1 / mt) / (ch0 / gain0 / mt)
+ * => 0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) /
+ * (ch0 / gain0)
+ * => 0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) *
+ * gain0 / ch0
+ * => 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt /ch0
+ *
+ * lx = (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) /
+ * mt + A
+ * => (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) /
+ * mt + 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt /
+ * ch0
+ *
+ * => (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0 +
+ * 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / ch0) /
+ * mt
+ *
+ * For (0.87 <= D1/D0 < 1.00)
+ * lx = (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 0.87) * (0.385) + 1)
+ * => (0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 *
+ * 100 * ch1 / gain1 / mt) * ((D1/D0 - 0.87) * (0.385) + 1)
+ * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
+ * ((D1/D0 - 0.87) * (0.385) + 1)
+ * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
+ * (0.385 * D1/D0 - 0.66505)
+ * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
+ * (0.385 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) - 0.66505)
+ * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
+ * (9856 * ch1 / gain1 / mt / (25600 * ch0 / gain0 / mt) + 0.66505)
+ * => 13.118336 * ch1 / (gain1 * mt)
+ * + 22.66064768 * ch0 / (gain0 * mt)
+ * + 8931.90144 * ch1 * ch1 * gain0 /
+ * (25600 * ch0 * gain1 * gain1 * mt)
+ * + 0.602694912 * ch1 / (gain1 * mt)
+ *
+ * => [0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1)
+ * + 22.66064768 * ch0 / gain0
+ * + 13.721030912 * ch1 / gain1
+ * ] / mt
+ *
+ * For (D1/D0 >= 1.00)
+ *
+ * lx = (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 2.0) * (-0.05) + 1)
+ * => (0.001331* D0 + 0.0000354 * D1) * (-0.05D1/D0 + 1.1)
+ * => (0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 *
+ * 100 * ch1 / gain1 / mt) * (-0.05D1/D0 + 1.1)
+ * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
+ * (-0.05 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) + 1.1)
+ * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
+ * (-1280 * ch1 / (gain1 * mt * 25600 * ch0 / gain0 / mt) + 1.1)
+ * => (34.0736 * ch0 * -1280 * ch1 * gain0 * mt /( gain0 * mt * gain1 * mt * 25600 * ch0)
+ * + 34.0736 * 1.1 * ch0 / (gain0 * mt)
+ * + 0.90624 * ch1 * -1280 * ch1 *gain0 * mt / (gain1 * mt *gain1 * mt * 25600 * ch0)
+ * + 1.1 * 0.90624 * ch1 / (gain1 * mt)
+ * => -43614.208 * ch1 / (gain1 * mt * 25600)
+ * + 37.48096 ch0 / (gain0 * mt)
+ * - 1159.9872 * ch1 * ch1 * gain0 / (gain1 * gain1 * mt * 25600 * ch0)
+ * + 0.996864 ch1 / (gain1 * mt)
+ * => [
+ * - 0.045312 * ch1 * ch1 * gain0 / (gain1 * gain1 * ch0)
+ * - 0.706816 * ch1 / gain1
+ * + 37.48096 ch0 /gain0
+ * ] * mt
+ *
+ *
+ * So, the first case (D1/D0 < 0.87) can be computed to a form:
+ *
+ * lx = (3.126528 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
+ * 115.7400832 * ch1 / gain1 +
+ * -68.1982976 * ch0 / gain0
+ * / mt
+ *
+ * Second case (0.87 <= D1/D0 < 1.00) goes to form:
+ *
+ * => [0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
+ * 13.721030912 * ch1 / gain1 +
+ * 22.66064768 * ch0 / gain0
+ * ] / mt
+ *
+ * Third case (D1/D0 >= 1.00) goes to form:
+ * => [-0.045312 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
+ * -0.706816 * ch1 / gain1 +
+ * 37.48096 ch0 /(gain0
+ * ] / mt
+ *
+ * This can be unified to format:
+ * lx = [
+ * A * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
+ * B * ch1 / gain1 +
+ * C * ch0 / gain0
+ * ] / mt
+ *
+ * For case 1:
+ * A = 3.126528,
+ * B = 115.7400832
+ * C = -68.1982976
+ *
+ * For case 2:
+ * A = 0.3489024
+ * B = 13.721030912
+ * C = 22.66064768
+ *
+ * For case 3:
+ * A = -0.045312
+ * B = -0.706816
+ * C = 37.48096
+ */
+
+struct bu27034_lx_coeff {
+ unsigned int A;
+ unsigned int B;
+ unsigned int C;
+ /* Indicate which of the coefficients above are negative */
+ bool is_neg[3];
+};
+
+static inline u64 gain_mul_div_helper(u64 val, unsigned int gain,
+ unsigned int div)
+{
+ /*
+ * Max gain for a channel is 4096. The max u64 (0xffffffffffffffffULL)
+ * divided by 4096 is 0xFFFFFFFFFFFFF (GENMASK_ULL(51, 0)) (floored).
+ * Thus, the 0xFFFFFFFFFFFFF is the largest value we can safely multiply
+ * with the gain, no matter what gain is set.
+ *
+ * So, multiplication with max gain may overflow if val is greater than
+ * 0xFFFFFFFFFFFFF (52 bits set)..
+ *
+ * If this is the case we divide first.
+ */
+ if (val < GENMASK_ULL(51, 0)) {
+ val *= gain;
+ do_div(val, div);
+ } else {
+ do_div(val, div);
+ val *= gain;
+ }
+
+ return val;
+}
+
+static u64 bu27034_fixp_calc_t1_64bit(unsigned int coeff, unsigned int ch0,
+ unsigned int ch1, unsigned int gain0,
+ unsigned int gain1)
+{
+ unsigned int helper;
+ u64 helper64;
+
+ helper64 = (u64)coeff * (u64)ch1 * (u64)ch1;
+
+ helper = gain1 * gain1;
+ if (helper > ch0) {
+ do_div(helper64, helper);
+
+ return gain_mul_div_helper(helper64, gain0, ch0);
+ }
+
+ do_div(helper64, ch0);
+
+ return gain_mul_div_helper(helper64, gain0, helper);
+
+}
+
+static u64 bu27034_fixp_calc_t1(unsigned int coeff, unsigned int ch0,
+ unsigned int ch1, unsigned int gain0,
+ unsigned int gain1)
+{
+ unsigned int helper, tmp;
+
+ /*
+ * Here we could overflow even the 64bit value. Hence we
+ * multiply with gain0 only after the divisions - even though
+ * it may result loss of accuracy
+ */
+ helper = coeff * ch1 * ch1;
+ tmp = helper * gain0;
+
+ helper = ch1 * ch1;
+
+ if (check_mul_overflow(helper, coeff, &helper))
+ return bu27034_fixp_calc_t1_64bit(coeff, ch0, ch1, gain0, gain1);
+
+ if (check_mul_overflow(helper, gain0, &tmp))
+ return bu27034_fixp_calc_t1_64bit(coeff, ch0, ch1, gain0, gain1);
+
+ return tmp / (gain1 * gain1) / ch0;
+
+}
+
+static u64 bu27034_fixp_calc_t23(unsigned int coeff, unsigned int ch,
+ unsigned int gain)
+{
+ unsigned int helper;
+ u64 helper64;
+
+ if (!check_mul_overflow(coeff, ch, &helper))
+ return helper / gain;
+
+ helper64 = (u64)coeff * (u64)ch;
+ do_div(helper64, gain);
+
+ return helper64;
+}
+
+static int bu27034_fixp_calc_lx(unsigned int ch0, unsigned int ch1,
+ unsigned int gain0, unsigned int gain1,
+ unsigned int meastime, int coeff_idx)
+{
+ static const struct bu27034_lx_coeff coeff[] = {
+ {
+ .A = 31265280, /* 3.126528 */
+ .B = 1157400832, /*115.7400832 */
+ .C = 681982976, /* -68.1982976 */
+ .is_neg = {false, false, true},
+ }, {
+ .A = 3489024, /* 0.3489024 */
+ .B = 137210309, /* 13.721030912 */
+ .C = 226606476, /* 22.66064768 */
+ /* All terms positive */
+ }, {
+ .A = 453120, /* -0.045312 */
+ .B = 7068160, /* -0.706816 */
+ .C = 374809600, /* 37.48096 */
+ .is_neg = {true, true, false},
+ }
+ };
+ const struct bu27034_lx_coeff *c = &coeff[coeff_idx];
+ u64 res = 0, terms[3];
+ int i;
+
+ if (coeff_idx >= ARRAY_SIZE(coeff))
+ return -EINVAL;
+
+ terms[0] = bu27034_fixp_calc_t1(c->A, ch0, ch1, gain0, gain1);
+ terms[1] = bu27034_fixp_calc_t23(c->B, ch1, gain1);
+ terms[2] = bu27034_fixp_calc_t23(c->C, ch0, gain0);
+
+ /* First, add positive terms */
+ for (i = 0; i < 3; i++)
+ if (!c->is_neg[i])
+ res += terms[i];
+
+ /* No positive term => zero lux */
+ if (!res)
+ return 0;
+
+ /* Then, subtract negative terms (if any) */
+ for (i = 0; i < 3; i++)
+ if (c->is_neg[i]) {
+ /*
+ * If the negative term is greater than positive - then
+ * the darkness has taken over and we are all doomed! Eh,
+ * I mean, then we can just return 0 lx and go out
+ */
+ if (terms[i] >= res)
+ return 0;
+
+ res -= terms[i];
+ }
+
+ meastime *= 10;
+ do_div(res, meastime);
+
+ return (int) res;
+}
+
+static bool bu27034_has_valid_sample(struct bu27034_data *data)
+{
+ int ret, val;
+
+ ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL4, &val);
+ if (ret) {
+ dev_err(data->dev, "Read failed %d\n", ret);
+
+ return false;
+ }
+
+ return val & BU27034_MASK_VALID;
+}
+
+/*
+ * Reading the register where VALID bit is clears this bit. (So does changing
+ * any gain / integration time configuration registers) The bit gets
+ * set when we have acquired new data. We use this bit to indicate data
+ * validity.
+ */
+static void bu27034_invalidate_read_data(struct bu27034_data *data)
+{
+ bu27034_has_valid_sample(data);
+}
+
+static int bu27034_read_result(struct bu27034_data *data, int chan, int *res)
+{
+ int reg[] = {
+ [BU27034_CHAN_DATA0] = BU27034_REG_DATA0_LO,
+ [BU27034_CHAN_DATA1] = BU27034_REG_DATA1_LO,
+ [BU27034_CHAN_DATA2] = BU27034_REG_DATA2_LO,
+ };
+ int valid, ret;
+ __le16 val;
+
+ ret = regmap_read_poll_timeout(data->regmap, BU27034_REG_MODE_CONTROL4,
+ valid, (valid & BU27034_MASK_VALID),
+ BU27034_DATA_WAIT_TIME_US, 0);
+ if (ret)
+ return ret;
+
+ ret = regmap_bulk_read(data->regmap, reg[chan], &val, sizeof(val));
+ if (ret)
+ return ret;
+
+ *res = le16_to_cpu(val);
+
+ return 0;
+}
+
+static int bu27034_get_result_unlocked(struct bu27034_data *data, __le16 *res,
+ int size)
+{
+ int ret = 0, retry_cnt = 0;
+
+retry:
+ /* Get new value from sensor if data is ready */
+ if (bu27034_has_valid_sample(data)) {
+ ret = regmap_bulk_read(data->regmap, BU27034_REG_DATA0_LO,
+ res, size);
+ if (ret)
+ return ret;
+
+ bu27034_invalidate_read_data(data);
+ } else {
+ /* No new data in sensor. Wait and retry */
+ retry_cnt++;
+
+ if (retry_cnt > BU27034_RETRY_LIMIT) {
+ dev_err(data->dev, "No data from sensor\n");
+
+ return -ETIMEDOUT;
+ }
+
+ msleep(25);
+
+ goto retry;
+ }
+
+ return ret;
+}
+
+static int bu27034_meas_set(struct bu27034_data *data, bool en)
+{
+ if (en)
+ return regmap_set_bits(data->regmap, BU27034_REG_MODE_CONTROL4,
+ BU27034_MASK_MEAS_EN);
+
+ return regmap_clear_bits(data->regmap, BU27034_REG_MODE_CONTROL4,
+ BU27034_MASK_MEAS_EN);
+}
+
+static int bu27034_get_single_result(struct bu27034_data *data, int chan,
+ int *val)
+{
+ int ret;
+
+ if (chan < BU27034_CHAN_DATA0 || chan > BU27034_CHAN_DATA2)
+ return -EINVAL;
+
+ ret = bu27034_meas_set(data, true);
+ if (ret)
+ return ret;
+
+ ret = bu27034_get_int_time(data);
+ if (ret < 0)
+ return ret;
+
+ msleep(ret / 1000);
+
+ return bu27034_read_result(data, chan, val);
+}
+
+/*
+ * The formula given by vendor for computing luxes out of data0 and data1
+ * (in open air) is as follows:
+ *
+ * Let's mark:
+ * D0 = data0/ch0_gain/meas_time_ms * 25600
+ * D1 = data1/ch1_gain/meas_time_ms * 25600
+ *
+ * Then:
+ * if (D1/D0 < 0.87)
+ * lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 3.45 + 1)
+ * else if (D1/D0 < 1)
+ * lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 0.385 + 1)
+ * else
+ * lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 2) * -0.05 + 1)
+ *
+ * We use it here. Users who have for example some colored lens
+ * need to modify the calculation but I hope this gives a starting point for
+ * those working with such devices.
+ */
+
+static int bu27034_calc_mlux(struct bu27034_data *data, __le16 *res, int *val)
+{
+ unsigned int gain0, gain1, meastime;
+ unsigned int d1_d0_ratio_scaled;
+ u16 ch0, ch1;
+ u64 helper64;
+ int ret;
+
+ /*
+ * We return 0 lux if calculation fails. This should be reasonably
+ * easy to spot from the buffers especially if raw-data channels show
+ * valid values
+ */
+ *val = 0;
+
+ ch0 = max_t(u16, 1, le16_to_cpu(res[0]));
+ ch1 = max_t(u16, 1, le16_to_cpu(res[1]));
+
+ ret = bu27034_get_gain(data, BU27034_CHAN_DATA0, &gain0);
+ if (ret)
+ return ret;
+
+ ret = bu27034_get_gain(data, BU27034_CHAN_DATA1, &gain1);
+ if (ret)
+ return ret;
+
+ ret = bu27034_get_int_time(data);
+ if (ret < 0)
+ return ret;
+
+ meastime = ret;
+
+ d1_d0_ratio_scaled = (unsigned int)ch1 * (unsigned int)gain0 * 100;
+ helper64 = (u64)ch1 * (u64)gain0 * 100LLU;
+
+ if (helper64 != d1_d0_ratio_scaled) {
+ unsigned int div = (unsigned int)ch0 * gain1;
+
+ do_div(helper64, div);
+ d1_d0_ratio_scaled = helper64;
+ } else {
+ d1_d0_ratio_scaled /= ch0 * gain1;
+ }
+
+ if (d1_d0_ratio_scaled < 87)
+ ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 0);
+ else if (d1_d0_ratio_scaled < 100)
+ ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 1);
+ else
+ ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 2);
+
+ if (ret < 0)
+ return ret;
+
+ *val = ret;
+
+ return 0;
+
+}
+
+static int bu27034_get_mlux(struct bu27034_data *data, int chan, int *val)
+{
+ __le16 res[3];
+ int ret;
+
+ ret = bu27034_meas_set(data, true);
+ if (ret)
+ return ret;
+
+ ret = bu27034_get_result_unlocked(data, &res[0], sizeof(res));
+ if (ret)
+ return ret;
+
+ ret = bu27034_calc_mlux(data, res, val);
+ if (ret)
+ return ret;
+
+ ret = bu27034_meas_set(data, false);
+ if (ret)
+ dev_err(data->dev, "failed to disable measurement\n");
+
+ return 0;
+}
+
+static int bu27034_read_raw(struct iio_dev *idev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct bu27034_data *data = iio_priv(idev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_INT_TIME:
+ *val = bu27034_get_int_time(data);
+ if (*val < 0)
+ return *val;
+
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ return bu27034_get_scale(data, chan->channel, val, val2);
+
+ case IIO_CHAN_INFO_RAW:
+ {
+ int (*result_get)(struct bu27034_data *data, int chan, int *val);
+
+ if (chan->type == IIO_INTENSITY)
+ result_get = bu27034_get_single_result;
+ else if (chan->type == IIO_LIGHT)
+ result_get = bu27034_get_mlux;
+ else
+ return -EINVAL;
+
+ /* Don't mess with measurement enabling while buffering */
+ ret = iio_device_claim_direct_mode(idev);
+ if (ret)
+ return ret;
+
+ mutex_lock(&data->mutex);
+ /*
+ * Reading one channel at a time is inefficient but we
+ * don't care here. Buffered version should be used if
+ * performance is an issue.
+ */
+ ret = result_get(data, chan->channel, val);
+
+ mutex_unlock(&data->mutex);
+ iio_device_release_direct_mode(idev);
+
+ if (ret)
+ return ret;
+
+ return IIO_VAL_INT;
+ }
+ default:
+ return -EINVAL;
+
+ }
+}
+
+static int bu27034_write_raw(struct iio_dev *idev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct bu27034_data *data = iio_priv(idev);
+ int ret;
+
+ ret = iio_device_claim_direct_mode(idev);
+ if (ret)
+ return ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SCALE:
+ ret = bu27034_set_scale(data, chan->channel, val, val2);
+ break;
+ case IIO_CHAN_INFO_INT_TIME:
+ ret = bu27034_try_set_int_time(data, val);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ iio_device_release_direct_mode(idev);
+
+ return ret;
+}
+
+static int bu27034_read_avail(struct iio_dev *idev,
+ struct iio_chan_spec const *chan, const int **vals,
+ int *type, int *length, long mask)
+{
+ struct bu27034_data *data = iio_priv(idev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_INT_TIME:
+ return iio_gts_avail_times(&data->gts, vals, type, length);
+ case IIO_CHAN_INFO_SCALE:
+ return iio_gts_all_avail_scales(&data->gts, vals, type, length);
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info bu27034_info = {
+ .read_raw = &bu27034_read_raw,
+ .write_raw = &bu27034_write_raw,
+ .read_avail = &bu27034_read_avail,
+};
+
+static int bu27034_chip_init(struct bu27034_data *data)
+{
+ int ret, sel;
+
+ /* Reset */
+ ret = regmap_update_bits(data->regmap, BU27034_REG_SYSTEM_CONTROL,
+ BU27034_MASK_SW_RESET, BU27034_MASK_SW_RESET);
+ if (ret)
+ return dev_err_probe(data->dev, ret, "Sensor reset failed\n");
+
+ msleep(1);
+ /*
+ * Read integration time here to ensure it is in regmap cache. We do
+ * this to speed-up the int-time acquisition in the start of the buffer
+ * handling thread where longer delays could make it more likely we end
+ * up skipping a sample, and where the longer delays make timestamps
+ * less accurate.
+ */
+ ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL1, &sel);
+ if (ret)
+ dev_err(data->dev, "reading integration time failed\n");
+
+ return 0;
+}
+
+static int bu27034_wait_for_data(struct bu27034_data *data)
+{
+ int ret, val;
+
+ ret = regmap_read_poll_timeout(data->regmap, BU27034_REG_MODE_CONTROL4,
+ val, val & BU27034_MASK_VALID,
+ BU27034_DATA_WAIT_TIME_US,
+ BU27034_TOTAL_DATA_WAIT_TIME_US);
+ if (ret) {
+ dev_err(data->dev, "data polling %s\n",
+ !(val & BU27034_MASK_VALID) ? "timeout" : "fail");
+
+ return ret;
+ }
+
+ ret = regmap_bulk_read(data->regmap, BU27034_REG_DATA0_LO,
+ &data->scan.channels[0],
+ sizeof(data->scan.channels));
+ if (ret)
+ return ret;
+
+ bu27034_invalidate_read_data(data);
+
+ return 0;
+}
+
+static int bu27034_buffer_thread(void *arg)
+{
+ struct iio_dev *idev = arg;
+ struct bu27034_data *data;
+ int wait_ms;
+
+ data = iio_priv(idev);
+
+ wait_ms = bu27034_get_int_time(data);
+ wait_ms /= 1000;
+
+ wait_ms -= BU27034_MEAS_WAIT_PREMATURE_MS;
+
+ while (!kthread_should_stop()) {
+ int ret;
+ int64_t tstamp;
+
+ msleep(wait_ms);
+ ret = bu27034_wait_for_data(data);
+ if (ret)
+ continue;
+
+ tstamp = iio_get_time_ns(idev);
+
+ if (test_bit(BU27034_CHAN_ALS, idev->active_scan_mask)) {
+ int mlux;
+
+ ret = bu27034_calc_mlux(data, &data->scan.channels[0],
+ &mlux);
+ if (ret)
+ dev_err(data->dev, "failed to calculate lux\n");
+
+ /*
+ * The maximum Milli lux value we get with gain 1x time
+ * 55mS data ch0 = 0xffff ch1 = 0xffff fits in 26 bits
+ * so there should be no problem returning int from
+ * computations and casting it to u32
+ */
+ data->scan.mlux = (u32)mlux;
+ }
+ iio_push_to_buffers_with_timestamp(idev, &data->scan, tstamp);
+ }
+
+ return 0;
+}
+
+static int bu27034_buffer_enable(struct iio_dev *idev)
+{
+ struct bu27034_data *data = iio_priv(idev);
+ struct task_struct *task;
+ int ret;
+
+ mutex_lock(&data->mutex);
+ ret = bu27034_meas_set(data, true);
+ if (ret)
+ goto unlock_out;
+
+ task = kthread_run(bu27034_buffer_thread, idev,
+ "bu27034-buffering-%u",
+ iio_device_id(idev));
+ if (IS_ERR(task)) {
+ ret = PTR_ERR(task);
+ goto unlock_out;
+ }
+
+ data->task = task;
+
+unlock_out:
+ mutex_unlock(&data->mutex);
+
+ return ret;
+}
+
+static int bu27034_buffer_disable(struct iio_dev *idev)
+{
+ struct bu27034_data *data = iio_priv(idev);
+ int ret;
+
+ mutex_lock(&data->mutex);
+ if (data->task) {
+ kthread_stop(data->task);
+ data->task = NULL;
+ }
+
+ ret = bu27034_meas_set(data, false);
+ mutex_unlock(&data->mutex);
+
+ return ret;
+}
+
+static const struct iio_buffer_setup_ops bu27034_buffer_ops = {
+ .postenable = &bu27034_buffer_enable,
+ .predisable = &bu27034_buffer_disable,
+};
+
+static int bu27034_probe(struct i2c_client *i2c)
+{
+ struct device *dev = &i2c->dev;
+ struct bu27034_data *data;
+ struct regmap *regmap;
+ struct iio_dev *idev;
+ unsigned int part_id, reg;
+ int ret;
+
+ regmap = devm_regmap_init_i2c(i2c, &bu27034_regmap);
+ if (IS_ERR(regmap))
+ return dev_err_probe(dev, PTR_ERR(regmap),
+ "Failed to initialize Regmap\n");
+
+ idev = devm_iio_device_alloc(dev, sizeof(*data));
+ if (!idev)
+ return -ENOMEM;
+
+ ret = devm_regulator_get_enable(dev, "vdd");
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to get regulator\n");
+
+ data = iio_priv(idev);
+
+ ret = regmap_read(regmap, BU27034_REG_SYSTEM_CONTROL, ®);
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to access sensor\n");
+
+ part_id = FIELD_GET(BU27034_MASK_PART_ID, reg);
+
+ if (part_id != BU27034_ID)
+ dev_warn(dev, "unknown device 0x%x\n", part_id);
+
+ ret = devm_iio_init_iio_gts(dev, BU27034_SCALE_1X, 0, bu27034_gains,
+ ARRAY_SIZE(bu27034_gains), bu27034_itimes,
+ ARRAY_SIZE(bu27034_itimes), &data->gts);
+ if (ret)
+ return ret;
+
+ mutex_init(&data->mutex);
+ data->regmap = regmap;
+ data->dev = dev;
+
+ idev->channels = bu27034_channels;
+ idev->num_channels = ARRAY_SIZE(bu27034_channels);
+ idev->name = "bu27034";
+ idev->info = &bu27034_info;
+
+ idev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
+ idev->available_scan_masks = bu27034_scan_masks;
+
+ ret = bu27034_chip_init(data);
+ if (ret)
+ return ret;
+
+ ret = devm_iio_kfifo_buffer_setup(dev, idev, &bu27034_buffer_ops);
+ if (ret)
+ return dev_err_probe(dev, ret, "buffer setup failed\n");
+
+ ret = devm_iio_device_register(dev, idev);
+ if (ret < 0)
+ return dev_err_probe(dev, ret,
+ "Unable to register iio device\n");
+
+ return ret;
+}
+
+static const struct of_device_id bu27034_of_match[] = {
+ { .compatible = "rohm,bu27034" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, bu27034_of_match);
+
+static struct i2c_driver bu27034_i2c_driver = {
+ .driver = {
+ .name = "bu27034-als",
+ .of_match_table = bu27034_of_match,
+ },
+ .probe_new = bu27034_probe,
+};
+module_i2c_driver(bu27034_i2c_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
+MODULE_DESCRIPTION("ROHM BU27034 ambient light sensor driver");
+MODULE_IMPORT_NS(IIO_GTS_HELPER);