iio: light: as73211: New driver

Support for AMS AS73211 JENCOLOR(R) Digital XYZ Sensor.

This driver has no built-in trigger. In order for making triggered
measurements, an external (software) trigger driver like
iio-trig-hrtimer or iio-trig-sysfs is required.

The sensor supports single and continuous measurement modes. The latter
is not used by design as this would require tight timing synchronization
between hardware and driver without much benefit.

Datasheet: https://ams.com/documents/20143/36005/AS73211_DS000556_3-01.pdf
Signed-off-by: Christian Eggers <ceggers@arri.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

4 files changed, 824 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 39bf100972e9..2e9d0ccd66a1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -943,6 +943,13 @@ S:	Supported
 F:	arch/arm64/boot/dts/amd/amd-seattle-xgbe*.dtsi
 F:	drivers/net/ethernet/amd/xgbe/
 
+AMS AS73211 DRIVER
+M:	Christian Eggers <ceggers@arri.de>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/light/ams,as73211.yaml
+F:	drivers/iio/light/as73211.c
+
 ANALOG DEVICES INC AD5686 DRIVER
 M:	Michael Hennerich <Michael.Hennerich@analog.com>
 L:	linux-pm@vger.kernel.org
diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index 182bd18c4bb2..cade6dc0305b 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -86,6 +86,21 @@ config APDS9960
 	  To compile this driver as a module, choose M here: the
 	  module will be called apds9960
 
+config AS73211
+	tristate "AMS AS73211 XYZ color sensor"
+	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	 If you say yes here you get support for the AMS AS73211
+	 JENCOLOR(R) Digital XYZ Sensor.
+
+	 For triggered measurements, you will need an additional trigger driver
+	 like IIO_HRTIMER_TRIGGER or IIO_SYSFS_TRIGGER.
+
+	 This driver can also be built as a module.  If so, the module
+	 will be called as73211.
+
 config BH1750
 	tristate "ROHM BH1750 ambient light sensor"
 	depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index d1c8aa30b9a8..ea376deaca54 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_AL3010)		+= al3010.o
 obj-$(CONFIG_AL3320A)		+= al3320a.o
 obj-$(CONFIG_APDS9300)		+= apds9300.o
 obj-$(CONFIG_APDS9960)		+= apds9960.o
+obj-$(CONFIG_AS73211)		+= as73211.o
 obj-$(CONFIG_BH1750)		+= bh1750.o
 obj-$(CONFIG_BH1780)		+= bh1780.o
 obj-$(CONFIG_CM32181)		+= cm32181.o
diff --git a/drivers/iio/light/as73211.c b/drivers/iio/light/as73211.c
new file mode 100644
index 000000000000..b1178dfc1f65
--- /dev/null
+++ b/drivers/iio/light/as73211.c
@@ -0,0 +1,801 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Support for AMS AS73211 JENCOLOR(R) Digital XYZ Sensor
+ *
+ * Author: Christian Eggers <ceggers@arri.de>
+ *
+ * Copyright (c) 2020 ARRI Lighting
+ *
+ * Color light sensor with 16-bit channels for x, y, z and temperature);
+ * 7-bit I2C slave address 0x74 .. 0x77.
+ *
+ * Datasheet: https://ams.com/documents/20143/36005/AS73211_DS000556_3-01.pdf
+ */
+
+#include <linux/bitfield.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pm.h>
+
+#define HZ_PER_KHZ 1000
+
+#define AS73211_DRV_NAME "as73211"
+
+/* AS73211 configuration registers */
+#define AS73211_REG_OSR    0x0
+#define AS73211_REG_AGEN   0x2
+#define AS73211_REG_CREG1  0x6
+#define AS73211_REG_CREG2  0x7
+#define AS73211_REG_CREG3  0x8
+
+/* AS73211 output register bank */
+#define AS73211_OUT_OSR_STATUS    0
+#define AS73211_OUT_TEMP          1
+#define AS73211_OUT_MRES1         2
+#define AS73211_OUT_MRES2         3
+#define AS73211_OUT_MRES3         4
+
+#define AS73211_OSR_SS            BIT(7)
+#define AS73211_OSR_PD            BIT(6)
+#define AS73211_OSR_SW_RES        BIT(3)
+#define AS73211_OSR_DOS_MASK      GENMASK(2, 0)
+#define AS73211_OSR_DOS_CONFIG    FIELD_PREP(AS73211_OSR_DOS_MASK, 0x2)
+#define AS73211_OSR_DOS_MEASURE   FIELD_PREP(AS73211_OSR_DOS_MASK, 0x3)
+
+#define AS73211_AGEN_DEVID_MASK   GENMASK(7, 4)
+#define AS73211_AGEN_DEVID(x)     FIELD_PREP(AS73211_AGEN_DEVID_MASK, (x))
+#define AS73211_AGEN_MUT_MASK     GENMASK(3, 0)
+#define AS73211_AGEN_MUT(x)       FIELD_PREP(AS73211_AGEN_MUT_MASK, (x))
+
+#define AS73211_CREG1_GAIN_MASK   GENMASK(7, 4)
+#define AS73211_CREG1_GAIN_1      11
+#define AS73211_CREG1_TIME_MASK   GENMASK(3, 0)
+
+#define AS73211_CREG3_CCLK_MASK   GENMASK(1, 0)
+
+#define AS73211_OSR_STATUS_OUTCONVOF  BIT(15)
+#define AS73211_OSR_STATUS_MRESOF     BIT(14)
+#define AS73211_OSR_STATUS_ADCOF      BIT(13)
+#define AS73211_OSR_STATUS_LDATA      BIT(12)
+#define AS73211_OSR_STATUS_NDATA      BIT(11)
+#define AS73211_OSR_STATUS_NOTREADY   BIT(10)
+
+#define AS73211_SAMPLE_FREQ_BASE      1024000
+
+#define AS73211_SAMPLE_TIME_NUM       15
+#define AS73211_SAMPLE_TIME_MAX_MS    BIT(AS73211_SAMPLE_TIME_NUM - 1)
+
+/* Available sample frequencies are 1.024MHz multiplied by powers of two. */
+static const int as73211_samp_freq_avail[] = {
+	AS73211_SAMPLE_FREQ_BASE * 1,
+	AS73211_SAMPLE_FREQ_BASE * 2,
+	AS73211_SAMPLE_FREQ_BASE * 4,
+	AS73211_SAMPLE_FREQ_BASE * 8,
+};
+
+static const int as73211_hardwaregain_avail[] = {
+	1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048,
+};
+
+/**
+ * struct as73211_data - Instance data for one AS73211
+ * @client: I2C client.
+ * @osr:    Cached Operational State Register.
+ * @creg1:  Cached Configuration Register 1.
+ * @creg2:  Cached Configuration Register 2.
+ * @creg3:  Cached Configuration Register 3.
+ * @mutex:  Keeps cached registers in sync with the device.
+ * @completion: Completion to wait for interrupt.
+ * @int_time_avail: Available integration times (depend on sampling frequency).
+ */
+struct as73211_data {
+	struct i2c_client *client;
+	u8 osr;
+	u8 creg1;
+	u8 creg2;
+	u8 creg3;
+	struct mutex mutex;
+	struct completion completion;
+	int int_time_avail[AS73211_SAMPLE_TIME_NUM * 2];
+};
+
+#define AS73211_COLOR_CHANNEL(_color, _si, _addr) { \
+	.type = IIO_INTENSITY, \
+	.modified = 1, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), \
+	.info_mask_shared_by_type = \
+		BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
+		BIT(IIO_CHAN_INFO_HARDWAREGAIN) | \
+		BIT(IIO_CHAN_INFO_INT_TIME), \
+	.info_mask_shared_by_type_available = \
+		BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
+		BIT(IIO_CHAN_INFO_HARDWAREGAIN) | \
+		BIT(IIO_CHAN_INFO_INT_TIME), \
+	.channel2 = IIO_MOD_##_color, \
+	.address = _addr, \
+	.scan_index = _si, \
+	.scan_type = { \
+		.sign = 'u', \
+		.realbits = 16, \
+		.storagebits = 16, \
+		.endianness = IIO_LE, \
+	}, \
+}
+
+#define AS73211_OFFSET_TEMP_INT    (-66)
+#define AS73211_OFFSET_TEMP_MICRO  900000
+#define AS73211_SCALE_TEMP_INT     0
+#define AS73211_SCALE_TEMP_MICRO   50000
+
+#define AS73211_SCALE_X 277071108  /* nW/m^2 */
+#define AS73211_SCALE_Y 298384270  /* nW/m^2 */
+#define AS73211_SCALE_Z 160241927  /* nW/m^2 */
+
+/* Channel order MUST match devices result register order */
+#define AS73211_SCAN_INDEX_TEMP 0
+#define AS73211_SCAN_INDEX_X    1
+#define AS73211_SCAN_INDEX_Y    2
+#define AS73211_SCAN_INDEX_Z    3
+#define AS73211_SCAN_INDEX_TS   4
+
+#define AS73211_SCAN_MASK_COLOR ( \
+	BIT(AS73211_SCAN_INDEX_X) |   \
+	BIT(AS73211_SCAN_INDEX_Y) |   \
+	BIT(AS73211_SCAN_INDEX_Z))
+
+#define AS73211_SCAN_MASK_ALL (    \
+	BIT(AS73211_SCAN_INDEX_TEMP) | \
+	AS73211_SCAN_MASK_COLOR)
+
+static const struct iio_chan_spec as73211_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_OFFSET) |
+			BIT(IIO_CHAN_INFO_SCALE),
+		.address = AS73211_OUT_TEMP,
+		.scan_index = AS73211_SCAN_INDEX_TEMP,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_LE,
+		}
+	},
+	AS73211_COLOR_CHANNEL(X, AS73211_SCAN_INDEX_X, AS73211_OUT_MRES1),
+	AS73211_COLOR_CHANNEL(Y, AS73211_SCAN_INDEX_Y, AS73211_OUT_MRES2),
+	AS73211_COLOR_CHANNEL(Z, AS73211_SCAN_INDEX_Z, AS73211_OUT_MRES3),
+	IIO_CHAN_SOFT_TIMESTAMP(AS73211_SCAN_INDEX_TS),
+};
+
+static unsigned int as73211_integration_time_1024cyc(struct as73211_data *data)
+{
+	/*
+	 * Return integration time in units of 1024 clock cycles. Integration time
+	 * in CREG1 is in powers of 2 (x 1024 cycles).
+	 */
+	return BIT(FIELD_GET(AS73211_CREG1_TIME_MASK, data->creg1));
+}
+
+static unsigned int as73211_integration_time_us(struct as73211_data *data,
+						 unsigned int integration_time_1024cyc)
+{
+	/*
+	 * f_samp is configured in CREG3 in powers of 2 (x 1.024 MHz)
+	 * t_cycl is configured in CREG1 in powers of 2 (x 1024 cycles)
+	 * t_int_us = 1 / (f_samp) * t_cycl * US_PER_SEC
+	 *          = 1 / (2^CREG3_CCLK * 1,024,000) * 2^CREG1_CYCLES * 1,024 * US_PER_SEC
+	 *          = 2^(-CREG3_CCLK) * 2^CREG1_CYCLES * 1,000
+	 * In order to get rid of negative exponents, we extend the "fraction"
+	 * by 2^3 (CREG3_CCLK,max = 3)
+	 * t_int_us = 2^(3-CREG3_CCLK) * 2^CREG1_CYCLES * 125
+	 */
+	return BIT(3 - FIELD_GET(AS73211_CREG3_CCLK_MASK, data->creg3)) *
+		integration_time_1024cyc * 125;
+}
+
+static void as73211_integration_time_calc_avail(struct as73211_data *data)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(data->int_time_avail) / 2; i++) {
+		unsigned int time_us = as73211_integration_time_us(data, BIT(i));
+
+		data->int_time_avail[i * 2 + 0] = time_us / USEC_PER_SEC;
+		data->int_time_avail[i * 2 + 1] = time_us % USEC_PER_SEC;
+	}
+}
+
+static unsigned int as73211_gain(struct as73211_data *data)
+{
+	/* gain can be calculated from CREG1 as 2^(11 - CREG1_GAIN) */
+	return BIT(AS73211_CREG1_GAIN_1 - FIELD_GET(AS73211_CREG1_GAIN_MASK, data->creg1));
+}
+
+/* must be called with as73211_data::mutex held. */
+static int as73211_req_data(struct as73211_data *data)
+{
+	unsigned int time_us = as73211_integration_time_us(data,
+							    as73211_integration_time_1024cyc(data));
+	struct device *dev = &data->client->dev;
+	union i2c_smbus_data smbus_data;
+	u16 osr_status;
+	int ret;
+
+	if (data->client->irq)
+		reinit_completion(&data->completion);
+
+	/*
+	 * During measurement, there should be no traffic on the i2c bus as the
+	 * electrical noise would disturb the measurement process.
+	 */
+	i2c_lock_bus(data->client->adapter, I2C_LOCK_SEGMENT);
+
+	data->osr &= ~AS73211_OSR_DOS_MASK;
+	data->osr |= AS73211_OSR_DOS_MEASURE | AS73211_OSR_SS;
+
+	smbus_data.byte = data->osr;
+	ret = __i2c_smbus_xfer(data->client->adapter, data->client->addr,
+			data->client->flags, I2C_SMBUS_WRITE,
+			AS73211_REG_OSR, I2C_SMBUS_BYTE_DATA, &smbus_data);
+	if (ret < 0) {
+		i2c_unlock_bus(data->client->adapter, I2C_LOCK_SEGMENT);
+		return ret;
+	}
+
+	/*
+	 * Reset AS73211_OSR_SS (is self clearing) in order to avoid unintentional
+	 * triggering of further measurements later.
+	 */
+	data->osr &= ~AS73211_OSR_SS;
+
+	/*
+	 * Add some extra margin for the timeout. sensor timing is not as precise
+	 * as our one ...
+	 */
+	time_us += time_us / 8;
+	if (data->client->irq) {
+		ret = wait_for_completion_timeout(&data->completion, usecs_to_jiffies(time_us));
+		if (!ret) {
+			dev_err(dev, "timeout waiting for READY IRQ\n");
+			i2c_unlock_bus(data->client->adapter, I2C_LOCK_SEGMENT);
+			return -ETIMEDOUT;
+		}
+	} else {
+		/* Wait integration time */
+		usleep_range(time_us, 2 * time_us);
+	}
+
+	i2c_unlock_bus(data->client->adapter, I2C_LOCK_SEGMENT);
+
+	ret = i2c_smbus_read_word_data(data->client, AS73211_OUT_OSR_STATUS);
+	if (ret < 0)
+		return ret;
+
+	osr_status = ret;
+	if (osr_status != (AS73211_OSR_DOS_MEASURE | AS73211_OSR_STATUS_NDATA)) {
+		if (osr_status & AS73211_OSR_SS) {
+			dev_err(dev, "%s() Measurement has not stopped\n", __func__);
+			return -ETIME;
+		}
+		if (osr_status & AS73211_OSR_STATUS_NOTREADY) {
+			dev_err(dev, "%s() Data is not ready\n", __func__);
+			return -ENODATA;
+		}
+		if (!(osr_status & AS73211_OSR_STATUS_NDATA)) {
+			dev_err(dev, "%s() No new data available\n", __func__);
+			return -ENODATA;
+		}
+		if (osr_status & AS73211_OSR_STATUS_LDATA) {
+			dev_err(dev, "%s() Result buffer overrun\n", __func__);
+			return -ENOBUFS;
+		}
+		if (osr_status & AS73211_OSR_STATUS_ADCOF) {
+			dev_err(dev, "%s() ADC overflow\n", __func__);
+			return -EOVERFLOW;
+		}
+		if (osr_status & AS73211_OSR_STATUS_MRESOF) {
+			dev_err(dev, "%s() Measurement result overflow\n", __func__);
+			return -EOVERFLOW;
+		}
+		if (osr_status & AS73211_OSR_STATUS_OUTCONVOF) {
+			dev_err(dev, "%s() Timer overflow\n", __func__);
+			return -EOVERFLOW;
+		}
+		dev_err(dev, "%s() Unexpected status value\n", __func__);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int as73211_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct as73211_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		int ret;
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret < 0)
+			return ret;
+
+		ret = as73211_req_data(data);
+		if (ret < 0) {
+			iio_device_release_direct_mode(indio_dev);
+			return ret;
+		}
+
+		ret = i2c_smbus_read_word_data(data->client, chan->address);
+		iio_device_release_direct_mode(indio_dev);
+		if (ret < 0)
+			return ret;
+
+		*val = ret;
+		return IIO_VAL_INT;
+	}
+	case IIO_CHAN_INFO_OFFSET:
+		*val = AS73211_OFFSET_TEMP_INT;
+		*val2 = AS73211_OFFSET_TEMP_MICRO;
+		return IIO_VAL_INT_PLUS_MICRO;
+
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_TEMP:
+			*val = AS73211_SCALE_TEMP_INT;
+			*val2 = AS73211_SCALE_TEMP_MICRO;
+			return IIO_VAL_INT_PLUS_MICRO;
+
+		case IIO_INTENSITY: {
+			unsigned int scale;
+
+			switch (chan->channel2) {
+			case IIO_MOD_X:
+				scale = AS73211_SCALE_X;
+				break;
+			case IIO_MOD_Y:
+				scale = AS73211_SCALE_Y;
+				break;
+			case IIO_MOD_Z:
+				scale = AS73211_SCALE_Z;
+				break;
+			default:
+				return -EINVAL;
+			}
+			scale /= as73211_gain(data);
+			scale /= as73211_integration_time_1024cyc(data);
+			*val = scale;
+			return IIO_VAL_INT;
+
+		default:
+			return -EINVAL;
+		}}
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		/* f_samp is configured in CREG3 in powers of 2 (x 1.024 MHz) */
+		*val = BIT(FIELD_GET(AS73211_CREG3_CCLK_MASK, data->creg3)) *
+			AS73211_SAMPLE_FREQ_BASE;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		*val = as73211_gain(data);
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_INT_TIME: {
+		unsigned int time_us;
+
+		mutex_lock(&data->mutex);
+		time_us = as73211_integration_time_us(data, as73211_integration_time_1024cyc(data));
+		mutex_unlock(&data->mutex);
+		*val = time_us / USEC_PER_SEC;
+		*val2 = time_us % USEC_PER_SEC;
+		return IIO_VAL_INT_PLUS_MICRO;
+
+	default:
+		return -EINVAL;
+	}}
+}
+
+static int as73211_read_avail(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+			       const int **vals, int *type, int *length, long mask)
+{
+	struct as73211_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*length = ARRAY_SIZE(as73211_samp_freq_avail);
+		*vals = as73211_samp_freq_avail;
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_LIST;
+
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		*length = ARRAY_SIZE(as73211_hardwaregain_avail);
+		*vals = as73211_hardwaregain_avail;
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_LIST;
+
+	case IIO_CHAN_INFO_INT_TIME:
+		*length = ARRAY_SIZE(data->int_time_avail);
+		*vals = data->int_time_avail;
+		*type = IIO_VAL_INT_PLUS_MICRO;
+		return IIO_AVAIL_LIST;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int _as73211_write_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan __always_unused,
+			       int val, int val2, long mask)
+{
+	struct as73211_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ: {
+		int reg_bits, freq_kHz = val / HZ_PER_KHZ;  /* 1024, 2048, ... */
+
+		/* val must be 1024 * 2^x */
+		if (val < 0 || (freq_kHz * HZ_PER_KHZ) != val ||
+				!is_power_of_2(freq_kHz) || val2)
+			return -EINVAL;
+
+		/* f_samp is configured in CREG3 in powers of 2 (x 1.024 MHz (=2^10)) */
+		reg_bits = ilog2(freq_kHz) - 10;
+		if (!FIELD_FIT(AS73211_CREG3_CCLK_MASK, reg_bits))
+			return -EINVAL;
+
+		data->creg3 &= ~AS73211_CREG3_CCLK_MASK;
+		data->creg3 |= FIELD_PREP(AS73211_CREG3_CCLK_MASK, reg_bits);
+		as73211_integration_time_calc_avail(data);
+
+		ret = i2c_smbus_write_byte_data(data->client, AS73211_REG_CREG3, data->creg3);
+		if (ret < 0)
+			return ret;
+
+		return 0;
+	}
+	case IIO_CHAN_INFO_HARDWAREGAIN: {
+		unsigned int reg_bits;
+
+		if (val < 0 || !is_power_of_2(val) || val2)
+			return -EINVAL;
+
+		/* gain can be calculated from CREG1 as 2^(11 - CREG1_GAIN) */
+		reg_bits = AS73211_CREG1_GAIN_1 - ilog2(val);
+		if (!FIELD_FIT(AS73211_CREG1_GAIN_MASK, reg_bits))
+			return -EINVAL;
+
+		data->creg1 &= ~AS73211_CREG1_GAIN_MASK;
+		data->creg1 |= FIELD_PREP(AS73211_CREG1_GAIN_MASK, reg_bits);
+
+		ret = i2c_smbus_write_byte_data(data->client, AS73211_REG_CREG1, data->creg1);
+		if (ret < 0)
+			return ret;
+
+		return 0;
+	}
+	case IIO_CHAN_INFO_INT_TIME: {
+		int val_us = val * USEC_PER_SEC + val2;
+		int time_ms;
+		int reg_bits;
+
+		/* f_samp is configured in CREG3 in powers of 2 (x 1.024 MHz) */
+		int f_samp_1_024mhz = BIT(FIELD_GET(AS73211_CREG3_CCLK_MASK, data->creg3));
+
+		/*
+		 * time_ms = time_us * US_PER_MS * f_samp_1_024mhz / MHZ_PER_HZ
+		 *         = time_us * f_samp_1_024mhz / 1000
+		 */
+		time_ms = (val_us * f_samp_1_024mhz) / 1000;  /* 1 ms, 2 ms, ... (power of two) */
+		if (time_ms < 0 || !is_power_of_2(time_ms) || time_ms > AS73211_SAMPLE_TIME_MAX_MS)
+			return -EINVAL;
+
+		reg_bits = ilog2(time_ms);
+		if (!FIELD_FIT(AS73211_CREG1_TIME_MASK, reg_bits))
+			return -EINVAL;  /* not possible due to previous tests */
+
+		data->creg1 &= ~AS73211_CREG1_TIME_MASK;
+		data->creg1 |= FIELD_PREP(AS73211_CREG1_TIME_MASK, reg_bits);
+
+		ret = i2c_smbus_write_byte_data(data->client, AS73211_REG_CREG1, data->creg1);
+		if (ret < 0)
+			return ret;
+
+		return 0;
+
+	default:
+		return -EINVAL;
+	}}
+}
+
+static int as73211_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+			      int val, int val2, long mask)
+{
+	struct as73211_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->mutex);
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret < 0)
+		goto error_unlock;
+
+	/* Need to switch to config mode ... */
+	if ((data->osr & AS73211_OSR_DOS_MASK) != AS73211_OSR_DOS_CONFIG) {
+		data->osr &= ~AS73211_OSR_DOS_MASK;
+		data->osr |= AS73211_OSR_DOS_CONFIG;
+
+		ret = i2c_smbus_write_byte_data(data->client, AS73211_REG_OSR, data->osr);
+		if (ret < 0)
+			goto error_release;
+	}
+
+	ret = _as73211_write_raw(indio_dev, chan, val, val2, mask);
+
+error_release:
+	iio_device_release_direct_mode(indio_dev);
+error_unlock:
+	mutex_unlock(&data->mutex);
+	return ret;
+}
+
+static irqreturn_t as73211_ready_handler(int irq __always_unused, void *priv)
+{
+	struct as73211_data *data = iio_priv(priv);
+
+	complete(&data->completion);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t as73211_trigger_handler(int irq __always_unused, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct as73211_data *data = iio_priv(indio_dev);
+	struct {
+		__le16 chan[4];
+		s64 ts __aligned(8);
+	} scan;
+	int data_result, ret;
+
+	mutex_lock(&data->mutex);
+
+	data_result = as73211_req_data(data);
+	if (data_result < 0 && data_result != -EOVERFLOW)
+		goto done;  /* don't push any data for errors other than EOVERFLOW */
+
+	if (*indio_dev->active_scan_mask == AS73211_SCAN_MASK_ALL) {
+		/* Optimization for reading all (color + temperature) channels */
+		u8 addr = as73211_channels[0].address;
+		struct i2c_msg msgs[] = {
+			{
+				.addr = data->client->addr,
+				.flags = 0,
+				.len = 1,
+				.buf = &addr,
+			},
+			{
+				.addr = data->client->addr,
+				.flags = I2C_M_RD,
+				.len = sizeof(scan.chan),
+				.buf = (u8 *)&scan.chan,
+			},
+		};
+
+		ret = i2c_transfer(data->client->adapter, msgs, ARRAY_SIZE(msgs));
+		if (ret < 0)
+			goto done;
+	} else {
+		/* Optimization for reading only color channels */
+
+		/* AS73211 starts reading at address 2 */
+		ret = i2c_master_recv(data->client,
+				(char *)&scan.chan[1], 3 * sizeof(scan.chan[1]));
+		if (ret < 0)
+			goto done;
+	}
+
+	if (data_result) {
+		/*
+		 * Saturate all channels (in case of overflows). Temperature channel
+		 * is not affected by overflows.
+		 */
+		scan.chan[1] = cpu_to_le16(U16_MAX);
+		scan.chan[2] = cpu_to_le16(U16_MAX);
+		scan.chan[3] = cpu_to_le16(U16_MAX);
+	}
+
+	iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev));
+
+done:
+	mutex_unlock(&data->mutex);
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static const struct iio_info as73211_info = {
+	.read_raw = as73211_read_raw,
+	.read_avail = as73211_read_avail,
+	.write_raw = as73211_write_raw,
+};
+
+static int as73211_power(struct iio_dev *indio_dev, bool state)
+{
+	struct as73211_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->mutex);
+
+	if (state)
+		data->osr &= ~AS73211_OSR_PD;
+	else
+		data->osr |= AS73211_OSR_PD;
+
+	ret = i2c_smbus_write_byte_data(data->client, AS73211_REG_OSR, data->osr);
+
+	mutex_unlock(&data->mutex);
+
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static void as73211_power_disable(void *data)
+{
+	struct iio_dev *indio_dev = data;
+
+	as73211_power(indio_dev, false);
+}
+
+static int as73211_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct as73211_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+
+	mutex_init(&data->mutex);
+	init_completion(&data->completion);
+
+	indio_dev->info = &as73211_info;
+	indio_dev->name = AS73211_DRV_NAME;
+	indio_dev->channels = as73211_channels;
+	indio_dev->num_channels = ARRAY_SIZE(as73211_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = i2c_smbus_read_byte_data(data->client, AS73211_REG_OSR);
+	if (ret < 0)
+		return ret;
+	data->osr = ret;
+
+	/* reset device */
+	data->osr |= AS73211_OSR_SW_RES;
+	ret = i2c_smbus_write_byte_data(data->client, AS73211_REG_OSR, data->osr);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, AS73211_REG_OSR);
+	if (ret < 0)
+		return ret;
+	data->osr = ret;
+
+	/*
+	 * Reading AGEN is only possible after reset (AGEN is not available if
+	 * device is in measurement mode).
+	 */
+	ret = i2c_smbus_read_byte_data(data->client, AS73211_REG_AGEN);
+	if (ret < 0)
+		return ret;
+
+	/* At the time of writing this driver, only DEVID 2 and MUT 1 are known. */
+	if ((ret & AS73211_AGEN_DEVID_MASK) != AS73211_AGEN_DEVID(2) ||
+	    (ret & AS73211_AGEN_MUT_MASK) != AS73211_AGEN_MUT(1))
+		return -ENODEV;
+
+	ret = i2c_smbus_read_byte_data(data->client, AS73211_REG_CREG1);
+	if (ret < 0)
+		return ret;
+	data->creg1 = ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, AS73211_REG_CREG2);
+	if (ret < 0)
+		return ret;
+	data->creg2 = ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, AS73211_REG_CREG3);
+	if (ret < 0)
+		return ret;
+	data->creg3 = ret;
+	as73211_integration_time_calc_avail(data);
+
+	ret = as73211_power(indio_dev, true);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, as73211_power_disable, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL, as73211_trigger_handler, NULL);
+	if (ret)
+		return ret;
+
+	if (client->irq) {
+		ret = devm_request_threaded_irq(&client->dev, client->irq,
+				NULL,
+				as73211_ready_handler,
+				IRQF_ONESHOT,
+				client->name, indio_dev);
+		if (ret)
+			return ret;
+	}
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static int __maybe_unused as73211_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+
+	return as73211_power(indio_dev, false);
+}
+
+static int __maybe_unused as73211_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+
+	return as73211_power(indio_dev, true);
+}
+
+static SIMPLE_DEV_PM_OPS(as73211_pm_ops, as73211_suspend, as73211_resume);
+
+static const struct of_device_id as73211_of_match[] = {
+	{ .compatible = "ams,as73211" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, as73211_of_match);
+
+static const struct i2c_device_id as73211_id[] = {
+	{ "as73211", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, as73211_id);
+
+static struct i2c_driver as73211_driver = {
+	.driver = {
+		.name           = AS73211_DRV_NAME,
+		.of_match_table = as73211_of_match,
+		.pm             = &as73211_pm_ops,
+	},
+	.probe_new  = as73211_probe,
+	.id_table   = as73211_id,
+};
+module_i2c_driver(as73211_driver);
+
+MODULE_AUTHOR("Christian Eggers <ceggers@arri.de>");
+MODULE_DESCRIPTION("AS73211 XYZ True Color Sensor driver");
+MODULE_LICENSE("GPL");