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Date:   Tue, 1 Sep 2020 19:46:00 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Christian Eggers <ceggers@arri.de>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Hartmut Knaack <knaack.h@gmx.de>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
        <linux-iio@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 2/2] iio: light: as73211: New driver
Message-ID: <20200901194600.4e9e7db6@archlinux>
In-Reply-To: <20200806184451.04293626@archlinux>
References: <20200805055744.31909-1-ceggers@arri.de>
        <20200805055744.31909-3-ceggers@arri.de>
        <20200806184451.04293626@archlinux>
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On Thu, 6 Aug 2020 18:44:51 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> On Wed, 5 Aug 2020 07:57:44 +0200
> Christian Eggers <ceggers@arri.de> wrote:
> 
> > 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>  
> 
> Hi Christian,
> 
> I'll take this, but please send a follow up patch to add documentation
> for in_intensity_x_raw and all the other new ABI this adds in
> Documentation/ABI/testing/sysfs-bus-iio
> I should have mentioned that earlier, but kind of assumed we already
> had these documented for some reason!
> 
> Applied to the togreg branch of iio.git and pushed out as testing for
> the autobuilders to play with it.
> 
> Thanks,
> 
> Jonathan
Unfortunatey I don't have the thread on this account / machine so I'll
reply here.

0-day highlighted an issue in here and Andy sent a suggested fix.

What Andy suggested almost works but there are some subtleties. So before
I make the change directly on the patch I wanted to confirm I haven't
gotten it horribly wrong!

I'm proposing just halving the range of the loop. See below.

Thanks,

Jonathan


> 
> 
> > ---
> >  MAINTAINERS                 |   7 +
> >  drivers/iio/light/Kconfig   |  15 +
> >  drivers/iio/light/Makefile  |   1 +
> >  drivers/iio/light/as73211.c | 801 ++++++++++++++++++++++++++++++++++++
> >  4 files changed, 824 insertions(+)
> >  create mode 100644 drivers/iio/light/as73211.c
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 068d6e94122b..673570414147 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -934,6 +934,13 @@ 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..3383aaacbf52
> > --- /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      13
> > +#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];

This is a flat array, as get_avail assumes.

> > +};
> > +
> > +#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); i++) {
This loops goes to double the size of the array.

I'd propose to just do ARRAY_SIZE(data->int_time_avail) / 2 here

> > +		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^(13 - 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);

This length is correct as read_avail expects it to be double
the number of entries, if using IIO_VAL_INT_PLUS_MICRO.

> > +		*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^(13 - 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");  
>