Re: [PATCH v7 1/1] iio/scmi: Adding support for IIO SCMI Based Sensors

[Jonathan Cameron]

On Tue,  9 Mar 2021 23:12:59 +0000
Jyoti Bhayana <jbhayana@xxxxxxxxxx> wrote:

> This change provides ARM SCMI Protocol based IIO device.
> This driver provides support for Accelerometer and Gyroscope using
> SCMI Sensor Protocol extensions added in the SCMIv3.0 ARM specification
> 
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Signed-off-by: Jyoti Bhayana <jbhayana@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20210212172235.507028-2-jbhayana@xxxxxxxxxx
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>

https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/log/?h=ib-iio-scmi-5.12-rc2

New immutable branch.  I move to rc2 as the base as the rc1 tag
has been removed for well publicized reasons.

Should have the 0-day results in tomorrow morning. I'll shout
if anything else shows up.

Also rebased the togreg branch for the same reason (hadn't pushed it
out as anything other than testing, so hopefully no one was basing
anything significant on top)

Thanks,

Jonathan

> ---
>  MAINTAINERS                                |   6 +
>  drivers/firmware/arm_scmi/driver.c         |   2 +-
>  drivers/iio/common/Kconfig                 |   1 +
>  drivers/iio/common/Makefile                |   1 +
>  drivers/iio/common/scmi_sensors/Kconfig    |  18 +
>  drivers/iio/common/scmi_sensors/Makefile   |   5 +
>  drivers/iio/common/scmi_sensors/scmi_iio.c | 683 +++++++++++++++++++++
>  7 files changed, 715 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/iio/common/scmi_sensors/Kconfig
>  create mode 100644 drivers/iio/common/scmi_sensors/Makefile
>  create mode 100644 drivers/iio/common/scmi_sensors/scmi_iio.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index d92f85ca831d..14227980f3d2 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8692,6 +8692,12 @@ S:	Maintained
>  F:	Documentation/devicetree/bindings/iio/multiplexer/io-channel-mux.txt
>  F:	drivers/iio/multiplexer/iio-mux.c
>  
> +IIO SCMI BASED DRIVER
> +M:	Jyoti Bhayana <jbhayana@xxxxxxxxxx>
> +L:	linux-iio@xxxxxxxxxxxxxxx
> +S:	Maintained
> +F:	drivers/iio/common/scmi_sensors/scmi_iio.c
> +
>  IIO SUBSYSTEM AND DRIVERS
>  M:	Jonathan Cameron <jic23@xxxxxxxxxx>
>  R:	Lars-Peter Clausen <lars@xxxxxxxxxx>
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index cacdf1589b10..3e748e57deab 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -741,7 +741,7 @@ static struct scmi_prot_devnames devnames[] = {
>  	{ SCMI_PROTOCOL_SYSTEM, { "syspower" },},
>  	{ SCMI_PROTOCOL_PERF,   { "cpufreq" },},
>  	{ SCMI_PROTOCOL_CLOCK,  { "clocks" },},
> -	{ SCMI_PROTOCOL_SENSOR, { "hwmon" },},
> +	{ SCMI_PROTOCOL_SENSOR, { "hwmon", "iiodev" },},
>  	{ SCMI_PROTOCOL_RESET,  { "reset" },},
>  	{ SCMI_PROTOCOL_VOLTAGE,  { "regulator" },},
>  };
> diff --git a/drivers/iio/common/Kconfig b/drivers/iio/common/Kconfig
> index 2b9ee9161abd..0334b4954773 100644
> --- a/drivers/iio/common/Kconfig
> +++ b/drivers/iio/common/Kconfig
> @@ -6,5 +6,6 @@
>  source "drivers/iio/common/cros_ec_sensors/Kconfig"
>  source "drivers/iio/common/hid-sensors/Kconfig"
>  source "drivers/iio/common/ms_sensors/Kconfig"
> +source "drivers/iio/common/scmi_sensors/Kconfig"
>  source "drivers/iio/common/ssp_sensors/Kconfig"
>  source "drivers/iio/common/st_sensors/Kconfig"
> diff --git a/drivers/iio/common/Makefile b/drivers/iio/common/Makefile
> index 4bc30bb548e2..fad40e1e1718 100644
> --- a/drivers/iio/common/Makefile
> +++ b/drivers/iio/common/Makefile
> @@ -11,5 +11,6 @@
>  obj-y += cros_ec_sensors/
>  obj-y += hid-sensors/
>  obj-y += ms_sensors/
> +obj-y += scmi_sensors/
>  obj-y += ssp_sensors/
>  obj-y += st_sensors/
> diff --git a/drivers/iio/common/scmi_sensors/Kconfig b/drivers/iio/common/scmi_sensors/Kconfig
> new file mode 100644
> index 000000000000..67e084cbb1ab
> --- /dev/null
> +++ b/drivers/iio/common/scmi_sensors/Kconfig
> @@ -0,0 +1,18 @@
> +#
> +# IIO over SCMI
> +#
> +# When adding new entries keep the list in alphabetical order
> +
> +menu "IIO SCMI Sensors"
> +
> +config IIO_SCMI
> +	tristate "IIO SCMI"
> +        depends on ARM_SCMI_PROTOCOL
> +        select IIO_BUFFER
> +        select IIO_KFIFO_BUF
> +	help
> +          Say yes here to build support for IIO SCMI Driver.
> +          This provides ARM SCMI Protocol based IIO device.
> +          This driver provides support for accelerometer and gyroscope
> +          sensors available on SCMI based platforms.
> +endmenu
> diff --git a/drivers/iio/common/scmi_sensors/Makefile b/drivers/iio/common/scmi_sensors/Makefile
> new file mode 100644
> index 000000000000..f13140a2575a
> --- /dev/null
> +++ b/drivers/iio/common/scmi_sensors/Makefile
> @@ -0,0 +1,5 @@
> +# SPDX - License - Identifier : GPL - 2.0 - only
> +#
> +# Makefile for the IIO over SCMI
> +#
> +obj-$(CONFIG_IIO_SCMI) += scmi_iio.o
> diff --git a/drivers/iio/common/scmi_sensors/scmi_iio.c b/drivers/iio/common/scmi_sensors/scmi_iio.c
> new file mode 100644
> index 000000000000..872d87ca6256
> --- /dev/null
> +++ b/drivers/iio/common/scmi_sensors/scmi_iio.c
> @@ -0,0 +1,683 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * System Control and Management Interface(SCMI) based IIO sensor driver
> + *
> + * Copyright (C) 2021 Google LLC
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/kfifo_buf.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/kernel.h>
> +#include <linux/kthread.h>
> +#include <linux/module.h>
> +#include <linux/scmi_protocol.h>
> +#include <linux/time.h>
> +#include <linux/types.h>
> +
> +#define SCMI_IIO_NUM_OF_AXIS 3
> +
> +struct scmi_iio_priv {
> +	struct scmi_handle *handle;
> +	const struct scmi_sensor_info *sensor_info;
> +	struct iio_dev *indio_dev;
> +	/* adding one additional channel for timestamp */
> +	s64 iio_buf[SCMI_IIO_NUM_OF_AXIS + 1];
> +	struct notifier_block sensor_update_nb;
> +	u32 *freq_avail;
> +};
> +
> +static int scmi_iio_sensor_update_cb(struct notifier_block *nb,
> +				     unsigned long event, void *data)
> +{
> +	struct scmi_sensor_update_report *sensor_update = data;
> +	struct iio_dev *scmi_iio_dev;
> +	struct scmi_iio_priv *sensor;
> +	s8 tstamp_scale;
> +	u64 time, time_ns;
> +	int i;
> +
> +	if (sensor_update->readings_count == 0)
> +		return NOTIFY_DONE;
> +
> +	sensor = container_of(nb, struct scmi_iio_priv, sensor_update_nb);
> +
> +	for (i = 0; i < sensor_update->readings_count; i++)
> +		sensor->iio_buf[i] = sensor_update->readings[i].value;
> +
> +	if (!sensor->sensor_info->timestamped) {
> +		time_ns = ktime_to_ns(sensor_update->timestamp);
> +	} else {
> +		/*
> +		 *  All the axes are supposed to have the same value for timestamp.
> +		 *  We are just using the values from the Axis 0 here.
> +		 */
> +		time = sensor_update->readings[0].timestamp;
> +
> +		/*
> +		 *  Timestamp returned by SCMI is in seconds and is equal to
> +		 *  time * power-of-10 multiplier(tstamp_scale) seconds.
> +		 *  Converting the timestamp to nanoseconds below.
> +		 */
> +		tstamp_scale = sensor->sensor_info->tstamp_scale +
> +			       const_ilog2(NSEC_PER_SEC) / const_ilog2(10);
> +		if (tstamp_scale < 0) {
> +			do_div(time, int_pow(10, abs(tstamp_scale)));
> +			time_ns = time;
> +		} else {
> +			time_ns = time * int_pow(10, tstamp_scale);
> +		}
> +	}
> +
> +	scmi_iio_dev = sensor->indio_dev;
> +	iio_push_to_buffers_with_timestamp(scmi_iio_dev, sensor->iio_buf,
> +					   time_ns);
> +	return NOTIFY_OK;
> +}
> +
> +static int scmi_iio_buffer_preenable(struct iio_dev *iio_dev)
> +{
> +	struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> +	u32 sensor_id = sensor->sensor_info->id;
> +	u32 sensor_config = 0;
> +	int err;
> +
> +	if (sensor->sensor_info->timestamped)
> +		sensor_config |= FIELD_PREP(SCMI_SENS_CFG_TSTAMP_ENABLED_MASK,
> +					    SCMI_SENS_CFG_TSTAMP_ENABLE);
> +
> +	sensor_config |= FIELD_PREP(SCMI_SENS_CFG_SENSOR_ENABLED_MASK,
> +				    SCMI_SENS_CFG_SENSOR_ENABLE);
> +
> +	err = sensor->handle->notify_ops->register_event_notifier(sensor->handle,
> +			SCMI_PROTOCOL_SENSOR, SCMI_EVENT_SENSOR_UPDATE,
> +			&sensor_id, &sensor->sensor_update_nb);
> +	if (err) {
> +		dev_err(&iio_dev->dev,
> +			"Error in registering sensor update notifier for sensor %s err %d",
> +			sensor->sensor_info->name, err);
> +		return err;
> +	}
> +
> +	err = sensor->handle->sensor_ops->config_set(sensor->handle,
> +			sensor->sensor_info->id, sensor_config);
> +	if (err) {
> +		sensor->handle->notify_ops->unregister_event_notifier(sensor->handle,
> +				SCMI_PROTOCOL_SENSOR,
> +				SCMI_EVENT_SENSOR_UPDATE, &sensor_id,
> +				&sensor->sensor_update_nb);
> +		dev_err(&iio_dev->dev, "Error in enabling sensor %s err %d",
> +			sensor->sensor_info->name, err);
> +	}
> +
> +	return err;
> +}
> +
> +static int scmi_iio_buffer_postdisable(struct iio_dev *iio_dev)
> +{
> +	struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> +	u32 sensor_id = sensor->sensor_info->id;
> +	u32 sensor_config = 0;
> +	int err;
> +
> +	sensor_config |= FIELD_PREP(SCMI_SENS_CFG_SENSOR_ENABLED_MASK,
> +				    SCMI_SENS_CFG_SENSOR_DISABLE);
> +
> +	err = sensor->handle->notify_ops->unregister_event_notifier(sensor->handle,
> +			SCMI_PROTOCOL_SENSOR, SCMI_EVENT_SENSOR_UPDATE,
> +			&sensor_id, &sensor->sensor_update_nb);
> +	if (err) {
> +		dev_err(&iio_dev->dev,
> +			"Error in unregistering sensor update notifier for sensor %s err %d",
> +			sensor->sensor_info->name, err);
> +		return err;
> +	}
> +
> +	err = sensor->handle->sensor_ops->config_set(sensor->handle, sensor_id,
> +						     sensor_config);
> +	if (err) {
> +		dev_err(&iio_dev->dev,
> +			"Error in disabling sensor %s with err %d",
> +			sensor->sensor_info->name, err);
> +	}
> +
> +	return err;
> +}
> +
> +static const struct iio_buffer_setup_ops scmi_iio_buffer_ops = {
> +	.preenable = scmi_iio_buffer_preenable,
> +	.postdisable = scmi_iio_buffer_postdisable,
> +};
> +
> +static int scmi_iio_set_odr_val(struct iio_dev *iio_dev, int val, int val2)
> +{
> +	struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> +	const unsigned long UHZ_PER_HZ = 1000000UL;
> +	u64 sec, mult, uHz, sf;
> +	u32 sensor_config;
> +	char buf[32];
> +
> +	int err = sensor->handle->sensor_ops->config_get(sensor->handle,
> +			sensor->sensor_info->id, &sensor_config);
> +	if (err) {
> +		dev_err(&iio_dev->dev,
> +			"Error in getting sensor config for sensor %s err %d",
> +			sensor->sensor_info->name, err);
> +		return err;
> +	}
> +
> +	uHz = val * UHZ_PER_HZ + val2;
> +
> +	/*
> +	 * The seconds field in the sensor interval in SCMI is 16 bits long
> +	 * Therefore seconds  = 1/Hz <= 0xFFFF. As floating point calculations are
> +	 * discouraged in the kernel driver code, to calculate the scale factor (sf)
> +	 * (1* 1000000 * sf)/uHz <= 0xFFFF. Therefore, sf <= (uHz * 0xFFFF)/1000000
> +	 * To calculate the multiplier,we convert the sf into char string  and
> +	 * count the number of characters
> +	 */
> +	sf = (u64)uHz * 0xFFFF;
> +	do_div(sf,  UHZ_PER_HZ);
> +	mult = scnprintf(buf, sizeof(buf), "%llu", sf) - 1;
> +
> +	sec = int_pow(10, mult) * UHZ_PER_HZ;
> +	do_div(sec, uHz);
> +	if (sec == 0) {
> +		dev_err(&iio_dev->dev,
> +			"Trying to set invalid sensor update value for sensor %s",
> +			sensor->sensor_info->name);
> +		return -EINVAL;
> +	}
> +
> +	sensor_config &= ~SCMI_SENS_CFG_UPDATE_SECS_MASK;
> +	sensor_config |= FIELD_PREP(SCMI_SENS_CFG_UPDATE_SECS_MASK, sec);
> +	sensor_config &= ~SCMI_SENS_CFG_UPDATE_EXP_MASK;
> +	sensor_config |= FIELD_PREP(SCMI_SENS_CFG_UPDATE_EXP_MASK, -mult);
> +
> +	if (sensor->sensor_info->timestamped) {
> +		sensor_config &= ~SCMI_SENS_CFG_TSTAMP_ENABLED_MASK;
> +		sensor_config |= FIELD_PREP(SCMI_SENS_CFG_TSTAMP_ENABLED_MASK,
> +					    SCMI_SENS_CFG_TSTAMP_ENABLE);
> +	}
> +
> +	sensor_config &= ~SCMI_SENS_CFG_ROUND_MASK;
> +	sensor_config |=
> +		FIELD_PREP(SCMI_SENS_CFG_ROUND_MASK, SCMI_SENS_CFG_ROUND_AUTO);
> +
> +	err = sensor->handle->sensor_ops->config_set(sensor->handle,
> +			sensor->sensor_info->id, sensor_config);
> +	if (err)
> +		dev_err(&iio_dev->dev,
> +			"Error in setting sensor update interval for sensor %s value %u err %d",
> +			sensor->sensor_info->name, sensor_config, err);
> +
> +	return err;
> +}
> +
> +static int scmi_iio_write_raw(struct iio_dev *iio_dev,
> +			      struct iio_chan_spec const *chan, int val,
> +			      int val2, long mask)
> +{
> +	int err;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		mutex_lock(&iio_dev->mlock);
> +		err = scmi_iio_set_odr_val(iio_dev, val, val2);
> +		mutex_unlock(&iio_dev->mlock);
> +		return err;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int scmi_iio_read_avail(struct iio_dev *iio_dev,
> +			       struct iio_chan_spec const *chan,
> +			       const int **vals, int *type, int *length,
> +			       long mask)
> +{
> +	struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*vals = sensor->freq_avail;
> +		*type = IIO_VAL_INT_PLUS_MICRO;
> +		*length = sensor->sensor_info->intervals.count * 2;
> +		if (sensor->sensor_info->intervals.segmented)
> +			return IIO_AVAIL_RANGE;
> +		else
> +			return IIO_AVAIL_LIST;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static void convert_ns_to_freq(u64 interval_ns, u64 *hz, u64 *uhz)
> +{
> +	u64 rem, freq;
> +
> +	freq = NSEC_PER_SEC;
> +	rem = do_div(freq, interval_ns);
> +	*hz = freq;
> +	*uhz = rem * 1000000UL;
> +	do_div(*uhz, interval_ns);
> +}
> +
> +static int scmi_iio_get_odr_val(struct iio_dev *iio_dev, int *val, int *val2)
> +{
> +	u64 sensor_update_interval, sensor_interval_mult, hz, uhz;
> +	struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> +	u32 sensor_config;
> +	int mult;
> +
> +	int err = sensor->handle->sensor_ops->config_get(sensor->handle,
> +			sensor->sensor_info->id, &sensor_config);
> +	if (err) {
> +		dev_err(&iio_dev->dev,
> +			"Error in getting sensor config for sensor %s err %d",
> +			sensor->sensor_info->name, err);
> +		return err;
> +	}
> +
> +	sensor_update_interval =
> +		SCMI_SENS_CFG_GET_UPDATE_SECS(sensor_config) * NSEC_PER_SEC;
> +
> +	mult = SCMI_SENS_CFG_GET_UPDATE_EXP(sensor_config);
> +	if (mult < 0) {
> +		sensor_interval_mult = int_pow(10, abs(mult));
> +		do_div(sensor_update_interval, sensor_interval_mult);
> +	} else {
> +		sensor_interval_mult = int_pow(10, mult);
> +		sensor_update_interval =
> +			sensor_update_interval * sensor_interval_mult;
> +	}
> +
> +	convert_ns_to_freq(sensor_update_interval, &hz, &uhz);
> +	*val = hz;
> +	*val2 = uhz;
> +	return 0;
> +}
> +
> +static int scmi_iio_read_raw(struct iio_dev *iio_dev,
> +			     struct iio_chan_spec const *ch, int *val,
> +			     int *val2, long mask)
> +{
> +	struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> +	s8 scale;
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		scale = sensor->sensor_info->axis[ch->scan_index].scale;
> +		if (scale < 0) {
> +			*val = 1;
> +			*val2 = int_pow(10, abs(scale));
> +			return IIO_VAL_FRACTIONAL;
> +		}
> +		*val = int_pow(10, scale);
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret = scmi_iio_get_odr_val(iio_dev, val, val2);
> +		return ret ? ret : IIO_VAL_INT_PLUS_MICRO;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info scmi_iio_info = {
> +	.read_raw = scmi_iio_read_raw,
> +	.read_avail = scmi_iio_read_avail,
> +	.write_raw = scmi_iio_write_raw,
> +};
> +
> +static ssize_t scmi_iio_get_raw_available(struct iio_dev *iio_dev,
> +					  uintptr_t private,
> +					  const struct iio_chan_spec *chan,
> +					  char *buf)
> +{
> +	struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> +	u64 resolution, rem;
> +	s64 min_range, max_range;
> +	s8 exponent, scale;
> +	int len = 0;
> +
> +	/*
> +	 * All the axes are supposed to have the same value for range and resolution.
> +	 * We are just using the values from the Axis 0 here.
> +	 */
> +	if (sensor->sensor_info->axis[0].extended_attrs) {
> +		min_range = sensor->sensor_info->axis[0].attrs.min_range;
> +		max_range = sensor->sensor_info->axis[0].attrs.max_range;
> +		resolution = sensor->sensor_info->axis[0].resolution;
> +		exponent = sensor->sensor_info->axis[0].exponent;
> +		scale = sensor->sensor_info->axis[0].scale;
> +
> +		/*
> +		 * To provide the raw value for the resolution to the userspace,
> +		 * need to divide the resolution exponent by the sensor scale
> +		 */
> +		exponent = exponent - scale;
> +		if (exponent < 0) {
> +			rem = do_div(resolution,
> +				     int_pow(10, abs(exponent))
> +				     );
> +			len = scnprintf(buf, PAGE_SIZE,
> +					"[%lld %llu.%llu %lld]\n", min_range,
> +					resolution, rem, max_range);
> +		} else {
> +			resolution = resolution * int_pow(10, exponent);
> +			len = scnprintf(buf, PAGE_SIZE, "[%lld %llu %lld]\n",
> +					min_range, resolution, max_range);
> +		}
> +	}
> +	return len;
> +}
> +
> +static const struct iio_chan_spec_ext_info scmi_iio_ext_info[] = {
> +	{
> +		.name = "raw_available",
> +		.read = scmi_iio_get_raw_available,
> +		.shared = IIO_SHARED_BY_TYPE,
> +	},
> +	{},
> +};
> +
> +static void scmi_iio_set_timestamp_channel(struct iio_chan_spec *iio_chan,
> +					   int scan_index)
> +{
> +	iio_chan->type = IIO_TIMESTAMP;
> +	iio_chan->channel = -1;
> +	iio_chan->scan_index = scan_index;
> +	iio_chan->scan_type.sign = 'u';
> +	iio_chan->scan_type.realbits = 64;
> +	iio_chan->scan_type.storagebits = 64;
> +}
> +
> +static void scmi_iio_set_data_channel(struct iio_chan_spec *iio_chan,
> +				      enum iio_chan_type type,
> +				      enum iio_modifier mod, int scan_index)
> +{
> +	iio_chan->type = type;
> +	iio_chan->modified = 1;
> +	iio_chan->channel2 = mod;
> +	iio_chan->info_mask_separate = BIT(IIO_CHAN_INFO_SCALE);
> +	iio_chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ);
> +	iio_chan->info_mask_shared_by_type_available =
> +		BIT(IIO_CHAN_INFO_SAMP_FREQ);
> +	iio_chan->scan_index = scan_index;
> +	iio_chan->scan_type.sign = 's';
> +	iio_chan->scan_type.realbits = 64;
> +	iio_chan->scan_type.storagebits = 64;
> +	iio_chan->scan_type.endianness = IIO_LE;
> +	iio_chan->ext_info = scmi_iio_ext_info;
> +}
> +
> +static int scmi_iio_get_chan_modifier(const char *name,
> +				      enum iio_modifier *modifier)
> +{
> +	char *pch, mod;
> +
> +	if (!name)
> +		return -EINVAL;
> +
> +	pch = strrchr(name, '_');
> +	if (!pch)
> +		return -EINVAL;
> +
> +	mod = *(pch + 1);
> +	switch (mod) {
> +	case 'X':
> +		*modifier = IIO_MOD_X;
> +		return 0;
> +	case 'Y':
> +		*modifier = IIO_MOD_Y;
> +		return 0;
> +	case 'Z':
> +		*modifier = IIO_MOD_Z;
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int scmi_iio_get_chan_type(u8 scmi_type, enum iio_chan_type *iio_type)
> +{
> +	switch (scmi_type) {
> +	case METERS_SEC_SQUARED:
> +		*iio_type = IIO_ACCEL;
> +		return 0;
> +	case RADIANS_SEC:
> +		*iio_type = IIO_ANGL_VEL;
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static u64 scmi_iio_convert_interval_to_ns(u32 val)
> +{
> +	u64 sensor_update_interval =
> +		SCMI_SENS_INTVL_GET_SECS(val) * NSEC_PER_SEC;
> +	u64 sensor_interval_mult;
> +	int mult;
> +
> +	mult = SCMI_SENS_INTVL_GET_EXP(val);
> +	if (mult < 0) {
> +		sensor_interval_mult = int_pow(10, abs(mult));
> +		do_div(sensor_update_interval, sensor_interval_mult);
> +	} else {
> +		sensor_interval_mult = int_pow(10, mult);
> +		sensor_update_interval =
> +			sensor_update_interval * sensor_interval_mult;
> +	}
> +	return sensor_update_interval;
> +}
> +
> +static int scmi_iio_set_sampling_freq_avail(struct iio_dev *iio_dev)
> +{
> +	u64 cur_interval_ns, low_interval_ns, high_interval_ns, step_size_ns,
> +		hz, uhz;
> +	unsigned int cur_interval, low_interval, high_interval, step_size;
> +	struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> +	int i;
> +
> +	sensor->freq_avail =
> +		devm_kzalloc(&iio_dev->dev,
> +			     sizeof(*sensor->freq_avail) *
> +				     (sensor->sensor_info->intervals.count * 2),
> +			     GFP_KERNEL);
> +	if (!sensor->freq_avail)
> +		return -ENOMEM;
> +
> +	if (sensor->sensor_info->intervals.segmented) {
> +		low_interval = sensor->sensor_info->intervals
> +				       .desc[SCMI_SENS_INTVL_SEGMENT_LOW];
> +		low_interval_ns = scmi_iio_convert_interval_to_ns(low_interval);
> +		convert_ns_to_freq(low_interval_ns, &hz, &uhz);
> +		sensor->freq_avail[0] = hz;
> +		sensor->freq_avail[1] = uhz;
> +
> +		step_size = sensor->sensor_info->intervals
> +				    .desc[SCMI_SENS_INTVL_SEGMENT_STEP];
> +		step_size_ns = scmi_iio_convert_interval_to_ns(step_size);
> +		convert_ns_to_freq(step_size_ns, &hz, &uhz);
> +		sensor->freq_avail[2] = hz;
> +		sensor->freq_avail[3] = uhz;
> +
> +		high_interval = sensor->sensor_info->intervals
> +					.desc[SCMI_SENS_INTVL_SEGMENT_HIGH];
> +		high_interval_ns =
> +			scmi_iio_convert_interval_to_ns(high_interval);
> +		convert_ns_to_freq(high_interval_ns, &hz, &uhz);
> +		sensor->freq_avail[4] = hz;
> +		sensor->freq_avail[5] = uhz;
> +	} else {
> +		for (i = 0; i < sensor->sensor_info->intervals.count; i++) {
> +			cur_interval = sensor->sensor_info->intervals.desc[i];
> +			cur_interval_ns =
> +				scmi_iio_convert_interval_to_ns(cur_interval);
> +			convert_ns_to_freq(cur_interval_ns, &hz, &uhz);
> +			sensor->freq_avail[i * 2] = hz;
> +			sensor->freq_avail[i * 2 + 1] = uhz;
> +		}
> +	}
> +	return 0;
> +}
> +
> +static int scmi_iio_buffers_setup(struct iio_dev *scmi_iiodev)
> +{
> +	struct iio_buffer *buffer;
> +
> +	buffer = devm_iio_kfifo_allocate(&scmi_iiodev->dev);
> +	if (!buffer)
> +		return -ENOMEM;
> +
> +	iio_device_attach_buffer(scmi_iiodev, buffer);
> +	scmi_iiodev->modes |= INDIO_BUFFER_SOFTWARE;
> +	scmi_iiodev->setup_ops = &scmi_iio_buffer_ops;
> +	return 0;
> +}
> +
> +static struct iio_dev *scmi_alloc_iiodev(struct device *dev,
> +					 struct scmi_handle *handle,
> +					 const struct scmi_sensor_info *sensor_info)
> +{
> +	struct iio_chan_spec *iio_channels;
> +	struct scmi_iio_priv *sensor;
> +	enum iio_modifier modifier;
> +	enum iio_chan_type type;
> +	struct iio_dev *iiodev;
> +	int i, ret;
> +
> +	iiodev = devm_iio_device_alloc(dev, sizeof(*sensor));
> +	if (!iiodev)
> +		return ERR_PTR(-ENOMEM);
> +
> +	iiodev->modes = INDIO_DIRECT_MODE;
> +	iiodev->dev.parent = dev;
> +	sensor = iio_priv(iiodev);
> +	sensor->handle = handle;
> +	sensor->sensor_info = sensor_info;
> +	sensor->sensor_update_nb.notifier_call = scmi_iio_sensor_update_cb;
> +	sensor->indio_dev = iiodev;
> +
> +	/* adding one additional channel for timestamp */
> +	iiodev->num_channels = sensor_info->num_axis + 1;
> +	iiodev->name = sensor_info->name;
> +	iiodev->info = &scmi_iio_info;
> +
> +	iio_channels =
> +		devm_kzalloc(dev,
> +			     sizeof(*iio_channels) * (iiodev->num_channels),
> +			     GFP_KERNEL);
> +	if (!iio_channels)
> +		return ERR_PTR(-ENOMEM);
> +
> +	ret = scmi_iio_set_sampling_freq_avail(iiodev);
> +	if (ret < 0)
> +		return ERR_PTR(ret);
> +
> +	for (i = 0; i < sensor_info->num_axis; i++) {
> +		ret = scmi_iio_get_chan_type(sensor_info->axis[i].type, &type);
> +		if (ret < 0)
> +			return ERR_PTR(ret);
> +
> +		ret = scmi_iio_get_chan_modifier(sensor_info->axis[i].name,
> +						 &modifier);
> +		if (ret < 0)
> +			return ERR_PTR(ret);
> +
> +		scmi_iio_set_data_channel(&iio_channels[i], type, modifier,
> +					  sensor_info->axis[i].id);
> +	}
> +
> +	scmi_iio_set_timestamp_channel(&iio_channels[i], i);
> +	iiodev->channels = iio_channels;
> +	return iiodev;
> +}
> +
> +static int scmi_iio_dev_probe(struct scmi_device *sdev)
> +{
> +	const struct scmi_sensor_info *sensor_info;
> +	struct scmi_handle *handle = sdev->handle;
> +	struct device *dev = &sdev->dev;
> +	struct iio_dev *scmi_iio_dev;
> +	u16 nr_sensors;
> +	int err = -ENODEV, i;
> +
> +	if (!handle || !handle->sensor_ops) {
> +		dev_err(dev, "SCMI device has no sensor interface\n");
> +		return -EINVAL;
> +	}
> +
> +	nr_sensors = handle->sensor_ops->count_get(handle);
> +	if (!nr_sensors) {
> +		dev_dbg(dev, "0 sensors found via SCMI bus\n");
> +		return -ENODEV;
> +	}
> +
> +	for (i = 0; i < nr_sensors; i++) {
> +		sensor_info = handle->sensor_ops->info_get(handle, i);
> +		if (!sensor_info) {
> +			dev_err(dev, "SCMI sensor %d has missing info\n", i);
> +			return -EINVAL;
> +		}
> +
> +		/* This driver only supports 3-axis accel and gyro, skipping other sensors */
> +		if (sensor_info->num_axis != SCMI_IIO_NUM_OF_AXIS)
> +			continue;
> +
> +		/* This driver only supports 3-axis accel and gyro, skipping other sensors */
> +		if (sensor_info->axis[0].type != METERS_SEC_SQUARED &&
> +		    sensor_info->axis[0].type != RADIANS_SEC)
> +			continue;
> +
> +		scmi_iio_dev = scmi_alloc_iiodev(dev, handle, sensor_info);
> +		if (IS_ERR(scmi_iio_dev)) {
> +			dev_err(dev,
> +				"failed to allocate IIO device for sensor %s: %ld\n",
> +				sensor_info->name, PTR_ERR(scmi_iio_dev));
> +			return PTR_ERR(scmi_iio_dev);
> +		}
> +
> +		err = scmi_iio_buffers_setup(scmi_iio_dev);
> +		if (err < 0) {
> +			dev_err(dev,
> +				"IIO buffer setup error at sensor %s: %d\n",
> +				sensor_info->name, err);
> +			return err;
> +		}
> +
> +		err = devm_iio_device_register(dev, scmi_iio_dev);
> +		if (err) {
> +			dev_err(dev,
> +				"IIO device registration failed at sensor %s: %d\n",
> +				sensor_info->name, err);
> +			return err;
> +		}
> +	}
> +	return err;
> +}
> +
> +static const struct scmi_device_id scmi_id_table[] = {
> +	{ SCMI_PROTOCOL_SENSOR, "iiodev" },
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(scmi, scmi_id_table);
> +
> +static struct scmi_driver scmi_iiodev_driver = {
> +	.name = "scmi-sensor-iiodev",
> +	.probe = scmi_iio_dev_probe,
> +	.id_table = scmi_id_table,
> +};
> +
> +module_scmi_driver(scmi_iiodev_driver);
> +
> +MODULE_AUTHOR("Jyoti Bhayana <jbhayana@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("SCMI IIO Driver");
> +MODULE_LICENSE("GPL v2");