virtualization/linux-yocto: Backport IIO SCMI based sensors driver.

This patch series is the latest implementation of ARM SCMI Protocol
based IIO Device. Patch was cherry-picked from branch [1] created by IIO
maintainer.

[1]: https://lore.kernel.org/lkml/20210311210844.34371d8d@archlinux/

Bug-AGL: SPEC-3865
Upstream-Status: Submitted [https://lore.kernel.org/lkml/20210309231259.78050-1-jbhayana@google.com/]
Signed-off-by: Andriy Tryshnivskyy <andriy.tryshnivskyy@opensynergy.com>
Change-Id: Idef6f0630887c49c1d8e651a5ac753ad74b20dc0

1 files changed, 797 insertions, 0 deletions

diff --git a/meta-egvirt/recipes-kernel/linux/linux-yocto/iio-scmi/0001-iio-scmi-Adding-support-for-IIO-SCMI-Based-Sensors.patch b/meta-egvirt/recipes-kernel/linux/linux-yocto/iio-scmi/0001-iio-scmi-Adding-support-for-IIO-SCMI-Based-Sensors.patch
new file mode 100644
index 00000000..15f6b6a3
--- /dev/null
+++ b/meta-egvirt/recipes-kernel/linux/linux-yocto/iio-scmi/0001-iio-scmi-Adding-support-for-IIO-SCMI-Based-Sensors.patch
@@ -0,0 +1,797 @@
+From df55878d8bb123266d301939a3ff90762fd466e1 Mon Sep 17 00:00:00 2001
+From: Jyoti Bhayana <jbhayana@google.com>
+Date: Fri, 12 Feb 2021 17:22:35 +0000
+Subject: [PATCH] iio/scmi: Adding support for IIO SCMI Based Sensors
+
+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
+
+Signed-off-by: Jyoti Bhayana <jbhayana@google.com>
+Link: https://lore.kernel.org/r/20210212172235.507028-2-jbhayana@google.com
+Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
+Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
+---
+ 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 | 678 +++++++++++++++++++++
+ 7 files changed, 710 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 d223a5c3f465..c3a0245a51d0 100644
+--- a/MAINTAINERS
++++ b/MAINTAINERS
+@@ -8593,6 +8593,12 @@ 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@google.com>
++L:	linux-iio@vger.kernel.org
++S:	Maintained
++F:	drivers/iio/common/scmi_sensors/scmi_iio.c
++
+ IIO SUBSYSTEM AND DRIVERS
+ M:	Jonathan Cameron <jic23@kernel.org>
+ R:	Lars-Peter Clausen <lars@metafoo.de>
+diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
+index 540a55285349..fa7279839397 100644
+--- a/drivers/firmware/arm_scmi/driver.c
++++ b/drivers/firmware/arm_scmi/driver.c
+@@ -808,7 +808,7 @@ 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" },},
+ };
+ 
+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..31977c3bc600
+--- /dev/null
++++ b/drivers/iio/common/scmi_sensors/scmi_iio.c
+@@ -0,0 +1,678 @@
++// 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 */
++	long long 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)
++			time_ns =
++				div64_u64(time, int_pow(10, abs(tstamp_scale)));
++		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;
++	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
++	 */
++	mult = scnprintf(buf, sizeof(buf), "%llu", ((u64)uHz * 0xFFFF) / UHZ_PER_HZ) - 1;
++
++	sec = div64_u64(int_pow(10, mult) * UHZ_PER_HZ, 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;
++
++	*hz = div64_u64_rem(NSEC_PER_SEC, interval_ns, &rem);
++	*uhz = (rem * 1000000UL) / 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));
++		sensor_update_interval =
++			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);
++	unsigned long long resolution, rem;
++	long long 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) {
++			resolution = div64_u64_rem(resolution,
++						   int_pow(10, abs(exponent)),
++						   &rem);
++			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));
++		sensor_update_interval =
++			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@google.com>");
++MODULE_DESCRIPTION("SCMI IIO Driver");
++MODULE_LICENSE("GPL v2");