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

[Jyoti Bhayana]

This change provides ARM SCMI Protocol based IIO device.
This driver provides support for Accelerometer and Gyroscope using
new SCMI Sensor Protocol defined by the upcoming SCMIv3.0
ARM specification

Signed-off-by: Jyoti Bhayana <jbhayana@xxxxxxxxxx>
---
 MAINTAINERS                 |   6 +
 drivers/iio/Kconfig         |   1 +
 drivers/iio/Makefile        |   1 +
 drivers/iio/scmi/Kconfig    |  18 +
 drivers/iio/scmi/Makefile   |   5 +
 drivers/iio/scmi/scmi_iio.c | 771 ++++++++++++++++++++++++++++++++++++
 6 files changed, 802 insertions(+)
 create mode 100644 drivers/iio/scmi/Kconfig
 create mode 100644 drivers/iio/scmi/Makefile
 create mode 100644 drivers/iio/scmi/scmi_iio.c

diff --git a/MAINTAINERS b/MAINTAINERS
index deaafb617361..11624961b13b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8477,6 +8477,12 @@ 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/scmi/scmi_iio.c
+
 IIO SUBSYSTEM AND DRIVERS
 M:	Jonathan Cameron <jic23@xxxxxxxxxx>
 R:	Hartmut Knaack <knaack.h@xxxxxx>
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index d5c073a8aa3e..d31e0ceb152e 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -94,6 +94,7 @@ source "drivers/iio/potentiostat/Kconfig"
 source "drivers/iio/pressure/Kconfig"
 source "drivers/iio/proximity/Kconfig"
 source "drivers/iio/resolver/Kconfig"
+source "drivers/iio/scmi/Kconfig"
 source "drivers/iio/temperature/Kconfig"
 
 endif # IIO
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 1712011c0f4a..2da7907da608 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -37,5 +37,6 @@ obj-y += potentiostat/
 obj-y += pressure/
 obj-y += proximity/
 obj-y += resolver/
+obj-y += scmi/
 obj-y += temperature/
 obj-y += trigger/
diff --git a/drivers/iio/scmi/Kconfig b/drivers/iio/scmi/Kconfig
new file mode 100644
index 000000000000..67e084cbb1ab
--- /dev/null
+++ b/drivers/iio/scmi/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/scmi/Makefile b/drivers/iio/scmi/Makefile
new file mode 100644
index 000000000000..f13140a2575a
--- /dev/null
+++ b/drivers/iio/scmi/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/scmi/scmi_iio.c b/drivers/iio/scmi/scmi_iio.c
new file mode 100644
index 000000000000..987c3a56abcf
--- /dev/null
+++ b/drivers/iio/scmi/scmi_iio.c
@@ -0,0 +1,771 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface(SCMI) based IIO sensor driver
+ *
+ * Copyright (C) 2020 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 NSEC_MULT_POW_10 (const_ilog2(NSEC_PER_SEC) / const_ilog2(10))
+#define UHZ_PER_HZ 1000000UL
+#define ODR_EXPAND(odr, uodr) (((odr) * 1000000ULL) + (uodr))
+#define SCMI_SENS_CFG_SET_TSTAMP_ENABLED(x) ((x) | BIT(1))
+#define SCMI_SENS_CFG_SET_ENABLE(x) ((x) | BIT(0))
+#define SCMI_SENS_CFG_SET_DISABLE(x) ((x) & ~BIT(0))
+#define SCMI_SENS_CFG_SET_UPDATE_SECS(x, v) ((x) | ((u32)(v) << 16))
+#define SCMI_SENS_CFG_SET_UPDATE_MULTI(x, v)                                   \
+	((x) | (((s16)(v) << 11) & GENMASK(15, 11)))
+#define SCMI_SENS_CFG_SET_AUTO_ROUND_UP(x) ((x) | BIT(10))
+
+//one additional channel for timestamp
+#define SCMI_IIO_EXTRA_CHANNELS 1
+
+struct scmi_iio_priv {
+	struct scmi_handle *handle;
+	const struct scmi_sensor_info *sensor_info;
+	struct iio_dev *indio_dev;
+	u8 *iio_buf;
+	struct notifier_block sensor_update_nb;
+};
+
+struct sensor_freq {
+	u64 hz;
+	u64 uhz;
+};
+
+static int scmi_iio_check_valid_sensor(struct scmi_iio_priv *sensor)
+{
+	if (!sensor || !sensor->handle || !sensor->sensor_info ||
+	    !sensor->indio_dev)
+		return -EINVAL;
+	else
+		return 0;
+}
+
+static int sensor_update_cb(struct notifier_block *nb, unsigned long event,
+			    void *data)
+{
+	struct scmi_sensor_update_report *sensor_update = data;
+	u64 time, time_ns;
+	s64 sensor_value;
+	struct scmi_iio_priv *sensor =
+		container_of(nb, struct scmi_iio_priv, sensor_update_nb);
+	struct iio_dev *scmi_iio_dev;
+	s8 tstamp_scale_ns;
+	int i, err;
+
+	err = scmi_iio_check_valid_sensor(sensor);
+
+	if (err)
+		return err;
+
+	scmi_iio_dev = sensor->indio_dev;
+
+	for (i = 0; i < sensor_update->readings_count; i++) {
+		sensor_value = sensor_update->readings[i].value;
+		time = sensor_update->readings[i].timestamp;
+		memcpy(&sensor->iio_buf[i * sizeof(s64)], &sensor_value,
+		       sizeof(s64));
+	}
+
+	if (!sensor->sensor_info->timestamped) {
+		time_ns = iio_get_time_ns(scmi_iio_dev);
+	} else {
+		tstamp_scale_ns =
+			sensor->sensor_info->tstamp_scale + NSEC_MULT_POW_10;
+		if (tstamp_scale_ns < 0) {
+			tstamp_scale_ns = -1 * tstamp_scale_ns;
+			time_ns = div64_u64(time, int_pow(10, tstamp_scale_ns));
+		} else {
+			time_ns = time * int_pow(10, tstamp_scale_ns);
+		}
+	}
+
+	iio_push_to_buffers_with_timestamp(scmi_iio_dev, sensor->iio_buf,
+					   time_ns);
+
+	return NOTIFY_OK;
+}
+
+static int scmi_iio_is_scalar_sensor(const struct scmi_sensor_info *sensor_info,
+				     bool *scalar)
+{
+	if (!sensor_info || !scalar)
+		return -EINVAL;
+
+	if (sensor_info->num_axis > 0)
+		*scalar = false;
+	else
+		*scalar = true;
+
+	return 0;
+}
+
+static int scmi_iio_buffer_preenable(struct iio_dev *dev)
+{
+	struct scmi_iio_priv *sensor = iio_priv(dev);
+	u32 sensor_config = 0;
+	int err = scmi_iio_check_valid_sensor(sensor);
+	u32 sensor_id = sensor->sensor_info->id;
+
+	if (err)
+		return err;
+
+	if (sensor->sensor_info->timestamped)
+		sensor_config = SCMI_SENS_CFG_SET_TSTAMP_ENABLED(sensor_config);
+
+	sensor_config = SCMI_SENS_CFG_SET_ENABLE(sensor_config);
+
+	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) {
+		pr_err("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)
+		pr_err("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_config = 0;
+	int err = scmi_iio_check_valid_sensor(sensor);
+	u32 sensor_id = sensor_id = sensor->sensor_info->id;
+
+	if (err)
+		return err;
+
+	sensor_config = SCMI_SENS_CFG_SET_DISABLE(sensor_config);
+
+	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) {
+		pr_err("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->sensor_info->id, sensor_config);
+
+	if (err)
+		pr_err("Error in disabling sensor %s with err %d",
+		       sensor->sensor_info->name, err);
+
+	return err;
+}
+
+static u64 convert_interval_to_ns(u32 val)
+{
+	u64 sensor_update_interval, sensor_interval_mult;
+	int mult;
+
+	mult = SCMI_SENS_INTVL_GET_EXP(val);
+	sensor_update_interval = SCMI_SENS_INTVL_GET_SECS(val) * NSEC_PER_SEC;
+	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 convert_ns_to_freq(u64 interval_ns, struct sensor_freq *freq)
+{
+	u64 rem;
+
+	if (!freq)
+		return -EINVAL;
+
+	freq->hz = div64_u64_rem(NSEC_PER_SEC, interval_ns, &rem);
+	freq->uhz = (rem * 1000000UL) / interval_ns;
+
+	return 0;
+}
+
+static ssize_t scmi_iio_sysfs_sampling_freq_avail(struct device *dev,
+						  struct device_attribute *attr,
+						  char *buf)
+{
+	struct scmi_iio_priv *sensor = iio_priv(dev_get_drvdata(dev));
+	int err = scmi_iio_check_valid_sensor(sensor);
+	struct sensor_freq freq;
+	u64 lowest_interval_ns, highest_interval_ns, cur_interval_ns,
+		step_size_ns;
+	unsigned int lowest_interval, highest_interval, step_size, cur_interval;
+	int i, len = 0;
+
+	if (err)
+		return err;
+
+	if (!sensor->sensor_info->intervals.segmented) {
+		for (i = 0; i < sensor->sensor_info->intervals.count; i++) {
+			cur_interval = sensor->sensor_info->intervals.desc[i];
+			cur_interval_ns = convert_interval_to_ns(cur_interval);
+			err = convert_ns_to_freq(cur_interval_ns, &freq);
+			if (err)
+				return 0;
+			len += scnprintf(buf + len, PAGE_SIZE - len,
+					 "%llu.%06llu ", freq.hz, freq.uhz);
+		}
+	} else {
+		// If the intervals are segmented, the intervals array is a triplet
+		// which constitues a segment in the form of
+		// [lowest_interval,highest_interval,step_size]
+		if (sensor->sensor_info->intervals.count != 3) {
+			pr_err("SCMI sensor %s has segmented update intervals count %d which is not a triplet",
+			       sensor->sensor_info->name,
+			       sensor->sensor_info->intervals.count);
+			return len;
+		}
+		lowest_interval = sensor->sensor_info->intervals.desc[0];
+		highest_interval = sensor->sensor_info->intervals.desc[1];
+		step_size = sensor->sensor_info->intervals.desc[2];
+		lowest_interval_ns = convert_interval_to_ns(lowest_interval);
+		highest_interval_ns = convert_interval_to_ns(highest_interval);
+		step_size_ns = convert_interval_to_ns(step_size);
+		cur_interval_ns = lowest_interval_ns;
+		while (cur_interval_ns <= highest_interval_ns) {
+			err = convert_ns_to_freq(cur_interval_ns, &freq);
+			if (err)
+				return 0;
+			len += scnprintf(buf + len, PAGE_SIZE - len,
+					 "%llu.%06llu ", freq.hz, freq.uhz);
+			cur_interval_ns += step_size_ns;
+		}
+	}
+
+	if (len > 0)
+		buf[len - 1] = '\n';
+	return len;
+}
+
+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);
+	int err = scmi_iio_check_valid_sensor(sensor);
+	u32 sensor_config = 0, cur_sensor_config;
+	u64 sec, mult, uHz;
+	char buf[32];
+
+	if (err)
+		return err;
+
+	err = sensor->handle->sensor_ops->config_get(
+		sensor->handle, sensor->sensor_info->id, &cur_sensor_config);
+
+	if (err) {
+		pr_err("%s: Error in getting sensor config for sensor %s err %d",
+		       __func__, sensor->sensor_info->name, err);
+		return err;
+	}
+
+	uHz = ODR_EXPAND(val, 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, 32, "%llu", ((u64)uHz * 0xFFFF) / UHZ_PER_HZ) - 1;
+
+	sec = div64_u64(int_pow(10, mult) * UHZ_PER_HZ, uHz);
+	if (sec == 0) {
+		pr_err("Trying to set invalid sensor update value for sensor %s",
+		       sensor->sensor_info->name);
+		return -EINVAL;
+	}
+
+	// Not able to use cur_sensor_config to build/modify the sensor config with
+	// new configuration as the SCMI macros below doesn't clear the old values
+	// and executes bitwise operations over them. Therefore, building new sensor config
+	// from scratch.
+	sensor_config = SCMI_SENS_CFG_SET_UPDATE_SECS(sensor_config, sec);
+	sensor_config = SCMI_SENS_CFG_SET_UPDATE_MULTI(sensor_config, -mult);
+	sensor_config = SCMI_SENS_CFG_SET_AUTO_ROUND_UP(sensor_config);
+	if (sensor->sensor_info->timestamped)
+		sensor_config = SCMI_SENS_CFG_SET_TSTAMP_ENABLED(sensor_config);
+	if (SCMI_SENS_CFG_IS_ENABLED(cur_sensor_config))
+		sensor_config = SCMI_SENS_CFG_SET_ENABLE(sensor_config);
+	else
+		sensor_config = SCMI_SENS_CFG_SET_DISABLE(sensor_config);
+
+	err = sensor->handle->sensor_ops->config_set(
+		sensor->handle, sensor->sensor_info->id, sensor_config);
+
+	if (err)
+		pr_err("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;
+
+	mutex_lock(&iio_dev->mlock);
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		err = scmi_iio_set_odr_val(iio_dev, val, val2);
+		break;
+	default:
+		err = -EINVAL;
+		break;
+	}
+	mutex_unlock(&iio_dev->mlock);
+
+	return err;
+}
+
+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);
+	int ret = scmi_iio_check_valid_sensor(sensor);
+	bool scalar_sensor;
+	s8 scale;
+
+	if (ret)
+		return ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		ret = scmi_iio_is_scalar_sensor(sensor->sensor_info,
+						&scalar_sensor);
+		if (ret)
+			return ret;
+		if (!scalar_sensor) {
+			if (!ch)
+				return -EINVAL;
+			scale = sensor->sensor_info->axis[ch->scan_index].scale;
+			if (scale < 0) {
+				scale = -scale;
+				*val = 1;
+				*val2 = int_pow(10, scale);
+				ret = IIO_VAL_FRACTIONAL;
+			} else {
+				*val = int_pow(10, scale);
+				ret = IIO_VAL_INT;
+			}
+		} else {
+			ret = -EINVAL;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static ssize_t scmi_iio_get_sensor_power(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct scmi_iio_priv *sensor = iio_priv(dev_get_drvdata(dev));
+	int err = scmi_iio_check_valid_sensor(sensor);
+	int len = 0;
+
+	if (err)
+		return err;
+
+	if (sensor->sensor_info->extended_scalar_attrs)
+		len = scnprintf(buf, PAGE_SIZE, "%u\n",
+				sensor->sensor_info->sensor_power);
+
+	return len;
+}
+
+static ssize_t scmi_iio_get_sensor_max_range(struct device *dev,
+					     struct device_attribute *attr,
+					     char *buf)
+{
+	struct scmi_iio_priv *sensor = iio_priv(dev_get_drvdata(dev));
+	int err = scmi_iio_check_valid_sensor(sensor);
+	int i;
+	s64 max_range = S64_MIN, max_range_axis;
+
+	if (err)
+		return err;
+
+	for (i = 0; i < sensor->sensor_info->num_axis; i++) {
+		if (sensor->sensor_info->axis[i].extended_attrs) {
+			max_range_axis =
+				sensor->sensor_info->axis[i].attrs.max_range;
+			max_range = max(max_range, max_range_axis);
+		}
+	}
+
+	return scnprintf(buf, PAGE_SIZE, "%lld\n", max_range);
+}
+
+static ssize_t scmi_iio_get_sensor_resolution(struct device *dev,
+					      struct device_attribute *attr,
+					      char *buf)
+{
+	struct scmi_iio_priv *sensor = iio_priv(dev_get_drvdata(dev));
+	bool scalar_sensor;
+	int len = 0;
+	int err = scmi_iio_check_valid_sensor(sensor);
+
+	if (err)
+		return err;
+
+	err = scmi_iio_is_scalar_sensor(sensor->sensor_info, &scalar_sensor);
+	if (err)
+		return err;
+
+	if (!scalar_sensor) {
+		// All the axes are supposed to have the same value for resolution
+		// and exponent. We are just using the values from the Axis 0 here.
+		if (sensor->sensor_info->axis[0].extended_attrs) {
+			u32 resolution =
+				sensor->sensor_info->axis[0].resolution;
+			s8 exponent = sensor->sensor_info->axis[0].exponent;
+			u32 multiplier = int_pow(10, abs(exponent));
+
+			if (exponent < 0) {
+				int vals[] = { resolution, multiplier };
+
+				len = iio_format_value(buf, IIO_VAL_FRACTIONAL,
+						       ARRAY_SIZE(vals), vals);
+			} else {
+				int vals[] = { resolution * multiplier };
+
+				len = iio_format_value(buf, IIO_VAL_INT,
+						       ARRAY_SIZE(vals), vals);
+			}
+		}
+	}
+
+	return len;
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(scmi_iio_sysfs_sampling_freq_avail);
+static IIO_DEVICE_ATTR(sensor_power, 0444, scmi_iio_get_sensor_power, NULL, 0);
+static IIO_DEVICE_ATTR(sensor_max_range, 0444, scmi_iio_get_sensor_max_range,
+		       NULL, 0);
+static IIO_DEVICE_ATTR(sensor_resolution, 0444, scmi_iio_get_sensor_resolution,
+		       NULL, 0);
+
+static struct attribute *scmi_iio_attributes[] = {
+	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
+	&iio_dev_attr_sensor_power.dev_attr.attr,
+	&iio_dev_attr_sensor_max_range.dev_attr.attr,
+	&iio_dev_attr_sensor_resolution.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group scmi_iio_attribute_group = {
+	.attrs = scmi_iio_attributes,
+};
+
+static const struct iio_info scmi_iio_info = {
+	.read_raw = scmi_iio_read_raw,
+	.write_raw = scmi_iio_write_raw,
+	.attrs = &scmi_iio_attribute_group,
+};
+
+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_get_chan_type(u8 scmi_type, enum iio_chan_type *iio_type)
+{
+	int ret = 0;
+
+	if (!iio_type)
+		return -EINVAL;
+
+	switch (scmi_type) {
+	case METERS_SEC_SQUARED:
+		*iio_type = IIO_ACCEL;
+		break;
+	case RADIANS_SEC:
+		*iio_type = IIO_ANGL_VEL;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static int scmi_iio_get_chan_modifier(const char *name,
+				      enum iio_modifier *modifier)
+{
+	int ret = 0;
+
+	if (!name || !modifier)
+		return -EINVAL;
+
+	if (strcasecmp(name, "X") == 0)
+		*modifier = IIO_MOD_X;
+	else if (strcasecmp(name, "Y") == 0)
+		*modifier = IIO_MOD_Y;
+	else if (strcasecmp(name, "Z") == 0)
+		*modifier = IIO_MOD_Z;
+	else
+		ret = -EINVAL;
+
+	return ret;
+}
+
+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)
+{
+	if (!iio_chan)
+		return;
+
+	iio_chan->type = type;
+	iio_chan->modified = 1;
+	iio_chan->channel2 = mod;
+	iio_chan->info_mask_separate =
+		BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE);
+	iio_chan->info_mask_shared_by_type = 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;
+}
+
+static void scmi_iio_set_timestamp_channel(struct iio_chan_spec *iio_chan,
+					   int scan_index)
+{
+	if (!iio_chan)
+		return;
+
+	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 int
+scmi_iio_alloc_nonscalar_sensor(struct device *dev, struct scmi_handle *handle,
+				const struct scmi_sensor_info *sensor_info,
+				struct iio_dev **scmi_iio_dev)
+{
+	struct scmi_iio_priv *sensor;
+	struct iio_chan_spec *iio_channels;
+	enum iio_chan_type type;
+	enum iio_modifier modifier;
+	struct iio_dev *iio_dev_temp;
+	int i, ret = 0;
+
+	if (!scmi_iio_dev)
+		return -EINVAL;
+
+	iio_dev_temp = devm_iio_device_alloc(dev, sizeof(struct scmi_iio_priv));
+	if (!iio_dev_temp)
+		return -ENOMEM;
+	iio_dev_temp->modes = INDIO_DIRECT_MODE;
+	iio_dev_temp->dev.parent = dev;
+	sensor = iio_priv(iio_dev_temp);
+	sensor->handle = handle;
+	sensor->sensor_info = sensor_info;
+	sensor->sensor_update_nb.notifier_call = sensor_update_cb;
+	sensor->indio_dev = iio_dev_temp;
+	iio_dev_temp->num_channels =
+		sensor_info->num_axis + SCMI_IIO_EXTRA_CHANNELS;
+	iio_dev_temp->name = sensor_info->name;
+	iio_dev_temp->info = &scmi_iio_info;
+	iio_channels = devm_kzalloc(dev,
+				    sizeof(struct iio_chan_spec) *
+					    (iio_dev_temp->num_channels),
+				    GFP_KERNEL);
+	if (!iio_channels)
+		return -ENOMEM;
+	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 ret;
+		ret = scmi_iio_get_chan_modifier(sensor_info->axis[i].name,
+						 &modifier);
+		if (ret < 0)
+			return 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);
+	iio_dev_temp->channels = iio_channels;
+	*scmi_iio_dev = iio_dev_temp;
+	return ret;
+}
+
+static int scmi_alloc_iiodev(struct device *dev, struct scmi_handle *handle,
+			     const struct scmi_sensor_info *sensor_info,
+			     struct iio_dev **scmi_iio_dev)
+{
+	int ret = 0;
+	bool scalar_sensor;
+
+	ret = scmi_iio_is_scalar_sensor(sensor_info, &scalar_sensor);
+
+	if (ret)
+		return ret;
+
+	if (!scalar_sensor)
+		ret = scmi_iio_alloc_nonscalar_sensor(dev, handle, sensor_info,
+						      scmi_iio_dev);
+	else
+		ret = -EINVAL;
+
+	return ret;
+}
+
+static int scmi_iio_buffers_setup(struct iio_dev *scmi_iiodev)
+{
+	struct iio_buffer *buffer = devm_iio_kfifo_allocate(&scmi_iiodev->dev);
+	struct scmi_iio_priv *sensor = iio_priv(scmi_iiodev);
+	int err = scmi_iio_check_valid_sensor(sensor);
+
+	if (!buffer)
+		return -ENOMEM;
+
+	if (err)
+		return err;
+
+	iio_device_attach_buffer(scmi_iiodev, buffer);
+	scmi_iiodev->modes |= INDIO_BUFFER_SOFTWARE;
+	scmi_iiodev->setup_ops = &scmi_iio_buffer_ops;
+	sensor->iio_buf =
+		devm_kzalloc(&scmi_iiodev->dev,
+			     sizeof(s64) * (scmi_iiodev->num_channels),
+			     GFP_KERNEL);
+	if (!sensor->iio_buf)
+		return -ENOMEM;
+	return 0;
+}
+
+static int scmi_iio_dev_probe(struct scmi_device *sdev)
+{
+	struct scmi_handle *handle;
+	u16 nr_sensors;
+	struct iio_dev *scmi_iio_dev;
+	const struct scmi_sensor_info *sensor_info;
+	int err = 0, i;
+	struct device *dev;
+
+	if (!sdev) {
+		pr_err("scmi_iio_dev: missing SCMI device\n");
+		return -ENODEV;
+	}
+
+	dev = &sdev->dev;
+
+	handle = sdev->handle;
+	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_warn(dev, "0 sensors found via SCMI bus\n");
+		return -EINVAL;
+	}
+
+	dev_info(dev, "%d sensors found via SCMI bus\n", nr_sensors);
+
+	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;
+		}
+		err = scmi_alloc_iiodev(dev, handle, sensor_info,
+					&scmi_iio_dev);
+		if (err < 0) {
+			dev_err(dev,
+				"memory allocation error at sensor %s: %d\n",
+				sensor_info->name, err);
+			return err;
+		}
+		if (!scmi_iio_dev) {
+			dev_err(dev, "memory allocation failed at sensor %s\n",
+				sensor_info->name);
+			return -ENOMEM;
+		}
+		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 void scmi_iio_dev_remove(struct scmi_device *sdev)
+{
+	pr_debug("scmi_iio_drv_remove\n");
+}
+
+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,
+	.remove = scmi_iio_dev_remove,
+	.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");
-- 
2.29.2.299.gdc1121823c-goog