diff mbox series

[v6,01/11] platform: chrome: sensorhub: Add FIFO support

Message ID 20200324202736.243314-2-gwendal@chromium.org (mailing list archive)
State New, archived
Headers show
Series Cros EC sensor hub FIFO support | expand

Commit Message

Gwendal Grignou March 24, 2020, 8:27 p.m. UTC
cros_ec_sensorhub registers a listener and query motion sense FIFO,
spread to iio sensors registers.

To test, we can use libiio:
iiod&
iio_readdev -u ip:localhost -T 10000 -s 25 -b 16 cros-ec-gyro | od -x

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
---
Changes in v6:
- Unify function naming in cros_ec_sensorhub: cros_ec_sensorhub_ring_...
- Kernel module name is now cros-ec-sensorhub
- Remove unneceassary warning messages.

Changes in v5:
- Use a goto in cros_ec_sensorhub_ring_handler to centralize error
  handling
- Use devm_add_action_or_reset to not need a .remove entry point for
  cros_sensor_hub.
- Fix logic error in cros_ec_sensorhub_register_push_data.
- Update kernel_doc documentation.
- Remve the need for comments in variable declaration section.
Changes in v4:
- Keep defining cros_ec_sensorhub in kernel-doc format
- Fix logic error when checking if sensor index outside array.
- Check patch with --strict option
    Use sizeof(*obj) instead of sizeof(struct ...obj)
    Alignement
    Use uX instead of uintX_t
    Use !ptr instead of ptr != NULL
Changes in v3:
- Do not use ret !=
- Simplfy errpr handling by removing a goto
- Fix doxygen comments
- Replace suspend/resume entry points with regular driver entry point;
  There was an issue in the past where the sensor stack was preventing
  device to suspend, but the proper fix has been implemented in cros_ec
  code (6ad16b78a039b "platform/chrome: don't report
EC_MKBP_EVENT_SENSOR_FIFO as wakeup")
- Reduce mutex scope by checking return code outside of it.
Changes in v2:
- Do not register a .remove routinge in plaform_driver. A
  devm_action_add is added later patch IIO driver register their
callback.
- Remove double lines, add lines before return calls.
- Handle FLUSH flag from EC.

- Use ktime_t for most timestamp measurements.
- Add doxygen comments
- Cleanup timestamp collection when processing FIFO.
- Rename fifo_toggle to fifo_enable


 drivers/platform/chrome/Makefile              |   4 +-
 drivers/platform/chrome/cros_ec_sensorhub.c   | 107 +++--
 .../platform/chrome/cros_ec_sensorhub_ring.c  | 425 ++++++++++++++++++
 .../linux/platform_data/cros_ec_sensorhub.h   |  91 ++++
 4 files changed, 599 insertions(+), 28 deletions(-)
 create mode 100644 drivers/platform/chrome/cros_ec_sensorhub_ring.c

Comments

Enric Balletbo i Serra March 25, 2020, 4:28 p.m. UTC | #1
Hi Gwendal,

Many thanks for sending this series upstream. Just one comment, other than that
looks good to me.

On 24/3/20 21:27, Gwendal Grignou wrote:
> cros_ec_sensorhub registers a listener and query motion sense FIFO,
> spread to iio sensors registers.
> 
> To test, we can use libiio:
> iiod&
> iio_readdev -u ip:localhost -T 10000 -s 25 -b 16 cros-ec-gyro | od -x
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>

[snip]

> +/**
> + * cros_ec_sensorhub_ring_handler() - The trigger handler function
> + *
> + * @sensorhub: Sensor Hub object.
> + *
> + * Called by the notifier, process the EC sensor FIFO queue.
> + */
> +static void cros_ec_sensorhub_ring_handler(struct cros_ec_sensorhub *sensorhub)
> +{
> +	struct cros_ec_fifo_info *fifo_info = &sensorhub->fifo_info;
> +	struct cros_ec_dev *ec = sensorhub->ec;
> +	ktime_t fifo_timestamp, current_timestamp;
> +	int i, j, number_data, ret;
> +	unsigned long sensor_mask = 0;
> +	struct ec_response_motion_sensor_data *in;
> +	struct cros_ec_sensors_ring_sample *out, *last_out;
> +
> +	mutex_lock(&sensorhub->cmd_lock);
> +
> +	/* Get FIFO information if there are lost vectors. */
> +	if (fifo_info->info.total_lost) {
> +		/* Need to retrieve the number of lost vectors per sensor */
> +		sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INFO;
> +		sensorhub->msg->outsize = 1;
> +		sensorhub->msg->insize =
> +			sizeof(struct ec_response_motion_sense_fifo_info) +
> +			sizeof(u16) * CROS_EC_SENSOR_MAX;
> +
> +		if (cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg) < 0)
> +			goto error;
> +
> +		memcpy(fifo_info, &sensorhub->resp->fifo_info,
> +		       sizeof(*fifo_info));
> +

Smatch is reporting:

cros_ec_sensorhub_ring_handler() error: memcpy() '&sensorhub->resp->fifo_info'
too small (10 vs 42)

Is it fine and safe to copy always the 42 bytes? I suspect that we should only
copy the number of lost events, total_lost , not always the maximum (16). Or the
EC is always sending the full array (16 bytes)?

Thanks,
Enric
Gwendal Grignou March 26, 2020, 8:56 a.m. UTC | #2
On Wed, Mar 25, 2020 at 9:28 AM Enric Balletbo i Serra
<enric.balletbo@collabora.com> wrote:
>
> Hi Gwendal,
>
> Many thanks for sending this series upstream. Just one comment, other than that
> looks good to me.
>
> On 24/3/20 21:27, Gwendal Grignou wrote:
> > cros_ec_sensorhub registers a listener and query motion sense FIFO,
> > spread to iio sensors registers.
> >
> > To test, we can use libiio:
> > iiod&
> > iio_readdev -u ip:localhost -T 10000 -s 25 -b 16 cros-ec-gyro | od -x
> >
> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
>
> [snip]
>
> > +/**
> > + * cros_ec_sensorhub_ring_handler() - The trigger handler function
> > + *
> > + * @sensorhub: Sensor Hub object.
> > + *
> > + * Called by the notifier, process the EC sensor FIFO queue.
> > + */
> > +static void cros_ec_sensorhub_ring_handler(struct cros_ec_sensorhub *sensorhub)
> > +{
> > +     struct cros_ec_fifo_info *fifo_info = &sensorhub->fifo_info;
> > +     struct cros_ec_dev *ec = sensorhub->ec;
> > +     ktime_t fifo_timestamp, current_timestamp;
> > +     int i, j, number_data, ret;
> > +     unsigned long sensor_mask = 0;
> > +     struct ec_response_motion_sensor_data *in;
> > +     struct cros_ec_sensors_ring_sample *out, *last_out;
> > +
> > +     mutex_lock(&sensorhub->cmd_lock);
> > +
> > +     /* Get FIFO information if there are lost vectors. */
> > +     if (fifo_info->info.total_lost) {
> > +             /* Need to retrieve the number of lost vectors per sensor */
> > +             sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INFO;
> > +             sensorhub->msg->outsize = 1;
> > +             sensorhub->msg->insize =
> > +                     sizeof(struct ec_response_motion_sense_fifo_info) +
> > +                     sizeof(u16) * CROS_EC_SENSOR_MAX;
> > +
> > +             if (cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg) < 0)
> > +                     goto error;
> > +
> > +             memcpy(fifo_info, &sensorhub->resp->fifo_info,
> > +                    sizeof(*fifo_info));
> > +
>
> Smatch is reporting:
Which version of smatch are you using? I am using
v0.5.0-6279-g2f013029 and the problem is not reported.
>
> cros_ec_sensorhub_ring_handler() error: memcpy() '&sensorhub->resp->fifo_info'
> too small (10 vs 42)
>
> Is it fine and safe to copy always the 42 bytes? I suspect that we should only
> copy the number of lost events, total_lost , not always the maximum (16). Or the
> EC is always sending the full array (16 bytes)?
EC will not fill the 42 bytes if it has less than 16 sensors. It is
safe because we are not looking at the bytes we don't need, but it is
not clean.
Working on a new patch set where I remove the CROS_EC_SENSOR_MAX
constant and dynamically allocate the data I need based on the number
of sensors.
>
> Thanks,
> Enric
>
diff mbox series

Patch

diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index 198c155c7c4d4..1223b028cefa0 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -20,7 +20,9 @@  obj-$(CONFIG_CROS_EC_CHARDEV)		+= cros_ec_chardev.o
 obj-$(CONFIG_CROS_EC_LIGHTBAR)		+= cros_ec_lightbar.o
 obj-$(CONFIG_CROS_EC_VBC)		+= cros_ec_vbc.o
 obj-$(CONFIG_CROS_EC_DEBUGFS)		+= cros_ec_debugfs.o
-obj-$(CONFIG_CROS_EC_SENSORHUB)		+= cros_ec_sensorhub.o
+obj-$(CONFIG_CROS_EC_SENSORHUB)                += cros-ec-sensorhub.o
+cros-ec-sensorhub-objs                 := cros_ec_sensorhub.o
+cros-ec-sensorhub-objs                 += cros_ec_sensorhub_ring.o
 obj-$(CONFIG_CROS_EC_SYSFS)		+= cros_ec_sysfs.o
 obj-$(CONFIG_CROS_USBPD_LOGGER)		+= cros_usbpd_logger.o
 obj-$(CONFIG_CROS_USBPD_NOTIFY)		+= cros_usbpd_notify.o
diff --git a/drivers/platform/chrome/cros_ec_sensorhub.c b/drivers/platform/chrome/cros_ec_sensorhub.c
index 79fefd3bb0fa6..bbb1c8f89905d 100644
--- a/drivers/platform/chrome/cros_ec_sensorhub.c
+++ b/drivers/platform/chrome/cros_ec_sensorhub.c
@@ -50,10 +50,8 @@  static int cros_ec_sensorhub_register(struct device *dev,
 				      struct cros_ec_sensorhub *sensorhub)
 {
 	int sensor_type[MOTIONSENSE_TYPE_MAX] = { 0 };
+	struct cros_ec_command *msg = sensorhub->msg;
 	struct cros_ec_dev *ec = sensorhub->ec;
-	struct ec_params_motion_sense *params;
-	struct ec_response_motion_sense *resp;
-	struct cros_ec_command *msg;
 	int ret, i, sensor_num;
 	char *name;
 
@@ -70,22 +68,13 @@  static int cros_ec_sensorhub_register(struct device *dev,
 		return -EINVAL;
 	}
 
-	/* Prepare a message to send INFO command to each sensor. */
-	msg = kzalloc(sizeof(*msg) + max(sizeof(*params), sizeof(*resp)),
-		      GFP_KERNEL);
-	if (!msg)
-		return -ENOMEM;
-
 	msg->version = 1;
-	msg->command = EC_CMD_MOTION_SENSE_CMD + ec->cmd_offset;
-	msg->outsize = sizeof(*params);
-	msg->insize = sizeof(*resp);
-	params = (struct ec_params_motion_sense *)msg->data;
-	resp = (struct ec_response_motion_sense *)msg->data;
+	msg->insize = sizeof(struct ec_response_motion_sense);
+	msg->outsize = sizeof(struct ec_params_motion_sense);
 
 	for (i = 0; i < sensor_num; i++) {
-		params->cmd = MOTIONSENSE_CMD_INFO;
-		params->info.sensor_num = i;
+		sensorhub->params->cmd = MOTIONSENSE_CMD_INFO;
+		sensorhub->params->info.sensor_num = i;
 
 		ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
 		if (ret < 0) {
@@ -94,7 +83,7 @@  static int cros_ec_sensorhub_register(struct device *dev,
 			continue;
 		}
 
-		switch (resp->info.type) {
+		switch (sensorhub->resp->info.type) {
 		case MOTIONSENSE_TYPE_ACCEL:
 			name = "cros-ec-accel";
 			break;
@@ -117,15 +106,16 @@  static int cros_ec_sensorhub_register(struct device *dev,
 			name = "cros-ec-activity";
 			break;
 		default:
-			dev_warn(dev, "unknown type %d\n", resp->info.type);
+			dev_warn(dev, "unknown type %d\n",
+				 sensorhub->resp->info.type);
 			continue;
 		}
 
 		ret = cros_ec_sensorhub_allocate_sensor(dev, name, i);
 		if (ret)
-			goto error;
+			return ret;
 
-		sensor_type[resp->info.type]++;
+		sensor_type[sensorhub->resp->info.type]++;
 	}
 
 	if (sensor_type[MOTIONSENSE_TYPE_ACCEL] >= 2)
@@ -137,29 +127,41 @@  static int cros_ec_sensorhub_register(struct device *dev,
 							"cros-ec-lid-angle",
 							0);
 		if (ret)
-			goto error;
+			return ret;
 	}
 
-	kfree(msg);
 	return 0;
-
-error:
-	kfree(msg);
-	return ret;
 }
 
 static int cros_ec_sensorhub_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct cros_ec_dev *ec = dev_get_drvdata(dev->parent);
 	struct cros_ec_sensorhub *data;
+	struct cros_ec_command *msg;
 	int ret;
 	int i;
 
+	msg = devm_kzalloc(dev, sizeof(struct cros_ec_command) +
+			   max((u16)sizeof(struct ec_params_motion_sense),
+			       ec->ec_dev->max_response), GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	msg->command = EC_CMD_MOTION_SENSE_CMD + ec->cmd_offset;
+
 	data = devm_kzalloc(dev, sizeof(struct cros_ec_sensorhub), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
-	data->ec = dev_get_drvdata(dev->parent);
+	mutex_init(&data->cmd_lock);
+
+	data->dev = dev;
+	data->ec = ec;
+	data->msg = msg;
+	data->params = (struct ec_params_motion_sense *)msg->data;
+	data->resp = (struct ec_response_motion_sense *)msg->data;
+
 	dev_set_drvdata(dev, data);
 
 	/* Check whether this EC is a sensor hub. */
@@ -180,12 +182,63 @@  static int cros_ec_sensorhub_probe(struct platform_device *pdev)
 		}
 	}
 
+	/*
+	 * If the EC does not have a FIFO, the sensors will query their data
+	 * themselves via sysfs or a software trigger.
+	 */
+	if (cros_ec_check_features(ec, EC_FEATURE_MOTION_SENSE_FIFO)) {
+		ret = cros_ec_sensorhub_ring_add(data);
+		if (ret)
+			return ret;
+		/*
+		 * The msg and its data is not under the control of the ring
+		 * handler.
+		 */
+		return devm_add_action_or_reset(dev,
+						cros_ec_sensorhub_ring_remove,
+						data);
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+/*
+ * When the EC is suspending, we must stop sending interrupt,
+ * we may use the same interrupt line for waking up the device.
+ * Tell the EC to stop sending non-interrupt event on the iio ring.
+ */
+static int cros_ec_sensorhub_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct cros_ec_sensorhub *sensorhub = platform_get_drvdata(pdev);
+	struct cros_ec_dev *ec = sensorhub->ec;
+
+	if (cros_ec_check_features(ec, EC_FEATURE_MOTION_SENSE_FIFO))
+		return cros_ec_sensorhub_ring_fifo_enable(sensorhub, false);
 	return 0;
 }
 
+static int cros_ec_sensorhub_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct cros_ec_sensorhub *sensorhub = platform_get_drvdata(pdev);
+	struct cros_ec_dev *ec = sensorhub->ec;
+
+	if (cros_ec_check_features(ec, EC_FEATURE_MOTION_SENSE_FIFO))
+		return cros_ec_sensorhub_ring_fifo_enable(sensorhub, true);
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(cros_ec_sensorhub_pm_ops,
+		cros_ec_sensorhub_suspend,
+		cros_ec_sensorhub_resume);
+
 static struct platform_driver cros_ec_sensorhub_driver = {
 	.driver = {
 		.name = DRV_NAME,
+		.pm = &cros_ec_sensorhub_pm_ops,
 	},
 	.probe = cros_ec_sensorhub_probe,
 };
diff --git a/drivers/platform/chrome/cros_ec_sensorhub_ring.c b/drivers/platform/chrome/cros_ec_sensorhub_ring.c
new file mode 100644
index 0000000000000..436f306899252
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_sensorhub_ring.c
@@ -0,0 +1,425 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for Chrome OS EC Sensor hub FIFO.
+ *
+ * Copyright 2020 Google LLC
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/iio/iio.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/platform_data/cros_ec_proto.h>
+#include <linux/platform_data/cros_ec_sensorhub.h>
+#include <linux/platform_device.h>
+#include <linux/sort.h>
+#include <linux/slab.h>
+
+static inline int
+cros_sensorhub_send_sample(struct cros_ec_sensorhub *sensorhub,
+			   struct cros_ec_sensors_ring_sample *sample)
+{
+	cros_ec_sensorhub_push_data_cb_t cb;
+	int id = sample->sensor_id;
+	struct iio_dev *indio_dev;
+
+	if (id > CROS_EC_SENSOR_MAX)
+		return -EINVAL;
+
+	cb = sensorhub->push_data[id].push_data_cb;
+	if (!cb)
+		return 0;
+
+	indio_dev = sensorhub->push_data[id].indio_dev;
+
+	if (sample->flag & MOTIONSENSE_SENSOR_FLAG_FLUSH)
+		return 0;
+
+	return cb(indio_dev, sample->vector, sample->timestamp);
+}
+
+/**
+ * cros_ec_sensorhub_register_push_data() - register the callback to the hub.
+ *
+ * @sensorhub : Sensor Hub object
+ * @sensor_num : The sensor the caller is interested in.
+ * @indio_dev : The iio device to use when a sample arrives.
+ * @cb : The callback to call when a sample arrives.
+ *
+ * The callback cb will be used by cros_ec_sensorhub_ring to distribute events
+ * from the EC.
+ *
+ * Return: 0 when callback is registered.
+ *         EINVAL is the sensor number is invalid or the slot already used.
+ */
+int cros_ec_sensorhub_register_push_data(struct cros_ec_sensorhub *sensorhub,
+					 u8 sensor_num,
+					 struct iio_dev *indio_dev,
+					 cros_ec_sensorhub_push_data_cb_t cb)
+{
+	if (sensor_num >= CROS_EC_SENSOR_PDEV_MAX)
+		return -EINVAL;
+	if (sensorhub->push_data[sensor_num].indio_dev)
+		return -EINVAL;
+
+	sensorhub->push_data[sensor_num].indio_dev = indio_dev;
+	sensorhub->push_data[sensor_num].push_data_cb = cb;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cros_ec_sensorhub_register_push_data);
+
+void cros_ec_sensorhub_unregister_push_data(struct cros_ec_sensorhub *sensorhub,
+					    u8 sensor_num)
+{
+	sensorhub->push_data[sensor_num].indio_dev = NULL;
+	sensorhub->push_data[sensor_num].push_data_cb = NULL;
+}
+EXPORT_SYMBOL_GPL(cros_ec_sensorhub_unregister_push_data);
+
+/**
+ * cros_ec_sensorhub_ring_fifo_enable() - Enable or disable interrupt generation
+ *					  for FIFO events.
+ * @sensorhub: Sensor Hub object
+ * @on: true when events are requested.
+ *
+ * To be called before sleeping or when noone is listening.
+ * Return: 0 on success, or an error when we can not communicate with the EC.
+ *
+ */
+int cros_ec_sensorhub_ring_fifo_enable(struct cros_ec_sensorhub *sensorhub,
+				       bool on)
+{
+	int ret;
+
+	mutex_lock(&sensorhub->cmd_lock);
+	sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INT_ENABLE;
+	sensorhub->params->fifo_int_enable.enable = on;
+
+	sensorhub->msg->outsize = sizeof(struct ec_params_motion_sense);
+	sensorhub->msg->insize = sizeof(struct ec_response_motion_sense);
+
+	ret = cros_ec_cmd_xfer_status(sensorhub->ec->ec_dev, sensorhub->msg);
+	mutex_unlock(&sensorhub->cmd_lock);
+
+	/* We expect to receive a payload of 4 bytes, ignore. */
+	if (ret > 0)
+		ret = 0;
+
+	return ret;
+}
+
+/**
+ * cros_ec_sensor_ring_process_event() - process one EC FIFO event
+ *
+ * @sensorhub: Sensor Hub object.
+ * @fifo_info: FIFO information from the EC (includes b point, EC timebase).
+ * @fifo_timestamp: EC IRQ, kernel timebase (aka c).
+ * @current_timestamp: calculated event timestamp, kernel timebase (aka a').
+ * @in: incoming FIFO event from EC (includes a point, EC timebase).
+ * @out: outgoing event to user space (includes a').
+ *
+ * Process one EC event, add it in the ring if necessary.
+ *
+ * Return: true if out event has been populated.
+ */
+static bool
+cros_ec_sensor_ring_process_event(struct cros_ec_sensorhub *sensorhub,
+				  const struct cros_ec_fifo_info *fifo_info,
+				  const ktime_t fifo_timestamp,
+				  ktime_t *current_timestamp,
+				  struct ec_response_motion_sensor_data *in,
+				  struct cros_ec_sensors_ring_sample *out)
+{
+	const s64 now = cros_ec_get_time_ns();
+	int axis, async_flags;
+
+	/* Do not populate the filter based on asynchronous events. */
+	async_flags = in->flags &
+		(MOTIONSENSE_SENSOR_FLAG_ODR | MOTIONSENSE_SENSOR_FLAG_FLUSH);
+
+	if (in->flags & MOTIONSENSE_SENSOR_FLAG_TIMESTAMP && !async_flags) {
+		s64 new_timestamp;
+
+		/*
+		 * Disable filtering since we might add more jitter
+		 * if b is in a random point in time.
+		 */
+		new_timestamp = fifo_timestamp -
+				fifo_info->info.timestamp  * 1000 +
+				in->timestamp * 1000;
+
+		/*
+		 * The timestamp can be stale if we had to use the fifo
+		 * info timestamp.
+		 */
+		if (new_timestamp - *current_timestamp > 0)
+			*current_timestamp = new_timestamp;
+	}
+
+	if (in->flags & MOTIONSENSE_SENSOR_FLAG_FLUSH) {
+		out->sensor_id = in->sensor_num;
+		out->timestamp = *current_timestamp;
+		out->flag = in->flags;
+		/*
+		 * No other payload information provided with
+		 * flush ack.
+		 */
+		return true;
+	}
+
+	if (in->flags & MOTIONSENSE_SENSOR_FLAG_TIMESTAMP)
+		/* If we just have a timestamp, skip this entry. */
+		return false;
+
+	/* Regular sample */
+	out->sensor_id = in->sensor_num;
+	if (*current_timestamp - now > 0)
+		/* If the timestamp is in the future. */
+		out->timestamp = now;
+	else
+		out->timestamp = *current_timestamp;
+
+	out->flag = in->flags;
+	for (axis = 0; axis < 3; axis++)
+		out->vector[axis] = in->data[axis];
+
+	return true;
+}
+
+/**
+ * cros_ec_sensorhub_ring_handler() - The trigger handler function
+ *
+ * @sensorhub: Sensor Hub object.
+ *
+ * Called by the notifier, process the EC sensor FIFO queue.
+ */
+static void cros_ec_sensorhub_ring_handler(struct cros_ec_sensorhub *sensorhub)
+{
+	struct cros_ec_fifo_info *fifo_info = &sensorhub->fifo_info;
+	struct cros_ec_dev *ec = sensorhub->ec;
+	ktime_t fifo_timestamp, current_timestamp;
+	int i, j, number_data, ret;
+	unsigned long sensor_mask = 0;
+	struct ec_response_motion_sensor_data *in;
+	struct cros_ec_sensors_ring_sample *out, *last_out;
+
+	mutex_lock(&sensorhub->cmd_lock);
+
+	/* Get FIFO information if there are lost vectors. */
+	if (fifo_info->info.total_lost) {
+		/* Need to retrieve the number of lost vectors per sensor */
+		sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INFO;
+		sensorhub->msg->outsize = 1;
+		sensorhub->msg->insize =
+			sizeof(struct ec_response_motion_sense_fifo_info) +
+			sizeof(u16) * CROS_EC_SENSOR_MAX;
+
+		if (cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg) < 0)
+			goto error;
+
+		memcpy(fifo_info, &sensorhub->resp->fifo_info,
+		       sizeof(*fifo_info));
+
+		/*
+		 * Update collection time, will not be as precise as the
+		 * non-error case.
+		 */
+		fifo_timestamp = cros_ec_get_time_ns();
+	} else {
+		fifo_timestamp =
+			sensorhub->fifo_timestamp[CROS_EC_SENSOR_NEW_TS];
+	}
+
+	if (fifo_info->info.count > sensorhub->fifo_size ||
+	    fifo_info->info.size != sensorhub->fifo_size) {
+		dev_warn(sensorhub->dev,
+			 "Mismatch EC data: count %d, size %d - expected %d",
+			 fifo_info->info.count, fifo_info->info.size,
+			 sensorhub->fifo_size);
+		goto error;
+	}
+
+	/* Copy elements in the main fifo */
+	current_timestamp = sensorhub->fifo_timestamp[CROS_EC_SENSOR_LAST_TS];
+	out = sensorhub->ring;
+	for (i = 0; i < fifo_info->info.count; i += number_data) {
+		sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_READ;
+		sensorhub->params->fifo_read.max_data_vector =
+			fifo_info->info.count - i;
+		sensorhub->msg->outsize =
+			sizeof(struct ec_params_motion_sense);
+		sensorhub->msg->insize =
+			sizeof(sensorhub->resp->fifo_read) +
+			sensorhub->params->fifo_read.max_data_vector *
+			  sizeof(struct ec_response_motion_sensor_data);
+		ret = cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg);
+		if (ret < 0) {
+			dev_warn(sensorhub->dev, "Fifo error: %d\n", ret);
+			break;
+		}
+		number_data = sensorhub->resp->fifo_read.number_data;
+		if (number_data == 0) {
+			dev_dbg(sensorhub->dev, "Unexpected empty FIFO\n");
+			break;
+		}
+		if (number_data > fifo_info->info.count - i) {
+			dev_warn(sensorhub->dev,
+				 "Invalid EC data: too many entry received: %d, expected %d",
+				 number_data, fifo_info->info.count - i);
+			break;
+		}
+		if (out + number_data >
+		    sensorhub->ring + fifo_info->info.count) {
+			dev_warn(sensorhub->dev,
+				 "Too many samples: %d (%zd data) to %d entries for expected %d entries",
+				 i, out - sensorhub->ring, i + number_data,
+				 fifo_info->info.count);
+			break;
+		}
+
+		for (in = sensorhub->resp->fifo_read.data, j = 0;
+		     j < number_data; j++, in++) {
+			if (cros_ec_sensor_ring_process_event(
+						sensorhub, fifo_info,
+						fifo_timestamp,
+						&current_timestamp,
+						in, out)) {
+				sensor_mask |= BIT(in->sensor_num);
+				out++;
+			}
+		}
+	}
+	mutex_unlock(&sensorhub->cmd_lock);
+	last_out = out;
+
+	if (out == sensorhub->ring)
+		/* Unexpected empty FIFO. */
+		goto ring_handler_end;
+
+	/*
+	 * Check if current_timestamp is ahead of the last sample.
+	 * Normally, the EC appends a timestamp after the last sample, but if
+	 * the AP is slow to respond to the IRQ, the EC may have added new
+	 * samples. Use the FIFO info timestamp as last timestamp then.
+	 */
+	if ((last_out - 1)->timestamp == current_timestamp)
+		current_timestamp = fifo_timestamp;
+
+	/* Warn on lost samples. */
+	for_each_set_bit(i, &sensor_mask, BITS_PER_LONG) {
+		int total_lost = fifo_info->info.total_lost;
+
+		if (total_lost) {
+			int lost = fifo_info->lost[i];
+
+			if (lost) {
+				dev_warn_ratelimited(sensorhub->dev,
+						     "Sensor %d: lost: %d out of %d\n",
+						     i, lost, total_lost);
+			}
+		}
+	}
+
+	/* Push the event into the FIFO. */
+	for (out = sensorhub->ring; out < last_out; out++)
+		cros_sensorhub_send_sample(sensorhub, out);
+
+ring_handler_end:
+	sensorhub->fifo_timestamp[CROS_EC_SENSOR_LAST_TS] = current_timestamp;
+	return;
+
+error:
+	mutex_unlock(&sensorhub->cmd_lock);
+}
+
+static int cros_ec_sensorhub_event(struct notifier_block *nb,
+				   unsigned long queued_during_suspend,
+				   void *_notify)
+{
+	struct cros_ec_sensorhub *sensorhub;
+	struct cros_ec_device *ec_dev;
+
+	sensorhub = container_of(nb, struct cros_ec_sensorhub, notifier);
+	ec_dev = sensorhub->ec->ec_dev;
+
+	if (ec_dev->event_data.event_type != EC_MKBP_EVENT_SENSOR_FIFO)
+		return NOTIFY_DONE;
+
+	if (ec_dev->event_size != sizeof(ec_dev->event_data.data.sensor_fifo)) {
+		dev_warn(ec_dev->dev, "Invalid fifo info size\n");
+		return NOTIFY_DONE;
+	}
+
+	if (queued_during_suspend)
+		return NOTIFY_OK;
+
+	sensorhub->fifo_info.info = ec_dev->event_data.data.sensor_fifo.info;
+	sensorhub->fifo_timestamp[CROS_EC_SENSOR_NEW_TS] =
+		ec_dev->last_event_time;
+	cros_ec_sensorhub_ring_handler(sensorhub);
+
+	return NOTIFY_OK;
+}
+
+/**
+ * cros_ec_sensorhub_ring_add() - Add the FIFO functionality if the EC
+ *				  supports it.
+ *
+ * @sensorhub : Sensor Hub object.
+ *
+ * Return: 0 on success.
+ */
+int cros_ec_sensorhub_ring_add(struct cros_ec_sensorhub *sensorhub)
+{
+	struct cros_ec_dev *ec = sensorhub->ec;
+	int ret;
+
+	/* Retrieve FIFO information */
+	sensorhub->msg->version = 2;
+	sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INFO;
+	sensorhub->msg->outsize = 1;
+	sensorhub->msg->insize =
+		sizeof(struct ec_response_motion_sense_fifo_info) +
+		sizeof(u16) * CROS_EC_SENSOR_MAX;
+
+	ret = cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Allocate the full fifo. We need to copy the whole FIFO to set
+	 * timestamps properly.
+	 */
+	sensorhub->fifo_size = sensorhub->resp->fifo_info.size;
+	sensorhub->ring = devm_kcalloc(sensorhub->dev, sensorhub->fifo_size,
+				       sizeof(*sensorhub->ring), GFP_KERNEL);
+	if (!sensorhub->ring)
+		return -ENOMEM;
+
+	sensorhub->fifo_timestamp[CROS_EC_SENSOR_LAST_TS] =
+		cros_ec_get_time_ns();
+
+	/* Register the notifier that will act as a top half interrupt. */
+	sensorhub->notifier.notifier_call = cros_ec_sensorhub_event;
+	ret = blocking_notifier_chain_register(&ec->ec_dev->event_notifier,
+					       &sensorhub->notifier);
+	if (ret < 0)
+		return ret;
+
+	/* Start collection samples. */
+	return cros_ec_sensorhub_ring_fifo_enable(sensorhub, true);
+}
+
+void cros_ec_sensorhub_ring_remove(void *arg)
+{
+	struct cros_ec_sensorhub *sensorhub = arg;
+	struct cros_ec_device *ec_dev = sensorhub->ec->ec_dev;
+
+	/* Disable the ring, prevent EC interrupt to the AP for nothing. */
+	cros_ec_sensorhub_ring_fifo_enable(sensorhub, false);
+	blocking_notifier_chain_unregister(&ec_dev->event_notifier,
+					   &sensorhub->notifier);
+}
diff --git a/include/linux/platform_data/cros_ec_sensorhub.h b/include/linux/platform_data/cros_ec_sensorhub.h
index bef7ffc7fce10..cb849a2da4f60 100644
--- a/include/linux/platform_data/cros_ec_sensorhub.h
+++ b/include/linux/platform_data/cros_ec_sensorhub.h
@@ -8,8 +8,22 @@ 
 #ifndef __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H
 #define __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H
 
+#include <linux/ktime.h>
+#include <linux/mutex.h>
+#include <linux/notifier.h>
 #include <linux/platform_data/cros_ec_commands.h>
 
+/* Maximal number of sensors supported by the EC. */
+#define CROS_EC_SENSOR_MAX 16
+
+/*
+ * Maximal number of sensors supported by the hub:
+ * We add one for the lid angle inclinometer sensor.
+ */
+#define CROS_EC_SENSOR_PDEV_MAX (CROS_EC_SENSOR_MAX + 1)
+
+struct iio_dev;
+
 /**
  * struct cros_ec_sensor_platform - ChromeOS EC sensor platform information.
  * @sensor_num: Id of the sensor, as reported by the EC.
@@ -18,13 +32,90 @@  struct cros_ec_sensor_platform {
 	u8 sensor_num;
 };
 
+/**
+ * typedef cros_ec_sensorhub_push_data_cb_t - Callback function to send datum
+ *					      to specific sensors.
+ *
+ * @indio_dev: The IIO device that will process the sample.
+ * @data: Vector array of the ring sample.
+ * @timestamp: Timestamp in host timespace when the sample was acquired by
+ *             the EC.
+ */
+typedef int (*cros_ec_sensorhub_push_data_cb_t)(struct iio_dev *indio_dev,
+						s16 *data,
+						s64 timestamp);
+
+struct cros_ec_sensorhub_sensor_push_data {
+	struct iio_dev *indio_dev;
+	cros_ec_sensorhub_push_data_cb_t push_data_cb;
+};
+
+enum {
+	CROS_EC_SENSOR_LAST_TS,
+	CROS_EC_SENSOR_NEW_TS,
+	CROS_EC_SENSOR_ALL_TS
+};
+
+struct __ec_todo_packed cros_ec_fifo_info {
+	struct ec_response_motion_sense_fifo_info info;
+	u16    lost[CROS_EC_SENSOR_MAX];
+};
+
+struct cros_ec_sensors_ring_sample {
+	u8  sensor_id;
+	u8  flag;
+	s16 vector[3];
+	s64 timestamp;
+} __packed;
+
 /**
  * struct cros_ec_sensorhub - Sensor Hub device data.
  *
+ * @dev: Device object, mostly used for logging.
  * @ec: Embedded Controller where the hub is located.
+ * @msg: Structure to send FIFO requests.
+ * @params: Pointer to parameters in msg.
+ * @resp: Pointer to responses in msg.
+ * @cmd_lock : Lock for sending msg.
+ * @notifier: Notifier to kick the FIFO interrupt.
+ * @ring: Preprocessed ring to store events.
+ * @fifo_timestamp: array for event timestamp and spreading.
+ * @fifo_info: copy of FIFO information coming from the EC.
+ * @fifo_size: size of the ring.
+ * @push_data: array of callback to send datums to iio sensor object.
  */
 struct cros_ec_sensorhub {
+	struct device *dev;
 	struct cros_ec_dev *ec;
+
+	struct cros_ec_command *msg;
+	struct ec_params_motion_sense *params;
+	struct ec_response_motion_sense *resp;
+	struct mutex cmd_lock;  /* Lock for protecting msg structure. */
+
+	struct notifier_block notifier;
+
+	struct cros_ec_sensors_ring_sample *ring;
+
+	ktime_t fifo_timestamp[CROS_EC_SENSOR_ALL_TS];
+	struct cros_ec_fifo_info fifo_info;
+	int fifo_size;
+
+	struct cros_ec_sensorhub_sensor_push_data
+		push_data[CROS_EC_SENSOR_PDEV_MAX];
 };
 
+int cros_ec_sensorhub_register_push_data(struct cros_ec_sensorhub *sensorhub,
+					 u8 sensor_num,
+					 struct iio_dev *indio_dev,
+					 cros_ec_sensorhub_push_data_cb_t cb);
+
+void cros_ec_sensorhub_unregister_push_data(struct cros_ec_sensorhub *sensorhub,
+					    u8 sensor_num);
+
+int cros_ec_sensorhub_ring_add(struct cros_ec_sensorhub *sensorhub);
+void cros_ec_sensorhub_ring_remove(void *arg);
+int cros_ec_sensorhub_ring_fifo_enable(struct cros_ec_sensorhub *sensorhub,
+				       bool on);
+
 #endif   /* __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H */