Message-ID: <17d7dc13-93fc-6a26-15cf-ca90d1d3a722@kernel.org>
Date:	Sun, 24 Jul 2016 14:51:18 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Enric Balletbo i Serra <enric.balletbo@...labora.com>,
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Cc:	Olof Johansson <olof@...om.net>, Lee Jones <lee.jones@...aro.org>,
	Hartmut Knaack <knaack.h@....de>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Peter Meerwald-Stadler <pmeerw@...erw.net>,
	Guenter Roeck <groeck@...omium.org>,
	Gwendal Grignou <gwendal@...omium.org>
Subject: Re: [PATCH v2 1/4] iio: cros_ec_sensors_core: Add common functions
 for the ChromeOS EC Sensor Hub.

On 20/07/16 10:22, Enric Balletbo i Serra wrote:
> Add the core functions to be able to support the sensors attached behind
> the ChromeOS Embedded Controller and used by other IIO cros-ec sensor
> drivers.
> 
> The cros_ec_sensor_core driver matches with current driver in ChromeOS
> 4.4 tree, so it includes all the fixes at the moment. The support for
> this driver was made by Gwendal Grignou. The original patch and all the
> fixes has been squashed and rebased on top of mainline.
> 
> Signed-off-by: Gwendal Grignou <gwendal@...omium.org>
> Signed-off-by: Guenter Roeck <groeck@...omium.org>
> [eballetbo: split, squash and rebase on top of mainline the patches
> found in ChromeOS tree]
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
Few minor bits inline.  I'm happy enough with the ABI (except that I would
like a justification for why userspace needs the id one)
We should see if anyone else has comments on that.

The location one may well become more general in future (to cover other
devices).

Jonathan
> ---
> 
> Changes since v1:
>   - Check kernel-doc documentation.
>   - Bring this in as an when you need it in the rest of the series.
>   - Fix some spelling mistakes.
>   - Include ABI documentation.
>   - Be more careful with buffer sizes (sprintf -> snprintf)
>   - Add cros_ec_sensors prefix to all function.
>   - Check return values on some functions.
> 
>  Documentation/ABI/testing/sysfs-bus-iio-cros-ec    |  25 +
>  drivers/iio/common/Kconfig                         |   1 +
>  drivers/iio/common/Makefile                        |   1 +
>  drivers/iio/common/cros_ec_sensors/Kconfig         |  14 +
>  drivers/iio/common/cros_ec_sensors/Makefile        |   5 +
>  .../common/cros_ec_sensors/cros_ec_sensors_core.c  | 505 +++++++++++++++++++++
>  .../common/cros_ec_sensors/cros_ec_sensors_core.h  | 177 ++++++++
>  include/linux/mfd/cros_ec.h                        |   9 +
>  include/linux/mfd/cros_ec_commands.h               |  99 +++-
>  9 files changed, 831 insertions(+), 5 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-cros-ec
>  create mode 100644 drivers/iio/common/cros_ec_sensors/Kconfig
>  create mode 100644 drivers/iio/common/cros_ec_sensors/Makefile
>  create mode 100644 drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
>  create mode 100644 drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-cros-ec b/Documentation/ABI/testing/sysfs-bus-iio-cros-ec
> new file mode 100644
> index 0000000..3e626b6
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-cros-ec
> @@ -0,0 +1,25 @@
> +What:		/sys/bus/iio/devices/iio:deviceX/calibrate
> +Date:		July 2015
> +KernelVersion:	4.7
> +Contact:	linux-iio@...r.kernel.org
> +Description:
> +		Writing '1' will perform a FOC (Fast Online Calibration). The
> +                corresponding calibration offsets can be read from *_calibbias
> +                entries.
This one is fine as far as I'm concerned.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/id
> +Date:		July 2015
> +KernelVersion:	4.7
> +Contact:	linux-iio@...r.kernel.org
> +Description:
> +                The id attribute holds an unique number for the motion sensor
> +                identification, as reported by the ChromeOS Embedded Controller.
Mostly with these, we've just spat the out to the kernel logs as dev_info
during startup.

Any reason this needs to be more explictly exposed to userspace?
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/location
> +Date:		July 2015
> +KernelVersion:	4.7
> +Contact:	linux-iio@...r.kernel.org
> +Description:
> +		This attribute returns a string with the physical location where
> +                the motion sensor is placed. For example, in a laptop a motion
> +                sensor can be located on the base or on the lid.
Interesting...

We'll probably want to ultimately use this one more generally.  This probably
won't be the last sensor where we have some means of finding this out!

Please include a list of possible values in the description.
> \ No newline at end of file
Fix that ;)
> diff --git a/drivers/iio/common/Kconfig b/drivers/iio/common/Kconfig
> index 26a6026..e108996 100644
> --- a/drivers/iio/common/Kconfig
> +++ b/drivers/iio/common/Kconfig
> @@ -2,6 +2,7 @@
>  # IIO common modules
>  #
>  
> +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/ssp_sensors/Kconfig"
> diff --git a/drivers/iio/common/Makefile b/drivers/iio/common/Makefile
> index 585da6a..6fa760e 100644
> --- a/drivers/iio/common/Makefile
> +++ b/drivers/iio/common/Makefile
> @@ -7,6 +7,7 @@
>  #
>  
>  # When adding new entries keep the list in alphabetical order
> +obj-y += cros_ec_sensors/
>  obj-y += hid-sensors/
>  obj-y += ms_sensors/
>  obj-y += ssp_sensors/
> diff --git a/drivers/iio/common/cros_ec_sensors/Kconfig b/drivers/iio/common/cros_ec_sensors/Kconfig
> new file mode 100644
> index 0000000..24743be
> --- /dev/null
> +++ b/drivers/iio/common/cros_ec_sensors/Kconfig
> @@ -0,0 +1,14 @@
> +#
> +# Chrome OS Embedded Controller managed sensors library
> +#
> +config IIO_CROS_EC_SENSORS_CORE
> +	tristate "ChromeOS EC Sensors Core"
> +	depends on SYSFS && MFD_CROS_EC
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	  Base module for the ChromeOS EC Sensors module.
> +	  Contains core functions used by other IIO CrosEC sensor
> +	  drivers.
> +	  Define common attributes and sysfs interrupt handler.
> +
> diff --git a/drivers/iio/common/cros_ec_sensors/Makefile b/drivers/iio/common/cros_ec_sensors/Makefile
> new file mode 100644
> index 0000000..95b6901
> --- /dev/null
> +++ b/drivers/iio/common/cros_ec_sensors/Makefile
> @@ -0,0 +1,5 @@
> +#
> +# Makefile for sensors seen through the ChromeOS EC sensor hub.
> +#
> +
> +obj-$(CONFIG_IIO_CROS_EC_SENSORS_CORE) += cros_ec_sensors_core.o
> diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
> new file mode 100644
> index 0000000..70e3c17
> --- /dev/null
> +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
> @@ -0,0 +1,505 @@
> +/*
> + * cros_ec_sensors_core - Common function for Chrome OS EC sensor driver.
> + *
> + * Copyright (C) 2016 Google, Inc
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/kfifo_buf.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/cros_ec.h>
> +#include <linux/mfd/cros_ec_commands.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +#include <linux/platform_device.h>
> +
> +#include "cros_ec_sensors_core.h"
> +
> +static char *cros_ec_loc[] = {
> +	[MOTIONSENSE_LOC_BASE] = "base",
> +	[MOTIONSENSE_LOC_LID] = "lid",
> +	[MOTIONSENSE_LOC_MAX] = "unknown",
> +};
> +
> +int cros_ec_sensors_core_init(struct platform_device *pdev,
> +			      struct iio_dev *indio_dev,
> +			      bool physical_device)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct cros_ec_sensors_core_state *state = iio_priv(indio_dev);
> +	struct cros_ec_dev *ec = dev_get_drvdata(pdev->dev.parent);
> +	struct cros_ec_sensor_platform *sensor_platform = dev_get_platdata(dev);
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	state->ec = ec->ec_dev;
> +	state->msg = devm_kzalloc(&pdev->dev,
> +				max((u16)sizeof(struct ec_params_motion_sense),
> +				state->ec->max_response), GFP_KERNEL);
> +	if (!state->msg)
> +		return -ENOMEM;
> +
> +	state->resp = (struct ec_response_motion_sense *)state->msg->data;
> +
> +	mutex_init(&state->cmd_lock);
> +
> +	/* Set up the host command structure. */
> +	state->msg->version = 2;
> +	state->msg->command = EC_CMD_MOTION_SENSE_CMD + ec->cmd_offset;
> +	state->msg->outsize = sizeof(struct ec_params_motion_sense);
> +
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->name = pdev->name;
> +
> +	if (physical_device) {
> +		indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +		state->param.cmd = MOTIONSENSE_CMD_INFO;
> +		state->param.info.sensor_num = sensor_platform->sensor_num;
> +		if (cros_ec_motion_send_host_cmd(state, 0)) {
> +			dev_warn(dev, "Can not access sensor info\n");
> +			return -EIO;
> +		}
> +		state->type = state->resp->info.type;
> +		state->loc = state->resp->info.location;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(cros_ec_sensors_core_init);
> +
> +int cros_ec_motion_send_host_cmd(struct cros_ec_sensors_core_state *state,
> +				 u16 opt_length)
> +{
> +	int ret;
> +
> +	if (opt_length)
> +		state->msg->insize = min(opt_length, state->ec->max_response);
> +	else
> +		state->msg->insize = state->ec->max_response;
> +
> +	memcpy(state->msg->data, &state->param, sizeof(state->param));
> +
> +	ret = cros_ec_cmd_xfer_status(state->ec, state->msg);
> +	if (ret < 0)
> +		return -EIO;
> +
> +	if (ret &&
> +	    state->resp != (struct ec_response_motion_sense *)state->msg->data)
> +		memcpy(state->resp, state->msg->data, ret);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(cros_ec_motion_send_host_cmd);
> +
> +static ssize_t cros_ec_sensors_calibrate(struct iio_dev *indio_dev,
> +		uintptr_t private, const struct iio_chan_spec *chan,
> +		const char *buf, size_t len)
> +{
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> +	int ret, i;
> +	bool calibrate;
> +
> +	ret = strtobool(buf, &calibrate);
> +	if (ret < 0)
> +		return ret;
> +	if (!calibrate)
> +		return -EINVAL;
> +
> +	mutex_lock(&st->cmd_lock);
> +	st->param.cmd = MOTIONSENSE_CMD_PERFORM_CALIB;
> +	ret = cros_ec_motion_send_host_cmd(st, 0);
> +	if (ret != 0) {
> +		dev_warn(&indio_dev->dev, "Unable to calibrate sensor\n");
> +	} else {
> +		/* Save values */
> +		for (i = CROS_EC_SENSOR_X; i < CROS_EC_SENSOR_MAX_AXIS; i++)
> +			st->calib[i].offset = st->resp->perform_calib.offset[i];
> +	}
> +	mutex_unlock(&st->cmd_lock);
> +
> +	return ret ? ret : len;
> +}
> +
> +static ssize_t cros_ec_sensors_id(struct iio_dev *indio_dev,
> +		uintptr_t private, const struct iio_chan_spec *chan,
> +		char *buf)
> +{
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> +
> +	return snprintf(buf, PAGE_SIZE, "%d\n", st->param.info.sensor_num);
> +}
> +
> +static ssize_t cros_ec_sensors_loc(struct iio_dev *indio_dev,
> +		uintptr_t private, const struct iio_chan_spec *chan,
> +		char *buf)
> +{
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> +
> +	return snprintf(buf, PAGE_SIZE, "%s\n", cros_ec_loc[st->loc]);
> +}
> +
> +const struct iio_chan_spec_ext_info cros_ec_sensors_ext_info[] = {
> +	{
> +		.name = "calibrate",
> +		.shared = IIO_SHARED_BY_ALL,
> +		.write = cros_ec_sensors_calibrate
> +	},
> +	{
> +		.name = "id",
> +		.shared = IIO_SHARED_BY_ALL,
> +		.read = cros_ec_sensors_id
> +	},
> +	{
> +		.name = "location",
> +		.shared = IIO_SHARED_BY_ALL,
> +		.read = cros_ec_sensors_loc
> +	},
> +	{ },
> +};
> +EXPORT_SYMBOL_GPL(cros_ec_sensors_ext_info);
> +
> +/**
> + * cros_ec_sensors_idx_to_reg - convert index into offset in shared memory
> + * @st:		pointer to state information for device
> + * @idx:	sensor index (should be element of enum sensor_index)
> + *
> + * Return:	address to read at
> + */
> +static unsigned int cros_ec_sensors_idx_to_reg(
> +					struct cros_ec_sensors_core_state *st,
> +					unsigned int idx)
> +{
> +	/*
> +	 * When using LPC interface, only space for 2 Accel and one Gyro.
> +	 * First halfword of MOTIONSENSE_TYPE_ACCEL is used by angle.
> +	 */
> +	if (st->type == MOTIONSENSE_TYPE_ACCEL)
> +		return EC_MEMMAP_ACC_DATA + sizeof(u16) *
> +			(1 + idx + st->param.info.sensor_num *
> +			 CROS_EC_SENSOR_MAX_AXIS);
> +	else
> +		return EC_MEMMAP_GYRO_DATA + sizeof(u16) * idx;
> +}
> +
> +static int cros_ec_sensors_cmd_read_u8(struct cros_ec_device *ec,
> +				       unsigned int offset, u8 *dest)
> +{
> +	return ec->cmd_readmem(ec, offset, 1, dest);
> +}
> +
> +static int cros_ec_sensors_cmd_read_u16(struct cros_ec_device *ec,
> +					 unsigned int offset, u16 *dest)
> +{
> +	__le16 tmp;
> +	int ret = ec->cmd_readmem(ec, offset, 2, &tmp);
> +
> +	*dest = le16_to_cpu(tmp);
> +
> +	return ret;
> +}
> +
> +/**
> + * cros_ec_sensors_read_until_not_busy() - read until is not busy
> + *
> + * @st:	pointer to state information for device
> + *
> + * Read from EC status byte until it reads not busy.
> + * Return: 8-bit status if ok, -errno on failure.
> + */
> +static int cros_ec_sensors_read_until_not_busy(
> +					struct cros_ec_sensors_core_state *st)
> +{
> +	struct cros_ec_device *ec = st->ec;
> +	u8 status;
> +	int ret, attempts = 0;
> +
> +	ret = cros_ec_sensors_cmd_read_u8(ec, EC_MEMMAP_ACC_STATUS, &status);
> +	if (ret < 0)
> +		return ret;
> +
> +	while (status & EC_MEMMAP_ACC_STATUS_BUSY_BIT) {
> +		/* Give up after enough attempts, return error. */
> +		if (attempts++ >= 50)
> +			return -EIO;
> +
> +		/* Small delay every so often. */
> +		if (attempts % 5 == 0)
> +			msleep(25);
> +
> +		ret = cros_ec_sensors_cmd_read_u8(ec, EC_MEMMAP_ACC_STATUS,
> +						  &status);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	return status;
> +}
> +
> +/**
> + * read_ec_sensors_data_unsafe() - read acceleration data from EC shared memory
> + * @indio_dev:	pointer to IIO device
> + * @scan_mask:	bitmap of the sensor indices to scan
> + * @data:	location to store data
> + *
> + * This is the unsafe function for reading the EC data. It does not guarantee
> + * that the EC will not modify the data as it is being read in.
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +static int cros_ec_sensors_read_data_unsafe(struct iio_dev *indio_dev,
> +			 unsigned long scan_mask, s16 *data)
> +{
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> +	struct cros_ec_device *ec = st->ec;
> +	unsigned int i;
> +	int ret;
> +
> +	/* Read all sensors enabled in scan_mask. Each value is 2 bytes. */
> +	for_each_set_bit(i, &scan_mask, indio_dev->masklength) {
> +		ret = cros_ec_sensors_cmd_read_u16(ec,
> +					     cros_ec_sensors_idx_to_reg(st, i),
> +					     data);
> +		if (ret < 0)
> +			return ret;
> +
> +		data++;
> +	}
> +
> +	return 0;
> +}
> +
> +int cros_ec_sensors_read_lpc(struct iio_dev *indio_dev,
> +			     unsigned long scan_mask, s16 *data)
> +{
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> +	struct cros_ec_device *ec = st->ec;
> +	u8 samp_id = 0xff, status = 0;
> +	int ret, attempts = 0;
> +
> +	/*
> +	 * Continually read all data from EC until the status byte after
> +	 * all reads reflects that the EC is not busy and the sample id
> +	 * matches the sample id from before all reads. This guarantees
> +	 * that data read in was not modified by the EC while reading.
> +	 */
> +	while ((status & (EC_MEMMAP_ACC_STATUS_BUSY_BIT |
> +			  EC_MEMMAP_ACC_STATUS_SAMPLE_ID_MASK)) != samp_id) {
> +		/* If we have tried to read too many times, return error. */
> +		if (attempts++ >= 5)
> +			return -EIO;
> +
> +		/* Read status byte until EC is not busy. */
> +		status = cros_ec_sensors_read_until_not_busy(st);
> +		if (status < 0)
> +			return status;
> +
> +		/*
> +		 * Store the current sample id so that we can compare to the
> +		 * sample id after reading the data.
> +		 */
> +		samp_id = status & EC_MEMMAP_ACC_STATUS_SAMPLE_ID_MASK;
> +
> +		/* Read all EC data, format it, and store it into data. */
> +		ret = cros_ec_sensors_read_data_unsafe(indio_dev, scan_mask,
> +						       data);
> +		if (ret < 0)
> +			return ret;
> +
> +		/* Read status byte. */
> +		ret = cros_ec_sensors_cmd_read_u8(ec, EC_MEMMAP_ACC_STATUS,
> +						  &status);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(cros_ec_sensors_read_lpc);
> +
> +int cros_ec_sensors_read_cmd(struct iio_dev *indio_dev,
> +			     unsigned long scan_mask, s16 *data)
> +{
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> +	int ret;
> +	unsigned int i = 0;
> +
> +	/* Read all sensor data through a command. */
> +	st->param.cmd = MOTIONSENSE_CMD_DATA;
> +	ret = cros_ec_motion_send_host_cmd(st, sizeof(st->resp->data));
> +	if (ret != 0) {
> +		dev_warn(&indio_dev->dev, "Unable to read sensor data\n");
> +		return ret;
> +	}
> +
> +	for_each_set_bit(i, &scan_mask, indio_dev->masklength) {
> +		*data = st->resp->data.data[i];
> +		data++;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(cros_ec_sensors_read_cmd);
> +
> +irqreturn_t cros_ec_sensors_capture(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&st->cmd_lock);
> +
> +	/* Clear capture data. */
> +	memset(st->samples, 0, indio_dev->scan_bytes);
> +
> +	/* Read data based on which channels are enabled in scan mask. */
> +	ret = st->read_ec_sensors_data(indio_dev,
> +				       *(indio_dev->active_scan_mask),
> +				       (s16 *)st->samples);
> +	if (ret < 0)
> +		goto done;
> +
> +	iio_push_to_buffers_with_timestamp(indio_dev, st->samples,
> +					   iio_get_time_ns());
The iio_get_time_ns now takes an indio_dev (as we support clock type
selection now).
> +
> +done:
> +	/*
> +	 * Tell the core we are done with this trigger and ready for the
> +	 * next one.
> +	 */
> +	iio_trigger_notify_done(indio_dev->trig);
> +
> +	mutex_unlock(&st->cmd_lock);
> +
> +	return IRQ_HANDLED;
> +}
> +EXPORT_SYMBOL_GPL(cros_ec_sensors_capture);
> +
> +int cros_ec_sensors_core_read(struct cros_ec_sensors_core_state *st,
> +			  struct iio_chan_spec const *chan,
> +			  int *val, int *val2, long mask)
> +{
> +	int ret = IIO_VAL_INT;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		st->param.cmd = MOTIONSENSE_CMD_EC_RATE;
> +		st->param.ec_rate.data =
> +			EC_MOTION_SENSE_NO_VALUE;
> +
> +		if (cros_ec_motion_send_host_cmd(st, 0))
> +			ret = -EIO;
> +		else
> +			*val = st->resp->ec_rate.ret;
> +		break;
> +	case IIO_CHAN_INFO_FREQUENCY:
> +		st->param.cmd = MOTIONSENSE_CMD_SENSOR_ODR;
> +		st->param.sensor_odr.data =
> +			EC_MOTION_SENSE_NO_VALUE;
> +
> +		if (cros_ec_motion_send_host_cmd(st, 0))
> +			ret = -EIO;
> +		else
> +			*val = st->resp->sensor_odr.ret;
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(cros_ec_sensors_core_read);
> +
> +int cros_ec_sensors_core_write(struct cros_ec_sensors_core_state *st,
> +			       struct iio_chan_spec const *chan,
> +			       int val, int val2, long mask)
> +{
> +	int ret = 0;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_FREQUENCY:
> +		st->param.cmd = MOTIONSENSE_CMD_SENSOR_ODR;
> +		st->param.sensor_odr.data = val;
> +
> +		/* Always roundup, so caller gets at least what it asks for. */
> +		st->param.sensor_odr.roundup = 1;
> +
> +		if (cros_ec_motion_send_host_cmd(st, 0))
> +			ret = -EIO;
> +		break;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		st->param.cmd = MOTIONSENSE_CMD_EC_RATE;
> +		st->param.ec_rate.data = val;
> +
> +		if (cros_ec_motion_send_host_cmd(st, 0))
> +			ret = -EIO;
> +		else
> +			st->curr_sampl_freq = val;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(cros_ec_sensors_core_write);
> +
> +static int __maybe_unused cros_ec_sensors_prepare(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> +
> +	if (st->curr_sampl_freq == 0)
> +		return 0;
> +
> +	/*
> +	 * If the sensors are sampled at high frequency, we will not be able to
> +	 * sleep. Set to sampling to a long period if necessary.
> +	 */
> +	if (st->curr_sampl_freq < CROS_EC_MIN_SUSPEND_SAMPLING_FREQUENCY) {
> +		mutex_lock(&st->cmd_lock);
> +		st->param.cmd = MOTIONSENSE_CMD_EC_RATE;
> +		st->param.ec_rate.data = CROS_EC_MIN_SUSPEND_SAMPLING_FREQUENCY;
> +		cros_ec_motion_send_host_cmd(st, 0);
> +		mutex_unlock(&st->cmd_lock);
> +	}
> +
> +	return 0;
> +}
> +
> +static void __maybe_unused cros_ec_sensors_complete(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> +
> +	if (st->curr_sampl_freq == 0)
> +		return;
> +
> +	if (st->curr_sampl_freq < CROS_EC_MIN_SUSPEND_SAMPLING_FREQUENCY) {
> +		mutex_lock(&st->cmd_lock);
> +		st->param.cmd = MOTIONSENSE_CMD_EC_RATE;
> +		st->param.ec_rate.data = st->curr_sampl_freq;
> +		cros_ec_motion_send_host_cmd(st, 0);
> +		mutex_unlock(&st->cmd_lock);
> +	}
> +}
> +
> +MODULE_DESCRIPTION("ChromeOS EC sensor hub core functions");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.h b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.h
> new file mode 100644
> index 0000000..69e09dc
> --- /dev/null
> +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.h
> @@ -0,0 +1,177 @@
> +/*
> + * ChromeOS EC sensor hub
> + *
> + * Copyright (C) 2016 Google, Inc
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef __CROS_EC_SENSORS_CORE_H
> +#define __CROS_EC_SENSORS_CORE_H
> +
> +#include <linux/irqreturn.h>
> +
> +enum {
> +	CROS_EC_SENSOR_X,
> +	CROS_EC_SENSOR_Y,
> +	CROS_EC_SENSOR_Z,
> +	CROS_EC_SENSOR_MAX_AXIS,
> +};
> +
> +/* EC returns sensor values using signed 16 bit registers */
> +#define CROS_EC_SENSOR_BITS 16
> +
> +/*
> + * 4 16 bit channels are allowed.
> + * Good enough for current sensors, they use up to 3 16 bit vectors.
> + */
> +#define CROS_EC_SAMPLE_SIZE  (sizeof(s64) * 2)
> +
> +/* Minimum sampling period to use when device is suspending */
> +#define CROS_EC_MIN_SUSPEND_SAMPLING_FREQUENCY 1000  /* 1 second */
> +
> +/**
> + * struct cros_ec_sensors_core_state - state data for EC sensors IIO driver
> + * @ec:				cros EC device structure
> + * @cmd_lock:			lock used to prevent simultaneous access to the
> + *				commands.
> + * @msg:			cros EC command structure
> + * @param:			motion sensor parameters structure
> + * @resp:			motion sensor response structure
> + * @type:			type of motion sensor
> + * @loc:			location where the motion sensor is placed
> + * @calib:			calibration parameters. Nothe that trigger
> + *				captured data will always provide the calibrated
> + *				data
> + * @samples:			static array to hold data from a single capture.
> + *				For each channel we need 2 bytees, except for
typo : bytes
> + *				the timestamp. The timestamp is always last and
> + *				is always 8-byte aligned.
> + * @read_ec_sensors_data:	function used for accessing sensors values
> + * @cuur_sampl_freq:		current sampling period
> + */
> +struct cros_ec_sensors_core_state {
> +	struct cros_ec_device *ec;
> +	struct mutex cmd_lock;
> +
> +	struct cros_ec_command *msg;
> +	struct ec_params_motion_sense param;
> +	struct ec_response_motion_sense *resp;
> +
> +	enum motionsensor_type type;
> +	enum motionsensor_location loc;
> +
> +	struct calib_data {
> +		s16 offset;
> +	} calib[CROS_EC_SENSOR_MAX_AXIS];
> +
> +	u8 samples[CROS_EC_SAMPLE_SIZE];
> +
> +	int (*read_ec_sensors_data)(struct iio_dev *indio_dev,
> +				    unsigned long scan_mask, s16 *data);
> +
> +	int curr_sampl_freq;
> +};
> +
> +/**
> + * cros_ec_sensors_read_lpc() - retrieve data from EC shared memory
> + * @indio_dev:	pointer to IIO device
> + * @scan_mask:	bitmap of the sensor indices to scan
> + * @data:	location to store data
> + *
> + * This is the safe function for reading the EC data. It guarantees that the
> + * data sampled was not modified by the EC while being read.
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +int cros_ec_sensors_read_lpc(struct iio_dev *indio_dev, unsigned long scan_mask,
> +			     s16 *data);
> +
> +/**
> + * cros_ec_sensors_read_cmd() - retrieve data using the EC command protocol
> + * @indio_dev:	pointer to IIO device
> + * @scan_mask:	bitmap of the sensor indices to scan
> + * @data:	location to store data
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +int cros_ec_sensors_read_cmd(struct iio_dev *indio_dev, unsigned long scan_mask,
> +			     s16 *data);
> +
> +/**
> + * cros_ec_sensors_core_init() - basic initialization of the core structure
> + * @pdev:		platform device created for the sensors
> + * @indio_dev:		iio device structure of the device
> + * @physical_device:	true if the device refers to a physical device
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +int cros_ec_sensors_core_init(struct platform_device *pdev,
> +			      struct iio_dev *indio_dev, bool physical_device);
> +
> +/**
> + * cros_ec_sensors_capture() - the trigger handler function
> + * @irq:	the interrupt number.
> + * @p:		a pointer to the poll function.
> + *
> + * On a trigger event occurring, if the pollfunc is attached then this
> + * handler is called as a threaded interrupt (and hence may sleep). It
> + * is responsible for grabbing data from the device and pushing it into
> + * the associated buffer.
> + *
> + * Return: IRQ_HANDLED
> + */
> +irqreturn_t cros_ec_sensors_capture(int irq, void *p);
> +
> +/**
> + * cros_ec_motion_send_host_cmd() - send motion sense host command
> + * @st:		pointer to state information for device
> + * @opt_length:	optional length to reduce the response size, useful on the data
> + *		path. Otherwise, the maximal allowed response size is used
> + *
> + * When called, the sub-command is assumed to be set in param->cmd.
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +int cros_ec_motion_send_host_cmd(struct cros_ec_sensors_core_state *st,
> +				 u16 opt_length);
> +
> +/**
> + * cros_ec_sensors_core_read() - function to request a value from the sensor
> + * @st:		pointer to state information for device
> + * @chan:	channel specification structure table
> + * @val:	will contain one element making up the returned value
> + * @val2:	will contain another element making up the returned value
> + * @mask:	specifies which values to be requested
> + *
> + * Return:	the type of value returned by the device
> + */
> +int cros_ec_sensors_core_read(struct cros_ec_sensors_core_state *st,
> +			      struct iio_chan_spec const *chan,
> +			      int *val, int *val2, long mask);
> +
> +/**
> + * cros_ec_sensors_core_write() - function to write a value to the sensor
> + * @st:		pointer to state information for device
> + * @chan:	channel specification structure table
> + * @val:	first part of value to write
> + * @val2:	second part of value to write
> + * @mask:	specifies which values to write
> + *
> + * Return:	the type of value returned by the device
> + */
> +int cros_ec_sensors_core_write(struct cros_ec_sensors_core_state *st,
> +			       struct iio_chan_spec const *chan,
> +			       int val, int val2, long mask);
> +
> +/* List of extended channel specification for all sensors */
> +extern const struct iio_chan_spec_ext_info cros_ec_sensors_ext_info[];
> +
> +#endif  /* __CROS_EC_SENSORS_CORE_H */
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index d6539c1..7769ea6 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -151,6 +151,15 @@ struct cros_ec_device {
>  	int event_size;
>  };
>  
> +/**
> + * struct cros_ec_sensor_platform - ChromeOS EC sensor platform information
> + *
> + * @sensor_num: Id of the sensor, as reported by the EC.
> + */
> +struct cros_ec_sensor_platform {
> +	u8 sensor_num;
> +};
> +
>  /* struct cros_ec_platform - ChromeOS EC platform information
>   *
>   * @ec_name: name of EC device (e.g. 'cros-ec', 'cros-pd', ...)
> diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h
> index 76728ff..8826e0f 100644
> --- a/include/linux/mfd/cros_ec_commands.h
> +++ b/include/linux/mfd/cros_ec_commands.h
> @@ -1315,6 +1315,24 @@ enum motionsense_command {
>  	 */
>  	MOTIONSENSE_CMD_KB_WAKE_ANGLE = 5,
>  
> +	/*
> +	 * Returns a single sensor data.
> +	 */
> +	MOTIONSENSE_CMD_DATA = 6,
> +
> +	/*
> +	 * Perform low level calibration.. On sensors that support it, ask to
> +	 * do offset calibration.
> +	 */
> +	MOTIONSENSE_CMD_PERFORM_CALIB = 10,
> +
> +	/*
> +	 * Sensor Offset command is a setter/getter command for the offset used
> +	 * for calibration. The offsets can be calculated by the host, or via
> +	 * PERFORM_CALIB command.
> +	 */
> +	MOTIONSENSE_CMD_SENSOR_OFFSET = 11,
> +
>  	/* Number of motionsense sub-commands. */
>  	MOTIONSENSE_NUM_CMDS
>  };
> @@ -1335,12 +1353,18 @@ enum motionsensor_id {
>  enum motionsensor_type {
>  	MOTIONSENSE_TYPE_ACCEL = 0,
>  	MOTIONSENSE_TYPE_GYRO = 1,
> +	MOTIONSENSE_TYPE_MAG = 2,
> +	MOTIONSENSE_TYPE_PROX = 3,
> +	MOTIONSENSE_TYPE_LIGHT = 4,
> +	MOTIONSENSE_TYPE_ACTIVITY = 5,
> +	MOTIONSENSE_TYPE_MAX
>  };
>  
>  /* List of motion sensor locations. */
>  enum motionsensor_location {
>  	MOTIONSENSE_LOC_BASE = 0,
>  	MOTIONSENSE_LOC_LID = 1,
> +	MOTIONSENSE_LOC_MAX,
>  };
>  
>  /* List of motion sensor chips. */
> @@ -1361,6 +1385,31 @@ enum motionsensor_chip {
>   */
>  #define EC_MOTION_SENSE_NO_VALUE -1
>  
> +#define EC_MOTION_SENSE_INVALID_CALIB_TEMP 0x8000
> +
> +/* Set Calibration information */
> +#define MOTION_SENSE_SET_OFFSET	1
> +
> +struct ec_response_motion_sensor_data {
> +	/* Flags for each sensor. */
> +	uint8_t flags;
> +	/* Sensor number the data comes from */
> +	uint8_t sensor_num;
> +	/* Each sensor is up to 3-axis. */
> +	union {
> +		int16_t             data[3];
> +		struct {
> +			uint16_t    rsvd;
> +			uint32_t    timestamp;
> +		} __packed;
> +		struct {
> +			uint8_t     activity; /* motionsensor_activity */
> +			uint8_t     state;
> +			int16_t     add_info[2];
> +		};
> +	};
> +} __packed;
> +
>  struct ec_params_motion_sense {
>  	uint8_t cmd;
>  	union {
> @@ -1378,9 +1427,37 @@ struct ec_params_motion_sense {
>  			int16_t data;
>  		} ec_rate, kb_wake_angle;
>  
> +		/* Used for MOTIONSENSE_CMD_SENSOR_OFFSET */
> +		struct {
> +			uint8_t sensor_num;
> +
> +			/*
> +			 * bit 0: If set (MOTION_SENSE_SET_OFFSET), set
> +			 * the calibration information in the EC.
> +			 * If unset, just retrieve calibration information.
> +			 */
> +			uint16_t flags;
> +
> +			/*
> +			 * Temperature at calibration, in units of 0.01 C
> +			 * 0x8000: invalid / unknown.
> +			 * 0x0: 0C
> +			 * 0x7fff: +327.67C
> +			 */
> +			int16_t temp;
> +
> +			/*
> +			 * Offset for calibration.
> +			 * Unit:
> +			 * Accelerometer: 1/1024 g
> +			 * Gyro:          1/1024 deg/s
> +			 * Compass:       1/16 uT
> +			 */
> +			int16_t offset[3];
> +		} __packed sensor_offset;
> +
>  		/* Used for MOTIONSENSE_CMD_INFO. */
>  		struct {
> -			/* Should be element of enum motionsensor_id. */
>  			uint8_t sensor_num;
>  		} info;
>  
> @@ -1410,11 +1487,14 @@ struct ec_response_motion_sense {
>  			/* Flags representing the motion sensor module. */
>  			uint8_t module_flags;
>  
> -			/* Flags for each sensor in enum motionsensor_id. */
> -			uint8_t sensor_flags[EC_MOTION_SENSOR_COUNT];
> +			/* Number of sensors managed directly by the EC. */
> +			uint8_t sensor_count;
>  
> -			/* Array of all sensor data. Each sensor is 3-axis. */
> -			int16_t data[3*EC_MOTION_SENSOR_COUNT];
> +			/*
> +			 * Sensor data is truncated if response_max is too small
> +			 * for holding all the data.
> +			 */
> +			struct ec_response_motion_sensor_data sensor[0];
>  		} dump;
>  
>  		/* Used for MOTIONSENSE_CMD_INFO. */
> @@ -1429,6 +1509,9 @@ struct ec_response_motion_sense {
>  			uint8_t chip;
>  		} info;
>  
> +		/* Used for MOTIONSENSE_CMD_DATA */
> +		struct ec_response_motion_sensor_data data;
> +
>  		/*
>  		 * Used for MOTIONSENSE_CMD_EC_RATE, MOTIONSENSE_CMD_SENSOR_ODR,
>  		 * MOTIONSENSE_CMD_SENSOR_RANGE, and
> @@ -1438,6 +1521,12 @@ struct ec_response_motion_sense {
>  			/* Current value of the parameter queried. */
>  			int32_t ret;
>  		} ec_rate, sensor_odr, sensor_range, kb_wake_angle;
> +
> +		/* Used for MOTIONSENSE_CMD_SENSOR_OFFSET */
> +		struct {
> +			int16_t temp;
> +			int16_t offset[3];
> +		} sensor_offset, perform_calib;
>  	};
>  } __packed;
>  
> 

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