Date:	Mon, 18 Jul 2016 17:09:17 +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 05/10] iio: cros_ec_sensors: add ChromeOS EC Contiguous
 Sensors driver

On 18/07/16 08:02, Enric Balletbo i Serra wrote:
> Handle 3d contiguous sensors like Accelerometers, Gyroscope and
> Magnetometer that are presented by the ChromeOS EC Sensor hub.
> 
> Signed-off-by: Guenter Roeck <groeck@...omium.org>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
Various nitpicks inline.

Jonathan
> ---
>  drivers/iio/common/cros_ec_sensors/Kconfig         |   8 +
>  drivers/iio/common/cros_ec_sensors/Makefile        |   1 +
>  .../iio/common/cros_ec_sensors/cros_ec_sensors.c   | 322 +++++++++++++++++++++
>  3 files changed, 331 insertions(+)
>  create mode 100644 drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
> 
> diff --git a/drivers/iio/common/cros_ec_sensors/Kconfig b/drivers/iio/common/cros_ec_sensors/Kconfig
> index a30f41e..18002d6 100644
> --- a/drivers/iio/common/cros_ec_sensors/Kconfig
> +++ b/drivers/iio/common/cros_ec_sensors/Kconfig
> @@ -12,3 +12,11 @@ config IIO_CROS_EC_SENSORS_CORE
>  	  driver.
>  	  Define common attributes and sysfs interrupt handler.
>  
> +config IIO_CROS_EC_SENSORS
> +	tristate "ChromeOS EC Contiguous Sensors"
> +	select IIO_CROS_EC_SENSORS_CORE
> +	help
> +	  Module to handle 3d contiguous sensors like
> +	  Accelerometers, Gyroscope and Magnetometer that are
> +	  presented by the ChromeOS EC Sensor hub.
> +	  Creates an IIO device for each functions.
> diff --git a/drivers/iio/common/cros_ec_sensors/Makefile b/drivers/iio/common/cros_ec_sensors/Makefile
> index 95b6901..ec716ff 100644
> --- a/drivers/iio/common/cros_ec_sensors/Makefile
> +++ b/drivers/iio/common/cros_ec_sensors/Makefile
> @@ -3,3 +3,4 @@
>  #
>  
>  obj-$(CONFIG_IIO_CROS_EC_SENSORS_CORE) += cros_ec_sensors_core.o
> +obj-$(CONFIG_IIO_CROS_EC_SENSORS) += cros_ec_sensors.o
> diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
> new file mode 100644
> index 0000000..4741118
> --- /dev/null
> +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
> @@ -0,0 +1,322 @@
> +/*
> + * cros_ec_sensors - Driver for Chrome OS Embedded Controller sensors.
> + *
> + * Copyright (C) 2015 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.
> + *
> + * This driver uses the cros-ec interface to communicate with the Chrome OS
> + * EC about accelerometer data. Accelerometer access is presented through
> + * iio sysfs.
> + */
> +
> +#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/iio/triggered_buffer.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"
> +
> +#define MAX_CHANNELS (MAX_AXIS + 1)
Really needs a prefix - chances of another define for MAX_CHANNELS in an
included header is way too high!
Same for MAX_AXIS etc...  Basically prefix everything and you'll have it
about right...
> +
> +/* State data for ec_sensors iio driver. */
> +struct cros_ec_sensors_state {
> +	/* Shared by all sensors */
> +	struct cros_ec_sensors_core_state core;
> +
> +	struct iio_chan_spec channels[MAX_CHANNELS];
> +};
> +
> +static int cros_ec_sensors_read(struct iio_dev *indio_dev,
> +			  struct iio_chan_spec const *chan,
> +			  int *val, int *val2, long mask)
> +{
> +	struct cros_ec_sensors_state *st = iio_priv(indio_dev);
> +	s16 data = 0;
> +	s64 val64;
> +	int i;
> +	int ret = IIO_VAL_INT;
> +	int idx = chan->scan_index;
> +
> +	mutex_lock(&st->core.cmd_lock);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (st->core.read_ec_sensors_data(indio_dev,
> +						  1 << idx, &data) < 0)
> +			ret = -EIO;
Never get any useful errors in from the function?  Seems like you are eating
it if there is.
> +		*val = data;
> +		break;
> +	case IIO_CHAN_INFO_CALIBBIAS:
> +		st->core.param.cmd = MOTIONSENSE_CMD_SENSOR_OFFSET;
> +		st->core.param.sensor_offset.flags = 0;
> +
> +		if (cros_ec_motion_send_host_cmd(&st->core, 0)) {
< 0 for consistency?
> +			ret = -EIO;
> +			break;
> +		}
> +
> +		/* Save values */
> +		for (i = X; i < MAX_AXIS; i++)
> +			st->core.calib[i].offset =
> +				st->core.resp->sensor_offset.offset[i];
> +
> +		*val = st->core.calib[idx].offset;
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		st->core.param.cmd = MOTIONSENSE_CMD_SENSOR_RANGE;
> +		st->core.param.sensor_range.data =
> +			EC_MOTION_SENSE_NO_VALUE;
> +
> +		if (cros_ec_motion_send_host_cmd(&st->core, 0)) {
> +			ret = -EIO;
> +			break;
> +		}
> +		val64 = st->core.resp->sensor_range.ret;
> +		switch (st->core.type) {
> +		case MOTIONSENSE_TYPE_ACCEL:
> +			/*
> +			 * EC returns data in g, iio exepects m/s^2.
> +			 * Do not use IIO_G_TO_M_S_2 to avoid precision loss.
> +			 */
> +			*val = div_s64(val64 * 980665, 10);
> +			*val2 = 10000 << (CROS_EC_SENSOR_BITS - 1);
> +			ret = IIO_VAL_FRACTIONAL;
> +			break;
> +		case MOTIONSENSE_TYPE_GYRO:
> +			/* EC returns date in dps, iio expects rad/s.
Fixup any multiline comment syntax issues please.
> +			 * Do not use IIO_DEGREE_TO_RAD to avoid precision
> +			 * loss. Round to the nearest integer.
> +			 */
> +			*val = div_s64(val64 * 314159 + 9000000ULL, 1000);
> +			*val2 = 18000 << (CROS_EC_SENSOR_BITS - 1);
> +			ret = IIO_VAL_FRACTIONAL;
> +			break;
> +		case MOTIONSENSE_TYPE_MAG:
> +			/*
> +			 * EC returns date in 16LSB / uT,
> +			 * iio expects Gauss
> +			 */
> +			*val = val64;
> +			*val2 = 100 << (CROS_EC_SENSOR_BITS - 1);
> +			ret = IIO_VAL_FRACTIONAL;
> +			break;
> +		default:
> +			ret = -EINVAL;
> +		}
> +		break;
> +	default:
> +		ret = cros_ec_sensors_core_read(
> +				&st->core, chan, val, val2, mask);
> +		break;
> +	}
> +	mutex_unlock(&st->core.cmd_lock);
> +	return ret;
> +}
> +
> +static int cros_ec_sensors_write(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan,
> +			       int val, int val2, long mask)
> +{
> +	struct cros_ec_sensors_state *st = iio_priv(indio_dev);
> +	int i;
> +	int ret = 0;
> +	int idx = chan->scan_index;
> +
> +	mutex_lock(&st->core.cmd_lock);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_CALIBBIAS:
> +		st->core.calib[idx].offset = val;
Spacing wise I'd expect a blank line here as I think this refers to the
stuff below.

> +		/* Send to EC for each axis, even if not complete */
> +
> +		st->core.param.cmd = MOTIONSENSE_CMD_SENSOR_OFFSET;
> +		st->core.param.sensor_offset.flags =
> +			MOTION_SENSE_SET_OFFSET;
> +		for (i = X; i < MAX_AXIS; i++)
> +			st->core.param.sensor_offset.offset[i] =
> +				st->core.calib[i].offset;
> +		st->core.param.sensor_offset.temp =
> +			EC_MOTION_SENSE_INVALID_CALIB_TEMP;
> +
> +		if (cros_ec_motion_send_host_cmd(&st->core, 0))
> +			ret = -EIO;
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		if (st->core.type == MOTIONSENSE_TYPE_MAG) {
> +			ret = -EINVAL;
> +			break;
> +		}
> +		st->core.param.cmd = MOTIONSENSE_CMD_SENSOR_RANGE;
> +		st->core.param.sensor_range.data = val;
> +
> +		/* Always roundup, so caller gets at least what it asks for. */
> +		st->core.param.sensor_range.roundup = 1;
> +
> +		if (cros_ec_motion_send_host_cmd(&st->core, 0))
> +			ret = -EIO;
> +		break;
> +	default:
> +		ret = cros_ec_sensors_core_write(
> +				&st->core, chan, val, val2, mask);
> +		break;
> +	}
> +
> +	mutex_unlock(&st->core.cmd_lock);
> +	return ret;
> +}
> +
> +static const struct iio_info ec_sensors_info = {
> +	.read_raw = &cros_ec_sensors_read,
> +	.write_raw = &cros_ec_sensors_write,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int cros_ec_sensors_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
> +	struct cros_ec_device *ec_device;
> +	struct iio_dev *indio_dev;
> +	struct cros_ec_sensors_state *state;
> +	struct iio_chan_spec *channel;
> +	int ret, i;
> +
> +	if (!ec_dev || !ec_dev->ec_dev) {
> +		dev_warn(&pdev->dev, "No CROS EC device found.\n");
> +		return -EINVAL;
> +	}
> +	ec_device = ec_dev->ec_dev;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*state));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->info = &ec_sensors_info;
> +	state = iio_priv(indio_dev);
> +	for (channel = state->channels, i = X; i < MAX_AXIS; i++, channel++) {
> +		/* common part */
> +		channel->info_mask_separate =
> +			BIT(IIO_CHAN_INFO_RAW) |
> +			BIT(IIO_CHAN_INFO_CALIBBIAS);
> +		channel->info_mask_shared_by_all =
> +			BIT(IIO_CHAN_INFO_SCALE) |
> +			BIT(IIO_CHAN_INFO_FREQUENCY) |
> +			BIT(IIO_CHAN_INFO_SAMP_FREQ);
> +		channel->scan_type.realbits = CROS_EC_SENSOR_BITS;
> +		channel->scan_type.storagebits = CROS_EC_SENSOR_BITS;
> +		channel->scan_type.shift = 0;
> +		channel->scan_index = i;
> +		channel->ext_info = cros_ec_sensors_ext_info;
> +		channel->modified = 1;
> +		channel->channel2 = IIO_MOD_X + i;
> +		channel->scan_type.sign = 's';
> +
> +		state->core.calib[i].offset = 0;
> +
> +		/* sensor specific */
> +		switch (state->core.type) {
> +		case MOTIONSENSE_TYPE_ACCEL:
> +			channel->type = IIO_ACCEL;
> +			break;
> +		case MOTIONSENSE_TYPE_GYRO:
> +			channel->type = IIO_ANGL_VEL;
> +			break;
> +		case MOTIONSENSE_TYPE_MAG:
> +			channel->type = IIO_MAGN;
> +			break;
> +		default:
> +			dev_warn(&pdev->dev, "unknown\n");
> +		}
> +	}
> +
> +	/* Timestamp */
> +	channel->type = IIO_TIMESTAMP;
> +	channel->channel = -1;
> +	channel->scan_index = MAX_AXIS;
> +	channel->scan_type.sign = 's';
> +	channel->scan_type.realbits = 64;
> +	channel->scan_type.storagebits = 64;
> +
> +	indio_dev->channels = state->channels;
> +	indio_dev->num_channels = MAX_CHANNELS;
This needs to be precisely the number of channels, so a generic value called
MAX_CHANNELS seems a little wrong.  If it's always 4, then just put a 4 here
(guessing!)
> +
> +	/* There is only enough room for accel and gyro in the io space */
*laughs* - genious ;)
> +	if ((state->core.ec->cmd_readmem != NULL) &&
> +	    (state->core.type != MOTIONSENSE_TYPE_MAG))
> +		state->core.read_ec_sensors_data = cros_ec_sensors_read_lpc;
> +	else
> +		state->core.read_ec_sensors_data = cros_ec_sensors_read_cmd;
> +
> +	ret = iio_triggered_buffer_setup(indio_dev, NULL,
> +					 cros_ec_sensors_capture, NULL);
> +	if (ret)
> +		return ret;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret)
> +		goto error_uninit_buffer;
> +	return 0;
> +
> +error_uninit_buffer:
> +	iio_triggered_buffer_cleanup(indio_dev);
> +	return ret;
> +}
> +
> +static int cros_ec_sensors_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +
> +	iio_device_unregister(indio_dev);
> +	iio_triggered_buffer_cleanup(indio_dev);
blank line here preferred (and in similar locations).

> +	return 0;
> +}
> +
> +static const struct platform_device_id cros_ec_sensors_ids[] = {
> +	{
> +		.name = "cros-ec-accel",
> +	},
> +	{
> +		.name = "cros-ec-gyro",
> +	},
> +	{
> +		.name = "cros-ec-mag",
> +	},
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(platform, cros_ec_sensors_ids);
> +
> +static struct platform_driver cros_ec_sensors_platform_driver = {
> +	.driver = {
> +		.name	= "cros-ec-sensors",
> +		.pm	= &cros_ec_sensors_pm_ops,
> +	},
> +	.probe		= cros_ec_sensors_probe,
> +	.remove		= cros_ec_sensors_remove,
> +	.id_table	= cros_ec_sensors_ids,
> +};
> +module_platform_driver(cros_ec_sensors_platform_driver);
> +
> +MODULE_DESCRIPTION("ChromeOS EC 3-axis sensors driver");
> +MODULE_LICENSE("GPL v2");
> 

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