Message-ID: <53497627.3000903@kernel.org>
Date:	Sat, 12 Apr 2014 18:21:43 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
CC:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [Patch v3 5/6] iio: hid-sensors: Added device rotation support

On 09/04/14 01:56, Srinivas Pandruvada wrote:
> Added usage id processing for device rotation. This uses IIO
> interfaces for triggered buffer to present data to user
> mode.This uses HID sensor framework for registering callback
> events from the sensor hub.
> Data is exported to user space in the form of quaternion rotation
> format.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Very nice.  Happy to take this the moment we have a go ahead on
the devm_kmemdup and perhaps those minor tweaks I asked for in the
multi value handling patch.

Actually, may seem a random question, but what the heck are the scale
units you can read for the quaternion?  Firstly it's an integer, so
would only make the value bigger, and secondly we are dealing with
a quaternion, which is inherently scale free (when used for rotation anyway).
I suppose these units might be meant to transform to a unit quaternion
(though this can be easily established form the quaternion itself).

Looking quickly at the other HID drivers, I am a little confused as
to what is going on in general. Could you talk me through this stuff?
I have a vague recollection we went through this before, but can't
recall the result of those discussions.

At first glance, it looks like scale is being used to indicate the
base units (via magic numbers) and offset to contain exponents
to be applied also as magic numbers.  Neither of these is anywhere
near our ABI which is going to cause issues for any 'standard'
userspace library..

Thanks.

Jonathan
> ---
>   drivers/iio/orientation/Kconfig               |  12 +
>   drivers/iio/orientation/Makefile              |   1 +
>   drivers/iio/orientation/hid-sensor-rotation.c | 359 ++++++++++++++++++++++++++
>   include/linux/hid-sensor-ids.h                |   1 +
>   4 files changed, 373 insertions(+)
>   create mode 100644 drivers/iio/orientation/hid-sensor-rotation.c
>
> diff --git a/drivers/iio/orientation/Kconfig b/drivers/iio/orientation/Kconfig
> index 58c62c8..e3aa1e5 100644
> --- a/drivers/iio/orientation/Kconfig
> +++ b/drivers/iio/orientation/Kconfig
> @@ -16,4 +16,16 @@ config HID_SENSOR_INCLINOMETER_3D
>   	  Say yes here to build support for the HID SENSOR
>   	  Inclinometer 3D.
>
> +config HID_SENSOR_DEVICE_ROTATION
> +	depends on HID_SENSOR_HUB
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	select HID_SENSOR_IIO_COMMON
> +	select HID_SENSOR_IIO_TRIGGER
> +	tristate "HID Device Rotation"
> +	help
> +	  Say yes here to build support for the HID SENSOR
> +	  device rotation. The output of a device rotation sensor
> +	  is presented using quaternion format.
> +
>   endmenu
> diff --git a/drivers/iio/orientation/Makefile b/drivers/iio/orientation/Makefile
> index 2c97572..4734dab 100644
> --- a/drivers/iio/orientation/Makefile
> +++ b/drivers/iio/orientation/Makefile
> @@ -4,3 +4,4 @@
>
>   # When adding new entries keep the list in alphabetical order
>   obj-$(CONFIG_HID_SENSOR_INCLINOMETER_3D) += hid-sensor-incl-3d.o
> +obj-$(CONFIG_HID_SENSOR_DEVICE_ROTATION) += hid-sensor-rotation.o
> diff --git a/drivers/iio/orientation/hid-sensor-rotation.c b/drivers/iio/orientation/hid-sensor-rotation.c
> new file mode 100644
> index 0000000..5c7d558
> --- /dev/null
> +++ b/drivers/iio/orientation/hid-sensor-rotation.c
> @@ -0,0 +1,359 @@
> +/*
> + * HID Sensors Driver
> + * Copyright (c) 2014, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/slab.h>
> +#include <linux/hid-sensor-hub.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include "../common/hid-sensors/hid-sensor-trigger.h"
> +
> +struct dev_rot_state {
> +	struct hid_sensor_hub_callbacks callbacks;
> +	struct hid_sensor_common common_attributes;
> +	struct hid_sensor_hub_attribute_info quaternion;
> +	u32 sampled_vals[4];
> +};
> +
> +/* Channel definitions */
> +static const struct iio_chan_spec dev_rot_channels[] = {
> +	{
> +		.type = IIO_ROT,
> +		.modified = 1,
> +		.channel2 = IIO_MOD_QUATERNION,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
> +					BIT(IIO_CHAN_INFO_SAMP_FREQ) |
> +					BIT(IIO_CHAN_INFO_HYSTERESIS) |
> +					BIT(IIO_CHAN_INFO_RAW),
> +	}
> +};
> +
> +/* Adjust channel real bits based on report descriptor */
> +static void dev_rot_adjust_channel_bit_mask(struct iio_chan_spec *chan,
> +						int size)
> +{
> +	chan->scan_type.sign = 's';
> +	/* Real storage bits will change based on the report desc. */
> +	chan->scan_type.realbits = size * 8;
> +	/* Maximum size of a sample to capture is u32 */
> +	chan->scan_type.storagebits = sizeof(u32) * 8;
> +	chan->scan_type.repeat = 4;
> +}
> +
> +/* Channel read_raw handler */
> +static int dev_rot_read_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan,
> +				int size, int *vals, int *val_len,
> +				long mask)
> +{
> +	struct dev_rot_state *rot_state = iio_priv(indio_dev);
> +	int ret_type;
> +	int i;
> +
> +	vals[0] = 0;
> +	vals[1] = 0;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (size >= 4) {
> +			for (i = 0; i < 4; ++i)
> +				vals[i] = rot_state->sampled_vals[i];
> +			ret_type = IIO_VAL_INT_MULTIPLE;
> +			*val_len =  4;
> +		} else
> +			ret_type = -EINVAL;
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		vals[0] = rot_state->quaternion.units;
> +		ret_type = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_OFFSET:
> +		vals[1] = hid_sensor_convert_exponent(
> +			rot_state->quaternion.unit_expo);
> +		ret_type = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret_type = hid_sensor_read_samp_freq_value(
> +			&rot_state->common_attributes, &vals[0], &vals[1]);
> +		break;
> +	case IIO_CHAN_INFO_HYSTERESIS:
> +		ret_type = hid_sensor_read_raw_hyst_value(
> +			&rot_state->common_attributes, &vals[0], &vals[1]);
> +		break;
> +	default:
> +		ret_type = -EINVAL;
> +		break;
> +	}
> +
> +	return ret_type;
> +}
> +
> +/* Channel write_raw handler */
> +static int dev_rot_write_raw(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan,
> +			       int val,
> +			       int val2,
> +			       long mask)
> +{
> +	struct dev_rot_state *rot_state = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret = hid_sensor_write_samp_freq_value(
> +				&rot_state->common_attributes, val, val2);
> +		break;
> +	case IIO_CHAN_INFO_HYSTERESIS:
> +		ret = hid_sensor_write_raw_hyst_value(
> +				&rot_state->common_attributes, val, val2);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct iio_info dev_rot_info = {
> +	.driver_module = THIS_MODULE,
> +	.read_raw_multi = &dev_rot_read_raw,
> +	.write_raw = &dev_rot_write_raw,
> +};
> +
> +/* Function to push data to buffer */
> +static void hid_sensor_push_data(struct iio_dev *indio_dev, u8 *data, int len)
> +{
> +	dev_dbg(&indio_dev->dev, "hid_sensor_push_data >>\n");
> +	iio_push_to_buffers(indio_dev, (u8 *)data);
> +	dev_dbg(&indio_dev->dev, "hid_sensor_push_data <<\n");
> +
> +}
> +
> +/* Callback handler to send event after all samples are received and captured */
> +static int dev_rot_proc_event(struct hid_sensor_hub_device *hsdev,
> +				unsigned usage_id,
> +				void *priv)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(priv);
> +	struct dev_rot_state *rot_state = iio_priv(indio_dev);
> +
> +	dev_dbg(&indio_dev->dev, "dev_rot_proc_event [%d]\n",
> +				rot_state->common_attributes.data_ready);
> +
> +	if (rot_state->common_attributes.data_ready)
> +		hid_sensor_push_data(indio_dev,
> +				(u8 *)rot_state->sampled_vals,
> +				sizeof(rot_state->sampled_vals));
> +
> +	return 0;
> +}
> +
> +/* Capture samples in local storage */
> +static int dev_rot_capture_sample(struct hid_sensor_hub_device *hsdev,
> +				unsigned usage_id,
> +				size_t raw_len, char *raw_data,
> +				void *priv)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(priv);
> +	struct dev_rot_state *rot_state = iio_priv(indio_dev);
> +
> +	if (usage_id == HID_USAGE_SENSOR_ORIENT_QUATERNION) {
> +		memcpy(rot_state->sampled_vals, raw_data,
> +					sizeof(rot_state->sampled_vals));
> +		dev_dbg(&indio_dev->dev, "Recd Quat len:%zu::%zu\n", raw_len,
> +					sizeof(rot_state->sampled_vals));
> +	}
> +
> +	return 0;
> +}
> +
> +/* Parse report which is specific to an usage id*/
> +static int dev_rot_parse_report(struct platform_device *pdev,
> +				struct hid_sensor_hub_device *hsdev,
> +				struct iio_chan_spec *channels,
> +				unsigned usage_id,
> +				struct dev_rot_state *st)
> +{
> +	int ret;
> +
> +	ret = sensor_hub_input_get_attribute_info(hsdev,
> +				HID_INPUT_REPORT,
> +				usage_id,
> +				HID_USAGE_SENSOR_ORIENT_QUATERNION,
> +				&st->quaternion);
> +	if (ret)
> +		return ret;
> +
> +	dev_rot_adjust_channel_bit_mask(&channels[0],
> +		st->quaternion.size / 4);
> +
> +	dev_dbg(&pdev->dev, "dev_rot %x:%x\n", st->quaternion.index,
> +		st->quaternion.report_id);
> +
> +	dev_dbg(&pdev->dev, "dev_rot: attrib size %d\n",
> +				st->quaternion.size);
> +
> +	/* Set Sensitivity field ids, when there is no individual modifier */
> +	if (st->common_attributes.sensitivity.index < 0) {
> +		sensor_hub_input_get_attribute_info(hsdev,
> +			HID_FEATURE_REPORT, usage_id,
> +			HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSITIVITY_ABS |
> +			HID_USAGE_SENSOR_DATA_ORIENTATION,
> +			&st->common_attributes.sensitivity);
> +		dev_dbg(&pdev->dev, "Sensitivity index:report %d:%d\n",
> +			st->common_attributes.sensitivity.index,
> +			st->common_attributes.sensitivity.report_id);
> +	}
> +
> +	return 0;
> +}
> +
> +/* Function to initialize the processing for usage id */
> +static int hid_dev_rot_probe(struct platform_device *pdev)
> +{
> +	int ret;
> +	static char *name = "dev_rotation";
> +	struct iio_dev *indio_dev;
> +	struct dev_rot_state *rot_state;
> +	struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
> +	struct iio_chan_spec *channels;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev,
> +					  sizeof(struct dev_rot_state));
> +	if (indio_dev == NULL)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	rot_state = iio_priv(indio_dev);
> +	rot_state->common_attributes.hsdev = hsdev;
> +	rot_state->common_attributes.pdev = pdev;
> +
> +	ret = hid_sensor_parse_common_attributes(hsdev,
> +				HID_USAGE_SENSOR_DEVICE_ORIENTATION,
> +				&rot_state->common_attributes);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to setup common attributes\n");
> +		return ret;
> +	}
> +
> +	channels = devm_kmemdup(&pdev->dev, dev_rot_channels, sizeof(dev_rot_channels),
> +			   GFP_KERNEL);
> +	if (!channels) {
> +		dev_err(&pdev->dev, "failed to duplicate channels\n");
> +		return -ENOMEM;
> +	}
> +
> +	ret = dev_rot_parse_report(pdev, hsdev, channels,
> +			HID_USAGE_SENSOR_DEVICE_ORIENTATION, rot_state);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to setup attributes\n");
> +		return ret;
> +	}
> +
> +	indio_dev->channels = channels;
> +	indio_dev->num_channels = ARRAY_SIZE(dev_rot_channels);
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->info = &dev_rot_info;
> +	indio_dev->name = name;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
> +		NULL, NULL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to initialize trigger buffer\n");
> +		return ret;
> +	}
> +	rot_state->common_attributes.data_ready = false;
> +	ret = hid_sensor_setup_trigger(indio_dev, name,
> +					&rot_state->common_attributes);
> +	if (ret) {
> +		dev_err(&pdev->dev, "trigger setup failed\n");
> +		goto error_unreg_buffer_funcs;
> +	}
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "device register failed\n");
> +		goto error_remove_trigger;
> +	}
> +
> +	rot_state->callbacks.send_event = dev_rot_proc_event;
> +	rot_state->callbacks.capture_sample = dev_rot_capture_sample;
> +	rot_state->callbacks.pdev = pdev;
> +	ret = sensor_hub_register_callback(hsdev,
> +					HID_USAGE_SENSOR_DEVICE_ORIENTATION,
> +					&rot_state->callbacks);
> +	if (ret) {
> +		dev_err(&pdev->dev, "callback reg failed\n");
> +		goto error_iio_unreg;
> +	}
> +
> +	return 0;
> +
> +error_iio_unreg:
> +	iio_device_unregister(indio_dev);
> +error_remove_trigger:
> +	hid_sensor_remove_trigger(&rot_state->common_attributes);
> +error_unreg_buffer_funcs:
> +	iio_triggered_buffer_cleanup(indio_dev);
> +	return ret;
> +}
> +
> +/* Function to deinitialize the processing for usage id */
> +static int hid_dev_rot_remove(struct platform_device *pdev)
> +{
> +	struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct dev_rot_state *rot_state = iio_priv(indio_dev);
> +
> +	sensor_hub_remove_callback(hsdev, HID_USAGE_SENSOR_DEVICE_ORIENTATION);
> +	iio_device_unregister(indio_dev);
> +	hid_sensor_remove_trigger(&rot_state->common_attributes);
> +	iio_triggered_buffer_cleanup(indio_dev);
> +
> +	return 0;
> +}
> +
> +static struct platform_device_id hid_dev_rot_ids[] = {
> +	{
> +		/* Format: HID-SENSOR-usage_id_in_hex_lowercase */
> +		.name = "HID-SENSOR-20008a",
> +	},
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(platform, hid_dev_rot_ids);
> +
> +static struct platform_driver hid_dev_rot_platform_driver = {
> +	.id_table = hid_dev_rot_ids,
> +	.driver = {
> +		.name	= KBUILD_MODNAME,
> +		.owner	= THIS_MODULE,
> +	},
> +	.probe		= hid_dev_rot_probe,
> +	.remove		= hid_dev_rot_remove,
> +};
> +module_platform_driver(hid_dev_rot_platform_driver);
> +
> +MODULE_DESCRIPTION("HID Sensor Device Rotation");
> +MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/hid-sensor-ids.h b/include/linux/hid-sensor-ids.h
> index 14ead9e..109f0e6 100644
> --- a/include/linux/hid-sensor-ids.h
> +++ b/include/linux/hid-sensor-ids.h
> @@ -76,6 +76,7 @@
>   #define HID_USAGE_SENSOR_ORIENT_TILT_Y				0x200480
>   #define HID_USAGE_SENSOR_ORIENT_TILT_Z				0x200481
>
> +#define HID_USAGE_SENSOR_DEVICE_ORIENTATION			0x20008A
>   #define HID_USAGE_SENSOR_ORIENT_ROTATION_MATRIX			0x200482
>   #define HID_USAGE_SENSOR_ORIENT_QUATERNION			0x200483
>   #define HID_USAGE_SENSOR_ORIENT_MAGN_FLUX			0x200484
>

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