Re: [PATCH 8/8] iio: position: Add support for Azoteq IQS624/625 angle sensor

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 20 Oct 2019 23:11:23 -0500
Jeff LaBundy <jeff@labundy.com> wrote:

> This patch adds support for the Azoteq IQS624 and IQS625 angular position
> sensors, capable of reporting the angle of a rotating shaft down to 1 and
> 10 degrees of accuracy, respectively.
> 
> This patch also introduces a home for linear and angular position sensors.
> Unlike resolvers, they are typically contactless and use the Hall effect.
Hmm. I wonder if it makes sense to just move the resolvers into this directory
and not maintain the distinction.  Guess we can do that in the future if we
feel like it! :)

This one looks good to me.

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

I'm assuming these will all go through mfd and an immutable branch once
everyone is happy.

Thanks,

Jonathan

> 
> Signed-off-by: Jeff LaBundy <jeff@labundy.com>
> ---
>  drivers/iio/Kconfig               |   1 +
>  drivers/iio/Makefile              |   1 +
>  drivers/iio/position/Kconfig      |  19 +++
>  drivers/iio/position/Makefile     |   7 +
>  drivers/iio/position/iqs624-pos.c | 302 ++++++++++++++++++++++++++++++++++++++
>  5 files changed, 330 insertions(+)
>  create mode 100644 drivers/iio/position/Kconfig
>  create mode 100644 drivers/iio/position/Makefile
>  create mode 100644 drivers/iio/position/iqs624-pos.c
> 
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 5bd5185..d5c073a 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -88,6 +88,7 @@ source "drivers/iio/orientation/Kconfig"
>  if IIO_TRIGGER
>     source "drivers/iio/trigger/Kconfig"
>  endif #IIO_TRIGGER
> +source "drivers/iio/position/Kconfig"
>  source "drivers/iio/potentiometer/Kconfig"
>  source "drivers/iio/potentiostat/Kconfig"
>  source "drivers/iio/pressure/Kconfig"
> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
> index bff682a..1712011 100644
> --- a/drivers/iio/Makefile
> +++ b/drivers/iio/Makefile
> @@ -31,6 +31,7 @@ obj-y += light/
>  obj-y += magnetometer/
>  obj-y += multiplexer/
>  obj-y += orientation/
> +obj-y += position/
>  obj-y += potentiometer/
>  obj-y += potentiostat/
>  obj-y += pressure/
> diff --git a/drivers/iio/position/Kconfig b/drivers/iio/position/Kconfig
> new file mode 100644
> index 0000000..ed9f975
> --- /dev/null
> +++ b/drivers/iio/position/Kconfig
> @@ -0,0 +1,19 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# Linear and angular position sensors
> +#
> +# When adding new entries keep the list in alphabetical order
> +
> +menu "Linear and angular position sensors"
> +
> +config IQS624_POS
> +	tristate "Azoteq IQS624/625 angular position sensor"
> +	depends on MFD_IQS62X
> +	help
> +	  Say Y here if you want to build support for the Azoteq IQS624
> +	  and IQS625 angular position sensors.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called iqs624-pos.
> +
> +endmenu
> diff --git a/drivers/iio/position/Makefile b/drivers/iio/position/Makefile
> new file mode 100644
> index 0000000..3cbe7a7
> --- /dev/null
> +++ b/drivers/iio/position/Makefile
> @@ -0,0 +1,7 @@
> +#
> +# Makefile for IIO linear and angular position sensors
> +#
> +
> +# When adding new entries keep the list in alphabetical order
> +
> +obj-$(CONFIG_IQS624_POS)	+= iqs624-pos.o
> diff --git a/drivers/iio/position/iqs624-pos.c b/drivers/iio/position/iqs624-pos.c
> new file mode 100644
> index 0000000..d975065
> --- /dev/null
> +++ b/drivers/iio/position/iqs624-pos.c
> @@ -0,0 +1,302 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Azoteq IQS624/625 Angular Position Sensor
> + *
> + * Copyright (C) 2019
> + * Author: Jeff LaBundy <jeff@labundy.com>
> + */
> +
> +#include <linux/device.h>
> +#include <linux/iio/events.h>
> +#include <linux/iio/iio.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/iqs62x.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/notifier.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#define IQS624_POS_DEG_OUT			0x16
> +
> +#define IQS624_POS_SCALE1			(314159 / 180)
> +#define IQS624_POS_SCALE2			100000
> +
> +struct iqs624_pos_private {
> +	struct iqs62x_core *iqs62x;
> +	struct notifier_block notifier;
> +	struct mutex lock;
> +	bool event_en;
> +	union {
> +		u16 angle;
> +		u8 interval;
> +	};
> +};
> +
> +static int iqs624_pos_init(struct iqs624_pos_private *iqs624_pos)
> +{
> +	struct iqs62x_core *iqs62x = iqs624_pos->iqs62x;
> +	unsigned int val;
> +	int error;
> +	__le16 val_buf;
> +
> +	if (iqs62x->dev_desc->prod_num == IQS624_PROD_NUM) {
> +		error = regmap_raw_read(iqs62x->map, IQS624_POS_DEG_OUT,
> +					&val_buf, sizeof(val_buf));
> +		if (error)
> +			return error;
> +
> +		iqs624_pos->angle = le16_to_cpu(val_buf);
> +	} else {
> +		error = regmap_read(iqs62x->map, iqs62x->dev_desc->interval,
> +				    &val);
> +		if (error)
> +			return error;
> +
> +		iqs624_pos->interval = val;
> +	}
> +
> +	mutex_lock(&iqs624_pos->lock);
> +
> +	/*
> +	 * The IQS625 reports angular position in the form of coarse intervals,
> +	 * so only interval change events are unmasked. Conversely, the IQS624
> +	 * reports angular position down to one degree of resolution, so wheel
> +	 * movement events are unmasked instead.
> +	 */
> +	error = regmap_update_bits(iqs62x->map, IQS624_HALL_UI,
> +				   iqs62x->dev_desc->prod_num ==
> +				   IQS624_PROD_NUM ? IQS624_HALL_UI_WHL_EVENT :
> +						     IQS624_HALL_UI_INT_EVENT,
> +				   iqs624_pos->event_en ? 0 : 0xFF);
> +
> +	mutex_unlock(&iqs624_pos->lock);
> +
> +	return error;
> +}
> +
> +static int iqs624_pos_notifier(struct notifier_block *notifier,
> +			       unsigned long event_flags, void *context)
> +{
> +	struct iqs62x_event_data *event_data = context;
> +	struct iqs624_pos_private *iqs624_pos;
> +	struct iqs62x_core *iqs62x;
> +	struct iio_dev *indio_dev;
> +	int error;
> +
> +	iqs624_pos = container_of(notifier, struct iqs624_pos_private,
> +				  notifier);
> +	indio_dev = iio_priv_to_dev(iqs624_pos);
> +	iqs62x = iqs624_pos->iqs62x;
> +
> +	if (event_flags & BIT(IQS62X_EVENT_SYS_RESET)) {
> +		error = iqs624_pos_init(iqs624_pos);
> +		if (error) {
> +			dev_err(indio_dev->dev.parent,
> +				"Failed to re-initialize device: %d\n", error);
> +			return NOTIFY_BAD;
> +		}
> +
> +		return NOTIFY_OK;
> +	}
> +
> +	if (iqs62x->dev_desc->prod_num == IQS624_PROD_NUM) {
> +		if (event_data->ui_data == iqs624_pos->angle)
> +			return NOTIFY_DONE;
> +
> +		iqs624_pos->angle = event_data->ui_data;
> +	} else {
> +		if (event_data->interval == iqs624_pos->interval)
> +			return NOTIFY_DONE;
> +
> +		iqs624_pos->interval = event_data->interval;
> +	}
> +
> +	if (!iqs624_pos->event_en)
> +		return NOTIFY_OK;
> +
> +	iio_push_event(indio_dev,
> +		       IIO_UNMOD_EVENT_CODE(IIO_ANGL, 0,
> +					    IIO_EV_TYPE_CHANGE,
> +					    IIO_EV_DIR_NONE),
> +		       iio_get_time_ns(indio_dev));
> +
> +	return NOTIFY_OK;
> +}
> +
> +static void iqs624_pos_notifier_unregister(void *context)
> +{
> +	struct iqs624_pos_private *iqs624_pos = context;
> +	struct iio_dev *indio_dev = iio_priv_to_dev(iqs624_pos);
> +	int error;
> +
> +	error = blocking_notifier_chain_unregister(&iqs624_pos->iqs62x->nh,
> +						   &iqs624_pos->notifier);
> +	if (error)
> +		dev_err(indio_dev->dev.parent,
> +			"Failed to unregister notifier: %d\n", error);
> +}
> +
> +static int iqs624_pos_read_raw(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan,
> +			       int *val, int *val2, long mask)
> +{
> +	struct iqs624_pos_private *iqs624_pos = iio_priv(indio_dev);
> +	struct iqs62x_core *iqs62x = iqs624_pos->iqs62x;
> +	int error;
> +	__le16 val_buf;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (iqs62x->dev_desc->prod_num == IQS624_PROD_NUM) {
> +			error = regmap_raw_read(iqs62x->map, IQS624_POS_DEG_OUT,
> +						&val_buf, sizeof(val_buf));
> +			if (error)
> +				return error;
> +
> +			*val = le16_to_cpu(val_buf);
> +		} else {
> +			error = regmap_read(iqs62x->map,
> +					    iqs62x->dev_desc->interval, val);
> +			if (error)
> +				return error;
> +		}
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		if (iqs62x->dev_desc->prod_num == IQS624_PROD_NUM) {
> +			*val = IQS624_POS_SCALE1;
> +		} else {
> +			error = regmap_read(iqs62x->map, IQS624_INTERVAL_DIV,
> +					    val);
> +			if (error)
> +				return error;
> +
> +			*val *= IQS624_POS_SCALE1;
> +		}
> +
> +		*val2 = IQS624_POS_SCALE2;
> +		return IIO_VAL_FRACTIONAL;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int iqs624_pos_read_event_config(struct iio_dev *indio_dev,
> +					const struct iio_chan_spec *chan,
> +					enum iio_event_type type,
> +					enum iio_event_direction dir)
> +{
> +	struct iqs624_pos_private *iqs624_pos = iio_priv(indio_dev);
> +
> +	return iqs624_pos->event_en;
> +}
> +
> +static int iqs624_pos_write_event_config(struct iio_dev *indio_dev,
> +					 const struct iio_chan_spec *chan,
> +					 enum iio_event_type type,
> +					 enum iio_event_direction dir,
> +					 int state)
> +{
> +	struct iqs624_pos_private *iqs624_pos = iio_priv(indio_dev);
> +	struct iqs62x_core *iqs62x = iqs624_pos->iqs62x;
> +	int error;
> +
> +	mutex_lock(&iqs624_pos->lock);
> +
> +	error = regmap_update_bits(iqs62x->map, IQS624_HALL_UI,
> +				   iqs62x->dev_desc->prod_num ==
> +				   IQS624_PROD_NUM ? IQS624_HALL_UI_WHL_EVENT :
> +						     IQS624_HALL_UI_INT_EVENT,
> +				   state ? 0 : 0xFF);
> +	if (!error)
> +		iqs624_pos->event_en = state;
> +
> +	mutex_unlock(&iqs624_pos->lock);
> +
> +	return error;
> +}
> +
> +static const struct iio_info iqs624_pos_info = {
> +	.read_raw = &iqs624_pos_read_raw,
> +	.read_event_config = iqs624_pos_read_event_config,
> +	.write_event_config = iqs624_pos_write_event_config,
> +};
> +
> +static const struct iio_event_spec iqs624_pos_events[] = {
> +	{
> +		.type = IIO_EV_TYPE_CHANGE,
> +		.dir = IIO_EV_DIR_NONE,
> +		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
> +	},
> +};
> +
> +static const struct iio_chan_spec iqs624_pos_channels[] = {
> +	{
> +		.type = IIO_ANGL,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE),
> +		.event_spec = iqs624_pos_events,
> +		.num_event_specs = ARRAY_SIZE(iqs624_pos_events),
> +	},
> +};
> +
> +static int iqs624_pos_probe(struct platform_device *pdev)
> +{
> +	struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
> +	struct iqs624_pos_private *iqs624_pos;
> +	struct iio_dev *indio_dev;
> +	int error;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*iqs624_pos));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->channels = iqs624_pos_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(iqs624_pos_channels);
> +	indio_dev->name = iqs62x->dev_desc->dev_name;
> +	indio_dev->info = &iqs624_pos_info;
> +
> +	iqs624_pos = iio_priv(indio_dev);
> +	iqs624_pos->iqs62x = iqs62x;
> +
> +	mutex_init(&iqs624_pos->lock);
> +
> +	error = iqs624_pos_init(iqs624_pos);
> +	if (error)
> +		return error;
> +
> +	iqs624_pos->notifier.notifier_call = iqs624_pos_notifier;
> +	error = blocking_notifier_chain_register(&iqs624_pos->iqs62x->nh,
> +						 &iqs624_pos->notifier);
> +	if (error) {
> +		dev_err(&pdev->dev, "Failed to register notifier: %d\n", error);
> +		return error;
> +	}
> +
> +	error = devm_add_action_or_reset(&pdev->dev,
> +					 iqs624_pos_notifier_unregister,
> +					 iqs624_pos);
> +	if (error) {
> +		dev_err(&pdev->dev, "Failed to add action: %d\n", error);
> +		return error;
> +	}
> +
> +	return devm_iio_device_register(&pdev->dev, indio_dev);
> +}
> +
> +static struct platform_driver iqs624_pos_platform_driver = {
> +	.driver = {
> +		.name	= IQS624_DRV_NAME_POS,
> +	},
> +	.probe		= iqs624_pos_probe,
> +};
> +module_platform_driver(iqs624_pos_platform_driver);
> +
> +MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
> +MODULE_DESCRIPTION("Azoteq IQS624/625 Angular Position Sensor");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:" IQS624_DRV_NAME_POS);