Re: [PATCH v2 7/7] iio: position: Add support for Azoteq IQS624/625 angle sensors

[Jeff LaBundy <jeff@labundy.com>]

Hi Jonathan,

Thank you for your continued support on this project.

On Sun, Dec 15, 2019 at 04:53:28PM +0000, Jonathan Cameron wrote:
> On Mon, 9 Dec 2019 00:38:41 +0000
> 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.
> > 
> > Signed-off-by: Jeff LaBundy <jeff@labundy.com>
> 
> Looks good
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> 
> My current assumption is that Lee will take this lot via an immutable branch
> in MFD once it's ready.  Shout if a different path makes sense.

Same here. @Lee, please let us know if you disagree.

> > ---
> > Changes in v2:
> >   - Merged 'Copyright' and 'Author' lines into one in introductory comments
> >   - Replaced 'error' with 'ret' throughout
> >   - Added iqs624_pos_angle_en and iqs624_pos_angle_get to remove duplicate
> >     logic previously used throughout
> >   - Refactored the logic in iqs624_pos_notifier and added a lock to safely
> >     evaluate variables that may change in response to user action
> >   - Refactored the logic in iqs624_pos_read_raw
> >   - Added a lock to iqs624_pos_read_event_config to account for cases in which
> >     the corresponding hardware state is in the process of being updated
> >   - Refactored the logic in iqs624_pos_write_event_config and read the initial
> >     angle in case it changed since having first been read in iqs624_pos_init
> >   - Removed iqs624_pos_init as its logic has since been absorbed elsewhere
> >   - Removed devm_add_action_or_reset failure message
> >   - Eliminated tabbed alignment of platform_driver struct members
> >   - Changed Kconfig "depends on" logic to MFD_IQS62X || COMPILE_TEST
> > 
> >  drivers/iio/Kconfig               |   1 +
> >  drivers/iio/Makefile              |   1 +
> >  drivers/iio/position/Kconfig      |  19 +++
> >  drivers/iio/position/Makefile     |   7 +
> >  drivers/iio/position/iqs624-pos.c | 284 ++++++++++++++++++++++++++++++++++++++
> >  5 files changed, 312 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..eda67f0
> > --- /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 sensors"
> > +	depends on MFD_IQS62X || COMPILE_TEST
> > +	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..af629bf5
> > --- /dev/null
> > +++ b/drivers/iio/position/iqs624-pos.c
> > @@ -0,0 +1,284 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Azoteq IQS624/625 Angular Position Sensors
> > + *
> > + * Copyright (C) 2019 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 angle_en;
> > +	u16 angle;
> > +};
> > +
> > +static int iqs624_pos_angle_en(struct iqs62x_core *iqs62x, bool angle_en)
> > +{
> > +	unsigned int event_mask = IQS624_HALL_UI_WHL_EVENT;
> > +
> > +	/*
> > +	 * 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.
> > +	 */
> > +	if (iqs62x->dev_desc->prod_num == IQS625_PROD_NUM)
> > +		event_mask = IQS624_HALL_UI_INT_EVENT;
> > +
> > +	return regmap_update_bits(iqs62x->map, IQS624_HALL_UI, event_mask,
> > +				  angle_en ? 0 : 0xFF);
> > +}
> > +
> > +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;
> > +	u16 angle = event_data->ui_data;
> > +	s64 timestamp;
> > +	int ret;
> > +
> > +	iqs624_pos = container_of(notifier, struct iqs624_pos_private,
> > +				  notifier);
> > +	indio_dev = iio_priv_to_dev(iqs624_pos);
> > +	timestamp = iio_get_time_ns(indio_dev);
> > +
> > +	iqs62x = iqs624_pos->iqs62x;
> > +	if (iqs62x->dev_desc->prod_num == IQS625_PROD_NUM)
> > +		angle = event_data->interval;
> > +
> > +	mutex_lock(&iqs624_pos->lock);
> > +
> > +	if (event_flags & BIT(IQS62X_EVENT_SYS_RESET)) {
> > +		ret = iqs624_pos_angle_en(iqs62x, iqs624_pos->angle_en);
> > +		if (ret) {
> > +			dev_err(indio_dev->dev.parent,
> > +				"Failed to re-initialize device: %d\n", ret);
> > +			ret = NOTIFY_BAD;
> > +		} else {
> > +			ret = NOTIFY_OK;
> > +		}
> > +	} else if (iqs624_pos->angle_en && (angle != iqs624_pos->angle)) {
> > +		iio_push_event(indio_dev,
> > +			       IIO_UNMOD_EVENT_CODE(IIO_ANGL, 0,
> > +						    IIO_EV_TYPE_CHANGE,
> > +						    IIO_EV_DIR_NONE),
> > +			       timestamp);
> > +
> > +		iqs624_pos->angle = angle;
> > +		ret = NOTIFY_OK;
> > +	} else {
> > +		ret = NOTIFY_DONE;
> > +	}
> > +
> > +	mutex_unlock(&iqs624_pos->lock);
> > +
> > +	return ret;
> > +}
> > +
> > +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 ret;
> > +
> > +	ret = blocking_notifier_chain_unregister(&iqs624_pos->iqs62x->nh,
> > +						 &iqs624_pos->notifier);
> > +	if (ret)
> > +		dev_err(indio_dev->dev.parent,
> > +			"Failed to unregister notifier: %d\n", ret);
> > +}
> > +
> > +static int iqs624_pos_angle_get(struct iqs62x_core *iqs62x, unsigned int *val)
> > +{
> > +	int ret;
> > +	__le16 val_buf;
> > +
> > +	if (iqs62x->dev_desc->prod_num == IQS625_PROD_NUM)
> > +		return regmap_read(iqs62x->map, iqs62x->dev_desc->interval,
> > +				   val);
> > +
> > +	ret = regmap_raw_read(iqs62x->map, IQS624_POS_DEG_OUT, &val_buf,
> > +			      sizeof(val_buf));
> > +	if (ret)
> > +		return ret;
> > +
> > +	*val = le16_to_cpu(val_buf);
> > +
> > +	return 0;
> > +}
> > +
> > +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;
> > +	unsigned int scale = 1;
> > +	int ret;
> > +
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_RAW:
> > +		ret = iqs624_pos_angle_get(iqs62x, val);
> > +		if (ret)
> > +			return ret;
> > +
> > +		return IIO_VAL_INT;
> > +
> > +	case IIO_CHAN_INFO_SCALE:
> > +		if (iqs62x->dev_desc->prod_num == IQS625_PROD_NUM) {
> > +			ret = regmap_read(iqs62x->map, IQS624_INTERVAL_DIV,
> > +					  &scale);
> > +			if (ret)
> > +				return ret;
> > +		}
> > +
> > +		*val = scale * 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);
> > +	int ret;
> > +
> > +	mutex_lock(&iqs624_pos->lock);
> > +	ret = iqs624_pos->angle_en;
> > +	mutex_unlock(&iqs624_pos->lock);
> > +
> > +	return ret;
> > +}
> > +
> > +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;
> > +	unsigned int val;
> > +	int ret;
> > +
> > +	mutex_lock(&iqs624_pos->lock);
> > +
> > +	ret = iqs624_pos_angle_get(iqs62x, &val);
> > +	if (ret)
> > +		goto err_mutex;
> > +
> > +	ret = iqs624_pos_angle_en(iqs62x, state);
> > +	if (ret)
> > +		goto err_mutex;
> > +
> > +	iqs624_pos->angle = val;
> > +	iqs624_pos->angle_en = state;
> > +
> > +err_mutex:
> > +	mutex_unlock(&iqs624_pos->lock);
> > +
> > +	return ret;
> > +}
> > +
> > +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 ret;
> > +
> > +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*iqs624_pos));
> > +	if (!indio_dev)
> > +		return -ENOMEM;
> > +
> > +	iqs624_pos = iio_priv(indio_dev);
> > +	iqs624_pos->iqs62x = iqs62x;
> > +
> > +	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;
> > +
> > +	mutex_init(&iqs624_pos->lock);
> > +
> > +	iqs624_pos->notifier.notifier_call = iqs624_pos_notifier;
> > +	ret = blocking_notifier_chain_register(&iqs624_pos->iqs62x->nh,
> > +					       &iqs624_pos->notifier);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = devm_add_action_or_reset(&pdev->dev,
> > +				       iqs624_pos_notifier_unregister,
> > +				       iqs624_pos);
> > +	if (ret)
> > +		return ret;
> > +
> > +	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 Sensors");
> > +MODULE_LICENSE("GPL");
> > +MODULE_ALIAS("platform:" IQS624_DRV_NAME_POS);
> > --
> > 2.7.4
> > 
> 

Wishing you a Happy New Year,
Jeff LaBundy