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

Jeff LaBundy
2019-12-09T00:38:54Z

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>
---
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