[PATCH 08/14] IIO: Trigger support added to core.

[Jonathan Cameron]

Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxx>

Add general registration support for IIO triggers.  These
are currently only used to initialize a 'poll' of a given
device.  Examples include the lis3l02dq's data ready signal
being used to initialize a read and gpio triggers being
used to allow externally synchronized sensor reading.

Each trigger can cause any number of 'consumer' devices
to be polled with each storing data into a related ring
buffer.

Two stage triggering is supported with 'fast' and 'slow'
paths.  The first is used for things like pulling a data
hold line high and the second for actual read which
may take far longer.

Changes since V2:
* As with IIO triggers now use a registration approach
  much closer to that of input leading to cleaner code.
---
 drivers/iio/Kconfig                  |    9 +
 drivers/iio/Makefile                 |    1 +
 drivers/iio/industrialio-trigger.c   |  400 ++++++++++++++++++++++++++++++++++
 include/linux/iio/trigger.h          |  148 +++++++++++++
 include/linux/iio/trigger_consumer.h |   21 ++-
 5 files changed, 578 insertions(+), 1 deletions(-)
 create mode 100644 drivers/iio/industrialio-trigger.c
 create mode 100644 include/linux/iio/trigger.h

diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 8eb3d4c..3aa2886 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -17,6 +17,15 @@ config IIO_RING_BUFFER
 	  Provide core support for various ring buffer based data
 	  acquisition methods.
 
+config IIO_TRIGGER
+	boolean "Enable triggered sampling support"
+	depends on IIO
+	help
+	  Provides IIO core support for triggers.  Currently these
+	  are used to initialize capture of samples to push into
+	  ring buffers.  The triggers are effectively a 'capture
+	  data now' interrupt.
+
 source drivers/iio/accel/Kconfig
 source drivers/iio/adc/Kconfig
 source drivers/iio/light/Kconfig
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 670b8f3..3271518 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -5,6 +5,7 @@
 obj-$(CONFIG_IIO) += industrialio.o
 industrialio-y := industrialio-core.o
 industrialio-$(CONFIG_IIO_RING_BUFFER) += industrialio-ring.o
+industrialio-$(CONFIG_IIO_TRIGGER) += industrialio-trigger.o
 
 obj-y += accel/
 obj-y += adc/
diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
new file mode 100644
index 0000000..88fcc8a
--- /dev/null
+++ b/drivers/iio/industrialio-trigger.c
@@ -0,0 +1,400 @@
+/* The industrial I/O core, trigger handling functions
+ *
+ * Copyright (c) 2008 Jonathan Cameron
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/idr.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+
+#include <linux/platform_device.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+
+/* RFC - Question of approach
+ * Make the common case (single sensor single trigger)
+ * simple by starting trigger capture from when first sensors
+ * is added.
+ *
+ * Complex simultaneous start requires use of 'hold' functionality
+ * of the trigger. (not implemented)
+ *
+ * Any other suggestions?
+ */
+
+
+static DEFINE_IDR(iio_trigger_idr);
+static DEFINE_SPINLOCK(iio_trigger_idr_lock);
+
+/* Single list of all available triggers */
+static LIST_HEAD(iio_trigger_list);
+static DEFINE_MUTEX(iio_trigger_list_lock);
+
+/**
+ * iio_trigger_register_sysfs() - create a device for this trigger
+ * @trig_info:	the trigger
+ *
+ * Also adds any control attribute registered by the trigger driver
+ **/
+static int iio_trigger_register_sysfs(struct iio_trigger *trig_info)
+{
+	int ret = 0;
+
+	if (trig_info->control_attrs)
+		ret = sysfs_create_group(&trig_info->dev.kobj,
+					 trig_info->control_attrs);
+
+	return ret;
+}
+
+static void iio_trigger_unregister_sysfs(struct iio_trigger *trig_info)
+{
+	if (trig_info->control_attrs)
+		sysfs_remove_group(&trig_info->dev.kobj,
+				   trig_info->control_attrs);
+}
+
+
+/**
+ * iio_trigger_register_id() - get a unique id for this trigger
+ * @trig_info:	the trigger
+ **/
+static int iio_trigger_register_id(struct iio_trigger *trig_info)
+{
+	int ret = 0;
+
+idr_again:
+	if (unlikely(idr_pre_get(&iio_trigger_idr, GFP_KERNEL) == 0))
+		return -ENOMEM;
+
+	spin_lock(&iio_trigger_idr_lock);
+	ret = idr_get_new(&iio_trigger_idr, NULL, &trig_info->id);
+	spin_unlock(&iio_trigger_idr_lock);
+	if (unlikely(ret == -EAGAIN))
+		goto idr_again;
+	else if (likely(!ret))
+		trig_info->id = trig_info->id & MAX_ID_MASK;
+
+	return ret;
+}
+
+/**
+ * iio_trigger_unregister_id() - free up unique id for use by another trigger
+ * @trig_info: the trigger
+ **/
+static void iio_trigger_unregister_id(struct iio_trigger *trig_info)
+{
+		spin_lock(&iio_trigger_idr_lock);
+		idr_remove(&iio_trigger_idr, trig_info->id);
+		spin_unlock(&iio_trigger_idr_lock);
+}
+
+int iio_trigger_register(struct iio_trigger *trig_info)
+{
+	int ret;
+
+	ret = iio_trigger_register_id(trig_info);
+	if (ret)
+		goto error_ret;
+	/* Set the name used for the sysfs directory etc */
+	dev_set_name(&trig_info->dev, "trigger%ld",
+		     (unsigned long) trig_info->id);
+
+	ret = device_add(&trig_info->dev);
+	if (ret)
+		goto error_unregister_id;
+
+	ret = iio_trigger_register_sysfs(trig_info);
+	if (ret)
+		goto error_device_del;
+
+	/* Add to list of available triggers held by the IIO core */
+	mutex_lock(&iio_trigger_list_lock);
+	list_add_tail(&trig_info->list, &iio_trigger_list);
+	mutex_unlock(&iio_trigger_list_lock);
+
+	return 0;
+
+error_device_del:
+	device_del(&trig_info->dev);
+error_unregister_id:
+	iio_trigger_unregister_id(trig_info);
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL(iio_trigger_register);
+
+void iio_trigger_unregister(struct iio_trigger *trig_info)
+{
+	struct iio_trigger *cursor;
+
+	mutex_lock(&iio_trigger_list_lock);
+	list_for_each_entry(cursor, &iio_trigger_list, list)
+		if (cursor == trig_info) {
+			list_del(&cursor->list);
+			break;
+		}
+	mutex_unlock(&iio_trigger_list_lock);
+
+	iio_trigger_unregister_sysfs(trig_info);
+	iio_trigger_unregister_id(trig_info);
+	/* Possible issue in here */
+	device_unregister(&trig_info->dev);
+}
+EXPORT_SYMBOL(iio_trigger_unregister);
+
+struct iio_trigger *iio_trigger_find_by_name(const char *name, size_t len)
+{
+	struct iio_trigger *trig;
+	bool found = false;
+
+	mutex_lock(&iio_trigger_list_lock);
+	list_for_each_entry(trig, &iio_trigger_list, list) {
+		if (strncmp(trig->name, name, len) == 0) {
+			found = true;
+			break;
+		}
+	}
+	mutex_unlock(&iio_trigger_list_lock);
+
+	return found ? trig : NULL;
+};
+EXPORT_SYMBOL(iio_trigger_find_by_name);
+
+void iio_trigger_poll(struct iio_trigger *trig)
+{
+	struct iio_poll_func *pf_cursor;
+
+	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
+		if (pf_cursor->poll_func_immediate) {
+			pf_cursor->poll_func_immediate(pf_cursor->private_data);
+			trig->use_count++;
+		}
+	}
+	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
+		if (pf_cursor->poll_func_main) {
+			pf_cursor->poll_func_main(pf_cursor->private_data);
+			trig->use_count++;
+		}
+	}
+}
+EXPORT_SYMBOL(iio_trigger_poll);
+
+void iio_trigger_notify_done(struct iio_trigger *trig)
+{
+	trig->use_count--;
+	if (trig->use_count == 0 && trig->try_reenable)
+		if (trig->try_reenable(trig)) {
+			/* Missed and interrupt so launch new poll now */
+			trig->timestamp = 0;
+			iio_trigger_poll(trig);
+		}
+}
+EXPORT_SYMBOL(iio_trigger_notify_done);
+
+/**
+ * iio_trigger_read_name() - retrieve useful identifying name
+ **/
+ssize_t iio_trigger_read_name(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	struct iio_trigger *trig = dev_get_drvdata(dev);
+	return sprintf(buf, "%s\n", trig->name);
+}
+EXPORT_SYMBOL(iio_trigger_read_name);
+
+/* Trigger Consumer related functions */
+
+/* Complexity in here.  With certain triggers (datardy) an acknowledgement
+ * may be needed if the pollfuncs do not include the data read for the
+ * triggering device.
+ * This is not currently handled.  Alternative of not enabling trigger unless
+ * the relevant function is in there may be the best option.
+ */
+/* Worth protecting against double additions?*/
+int iio_trigger_attach_poll_func(struct iio_trigger *trig,
+				 struct iio_poll_func *pf)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
+	list_add_tail(&pf->list, &trig->pollfunc_list);
+	spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
+
+	if (trig->set_trigger_state)
+		ret = trig->set_trigger_state(trig, true);
+	if (ret) {
+		printk(KERN_ERR "set trigger state failed\n");
+		list_del(&pf->list);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(iio_trigger_attach_poll_func);
+
+int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
+				  struct iio_poll_func *pf)
+{
+	struct iio_poll_func *pf_cursor;
+	unsigned long flags;
+	int ret = -EINVAL;
+
+	spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
+	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list)
+		if (pf_cursor == pf) {
+			ret = 0;
+			break;
+		}
+	if (!ret) {
+		if (list_is_singular(&trig->pollfunc_list)
+		    && trig->set_trigger_state) {
+			spin_unlock_irqrestore(&trig->pollfunc_list_lock,
+					       flags);
+			/* May sleep hence cannot hold the spin lock */
+			ret = trig->set_trigger_state(trig, false);
+			if (ret)
+				goto error_ret;
+			spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
+		}
+		/*
+		 * Now we can delete safe in the knowledge that, if this is
+		 * the last pollfunc then we have disabled the trigger anyway
+		 * and so nothing should be able to call the pollfunc.
+		 */
+		list_del(&pf_cursor->list);
+	}
+	spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
+
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL(iio_trigger_dettach_poll_func);
+
+/**
+ * iio_trigger_read_currrent() trigger consumer sysfs query which trigger
+ *
+ * For trigger consumers the current_trigger interface allows the trigger
+ * used by the device to be queried.
+ **/
+static ssize_t iio_trigger_read_current(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	int len = 0;
+	if (dev_info->trig)
+		len = snprintf(buf,
+			       IIO_TRIGGER_NAME_LENGTH,
+			       "%s\n",
+			       dev_info->trig->name);
+	return len;
+}
+
+/**
+ * iio_trigger_write_current() trigger consumer sysfs set current trigger
+ *
+ * For trigger consumers the current_trigger interface allows the trigger
+ * used for this device to be specified at run time based on the triggers
+ * name.
+ **/
+static ssize_t iio_trigger_write_current(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf,
+					 size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct iio_trigger *oldtrig = dev_info->trig;
+	mutex_lock(&dev_info->mlock);
+	if (dev_info->currentmode == INDIO_RING_TRIGGERED) {
+		mutex_unlock(&dev_info->mlock);
+		return -EBUSY;
+	}
+	mutex_unlock(&dev_info->mlock);
+
+	len = len < IIO_TRIGGER_NAME_LENGTH ? len : IIO_TRIGGER_NAME_LENGTH;
+
+	dev_info->trig = iio_trigger_find_by_name(buf, len);
+	if (oldtrig && dev_info->trig != oldtrig)
+		iio_put_trigger(oldtrig);
+	if (dev_info->trig)
+		iio_get_trigger(dev_info->trig);
+
+	return len;
+}
+
+DEVICE_ATTR(current_trigger, S_IRUGO | S_IWUSR,
+	    iio_trigger_read_current,
+	    iio_trigger_write_current);
+
+static struct attribute *iio_trigger_consumer_attrs[] = {
+	&dev_attr_current_trigger.attr,
+	NULL,
+};
+
+static const struct attribute_group iio_trigger_consumer_attr_group = {
+	.name = "trigger",
+	.attrs = iio_trigger_consumer_attrs,
+};
+
+static void iio_trig_release(struct device *device)
+{
+	struct iio_trigger *trig = to_iio_trigger(device);
+	kfree(trig);
+	iio_put();
+}
+
+static struct device_type iio_trig_type = {
+	.release = iio_trig_release,
+};
+
+struct iio_trigger *iio_allocate_trigger(void)
+{
+	struct iio_trigger *trig;
+	trig = kzalloc(sizeof *trig, GFP_KERNEL);
+	if (trig) {
+		trig->dev.type = &iio_trig_type;
+		trig->dev.class = &iio_class;
+		device_initialize(&trig->dev);
+		dev_set_drvdata(&trig->dev, (void *)trig);
+		spin_lock_init(&trig->pollfunc_list_lock);
+		INIT_LIST_HEAD(&trig->list);
+		INIT_LIST_HEAD(&trig->pollfunc_list);
+		iio_get();
+	}
+	return trig;
+}
+EXPORT_SYMBOL(iio_allocate_trigger);
+
+void iio_free_trigger(struct iio_trigger *trig)
+{
+	if (trig)
+		iio_put_trigger(trig);
+}
+EXPORT_SYMBOL(iio_free_trigger);
+
+int iio_device_register_trigger_consumer(struct iio_dev *dev_info)
+{
+	int ret;
+	ret = sysfs_create_group(&dev_info->dev.kobj,
+				 &iio_trigger_consumer_attr_group);
+	return ret;
+}
+EXPORT_SYMBOL(iio_device_register_trigger_consumer);
+
+int iio_device_unregister_trigger_consumer(struct iio_dev *dev_info)
+{
+	sysfs_remove_group(&dev_info->dev.kobj,
+			   &iio_trigger_consumer_attr_group);
+	return 0;
+}
+EXPORT_SYMBOL(iio_device_unregister_trigger_consumer);
+
diff --git a/include/linux/iio/trigger.h b/include/linux/iio/trigger.h
new file mode 100644
index 0000000..d53908c
--- /dev/null
+++ b/include/linux/iio/trigger.h
@@ -0,0 +1,148 @@
+/* The industrial I/O core, trigger handling functions
+ *
+ * Copyright (c) 2008 Jonathan Cameron
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+#ifndef _IIO_TRIGGER_H_
+#define _IIO_TRIGGER_H_
+#define IIO_TRIGGER_NAME_LENGTH 20
+#define IIO_TRIGGER_ID_PREFIX "iio:trigger"
+#define IIO_TRIGGER_ID_FORMAT IIO_TRIGGER_ID_PREFIX "%d"
+
+
+/**
+ * struct iio_trigger - industrial I/O trigger device
+ *
+ * @id:			[INTERN] unique id number
+ * @name:		[DRIVER] unique name
+ * @dev:		[DRIVER] associated device (if relevant)
+ * @sysfs_dev:		[INTERN] sysfs relevant device
+ * @private_data:	[DRIVER] device specific data
+ * @list:		[INTERN] used in maintenance of global trigger list
+ * @alloc_list:		[DRIVER] used for driver specific trigger list
+ * @poll_func_list_lock:[INTERN] protection of the polling function list
+ * @pollfunc_list:	[INTERN] list of functions to run on trigger.
+ * @control_attrs:	[DRIVER] sysfs attributes relevant to trigger type
+ * @set_trigger_state:	[DRIVER] switch on/off the trigger on demand
+ * @timestamp:		[INTERN] timestamp usesd by some trigs (e.g. datardy)
+ * @owner:		[DRIVER] used to monitor usage count of the trigger.
+ **/
+struct iio_trigger {
+	int				id;
+	const char			*name;
+	struct device			dev;
+
+	void				*private_data;
+	struct list_head		list;
+	struct list_head		alloc_list;
+	spinlock_t			pollfunc_list_lock;
+	struct list_head		pollfunc_list;
+	const struct attribute_group	*control_attrs;
+	s64				timestamp;
+	struct module			*owner;
+	int use_count;
+
+	int (*set_trigger_state)(struct iio_trigger *trig, bool state);
+	int (*try_reenable)(struct iio_trigger *trig);
+};
+
+static inline struct iio_trigger *to_iio_trigger(struct device *d)
+{
+	return container_of(d, struct iio_trigger, dev);
+};
+
+static inline void iio_put_trigger(struct iio_trigger *trig)
+{
+	put_device(&trig->dev);
+};
+
+static inline void iio_get_trigger(struct iio_trigger *trig)
+{
+	get_device(&trig->dev);
+};
+/**
+ * iio_trigger_read_name() - sysfs access function to get the trigger name
+ **/
+ssize_t iio_trigger_read_name(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf);
+
+#define IIO_TRIGGER_NAME_ATTR DEVICE_ATTR(name, S_IRUGO,		\
+					  iio_trigger_read_name,	\
+					  NULL);
+
+/**
+ * iio_trigger_find_by_name() - search global trigger list
+ **/
+struct iio_trigger *iio_trigger_find_by_name(const char *name, size_t len);
+
+/**
+ * iio_trigger_register() - register a trigger with the IIO core
+ * @trig_info:	trigger to be registered
+ **/
+int iio_trigger_register(struct iio_trigger *trig_info);
+
+/**
+ * iio_trigger_unregister() - unregister a trigger from the core
+ **/
+void iio_trigger_unregister(struct iio_trigger *trig_info);
+
+/**
+ * iio_trigger_attach_poll_func() - add a function pair to be run on trigger
+ * @trig:	trigger to which the function pair are being added
+ * @pf:	poll function pair
+ **/
+int iio_trigger_attach_poll_func(struct iio_trigger *trig,
+				 struct iio_poll_func *pf);
+
+/**
+ * iio_trigger_dettach_poll_func() -	remove function pair from those to be
+ *					run on trigger.
+ * @trig:	trigger from which the function is being removed.
+ * @pf:		poll function pair
+ **/
+int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
+				  struct iio_poll_func *pf);
+
+/**
+ * iio_trigger_poll() - called on a trigger occuring
+ * Typically called in relevant hardware interrupt handler.
+ **/
+void iio_trigger_poll(struct iio_trigger *);
+void iio_trigger_notify_done(struct iio_trigger *);
+
+/**
+ * struct iio_poll_func - poll function pair
+ *
+ * @list:			associate this with a triggers pollfunc_list
+ * @private_data:		data specific to device (passed into poll func)
+ * @poll_func_immediate:	function in here is run first. They should be
+ *				extremely lightweight.  Typically used for latch
+ *				control on sensor supporting it.
+ * @poll_func_main:		function in here is run after all immediates.
+ *				Reading from sensor etc typically involves
+ *				scheduling
+ *				from here.
+ *
+ * The two stage approach used here only important when multiple sensors are
+ * being triggered by a single trigger. This really comes into it's own with
+ * simultaneous sampling devices where a simple latch command can be used to
+ * make the device store the values on all inputs.
+ **/
+struct iio_poll_func {
+	struct				list_head list;
+	void				*private_data;
+	void (*poll_func_immediate)(struct iio_dev *indio_dev);
+	void (*poll_func_main)(struct iio_dev  *private_data);
+
+};
+
+struct iio_trigger *iio_allocate_trigger(void);
+
+void iio_free_trigger(struct iio_trigger *trig);
+
+
+#endif /* _IIO_TRIGGER_H_ */
diff --git a/include/linux/iio/trigger_consumer.h b/include/linux/iio/trigger_consumer.h
index a605389..4c7f527 100644
--- a/include/linux/iio/trigger_consumer.h
+++ b/include/linux/iio/trigger_consumer.h
@@ -8,6 +8,20 @@
  * the Free Software Foundation.
  */
 
+#ifdef CONFIG_IIO_TRIGGER
+/**
+ * iio_device_register_trigger_consumer() - set up an iio_dev to use triggers.
+ * @dev_info: iio_dev associated with the device that will consume the trigger
+ **/
+int iio_device_register_trigger_consumer(struct iio_dev *dev_info);
+/**
+ * iio_device_unregister_trigger_consumer() - reverse the registration process.
+ * @dev_info: iio_dev associated with the device that consumed the trigger
+ **/
+int iio_device_unregister_trigger_consumer(struct iio_dev *dev_info);
+
+#else
+
 /**
  * iio_device_register_trigger_consumer() - set up an iio_dev to use triggers.
  * @dev_info: iio_dev associated with the device that will consume the trigger
@@ -18,9 +32,14 @@ int iio_device_register_trigger_consumer(struct iio_dev *dev_info)
 };
 /**
  * iio_device_unregister_trigger_consumer() - reverse the registration process
-. * @dev_info: iio_dev associated with the device that consumed the trigger
+ * @dev_info: iio_dev associated with the device that consumed the trigger
  **/
 int iio_device_unregister_trigger_consumer(struct iio_dev *dev_info)
 {
 	return 0;
 };
+
+#endif /* CONFIG_TRIGGER_CONSUMER */
+
+
+
-- 
1.6.2

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