Staging: IIO: core support for device registration and management

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

7 files changed, 1716 insertions, 0 deletions

diff --git a/drivers/staging/iio/Kconfig b/drivers/staging/iio/Kconfig
new file mode 100644
index 00000000000..09e4101939e
--- /dev/null
+++ b/drivers/staging/iio/Kconfig
@@ -0,0 +1,11 @@
+#
+# Industrial I/O subsytem configuration
+#
+
+menuconfig IIO
+	tristate "Industrial I/O support"
+	---help---
+	  The industrial I/O subsystem provides a unified framework for
+	  drivers for many different types of embedded sensors using a
+	  number of different physical interfaces (i2c, spi etc). See
+	  Documentation/industrialio for more information.
diff --git a/drivers/staging/iio/Makefile b/drivers/staging/iio/Makefile
new file mode 100644
index 00000000000..92b462a125e
--- /dev/null
+++ b/drivers/staging/iio/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for the industrial I/O core.
+#
+
+obj-$(CONFIG_IIO) += industrialio.o
+industrialio-y := industrialio-core.o
diff --git a/drivers/staging/iio/chrdev.h b/drivers/staging/iio/chrdev.h
new file mode 100644
index 00000000000..8bc64bf0845
--- /dev/null
+++ b/drivers/staging/iio/chrdev.h
@@ -0,0 +1,118 @@
+/* The industrial I/O core - character device related
+ *
+ * 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_CHRDEV_H_
+#define _IIO_CHRDEV_H_
+struct iio_dev;
+
+/**
+ * struct iio_handler - Structure used to specify file operations
+ *			for a particular chrdev
+ * @chrdev:	character device structure
+ * @id:		the location in the handler table - used for deallocation.
+ * @flags:	file operations related flags including busy flag.
+ * @private:	handler specific data used by the fileops registered with
+ *		the chrdev.
+ */
+struct iio_handler {
+	struct cdev	chrdev;
+	int		id;
+	unsigned long	flags;
+	void		*private;
+};
+
+#define iio_cdev_to_handler(cd)				\
+	container_of(cd, struct iio_handler, chrdev)
+
+/**
+ * struct iio_event_data - The actual event being pushed to userspace
+ * @id:		event identifier
+ * @timestamp:	best estimate of time of event occurance (often from
+ *		the interrupt handler)
+ */
+struct iio_event_data {
+	int	id;
+	s64	timestamp;
+};
+
+/**
+ * struct iio_detected_event_list - list element for events that have occured
+ * @list:		linked list header
+ * @ev:			the event itself
+ * @shared_pointer:	used when the event is shared - i.e. can be escallated
+ *			on demand (eg ring buffer 50%->100% full)
+ */
+struct iio_detected_event_list {
+	struct list_head		list;
+	struct iio_event_data		ev;
+	struct iio_shared_ev_pointer	*shared_pointer;
+};
+/**
+ * struct iio_shared_ev_pointer - allows shared events to identify if currently
+ *				in the detected event list
+ * @ev_p:	pointer to detected event list element (null if not in list)
+ * @lock:	protect this element to prevent simultaneous edit and remove
+ */
+struct iio_shared_ev_pointer {
+	struct iio_detected_event_list	*ev_p;
+	spinlock_t			lock;
+};
+
+/**
+ * struct iio_event_interface - chrdev interface for an event line
+ * @dev:		device assocated with event interface
+ * @handler:		fileoperations and related control for the chrdev
+ * @wait:		wait queue to allow blocking reads of events
+ * @event_list_lock:	mutex to protect the list of detected events
+ * @det_events:		list of detected events
+ * @max_events:		maximum number of events before new ones are dropped
+ * @current_events:	number of events in detected list
+ * @id:			indentifier to allow the event interface to know which
+ *			physical line it corresponds to
+ * @owner:		ensure the driver module owns the file, not iio
+ * @private:		driver specific data
+ * @_name:		used internally to store the sysfs name for minor id
+ *			attribute
+ */
+struct iio_event_interface {
+	struct device				dev;
+	struct iio_handler			handler;
+	wait_queue_head_t			wait;
+	struct mutex				event_list_lock;
+	struct iio_detected_event_list		det_events;
+	int					max_events;
+	int					current_events;
+	int					id;
+	struct iio_chrdev_minor_attr		attr;
+	struct module				*owner;
+	void					*private;
+	char					_name[20];
+	char					_attrname[20];
+};
+
+/**
+ * struct iio_event_handler_list - element in list of handlers for events
+ * @list:		list header
+ * @refcount:		as the handler may be shared between multiple device
+ *			side events, reference counting ensures clean removal
+ * @exist_lock:		prevents race conditions related to refcount useage.
+ * @handler:		event handler function - called on event if this
+ *			event_handler is enabled.
+ *
+ * Each device has one list of these per interrupt line
+ **/
+struct iio_event_handler_list {
+	struct list_head	list;
+	int			refcount;
+	struct mutex		exist_lock;
+	int (*handler)(struct iio_dev *dev_info, int index, s64 timestamp,
+		       int no_test);
+};
+
+#endif
diff --git a/drivers/staging/iio/iio.h b/drivers/staging/iio/iio.h
new file mode 100644
index 00000000000..25ccb809221
--- /dev/null
+++ b/drivers/staging/iio/iio.h
@@ -0,0 +1,411 @@
+/* The industrial I/O core
+ *
+ * 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 _INDUSTRIAL_IO_H_
+#define _INDUSTRIAL_IO_H_
+
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include "sysfs.h"
+#include "chrdev.h"
+
+/* IIO TODO LIST */
+/* Static device specific elements (conversion factors etc)
+ * should be exported via sysfs
+ *
+ * Provide means of adjusting timer accuracy.
+ * Currently assumes nano seconds.
+ */
+
+/* Event interface flags */
+#define IIO_BUSY_BIT_POS 1
+
+struct iio_dev;
+
+/**
+ * iio_get_time_ns() - utility function to get a time stamp for events etc
+ **/
+static inline s64 iio_get_time_ns(void)
+{
+	struct timespec ts;
+	/*
+	 * calls getnstimeofday.
+	 * If hrtimers then up to ns accurate, if not microsecond.
+	 */
+	ktime_get_real_ts(&ts);
+
+	return timespec_to_ns(&ts);
+}
+
+/**
+ * iio_add_event_to_list() - Wraps adding to event lists
+ * @el:		the list element of the event to be handled.
+ * @head:	the list associated with the event handler being used.
+ *
+ * Does reference counting to allow shared handlers.
+ **/
+void iio_add_event_to_list(struct iio_event_handler_list *el,
+			   struct list_head *head);
+
+/**
+ * iio_remove_event_from_list() - Wraps removing from event list
+ * @el:		element to be removed
+ * @head:	associate list head for the interrupt handler.
+ *
+ * Does reference counting to allow shared handlers.
+ **/
+void iio_remove_event_from_list(struct iio_event_handler_list *el,
+				struct list_head *head);
+
+/* Device operating modes */
+#define INDIO_DIRECT_MODE		0x01
+#define INDIO_RING_TRIGGERED		0x02
+#define INDIO_RING_HARDWARE_BUFFER	0x08
+
+#define INDIO_ALL_RING_MODES (INDIO_RING_TRIGGERED | INDIO_RING_HARDWARE_BUFFER)
+
+/* Vast majority of this is set by the industrialio subsystem on a
+ * call to iio_device_register. */
+
+/**
+ * struct iio_dev - industrial I/O device
+ * @id:			[INTERN] used to identify device internally
+ * @dev_data:		[DRIVER] device specific data
+ * @modes:		[DRIVER] operating modes supported by device
+ * @currentmode:	[DRIVER] current operating mode
+ * @dev:		[DRIVER] device structure, should be assigned a parent
+ *			and owner
+ * @attrs:		[DRIVER] general purpose device attributes
+ * @driver_module:	[DRIVER] module structure used to ensure correct
+ *			ownership of chrdevs etc
+ * @num_interrupt_lines:[DRIVER] number of physical interrupt lines from device
+ * @interrupts:		[INTERN] interrupt line specific event lists etc
+ * @event_attrs:	[DRIVER] event control attributes
+ * @event_conf_attrs:	[DRIVER] event configuration attributes
+ * @event_interfaces:	[INTERN] event chrdevs associated with interrupt lines
+ * @ring:		[DRIVER] any ring buffer present
+ * @mlock:		[INTERN] lock used to prevent simultaneous device state
+ *			changes
+ * @scan_el_attrs:	[DRIVER] control of scan elements if that scan mode
+ *			control method is used
+ * @scan_count:	[INTERN] the number of elements in the current scan mode
+ * @scan_mask:		[INTERN] bitmask used in masking scan mode elements
+ * @scan_timestamp:	[INTERN] does the scan mode include a timestamp
+ * @trig:		[INTERN] current device trigger (ring buffer modes)
+ * @pollfunc:		[DRIVER] function run on trigger being recieved
+ **/
+struct iio_dev {
+	int				id;
+	void				*dev_data;
+	int				modes;
+	int				currentmode;
+	struct device			dev;
+	const struct attribute_group	*attrs;
+	struct module			*driver_module;
+
+	int				num_interrupt_lines;
+	struct iio_interrupt		**interrupts;
+	struct attribute_group		*event_attrs;
+	struct attribute_group		*event_conf_attrs;
+
+	struct iio_event_interface	*event_interfaces;
+
+	struct iio_ring_buffer		*ring;
+	struct mutex			mlock;
+
+	struct attribute_group		*scan_el_attrs;
+	int				scan_count;
+
+	u16				scan_mask;
+	bool				scan_timestamp;
+	struct iio_trigger		*trig;
+	struct iio_poll_func		*pollfunc;
+};
+
+/*
+ * These are mainly provided to allow for a change of implementation if a device
+ * has a large number of scan elements
+ */
+#define IIO_MAX_SCAN_LENGTH 15
+
+static inline int iio_scan_mask_query(struct iio_dev *dev_info, int bit)
+{
+	if (bit > IIO_MAX_SCAN_LENGTH)
+		return -EINVAL;
+	else
+		return !!(dev_info->scan_mask & (1 << bit));
+};
+
+static inline int iio_scan_mask_set(struct iio_dev *dev_info, int bit)
+{
+	if (bit > IIO_MAX_SCAN_LENGTH)
+		return -EINVAL;
+	dev_info->scan_mask |= (1 << bit);
+	dev_info->scan_count++;
+	return 0;
+};
+
+static inline int iio_scan_mask_clear(struct iio_dev *dev_info, int bit)
+{
+	if (bit > IIO_MAX_SCAN_LENGTH)
+		return -EINVAL;
+	dev_info->scan_mask &= ~(1 << bit);
+	dev_info->scan_count--;
+	return 0;
+};
+
+/**
+ * iio_scan_mask_count_to_right() - how many scan elements occur before here
+ * @dev_info: the iio_device whose scan mode we are querying
+ * @bit: which number scan element is this
+ **/
+static inline int iio_scan_mask_count_to_right(struct iio_dev *dev_info,
+int bit)
+{
+	int count = 0;
+	int mask = (1 << bit);
+	if (bit > IIO_MAX_SCAN_LENGTH)
+		return -EINVAL;
+	while (mask) {
+		mask >>= 1;
+		if (mask & dev_info->scan_mask)
+			count++;
+	}
+
+	return count;
+}
+
+/**
+ * iio_device_register() - register a device with the IIO subsystem
+ * @dev_info:		Device structure filled by the device driver
+ **/
+int iio_device_register(struct iio_dev *dev_info);
+
+/**
+ * iio_device_unregister() - unregister a device from the IIO subsystem
+ * @dev_info:		Device structure representing the device.
+ **/
+void iio_device_unregister(struct iio_dev *dev_info);
+
+/**
+ * struct iio_interrupt - wrapper used to allow easy handling of multiple
+ *			physical interrupt lines
+ * @dev_info:		the iio device for which the is an interrupt line
+ * @line_number:	associated line number
+ * @id:			idr allocated unique id number
+ * @irq:		associate interrupt number
+ * @ev_list:		event handler list for associated events
+ * @ev_list_lock:	ensure only one access to list at a time
+ **/
+struct iio_interrupt {
+	struct iio_dev			*dev_info;
+	int				line_number;
+	int				id;
+	int				irq;
+	struct list_head		ev_list;
+	spinlock_t			ev_list_lock;
+};
+
+#define to_iio_interrupt(i) container_of(i, struct iio_interrupt, ev_list)
+
+/**
+ * iio_register_interrupt_line() - Tell IIO about interrupt lines
+ *
+ * @irq:		Typically provided via platform data
+ * @dev_info:		IIO device info structure for device
+ * @line_number:	Which interrupt line of the device is this?
+ * @type:		Interrupt type (e.g. edge triggered etc)
+ * @name:		Identifying name.
+ **/
+int iio_register_interrupt_line(unsigned int			irq,
+				struct iio_dev			*dev_info,
+				int				line_number,
+				unsigned long			type,
+				const char			*name);
+
+void iio_unregister_interrupt_line(struct iio_dev *dev_info,
+				   int line_number);
+
+
+
+/**
+ * iio_push_event() - try to add event to the list for userspace reading
+ * @dev_info:		IIO device structure
+ * @ev_line:		Which event line (hardware interrupt)
+ * @ev_code:		What event
+ * @timestamp:		When the event occured
+ **/
+int iio_push_event(struct iio_dev *dev_info,
+		  int ev_line,
+		  int ev_code,
+		  s64 timestamp);
+
+/**
+ * struct iio_work_cont - container for when singleton handler case matters
+ * @ws:			[DEVICE]work_struct when not only possible event
+ * @ws_nocheck:		[DEVICE]work_struct when only possible event
+ * @address:		[DEVICE]associated register address
+ * @mask:		[DEVICE]associated mask for identifying event source
+ * @st:			[DEVICE]device specific state information
+ **/
+struct iio_work_cont {
+	struct work_struct	ws;
+	struct work_struct	ws_nocheck;
+	int			address;
+	int			mask;
+	void			*st;
+};
+
+#define to_iio_work_cont_check(_ws)			\
+	container_of(_ws, struct iio_work_cont, ws)
+
+#define to_iio_work_cont_no_check(_ws)				\
+	container_of(_ws, struct iio_work_cont, ws_nocheck)
+
+/**
+ * iio_init_work_cont() - intiialize the elements of a work container
+ * @cont: the work container
+ * @_checkfunc: function called when there are multiple possible int sources
+ * @_nocheckfunc: function for when there is only one int source
+ * @_add: driver dependant, typically a register address
+ * @_mask: driver dependant, typically a bit mask for a register
+ * @_st: driver dependant, typically pointer to a device state structure
+ **/
+static inline void
+iio_init_work_cont(struct iio_work_cont *cont,
+		   void (*_checkfunc)(struct work_struct *),
+		   void (*_nocheckfunc)(struct work_struct *),
+		   int _add, int _mask, void *_st)
+{
+	INIT_WORK(&(cont)->ws, _checkfunc);
+	INIT_WORK(&(cont)->ws_nocheck, _nocheckfunc);
+	cont->address = _add;
+	cont->mask = _mask;
+	cont->st = _st;
+}
+/**
+ * __iio_push_event() tries to add an event to the list associated with a chrdev
+ * @ev_int:		the event interface to which we are pushing the event
+ * @ev_code:		the outgoing event code
+ * @timestamp:		timestamp of the event
+ * @shared_pointer_p:	the shared event pointer
+ **/
+int __iio_push_event(struct iio_event_interface *ev_int,
+		    int ev_code,
+		    s64 timestamp,
+		    struct iio_shared_ev_pointer*
+		    shared_pointer_p);
+/**
+ * __iio_change_event() change an event code in case of event escallation
+ * @ev:			the evnet to be changed
+ * @ev_code:		new event code
+ * @timestamp:		new timestamp
+ **/
+void __iio_change_event(struct iio_detected_event_list *ev,
+			int ev_code,
+			s64 timestamp);
+
+/**
+ * iio_setup_ev_int() Configure an event interface (chrdev)
+ * @name:		name used for resulting sysfs directory etc.
+ * @ev_int:		interface we are configuring
+ * @owner:		module that is responsible for registering this ev_int
+ * @dev:		device whose ev_int this is
+ **/
+int iio_setup_ev_int(struct iio_event_interface *ev_int,
+		     const char *name,
+		     struct module *owner,
+		     struct device *dev);
+
+void iio_free_ev_int(struct iio_event_interface *ev_int);
+
+/**
+ * iio_allocate_chrdev() - Allocate a chrdev
+ * @handler:	struct that contains relevant file handling for chrdev
+ * @dev_info:	iio_dev for which chrdev is being created
+ **/
+int iio_allocate_chrdev(struct iio_handler *handler, struct iio_dev *dev_info);
+void iio_deallocate_chrdev(struct iio_handler *handler);
+
+/* Used to distinguish between bipolar and unipolar scan elemenents.
+ * Whilst this may seem obvious, we may well want to change the representation
+ * in the future!*/
+#define IIO_SIGNED(a) -(a)
+#define IIO_UNSIGNED(a) (a)
+
+extern dev_t iio_devt;
+extern struct class iio_class;
+
+/**
+ * iio_put_device() - reference counted deallocated of struct device
+ * @dev: the iio_device containing the device
+ **/
+static inline void iio_put_device(struct iio_dev *dev)
+{
+	if (dev)
+		put_device(&dev->dev);
+};
+
+/**
+ * to_iio_dev() - get iio_dev for which we have have the struct device
+ * @d: the struct device
+ **/
+static inline struct iio_dev *to_iio_dev(struct device *d)
+{
+	return container_of(d, struct iio_dev, dev);
+};
+
+/**
+ * iio_dev_get_devdata() - helper function gets device specific data
+ * @d: the iio_dev associated with the device
+ **/
+static inline void *iio_dev_get_devdata(struct iio_dev *d)
+{
+	return d->dev_data;
+}
+
+/**
+ * iio_allocate_device() - allocate an iio_dev from a driver
+ **/
+struct iio_dev *iio_allocate_device(void);
+
+/**
+ * iio_free_device() - free an iio_dev from a driver
+ **/
+void iio_free_device(struct iio_dev *dev);
+
+/**
+ * iio_put() - internal module reference count reduce
+ **/
+void iio_put(void);
+
+/**
+ * iio_get() - internal module reference count increase
+ **/
+void iio_get(void);
+
+/* Ring buffer related */
+int iio_device_get_chrdev_minor(void);
+void iio_device_free_chrdev_minor(int val);
+
+/**
+ * iio_ring_enabled() helper function to test if any form of ring enabled
+ **/
+static inline bool iio_ring_enabled(struct iio_dev *dev_info)
+{
+	return dev_info->currentmode
+		& (INDIO_RING_TRIGGERED
+		   | INDIO_RING_HARDWARE_BUFFER);
+};
+
+struct idr;
+
+int iio_get_new_idr_val(struct idr *this_idr);
+void iio_free_idr_val(struct idr *this_idr, int id);
+#endif /* _INDUSTRIAL_IO_H_ */
diff --git a/drivers/staging/iio/industrialio-core.c b/drivers/staging/iio/industrialio-core.c
new file mode 100644
index 00000000000..660a9c1a1f3
--- /dev/null
+++ b/drivers/staging/iio/industrialio-core.c
@@ -0,0 +1,851 @@
+/* The industrial I/O core
+ *
+ * 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.
+ *
+ * Based on elements of hwmon and input subsystems.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/idr.h>
+#include <linux/kdev_t.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <linux/poll.h>
+#include <linux/cdev.h>
+#include "iio.h"
+#include "trigger_consumer.h"
+
+#define IIO_ID_PREFIX "device"
+#define IIO_ID_FORMAT IIO_ID_PREFIX "%d"
+
+/* IDR to assign each registered device a unique id*/
+static DEFINE_IDR(iio_idr);
+
+/* IDR for general event identifiers */
+static DEFINE_IDR(iio_event_idr);
+/* IDR to allocate character device minor numbers */
+static DEFINE_IDR(iio_chrdev_idr);
+/* Lock used to protect both of the above */
+static DEFINE_SPINLOCK(iio_idr_lock);
+
+dev_t iio_devt;
+EXPORT_SYMBOL(iio_devt);
+
+#define IIO_DEV_MAX 256
+static char *iio_nodename(struct device *dev)
+{
+	return kasprintf(GFP_KERNEL, "iio/%s", dev_name(dev));
+}
+
+struct class iio_class = {
+	.name = "iio",
+	.nodename = iio_nodename,
+};
+EXPORT_SYMBOL(iio_class);
+
+void __iio_change_event(struct iio_detected_event_list *ev,
+			int ev_code,
+			s64 timestamp)
+{
+	ev->ev.id = ev_code;
+	ev->ev.timestamp = timestamp;
+}
+EXPORT_SYMBOL(__iio_change_event);
+
+/* Used both in the interrupt line put events and the ring buffer ones */
+
+/* Note that in it's current form someone has to be listening before events
+ * are queued. Hence a client MUST open the chrdev before the ring buffer is
+ * switched on.
+ */
+ int __iio_push_event(struct iio_event_interface *ev_int,
+		     int ev_code,
+		     s64 timestamp,
+		     struct iio_shared_ev_pointer *
+		     shared_pointer_p)
+{
+	struct iio_detected_event_list *ev;
+	int ret = 0;
+
+	/* Does anyone care? */
+	mutex_lock(&ev_int->event_list_lock);
+	if (test_bit(IIO_BUSY_BIT_POS, &ev_int->handler.flags)) {
+		if (ev_int->current_events == ev_int->max_events)
+			return 0;
+		ev = kmalloc(sizeof(*ev), GFP_KERNEL);
+		if (ev == NULL) {
+			ret = -ENOMEM;
+			goto error_ret;
+		}
+		ev->ev.id = ev_code;
+		ev->ev.timestamp = timestamp;
+		ev->shared_pointer = shared_pointer_p;
+		if (ev->shared_pointer)
+			shared_pointer_p->ev_p = ev;
+
+		list_add_tail(&ev->list, &ev_int->det_events.list);
+		ev_int->current_events++;
+		mutex_unlock(&ev_int->event_list_lock);
+		wake_up_interruptible(&ev_int->wait);
+	} else
+		mutex_unlock(&ev_int->event_list_lock);
+
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL(__iio_push_event);
+
+int iio_push_event(struct iio_dev *dev_info,
+		   int ev_line,
+		   int ev_code,
+		   s64 timestamp)
+{
+	return __iio_push_event(&dev_info->event_interfaces[ev_line],
+				ev_code, timestamp, NULL);
+}
+EXPORT_SYMBOL(iio_push_event);
+
+/* Generic interrupt line interrupt handler */
+irqreturn_t iio_interrupt_handler(int irq, void *_int_info)
+{
+	struct iio_interrupt *int_info = _int_info;
+	struct iio_dev *dev_info = int_info->dev_info;
+	struct iio_event_handler_list *p;
+	s64 time_ns;
+	unsigned long flags;
+
+	spin_lock_irqsave(&int_info->ev_list_lock, flags);
+	if (list_empty(&int_info->ev_list)) {
+		spin_unlock_irqrestore(&int_info->ev_list_lock, flags);
+		return IRQ_NONE;
+	}
+
+	time_ns = iio_get_time_ns();
+	/* detect single element list*/
+	if (list_is_singular(&int_info->ev_list)) {
+		disable_irq_nosync(irq);
+		p = list_first_entry(&int_info->ev_list,
+				     struct iio_event_handler_list,
+				     list);
+		/* single event handler - maybe shared */
+		p->handler(dev_info, 1, time_ns, !(p->refcount > 1));
+	} else
+		list_for_each_entry(p, &int_info->ev_list, list) {
+			disable_irq_nosync(irq);
+			p->handler(dev_info, 1, time_ns, 0);
+		}
+	spin_unlock_irqrestore(&int_info->ev_list_lock, flags);
+
+	return IRQ_HANDLED;
+}
+
+static struct iio_interrupt *iio_allocate_interrupt(void)
+{
+	struct iio_interrupt *i = kmalloc(sizeof *i, GFP_KERNEL);
+	if (i) {
+		spin_lock_init(&i->ev_list_lock);
+		INIT_LIST_HEAD(&i->ev_list);
+	}
+	return i;
+}
+
+/* Confirming the validity of supplied irq is left to drivers.*/
+int iio_register_interrupt_line(unsigned int irq,
+				struct iio_dev *dev_info,
+				int line_number,
+				unsigned long type,
+				const char *name)
+{
+	int ret;
+
+	dev_info->interrupts[line_number] = iio_allocate_interrupt();
+	if (dev_info->interrupts[line_number] == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	dev_info->interrupts[line_number]->line_number = line_number;
+	dev_info->interrupts[line_number]->irq = irq;
+	dev_info->interrupts[line_number]->dev_info = dev_info;
+
+	/* Possibly only request on demand?
+	 * Can see this may complicate the handling of interrupts.
+	 * However, with this approach we might end up handling lots of
+	 * events no-one cares about.*/
+	ret = request_irq(irq,
+			  &iio_interrupt_handler,
+			  type,
+			  name,
+			  dev_info->interrupts[line_number]);
+
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL(iio_register_interrupt_line);
+
+/* This turns up an awful lot */
+ssize_t iio_read_const_attr(struct device *dev,
+			    struct device_attribute *attr,
+			    char *buf)
+{
+	return sprintf(buf, "%s\n", to_iio_const_attr(attr)->string);
+}
+EXPORT_SYMBOL(iio_read_const_attr);
+
+/* Before this runs the interrupt generator must have been disabled */
+void iio_unregister_interrupt_line(struct iio_dev *dev_info, int line_number)
+{
+	/* make sure the interrupt handlers are all done */
+	flush_scheduled_work();
+	free_irq(dev_info->interrupts[line_number]->irq,
+		 dev_info->interrupts[line_number]);
+	kfree(dev_info->interrupts[line_number]);
+}
+EXPORT_SYMBOL(iio_unregister_interrupt_line);
+
+/* Reference counted add and remove */
+void iio_add_event_to_list(struct iio_event_handler_list *el,
+			  struct list_head *head)
+{
+	unsigned long flags;
+	struct iio_interrupt *inter = to_iio_interrupt(head);
+
+	/* take mutex to protect this element */
+	mutex_lock(&el->exist_lock);
+	if (el->refcount == 0) {
+		/* Take the event list spin lock */
+		spin_lock_irqsave(&inter->ev_list_lock, flags);
+		list_add(&el->list, head);
+		spin_unlock_irqrestore(&inter->ev_list_lock, flags);
+	}
+	el->refcount++;
+	mutex_unlock(&el->exist_lock);
+}
+EXPORT_SYMBOL(iio_add_event_to_list);
+
+void iio_remove_event_from_list(struct iio_event_handler_list *el,
+			       struct list_head *head)
+{
+	unsigned long flags;
+	struct iio_interrupt *inter = to_iio_interrupt(head);
+
+	mutex_lock(&el->exist_lock);
+	el->refcount--;
+	if (el->refcount == 0) {
+		/* Take the event list spin lock */
+		spin_lock_irqsave(&inter->ev_list_lock, flags);
+		list_del_init(&el->list);
+		spin_unlock_irqrestore(&inter->ev_list_lock, flags);
+	}
+	mutex_unlock(&el->exist_lock);
+}
+EXPORT_SYMBOL(iio_remove_event_from_list);
+
+ssize_t iio_event_chrdev_read(struct file *filep,
+			      char *buf,
+			      size_t count,
+			      loff_t *f_ps)
+{
+	struct iio_event_interface *ev_int = filep->private_data;
+	struct iio_detected_event_list *el;
+	int ret;
+	size_t len;
+
+	mutex_lock(&ev_int->event_list_lock);
+	if (list_empty(&ev_int->det_events.list)) {
+		if (filep->f_flags & O_NONBLOCK) {
+			ret = -EAGAIN;
+			goto error_mutex_unlock;
+		}
+		mutex_unlock(&ev_int->event_list_lock);
+		/* Blocking on device; waiting for something to be there */
+		ret = wait_event_interruptible(ev_int->wait,
+					       !list_empty(&ev_int
+							   ->det_events.list));
+		if (ret)
+			goto error_ret;
+		/* Single access device so noone else can get the data */
+		mutex_lock(&ev_int->event_list_lock);
+	}
+
+	el = list_first_entry(&ev_int->det_events.list,
+			      struct iio_detected_event_list,
+			      list);
+	len = sizeof el->ev;
+	if (copy_to_user(buf, &(el->ev), len)) {
+		ret = -EFAULT;
+		goto error_mutex_unlock;
+	}
+	list_del(&el->list);
+	ev_int->current_events--;
+	mutex_unlock(&ev_int->event_list_lock);
+	/*
+	 * Possible concurency issue if an update of this event is on its way
+	 * through. May lead to new even being removed whilst the reported event
+	 * was the unescalated event. In typical use case this is not a problem
+	 * as userspace will say read half the buffer due to a 50% full event
+	 * which would make the correct 100% full incorrect anyway.
+	 */
+	spin_lock(&el->shared_pointer->lock);
+	if (el->shared_pointer)
+		(el->shared_pointer->ev_p) = NULL;
+	spin_unlock(&el->shared_pointer->lock);
+
+	kfree(el);
+
+	return len;
+
+error_mutex_unlock:
+	mutex_unlock(&ev_int->event_list_lock);
+error_ret:
+
+	return ret;
+}
+
+int iio_event_chrdev_release(struct inode *inode, struct file *filep)
+{
+	struct iio_handler *hand = iio_cdev_to_handler(inode->i_cdev);
+	struct iio_event_interface *ev_int = hand->private;
+	struct iio_detected_event_list *el, *t;
+
+	mutex_lock(&ev_int->event_list_lock);
+	clear_bit(IIO_BUSY_BIT_POS, &ev_int->handler.flags);
+	/*
+	 * In order to maintain a clean state for reopening,
+	 * clear out any awaiting events. The mask will prevent
+	 * any new __iio_push_event calls running.
+	 */
+	list_for_each_entry_safe(el, t, &ev_int->det_events.list, list) {
+		list_del(&el->list);
+		kfree(el);
+	}
+	mutex_unlock(&ev_int->event_list_lock);
+
+	return 0;
+}
+
+int iio_event_chrdev_open(struct inode *inode, struct file *filep)
+{
+	struct iio_handler *hand = iio_cdev_to_handler(inode->i_cdev);
+	struct iio_event_interface *ev_int = hand->private;
+
+	mutex_lock(&ev_int->event_list_lock);
+	if (test_and_set_bit(IIO_BUSY_BIT_POS, &hand->flags)) {
+		fops_put(filep->f_op);
+		mutex_unlock(&ev_int->event_list_lock);
+		return -EBUSY;
+	}
+	filep->private_data = hand->private;
+	mutex_unlock(&ev_int->event_list_lock);
+
+	return 0;
+}
+
+static const struct file_operations iio_event_chrdev_fileops = {
+	.read =  iio_event_chrdev_read,
+	.release = iio_event_chrdev_release,
+	.open = iio_event_chrdev_open,
+	.owner = THIS_MODULE,
+};
+
+static void iio_event_dev_release(struct device *dev)
+{
+	struct iio_event_interface *ev_int
+		= container_of(dev, struct iio_event_interface, dev);
+	cdev_del(&ev_int->handler.chrdev);
+	iio_device_free_chrdev_minor(MINOR(dev->devt));
+};
+
+static struct device_type iio_event_type = {
+	.release = iio_event_dev_release,
+};
+
+int iio_device_get_chrdev_minor(void)
+{
+	int ret, val;
+
+idr_again:
+	if (unlikely(idr_pre_get(&iio_chrdev_idr, GFP_KERNEL) == 0))
+		return -ENOMEM;
+	spin_lock(&iio_idr_lock);
+	ret = idr_get_new(&iio_chrdev_idr, NULL, &val);
+	spin_unlock(&iio_idr_lock);
+	if (unlikely(ret == -EAGAIN))
+		goto idr_again;
+	else if (unlikely(ret))
+		return ret;
+	if (val > IIO_DEV_MAX)
+		return -ENOMEM;
+	return val;
+}
+
+void iio_device_free_chrdev_minor(int val)
+{
+	spin_lock(&iio_idr_lock);
+	idr_remove(&iio_chrdev_idr, val);
+	spin_unlock(&iio_idr_lock);
+}
+
+int iio_setup_ev_int(struct iio_event_interface *ev_int,
+		     const char *name,
+		     struct module *owner,
+		     struct device *dev)
+{
+	int ret, minor;
+
+	ev_int->dev.class = &iio_class;
+	ev_int->dev.parent = dev;
+	ev_int->dev.type = &iio_event_type;
+	device_initialize(&ev_int->dev);
+
+	minor = iio_device_get_chrdev_minor();
+	if (minor < 0) {
+		ret = minor;
+		goto error_device_put;
+	}
+	ev_int->dev.devt = MKDEV(MAJOR(iio_devt), minor);
+	dev_set_name(&ev_int->dev, "%s", name);
+
+	ret = device_add(&ev_int->dev);
+	if (ret)
+		goto error_free_minor;
+
+	cdev_init(&ev_int->handler.chrdev, &iio_event_chrdev_fileops);
+	ev_int->handler.chrdev.owner = owner;
+
+	mutex_init(&ev_int->event_list_lock);
+	/* discussion point - make this variable? */
+	ev_int->max_events = 10;
+	ev_int->current_events = 0;
+	INIT_LIST_HEAD(&ev_int->det_events.list);
+	init_waitqueue_head(&ev_int->wait);
+	ev_int->handler.private = ev_int;
+	ev_int->handler.flags = 0;
+
+	ret = cdev_add(&ev_int->handler.chrdev, ev_int->dev.devt, 1);
+	if (ret)
+		goto error_unreg_device;
+
+	return 0;
+
+error_unreg_device:
+	device_unregister(&ev_int->dev);
+error_free_minor:
+	iio_device_free_chrdev_minor(minor);
+error_device_put:
+	put_device(&ev_int->dev);
+
+	return ret;
+}
+
+void iio_free_ev_int(struct iio_event_interface *ev_int)
+{
+	device_unregister(&ev_int->dev);
+	put_device(&ev_int->dev);
+}
+
+static int __init iio_dev_init(void)
+{
+	int err;
+
+	err = alloc_chrdev_region(&iio_devt, 0, IIO_DEV_MAX, "iio");
+	if (err < 0)
+		printk(KERN_ERR "%s: failed to allocate char dev region\n",
+		       __FILE__);
+
+	return err;
+}
+
+static void __exit iio_dev_exit(void)
+{
+	if (iio_devt)
+		unregister_chrdev_region(iio_devt, IIO_DEV_MAX);
+}
+
+static int __init iio_init(void)
+{
+	int ret;
+
+	/* Create sysfs class */
+	ret  = class_register(&iio_class);
+	if (ret < 0) {
+		printk(KERN_ERR
+		       "%s could not create sysfs class\n",
+			__FILE__);
+		goto error_nothing;
+	}
+
+	ret = iio_dev_init();
+	if (ret < 0)
+		goto error_unregister_class;
+
+	return 0;
+
+error_unregister_class:
+	class_unregister(&iio_class);
+error_nothing:
+	return ret;
+}
+
+static void __exit iio_exit(void)
+{
+	iio_dev_exit();
+	class_unregister(&iio_class);
+}
+
+static int iio_device_register_sysfs(struct iio_dev *dev_info)
+{
+	int ret = 0;
+
+	ret = sysfs_create_group(&dev_info->dev.kobj, dev_info->attrs);
+	if (ret) {
+		dev_err(dev_info->dev.parent,
+			"Failed to register sysfs hooks\n");
+		goto error_ret;
+	}
+
+	if (dev_info->scan_el_attrs) {
+		ret = sysfs_create_group(&dev_info->dev.kobj,
+					 dev_info->scan_el_attrs);
+		if (ret)
+			dev_err(&dev_info->dev,
+				"Failed to add sysfs scan els\n");
+	}
+
+error_ret:
+	return ret;
+}
+
+static void iio_device_unregister_sysfs(struct iio_dev *dev_info)
+{
+	if (dev_info->scan_el_attrs)
+		sysfs_remove_group(&dev_info->dev.kobj,
+				   dev_info->scan_el_attrs);
+
+	sysfs_remove_group(&dev_info->dev.kobj, dev_info->attrs);
+}
+
+int iio_get_new_idr_val(struct idr *this_idr)
+{
+	int ret;
+	int val;
+
+idr_again:
+	if (unlikely(idr_pre_get(this_idr, GFP_KERNEL) == 0))
+		return -ENOMEM;
+
+	spin_lock(&iio_idr_lock);
+	ret = idr_get_new(this_idr, NULL, &val);
+	spin_unlock(&iio_idr_lock);
+	if (unlikely(ret == -EAGAIN))
+		goto idr_again;
+	else if (unlikely(ret))
+		return ret;
+
+	return val;
+}
+EXPORT_SYMBOL(iio_get_new_idr_val);
+
+void iio_free_idr_val(struct idr *this_idr, int id)
+{
+	spin_lock(&iio_idr_lock);
+	idr_remove(this_idr, id);
+	spin_unlock(&iio_idr_lock);
+}
+EXPORT_SYMBOL(iio_free_idr_val);
+
+static int iio_device_register_id(struct iio_dev *dev_info,
+				  struct idr *this_idr)
+{
+
+	dev_info->id = iio_get_new_idr_val(&iio_idr);
+	if (dev_info->id < 0)
+		return dev_info->id;
+	return 0;
+}
+
+static void iio_device_unregister_id(struct iio_dev *dev_info)
+{
+	iio_free_idr_val(&iio_idr, dev_info->id);
+}
+
+static inline int __iio_add_event_config_attrs(struct iio_dev *dev_info, int i)
+{
+	int ret;
+	/*p for adding, q for removing */
+	struct attribute **attrp, **attrq;
+
+	if (dev_info->event_conf_attrs && dev_info->event_conf_attrs[i].attrs) {
+		attrp = dev_info->event_conf_attrs[i].attrs;
+		while (*attrp) {
+			ret =  sysfs_add_file_to_group(&dev_info->dev.kobj,
+						       *attrp,
+						       dev_info
+						       ->event_attrs[i].name);
+			if (ret)
+				goto error_ret;
+			attrp++;
+		}
+	}
+	return 0;
+
+error_ret:
+	attrq = dev_info->event_conf_attrs[i].attrs;
+	while (attrq != attrp) {
+			sysfs_remove_file_from_group(&dev_info->dev.kobj,
+					     *attrq,
+					     dev_info->event_attrs[i].name);
+		attrq++;
+	}
+
+	return ret;
+}
+
+static inline int __iio_remove_event_config_attrs(struct iio_dev *dev_info,
+						  int i)
+{
+	struct attribute **attrq;
+
+	if (dev_info->event_conf_attrs
+		&& dev_info->event_conf_attrs[i].attrs) {
+		attrq = dev_info->event_conf_attrs[i].attrs;
+		while (*attrq) {
+			sysfs_remove_file_from_group(&dev_info->dev.kobj,
+						     *attrq,
+						     dev_info
+						     ->event_attrs[i].name);
+			attrq++;
+		}
+	}
+
+	return 0;
+}
+
+static int iio_device_register_eventset(struct iio_dev *dev_info)
+{
+	int ret = 0, i, j;
+
+	if (dev_info->num_interrupt_lines == 0)
+		return 0;
+
+	dev_info->event_interfaces =
+		kzalloc(sizeof(struct iio_event_interface)
+			*dev_info->num_interrupt_lines,
+			GFP_KERNEL);
+	if (dev_info->event_interfaces == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+
+	dev_info->interrupts = kzalloc(sizeof(struct iio_interrupt *)
+				       *dev_info->num_interrupt_lines,
+				       GFP_KERNEL);
+	if (dev_info->interrupts == NULL) {
+		ret = -ENOMEM;
+		goto error_free_event_interfaces;
+	}
+
+	for (i = 0; i < dev_info->num_interrupt_lines; i++) {
+		dev_info->event_interfaces[i].owner = dev_info->driver_module;
+		ret = iio_get_new_idr_val(&iio_event_idr);
+		if (ret)
+			goto error_free_setup_ev_ints;
+		else
+			dev_info->event_interfaces[i].id = ret;
+
+		snprintf(dev_info->event_interfaces[i]._name, 20,
+			 "event_line%d",
+			dev_info->event_interfaces[i].id);
+
+		ret = iio_setup_ev_int(&dev_info->event_interfaces[i],
+				       (const char *)(dev_info
+						      ->event_interfaces[i]
+						      ._name),
+				       dev_info->driver_module,
+				       &dev_info->dev);
+		if (ret) {
+			dev_err(&dev_info->dev,
+				"Could not get chrdev interface\n");
+			iio_free_idr_val(&iio_event_idr,
+					 dev_info->event_interfaces[i].id);
+			goto error_free_setup_ev_ints;
+		}
+	}
+
+	for (i = 0; i < dev_info->num_interrupt_lines; i++) {
+		snprintf(dev_info->event_interfaces[i]._attrname, 20,
+			"event_line%d_sources", i);
+		dev_info->event_attrs[i].name
+			= (const char *)
+			(dev_info->event_interfaces[i]._attrname);
+		ret = sysfs_create_group(&dev_info->dev.kobj,
+					 &dev_info->event_attrs[i]);
+		if (ret) {
+			dev_err(&dev_info->dev,
+				"Failed to register sysfs for event attrs");
+			goto error_remove_sysfs_interfaces;
+		}
+	}
+
+	for (i = 0; i < dev_info->num_interrupt_lines; i++) {
+		ret = __iio_add_event_config_attrs(dev_info, i);
+		if (ret)
+			goto error_unregister_config_attrs;
+	}
+
+	return 0;
+
+error_unregister_config_attrs:
+	for (j = 0; j < i; j++)
+		__iio_remove_event_config_attrs(dev_info, i);
+	i = dev_info->num_interrupt_lines - 1;
+error_remove_sysfs_interfaces:
+	for (j = 0; j < i; j++)
+		sysfs_remove_group(&dev_info->dev.kobj,
+				   &dev_info->event_attrs[j]);
+	i = dev_info->num_interrupt_lines - 1;
+error_free_setup_ev_ints:
+	for (j = 0; j < i; j++) {
+		iio_free_idr_val(&iio_event_idr,
+				 dev_info->event_interfaces[i].id);
+		iio_free_ev_int(&dev_info->event_interfaces[j]);
+	}
+	kfree(dev_info->interrupts);
+error_free_event_interfaces:
+	kfree(dev_info->event_interfaces);
+error_ret:
+
+	return ret;
+}
+
+static void iio_device_unregister_eventset(struct iio_dev *dev_info)
+{
+	int i;
+
+	if (dev_info->num_interrupt_lines == 0)
+		return;
+	for (i = 0; i < dev_info->num_interrupt_lines; i++)
+		sysfs_remove_group(&dev_info->dev.kobj,
+				   &dev_info->event_attrs[i]);
+
+	for (i = 0; i < dev_info->num_interrupt_lines; i++) {
+		iio_free_idr_val(&iio_event_idr,
+				 dev_info->event_interfaces[i].id);
+		iio_free_ev_int(&dev_info->event_interfaces[i]);
+	}
+	kfree(dev_info->interrupts);
+	kfree(dev_info->event_interfaces);
+}
+
+static void iio_dev_release(struct device *device)
+{
+	struct iio_dev *dev = to_iio_dev(device);
+
+	iio_put();
+	kfree(dev);
+}
+
+static struct device_type iio_dev_type = {
+	.name = "iio_device",
+	.release = iio_dev_release,
+};
+
+struct iio_dev *iio_allocate_device(void)
+{
+	struct iio_dev *dev = kzalloc(sizeof *dev, GFP_KERNEL);
+
+	if (dev) {
+		dev->dev.type = &iio_dev_type;
+		dev->dev.class = &iio_class;
+		device_initialize(&dev->dev);
+		dev_set_drvdata(&dev->dev, (void *)dev);
+		mutex_init(&dev->mlock);
+		iio_get();
+	}
+
+	return dev;
+}
+EXPORT_SYMBOL(iio_allocate_device);
+
+void iio_free_device(struct iio_dev *dev)
+{
+	if (dev)
+		iio_put_device(dev);
+}
+EXPORT_SYMBOL(iio_free_device);
+
+int iio_device_register(struct iio_dev *dev_info)
+{
+	int ret;
+
+	ret = iio_device_register_id(dev_info, &iio_idr);
+	if (ret) {
+		dev_err(&dev_info->dev, "Failed to get id\n");
+		goto error_ret;
+	}
+	dev_set_name(&dev_info->dev, "device%d", dev_info->id);
+
+	ret = device_add(&dev_info->dev);
+	if (ret)
+		goto error_free_idr;
+	ret = iio_device_register_sysfs(dev_info);
+	if (ret) {
+		dev_err(dev_info->dev.parent,
+			"Failed to register sysfs interfaces\n");
+		goto error_del_device;
+	}
+	ret = iio_device_register_eventset(dev_info);
+	if (ret) {
+		dev_err(dev_info->dev.parent,
+			"Failed to register event set \n");
+		goto error_free_sysfs;
+	}
+	if (dev_info->modes & INDIO_RING_TRIGGERED)
+		iio_device_register_trigger_consumer(dev_info);
+
+	return 0;
+
+error_free_sysfs:
+	iio_device_unregister_sysfs(dev_info);
+error_del_device:
+	device_del(&dev_info->dev);
+error_free_idr:
+	iio_device_unregister_id(dev_info);
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL(iio_device_register);
+
+void iio_device_unregister(struct iio_dev *dev_info)
+{
+	if (dev_info->modes & INDIO_RING_TRIGGERED)
+		iio_device_unregister_trigger_consumer(dev_info);
+	iio_device_unregister_eventset(dev_info);
+	iio_device_unregister_sysfs(dev_info);
+	iio_device_unregister_id(dev_info);
+	device_unregister(&dev_info->dev);
+}
+EXPORT_SYMBOL(iio_device_unregister);
+
+void iio_put(void)
+{
+	module_put(THIS_MODULE);
+}
+
+void iio_get(void)
+{
+	__module_get(THIS_MODULE);
+}
+
+subsys_initcall(iio_init);
+module_exit(iio_exit);
+
+MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
+MODULE_DESCRIPTION("Industrial I/O core");
+MODULE_LICENSE("GPL");
diff --git a/drivers/staging/iio/sysfs.h b/drivers/staging/iio/sysfs.h
new file mode 100644
index 00000000000..bfe4055c0ed
--- /dev/null
+++ b/drivers/staging/iio/sysfs.h
@@ -0,0 +1,293 @@
+/* The industrial I/O core
+ *
+ *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.
+ *
+ * General attributes
+ */
+
+#ifndef _INDUSTRIAL_IO_SYSFS_H_
+#define _INDUSTRIAL_IO_SYSFS_H_
+
+#include "iio.h"
+
+/**
+ * struct iio_event_attribute - event control attribute
+ * @dev_attr:	underlying device attribute
+ * @mask:	mask for the event when detecting
+ * @listel:	list header to allow addition to list of event handlers
+*/
+struct iio_event_attr {
+	struct device_attribute dev_attr;
+	int mask;
+	struct iio_event_handler_list *listel;
+};
+
+#define to_iio_event_attr(_dev_attr) \
+	container_of(_dev_attr, struct iio_event_attr, dev_attr)
+
+/**
+ * struct iio_chrdev_minor_attr - simple attribute to allow reading of chrdev
+ *				minor number
+ * @dev_attr:	underlying device attribute
+ * @minor:	the minor number
+ */
+struct iio_chrdev_minor_attr {
+	struct device_attribute dev_attr;
+	int minor;
+};
+
+void
+__init_iio_chrdev_minor_attr(struct iio_chrdev_minor_attr *minor_attr,
+			   const char *name,
+			   struct module *owner,
+			   int id);
+
+
+#define to_iio_chrdev_minor_attr(_dev_attr) \
+	container_of(_dev_attr, struct iio_chrdev_minor_attr, dev_attr);
+
+/**
+ * struct iio_dev_attr - iio specific device attribute
+ * @dev_attr:	underlying device attribute
+ * @address:	associated register address
+ */
+struct iio_dev_attr {
+	struct device_attribute dev_attr;
+	int address;
+	int val2;
+};
+
+#define to_iio_dev_attr(_dev_attr)				\
+	container_of(_dev_attr, struct iio_dev_attr, dev_attr)
+
+ssize_t iio_read_const_attr(struct device *dev,
+			    struct device_attribute *attr,
+			    char *len);
+
+/**
+ * struct iio_const_attr - constant device specific attribute
+ *                         often used for things like available modes
+ */
+struct iio_const_attr {
+	const char *string;
+	struct device_attribute dev_attr;
+};
+
+#define to_iio_const_attr(_dev_attr) \
+	container_of(_dev_attr, struct iio_const_attr, dev_attr)
+
+/* Some attributes will be hard coded (device dependant) and not require an
+   address, in these cases pass a negative */
+#define IIO_ATTR(_name, _mode, _show, _store, _addr)		\
+	{ .dev_attr = __ATTR(_name, _mode, _show, _store),	\
+	  .address = _addr }
+
+#define IIO_ATTR_2(_name, _mode, _show, _store, _addr, _val2)	\
+	{ .dev_attr = __ATTR(_name, _mode, _show, _store),	\
+			.address = _addr,			\
+			.val2 = _val2 }
+
+#define IIO_DEVICE_ATTR(_name, _mode, _show, _store, _addr)	\
+	struct iio_dev_attr iio_dev_attr_##_name		\
+	= IIO_ATTR(_name, _mode, _show, _store, _addr)
+
+
+#define IIO_DEVICE_ATTR_2(_name, _mode, _show, _store, _addr, _val2)	\
+	struct iio_dev_attr iio_dev_attr_##_name			\
+	= IIO_ATTR_2(_name, _mode, _show, _store, _addr, _val2)
+
+#define IIO_CONST_ATTR(_name, _string)					\
+	struct iio_const_attr iio_const_attr_##_name			\
+	= { .string = _string,						\
+	    .dev_attr = __ATTR(_name, S_IRUGO, iio_read_const_attr, NULL)}
+
+/* Generic attributes of onetype or another */
+
+/**
+ * IIO_DEV_ATTR_REG: revision number for the device
+ *
+ * Very much device dependent.
+ **/
+#define IIO_DEV_ATTR_REV(_show)			\
+	IIO_DEVICE_ATTR(revision, S_IRUGO, _show, NULL, 0)
+/**
+ * IIO_DEV_ATTR_NAME: chip type dependant identifier
+ **/
+#define IIO_DEV_ATTR_NAME(_show)				\
+	IIO_DEVICE_ATTR(name, S_IRUGO, _show, NULL, 0)
+
+/**
+ * IIO_DEV_ATTR_SAMP_FREQ: sets any internal clock frequency
+ **/
+#define IIO_DEV_ATTR_SAMP_FREQ(_mode, _show, _store)			\
+	IIO_DEVICE_ATTR(sampling_frequency, _mode, _show, _store, 0)
+
+/**
+ * IIO_DEV_ATTR_AVAIL_SAMP_FREQ: list available sampling frequencies.
+ *
+ * May be mode dependant on some devices
+ **/
+#define IIO_DEV_ATTR_AVAIL_SAMP_FREQ(_show)				\
+	IIO_DEVICE_ATTR(available_sampling_frequency, S_IRUGO, _show, NULL, 0)
+
+/**
+ * IIO_DEV_ATTR_CONST_AVAIL_SAMP_FREQ: list available sampling frequencies.
+ *
+ * Constant version
+ **/
+#define IIO_CONST_ATTR_AVAIL_SAMP_FREQ(_string)	\
+	IIO_CONST_ATTR(available_sampling_frequency, _string)
+/**
+ * IIO_DEV_ATTR_SCAN_MODE: select a scan mode
+ *
+ * This is used when only certain combinations of inputs may be read in one
+ * scan.
+ **/
+#define IIO_DEV_ATTR_SCAN_MODE(_mode, _show, _store)		\
+	IIO_DEVICE_ATTR(scan_mode, _mode, _show, _store, 0)
+/**
+ * IIO_DEV_ATTR_AVAIL_SCAN_MODES: list available scan modes
+ **/
+#define IIO_DEV_ATTR_AVAIL_SCAN_MODES(_show)				\
+	IIO_DEVICE_ATTR(available_scan_modes, S_IRUGO, _show, NULL, 0)
+
+/**
+ * IIO_DEV_ATTR_SCAN: result of scan of multiple channels
+ **/
+#define IIO_DEV_ATTR_SCAN(_show)		\
+	IIO_DEVICE_ATTR(scan, S_IRUGO, _show, NULL, 0);
+
+/**
+ * IIO_DEV_ATTR_INPUT: direct read of a single input channel
+ **/
+#define IIO_DEV_ATTR_INPUT(_number, _show)				\
+	IIO_DEVICE_ATTR(in##_number, S_IRUGO, _show, NULL, _number)
+
+
+/**
+ * IIO_DEV_ATTR_SW_RING_ENABLE: enable software ring buffer
+ *
+ * Success may be dependant on attachment of trigger previously
+ **/
+#define IIO_DEV_ATTR_SW_RING_ENABLE(_show, _store)			\
+	IIO_DEVICE_ATTR(sw_ring_enable, S_IRUGO | S_IWUSR, _show, _store, 0)
+
+/**
+ * IIO_DEV_ATTR_HW_RING_ENABLE: enable hardware ring buffer
+ *
+ * This is a different attribute from the software one as one can invision
+ * schemes where a combination of the two may be used.
+ **/
+#define IIO_DEV_ATTR_HW_RING_ENABLE(_show, _store)			\
+	IIO_DEVICE_ATTR(hw_ring_enable, S_IRUGO | S_IWUSR, _show, _store, 0)
+
+/**
+ * IIO_DEV_ATTR_BPSE: set number of bits per scan element
+ **/
+#define IIO_DEV_ATTR_BPSE(_mode, _show, _store)		\
+	IIO_DEVICE_ATTR(bpse, _mode, _show, _store, 0)
+
+/**
+ * IIO_DEV_ATTR_BPSE_AVAILABLE: no of bits per scan element supported
+ **/
+#define IIO_DEV_ATTR_BPSE_AVAILABLE(_show)				\
+	IIO_DEVICE_ATTR(bpse_available, S_IRUGO, _show, NULL, 0)
+
+/**
+ * IIO_DEV_ATTR_TEMP: many sensors have auxiliary temperature sensors
+ **/
+#define IIO_DEV_ATTR_TEMP(_show)			\
+	IIO_DEVICE_ATTR(temp, S_IRUGO, _show, NULL, 0)
+/**
+ * IIO_EVENT_SH: generic shared event handler
+ *
+ * This is used in cases where more than one event may result from a single
+ * handler.  Often the case that some alarm register must be read and multiple
+ * alarms may have been triggered.
+ **/
+#define IIO_EVENT_SH(_name, _handler)					\
+	static struct iio_event_handler_list				\
+	iio_event_##_name = {						\
+		.handler = _handler,					\
+		.refcount = 0,						\
+		.exist_lock = __MUTEX_INITIALIZER(iio_event_##_name	\
+						  .exist_lock),		\
+		.list = {						\
+			.next = &iio_event_##_name.list,		\
+			.prev = &iio_event_##_name.list,		\
+		},							\
+	};
+/**
+ * IIO_EVENT_ATTR_SH: generic shared event attribute
+ *
+ * An attribute with an associated IIO_EVENT_SH
+ **/
+#define IIO_EVENT_ATTR_SH(_name, _ev_list, _show, _store, _mask)	\
+	static struct iio_event_attr					\
+	iio_event_attr_##_name						\
+	= { .dev_attr = __ATTR(_name, S_IRUGO | S_IWUSR,		\
+			       _show, _store),				\
+	    .mask = _mask,						\
+	    .listel = &_ev_list };
+
+/**
+ * IIO_EVENT_ATTR: non shared event attribute
+ **/
+#define IIO_EVENT_ATTR(_name, _show, _store, _mask, _handler)		\
+	static struct iio_event_handler_list				\
+	iio_event_##_name = {						\
+		.handler = _handler,					\
+	};								\
+	static struct							\
+	iio_event_attr							\
+	iio_event_attr_##_name						\
+	= { .dev_attr = __ATTR(_name, S_IRUGO | S_IWUSR,		\
+			       _show, _store),				\
+	    .mask = _mask,						\
+	    .listel = &iio_event_##_name };				\
+
+/**
+ * IIO_EVENT_ATTR_DATA_RDY: event driven by data ready signal
+ *
+ * Not typically implemented in devices where full triggering support
+ * has been implemented
+ **/
+#define IIO_EVENT_ATTR_DATA_RDY(_show, _store, _mask, _handler) \
+	IIO_EVENT_ATTR(data_rdy, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_CODE_DATA_RDY		100
+#define IIO_EVENT_CODE_RING_BASE	200
+#define IIO_EVENT_CODE_ACCEL_BASE	300
+#define IIO_EVENT_CODE_GYRO_BASE	400
+#define IIO_EVENT_CODE_ADC_BASE		500
+#define IIO_EVENT_CODE_MISC_BASE	600
+
+#define IIO_EVENT_CODE_DEVICE_SPECIFIC	1000
+
+/**
+ * IIO_EVENT_ATTR_RING_50_FULL: ring buffer event to indicate 50% full
+ **/
+#define IIO_EVENT_ATTR_RING_50_FULL(_show, _store, _mask, _handler)	\
+	IIO_EVENT_ATTR(ring_50_full, _show, _store, _mask, _handler)
+
+/**
+ * IIO_EVENT_ATTR_RING_50_FULL_SH: shared ring event to indicate 50% full
+ **/
+#define IIO_EVENT_ATTR_RING_50_FULL_SH(_evlist, _show, _store, _mask)	\
+	IIO_EVENT_ATTR_SH(ring_50_full, _evlist, _show, _store, _mask)
+
+/**
+ * IIO_EVENT_ATTR_RING_75_FULL_SH: shared ring event to indicate 75% full
+ **/
+#define IIO_EVENT_ATTR_RING_75_FULL_SH(_evlist, _show, _store, _mask)	\
+	IIO_EVENT_ATTR_SH(ring_75_full, _evlist, _show, _store, _mask)
+
+#define IIO_EVENT_CODE_RING_50_FULL	IIO_EVENT_CODE_RING_BASE
+#define IIO_EVENT_CODE_RING_75_FULL	(IIO_EVENT_CODE_RING_BASE + 1)
+#define IIO_EVENT_CODE_RING_100_FULL	(IIO_EVENT_CODE_RING_BASE + 2)
+
+#endif /* _INDUSTRIAL_IO_SYSFS_H_ */
diff --git a/drivers/staging/iio/trigger_consumer.h b/drivers/staging/iio/trigger_consumer.h
new file mode 100644
index 00000000000..a6053892893
--- /dev/null
+++ b/drivers/staging/iio/trigger_consumer.h
@@ -0,0 +1,26 @@
+
+/* The industrial I/O core, trigger consumer 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.
+ */
+
+/**
+ * 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)
+{
+	return 0;
+};
+/**
+ * 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)
+{
+	return 0;
+};