[Patch 1/4] Industrialio Core

[Jonathan Cameron]

From: Jonathan Cameron <jic23@xxxxxxxxx>

Industrialio subsystem core patch. This subsystem is intended to support the use
of (initially) sensors within linux for the purposes of data capture and its use
within control applications. The intention is to provide consistent interfaces
(where it makes sense) with device control occuring through sysfs interfaces and
provision of events to userspace via chrdevs. Currently software ring buffers
are available if the sensor provides a data ready signal or a periodic rtc is
available (and registered with the subsystem in board init code).

Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxx>
---
The periodic timer code is a temporary stop gap until a more generic subsystem
becomes available.

The intention of publishing these patches is to generate feedback both at the
high level of suggestions / comments on the general approach taken by the
subsystem as a whole and at the low level of implementation details.

Areas that in my view need attention are the software ring buffer (particularly
careful analysis of corner cases and efficiency of it as a storage method).
Although none of the current drivers is capable of filling it in interrupt
context, I can envision some hardware may need to and this will clearly require
some changes.  The overall layout of the interfaces (and indeed the code) needs
some work, particularly with a view to cutting down the dependancies if a
given driver doesn't need all of the systems functionality.

Additional test drivers will obviously assist in working out many of these
issues and I hope to add several more over the comming weeks.

My sincerest thanks goes to anyone who takes the time to read through or test
this patch set.

drivers/Kconfig                                       |    3
drivers/Makefile                                      |    1
drivers/industrialio/Kconfig                          |   19
drivers/industrialio/Makefile                         |    7
drivers/industrialio/industrialio-core.c              |  787 ++++++++++++++++++
drivers/industrialio/industrialio-ring.c              |  770 +++++++++++++++++
drivers/industrialio/industrialio-rtc.c               |  134 +++
drivers/industrialio/industrialio_ptimer_board_info.c |   44 +
include/linux/industrialio.h                          |  374 ++++++++
include/linux/industrialio_ptimer.h                   |   18
include/linux/industrialio_sysfs.h                    |  274 ++++++
11 files changed, 2431 insertions(+)

------ a/drivers/Kconfig	2008-07-13 22:51:29.000000000 +0100
+++ b/drivers/Kconfig	2008-07-14 17:26:34.000000000 +0100
@@ -101,4 +101,7 @@ source "drivers/auxdisplay/Kconfig"
 source "drivers/uio/Kconfig"
 
 source "drivers/xen/Kconfig"
+
+source "drivers/industrialio/Kconfig" 
 endmenu
+
--- a/drivers/Makefile	2008-07-13 22:51:29.000000000 +0100
+++ b/drivers/Makefile	2008-07-14 17:26:34.000000000 +0100
@@ -62,6 +62,7 @@ obj-$(CONFIG_INPUT)		+= input/
 obj-$(CONFIG_I2O)		+= message/
 obj-$(CONFIG_RTC_LIB)		+= rtc/
 obj-y				+= i2c/
+obj-y				+= industrialio/
 obj-$(CONFIG_W1)		+= w1/
 obj-$(CONFIG_POWER_SUPPLY)	+= power/
 obj-$(CONFIG_HWMON)		+= hwmon/
--- a/drivers/industrialio/Kconfig	1970-01-01 01:00:00.000000000 +0100
+++ b/drivers/industrialio/Kconfig	2008-07-23 15:44:45.000000000 +0100
@@ -0,0 +1,19 @@
+#
+# Industrial I/O subsytem configuration
+#
+
+menuconfig INDUSTRIALIO
+	tristate "Industrial I/O support"
+	---help---
+	  The industrial IO subsystem provides a unified framework for drivers
+	  for many different types of embedded sensors using a number of
+	  different phyiscal interfaces (i2c, spi etc). See
+	  Documentation/industrialio for more information.
+
+if INDUSTRIALIO
+
+config INDUSTRIALIO_PTIMER_BOARDINFO
+       boolean
+       default y
+
+endif
--- a/drivers/industrialio/Makefile	1970-01-01 01:00:00.000000000 +0100
+++ b/drivers/industrialio/Makefile	2008-07-23 12:05:27.000000000 +0100
@@ -0,0 +1,7 @@
+#
+# Makefile for the industrial I/O core.
+#
+industrialio-objs := industrialio-core.o industrialio-ring.o industrialio-rtc.o
+
+obj-$(CONFIG_INDUSTRIALIO)	+= industrialio.o
+obj-$(CONFIG_INDUSTRIALIO_PTIMER_BOARDINFO) += industrialio_ptimer_board_info.o
--- a/include/linux/industrialio.h	1970-01-01 01:00:00.000000000 +0100
+++ b/include/linux/industrialio.h	2008-07-23 15:20:19.000000000 +0100
@@ -0,0 +1,374 @@
+/* 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/industrialio_sysfs.h>
+
+/* TODO LIST */
+/* Static device specific elements (conversion factors etc)
+   should be exported via sysfs
+   Break up this header - some drivers only want a fraction of this.
+*/
+
+
+/* Event interface flags */
+#define IIO_BUSY_BIT_POS 1
+
+
+struct iio_handler {
+	const struct file_operations *fops;
+	int id;
+	unsigned long flags;
+	void *private;
+};
+
+/* The actual event being pushed ot userspace */
+struct iio_event_data {
+	int id;
+	s64 timestamp;
+};
+
+
+struct iio_detected_event_list {
+	struct list_head list;
+	struct iio_event_data ev;
+	/* Part of shared event handling - (typicaly ring buffers) */
+	struct iio_shared_ev_pointer *shared_pointer;
+};
+
+/* Requires high resolution timers */
+/*  TODO - provide alternative if not available? */
+static inline s64 iio_get_time_ns(void)
+{
+	struct timespec ts;
+	ktime_get_ts(&ts);
+	return timespec_to_ns(&ts);
+}
+
+struct iio_dev;
+
+/* Each device has one of these per interrupt */
+struct iio_event_handler_list {
+	struct list_head list;
+	int (*handler)(struct iio_dev *dev_io, int index, s64 timestamp,
+		       int no_test);
+	/* This element may be shared */
+	int refcount;
+};
+
+/* Wraps adding to lists and does reference counting to allowed shared
+ * handlers.
+ */
+int iio_add_event_to_list(struct iio_event_handler_list *list,
+			  struct iio_event_handler_list *el);
+
+int iio_remove_event_from_list(struct iio_event_handler_list *el);
+
+struct iio_sw_ring_buffer;
+struct iio_hw_ring_buffer;
+
+#define INIT_IIO_RING_BUFFER(ring_buf, _bytes_per_datum, _length) {	\
+		(ring_buf)->size = _bytes_per_datum;			\
+		(ring_buf)->length = _length;				\
+		(ring_buf)->loopcount = 0;				\
+		(ring_buf)->shared_ev_pointer.ev_p = 0;			\
+		(ring_buf)->shared_ev_pointer.lock =			\
+			__SPIN_LOCK_UNLOCKED((ring_buf)			\
+					     ->shared_ev_pointer->loc);	\
+	}
+
+#define INIT_IIO_SW_RING_BUFFER(ring, _bytes_per_datum, _length) {	\
+		INIT_IIO_RING_BUFFER(&(ring)->buf,			\
+				     _bytes_per_datum,			\
+				     _length);				\
+		(ring)->read_p = 0;					\
+		(ring)->write_p = 0;					\
+		(ring)->last_written_p = 0;				\
+		(ring)->data = kmalloc(_length*(ring)->buf.size,	\
+				       GFP_KERNEL);			\
+		(ring)->use_count = 0;					\
+		(ring)->use_lock = __SPIN_LOCK_UNLOCKED((ring)->use_lock); \
+	}
+
+#define FREE_IIO_SW_RING_BUFFER(ring) kfree((ring)->data)
+
+
+
+int iio_store_to_sw_ring(struct iio_sw_ring_buffer *ring,
+		      unsigned char *data,
+		      s64 timestamp);
+
+/* Edge cases :
+   1) data at last_p is no longer valid - requires complete wrap around.
+   To detect, loop count has changed - if only by 1 then problem only
+   if current_lastp is equal to or greater than copy made at start.
+   If we have wrapped an entire int in this time (loopcount) then
+   something very very weird has occured!
+*/
+int iio_read_last_from_sw_ring(struct iio_sw_ring_buffer *ring,
+			       unsigned char *data);
+
+/* Up to the drivers to mark the ring whenever it must not change size
+ * and unmark when it may without problems */
+void iio_mark_sw_ring_buffer_in_use(struct iio_sw_ring_buffer *ring);
+
+void iio_unmark_sw_ring_buffer_in_use(struct iio_sw_ring_buffer *ring);
+
+int iio_request_sw_ring_buffer(int bytes_per_datum,
+			       int length,
+			       struct iio_sw_ring_buffer **ring,
+			       int id,
+			       struct module *owner,
+			       struct device *dev);
+
+int iio_request_update_sw_ring_buffer(struct iio_dev *dev_info, int id);
+
+void iio_free_sw_ring_buffer(struct iio_sw_ring_buffer *ring,
+			     struct device *dev);
+
+int iio_request_hw_ring_buffer(int bytes_per_datum,
+			       int length,
+			       struct iio_hw_ring_buffer **ring,
+			       int id,
+			       struct module *owner,
+			       struct device *dev,
+			       const struct file_operations *fops,
+			       void *private);
+
+void iio_free_hw_ring_buffer(struct iio_hw_ring_buffer *ring,
+			     struct device *dev);
+
+/* Device operating modes */
+#define INDIO_DIRECT_MODE		0x01
+#define INDIO_RING_POLLED		0x02
+#define INDIO_RING_DATA_RDY		0x04
+#define INDIO_RING_HARDWARE_BUFFER	0x08
+
+struct iio_event_interface {
+	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;
+	/* Integer id, used to differentiate this one form any others */
+	int					id;
+	struct iio_chrdev_minor_attr		attr;
+	struct module				*owner;
+	void					*private;
+	/* used to store name for associated sysfs file */
+	char					_name[20];
+};
+
+struct iio_shared_ev_pointer {
+	struct iio_detected_event_list	*ev_p;
+	spinlock_t lock;
+};
+
+/* A general ring buffer structure
+ *  Intended to be completely lock free as we always want fills from
+ * the interrupt handler to not have to wait.  This obviously increases
+ * the possible time required to read from the buffer.  */
+struct iio_ring_buffer {
+	/* Number of datums */
+	int			length;
+	/* length of single datum - including timestamp if there */
+	int			size;
+	int			loopcount;
+	/* accessing the ring buffer */
+	char			*access_minor_name;
+	struct iio_chrdev_minor_attr	access_minor_attr;
+	struct iio_handler		access_handler;
+	/* events triggered by the ring buffer */
+	char			*event_minor_name;
+	struct iio_event_interface ev_int;
+	/* a fully shared output event ? wtf?*/
+	struct iio_shared_ev_pointer shared_ev_pointer;
+};
+
+int iio_put_ring_event(struct iio_ring_buffer *ring_buf,
+		       int event_code,
+		       s64 timestamp);
+
+int iio_put_or_escallate_ring_event(struct iio_ring_buffer *ring_buf,
+				    int event_code,
+				    s64 timestamp);
+
+struct iio_sw_ring_buffer {
+	struct iio_ring_buffer buf;
+	unsigned char		*data;
+	unsigned char		*read_p;
+	unsigned char		*write_p;
+	unsigned char		*last_written_p;
+	/* used to act as a point at which to signal an event */
+	unsigned char		*half_p;
+	int			use_count;
+	int			update_needed;
+	spinlock_t		use_lock;
+};
+
+struct iio_hw_ring_buffer {
+	struct iio_ring_buffer buf;
+	void *private;
+};
+
+/* Vast majority of this is set by the industrialio subsystem on a
+ * call to iio_device_register. */
+/* TODO Macros to simplify setting the relevant stuff in the driver. */
+struct iio_dev {
+/* generic handling data used by ind io */
+	int id;
+/* device specific data */
+	void *dev_data;
+
+/* Modes the drivers supports */
+	int modes; /* Driver Set */
+	int currentmode;
+/* Direct sysfs related functionality */
+	struct device *sysfs_dev;
+	struct device *dev; /* Driver Set */
+	/* General attributes */
+	const struct attribute_group *attrs;
+
+/* Interrupt handling related */
+	struct module *driver_module;
+	int num_interrupt_lines; /* Driver Set */
+
+	struct iio_interrupt **interrupts;
+
+
+	/* Event control attributes */
+	struct attribute_group *event_attrs;
+	/* The character device related elements */
+	struct iio_event_interface *event_interfaces;
+
+/* Software Ring Buffer
+   - for now assuming only makes sense to have a single ring */
+	int ring_dimension;
+	int ring_bytes_per_datum;
+	int ring_length;
+	struct iio_sw_ring_buffer *ring;
+	struct attribute_group *ring_attrs_group;
+	struct iio_ring_attr *ring_attrs;
+	/* enabling / disabling related functions.
+	 * post / pre refer to relative to the change of current_mode. */
+	int (*ring_preenable)(struct iio_dev *);
+	int (*ring_postenable)(struct iio_dev *);
+	int (*ring_predisable)(struct iio_dev *);
+	int (*ring_postdisable)(struct iio_dev *);
+	void (*ring_poll_func)(void *private_data);
+	struct iio_periodic  *ptimer;
+
+	/* Device state lock.
+	 * Used to prevent simultaneous changes to device state.
+	 * In here rather than modules as some ring buffer changes must occur
+	 * with this locked.*/
+	struct mutex			mlock;
+
+	/* Name used to allow releasing of the relevant ptimer on exit.
+	 * Ideally the ptimers will only be held when the driver is actually
+	 * using them, but for now they have one the whole time they are loaded.
+	 */
+	const char *ptimer_name;
+};
+
+int iio_device_register(struct iio_dev *dev_info);
+void iio_device_unregister(struct iio_dev *dev_info);
+
+/* Wrapper class used to allow easy specification of different line numbers */
+struct iio_interrupt {
+	struct iio_dev *dev_info;
+	int line_number;
+	int irq;
+	struct iio_event_handler_list ev_list;
+};
+
+irqreturn_t iio_interrupt_handler(int irq, void *_int_info);
+
+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);
+
+
+/* Used to try inserting an event into the list for userspace reading via
+ * chrdev */
+int iio_put_event(struct iio_dev *dev_info,
+		  int ev_line,
+		  int ev_code,
+		  s64 timestamp);
+
+struct iio_work_cont {
+	struct work_struct ws;
+	struct work_struct ws_nocheck;
+	int address;
+	int mask;
+	void *st;
+};
+#define INIT_IIO_WORK_CONT(cont, _checkfunc, _nocheckfunc, _add, _mask, _st)\
+	do {								\
+	INIT_WORK(&(cont)->ws, _checkfunc);				\
+	INIT_WORK(&(cont)->ws_nocheck, _nocheckfunc);			\
+	(cont)->address = _add;						\
+	(cont)->mask = _mask;						\
+	(cont)->st = _st;						\
+	} while (0)
+
+/* Ring buffer related */
+int iio_device_register_sw_ring(struct iio_dev *dev_info, int id);
+void iio_device_unregister_sw_ring(struct iio_dev *dev_info);
+
+int __iio_put_event(struct iio_event_interface *ev_int,
+		int ev_code,
+		s64 timestamp,
+		struct iio_shared_ev_pointer*
+		shared_pointer_p);
+void __iio_change_event(struct iio_detected_event_list *ev,
+			int ev_code,
+			s64 timestamp);
+
+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,  struct device *dev);
+
+int iio_allocate_chrdev(struct iio_handler *handler);
+void iio_deallocate_chrdev(struct iio_handler *handler);
+
+ssize_t iio_show_attr_minor(struct device *dev,
+			    struct device_attribute *attr,
+			    char *buf);
+
+/* For now this is on the type of periodic timer used*/
+struct iio_periodic {
+	struct rtc_device *rtc;
+	int frequency;
+	struct rtc_task task;
+};
+
+int iio_ptimer_request_periodic_timer(char *name, struct iio_dev *indio_dev);
+void iio_ptimer_unrequest_periodic_timer(struct iio_dev *indio_dev);
+int iio_ptimer_set_freq(struct iio_periodic *ptimer, unsigned frequency);
+int iio_ptimer_irq_set_state(struct iio_dev *indio_dev, bool state);
+
+/* Board registration is handled by contents of
+ * industrialio_ptimer_board_info.c
+ */
+extern struct mutex industrialio_ptimer_board_lock;
+extern struct list_head industrialio_ptimer_board_info_list;
+#endif /* _INDUSTRIAL_IO_H_ */
--- a/include/linux/industrialio_ptimer.h	1970-01-01 01:00:00.000000000 +0100
+++ b/include/linux/industrialio_ptimer.h	2008-07-23 15:41:29.000000000 +0100
@@ -0,0 +1,18 @@
+#ifndef _INDUSTRIALIO_PTIMER_H_
+#define _INDUSTRIALIO_PTIMER_H_
+
+#define IIO_PTIMER_NAME_SIZE 10
+
+
+struct ptimer_info {
+	char name[IIO_PTIMER_NAME_SIZE];
+};
+struct ptimer_info_listel {
+	struct list_head list;
+	bool inuse;
+	struct ptimer_info info;
+};
+
+extern int
+industrialio_register_ptimer(struct ptimer_info const *info, unsigned n);
+#endif
--- a/include/linux/industrialio_sysfs.h	1970-01-01 01:00:00.000000000 +0100
+++ b/include/linux/industrialio_sysfs.h	2008-07-23 16:04:18.000000000 +0100
@@ -0,0 +1,274 @@
+/* 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 <linux/industrialio.h>
+
+
+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 {
+	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 {
+	struct device_attribute dev_attr;
+	int address;
+};
+
+
+#define to_iio_dev_attr(_dev_attr) \
+	container_of(_dev_attr, struct iio_dev_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_DEVICE_ATTR(_name, _mode, _show, _store, _addr)	\
+	struct iio_dev_attr iio_dev_attr_##_name		\
+	= IIO_ATTR(_name, _mode, _show, _store, _addr)
+
+/* This may get broken down into separate files later */
+
+/* Generic attributes of onetype or another */
+
+/* Revision number for the device. As the form of this varies greatly from
+ * device to device, no particular form is specified. In most cases this will
+ * only be for information to the user, not to effect functionality etc.
+ */
+#define IIO_DEV_ATTR_REV(_show)			\
+	IIO_DEVICE_ATTR(revision, S_IRUGO, _show, NULL, 0)
+
+/* For devices with internal clocks - and possibly poling later */
+
+#define IIO_DEV_ATTR_SAMP_FREQ(_mode, _show, _store)			\
+	IIO_DEVICE_ATTR(sampling_frequency, _mode, _show, _store, 0)
+
+#define IIO_DEV_ATTR_AVAIL_SAMP_FREQ(_show)				\
+	IIO_DEVICE_ATTR(available_sampling_frequency, S_IRUGO, _show, NULL, 0)
+
+/* ADC types of attibute */
+
+#define IIO_DEV_ATTR_AVAIL_SCAN_MODES(_show)				\
+	IIO_DEVICE_ATTR(available_scan_modes, S_IRUGO, _show, NULL, 0)
+
+#define IIO_DEV_ATTR_SCAN_MODE(_mode, _show, _store)		\
+	IIO_DEVICE_ATTR(scan_mode, _mode, _show, _store, 0)
+
+#define IIO_DEV_ATTR_INPUT(_number, _show)				\
+	IIO_DEVICE_ATTR(in##_number, S_IRUGO, _show, NULL, _number)
+
+#define IIO_DEV_ATTR_SCAN(_show)		\
+	IIO_DEVICE_ATTR(scan, S_IRUGO, _show, NULL, 0);
+/* Accelerometer types of attribute */
+
+#define IIO_DEV_ATTR_ACCEL_X_OFFSET(_mode, _show, _store, _addr) \
+	IIO_DEVICE_ATTR(x_offset, _mode, _show, _store, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_Y_OFFSET(_mode, _show, _store, _addr) \
+	IIO_DEVICE_ATTR(y_offset, _mode, _show, _store, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_Z_OFFSET(_mode, _show, _store, _addr) \
+	IIO_DEVICE_ATTR(z_offset, _mode, _show, _store, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_X_GAIN(_mode, _show, _store, _addr)	\
+	IIO_DEVICE_ATTR(x_gain, _mode, _show, _store, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_Y_GAIN(_mode, _show, _store, _addr)	\
+	IIO_DEVICE_ATTR(y_gain, _mode, _show, _store, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_Z_GAIN(_mode, _show, _store, _addr)	\
+	IIO_DEVICE_ATTR(z_gain, _mode, _show, _store, _addr)
+
+
+/* The actual device readings are always going to be read only */
+#define IIO_DEV_ATTR_ACCEL_X(_show, _addr)			\
+	IIO_DEVICE_ATTR(x, S_IRUGO, _show, NULL, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_Y(_show, _addr)			\
+	IIO_DEVICE_ATTR(y, S_IRUGO, _show, NULL, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_Z(_show, _addr)			\
+	IIO_DEVICE_ATTR(z, S_IRUGO, _show, NULL, _addr)
+
+#define IIO_DEV_ATTR_TEMP(_show)					\
+	IIO_DEVICE_ATTR(temp, S_IRUGO, _show, NULL, 0)
+/* Thresholds are somewhat chip dependent - may need quite a few defs here */
+/* For unified thesholds (shared across all directions */
+#define IIO_DEV_ATTR_ACCEL_THRESH(_mode, _show, _store, _addr)	\
+	IIO_DEVICE_ATTR(thresh, _mode, _show, _store, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_THRESH_X(_mode, _show, _store, _addr)	\
+	IIO_DEVICE_ATTR(thresh_x, _mode, _show, _store, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_THRESH_Y(_mode, _show, _store, _addr)	\
+	IIO_DEVICE_ATTR(thresh_y, _mode, _show, _store, _addr)
+
+#define IIO_DEV_ATTR_ACCEL_THRESH_Z(_mode, _show, _store, _addr)	\
+	IIO_DEVICE_ATTR(thresh_z, _mode, _show, _store, _addr)
+
+/* This is an event attr in some case and a dev in others - FIX*/
+#define IIO_DEV_ATTR_SW_RING_ENABLE(_show, _store)			\
+	IIO_DEVICE_ATTR(sw_ring_enable, S_IRUGO | S_IWUSR, _show, _store, 0)
+
+/* Hardware ring buffer related attributes */
+#define IIO_DEV_ATTR_HW_RING_ENABLE(_show, _store)			\
+	IIO_DEVICE_ATTR(hw_ring_enable, S_IRUGO | S_IWUSR, _show, _store, 0)
+
+#define IIO_DEV_ATTR_RING_BPS(_mode, _show, _store)		\
+	IIO_DEVICE_ATTR(ring_bps, _mode, _show, _store, 0)
+
+/* Bits per sample */
+#define IIO_DEV_ATTR_RING_BPS_AVAILABLE(_show)				\
+	IIO_DEVICE_ATTR(ring_bps_available, S_IRUGO, _show, NULL, 0)
+
+/* Events that the device may generate */
+
+#define IIO_EVENT_SH(_name, _handler)					\
+	static struct iio_event_handler_list				\
+	iio_event_##_name = {						\
+		.handler = _handler,					\
+		.refcount = 0,						\
+	};
+#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 };
+
+/*FIXME use the above to define this */
+#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 };		\
+/*FIXME, add line number to the above?*/
+
+/* In most of these cases, this actually corresponds to something with a
+   value attached */
+
+/* For some devices you can select whether all conditions or any condition
+   must be met for interrupt generation */
+#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
+
+/* Threshold pass events */
+#define IIO_EVENT_ATTR_ACCEL_X_HIGH(_show, _store, _mask, _handler) \
+	IIO_EVENT_ATTR(x_high, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_CODE_ACCEL_X_HIGH 1
+
+/* Shared handler version */
+#define IIO_EVENT_ATTR_ACCEL_X_HIGH_SH(_evlist, _show, _store, _mask)\
+	IIO_EVENT_ATTR_SH(x_high, _evlist, _show, _store, _mask)
+
+
+#define IIO_EVENT_ATTR_ACCEL_Y_HIGH(_show, _store, _mask, _handler) \
+	IIO_EVENT_ATTR(y_high, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_ATTR_ACCEL_Y_HIGH_SH(_evlist, _show, _store, _mask)\
+	IIO_EVENT_ATTR_SH(y_high, _evlist, _show, _store, _mask)
+
+#define IIO_EVENT_CODE_ACCEL_Y_HIGH 2
+
+#define IIO_EVENT_ATTR_ACCEL_Z_HIGH(_show, _store, _mask, _handler) \
+	IIO_EVENT_ATTR(z_high, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_ATTR_ACCEL_Z_HIGH_SH(_evlist, _show, _store, _mask)\
+	IIO_EVENT_ATTR_SH(z_high, _evlist, _show, _store, _mask)
+
+#define IIO_EVENT_CODE_ACCEL_Z_HIGH 3
+
+#define IIO_EVENT_ATTR_ACCEL_X_LOW(_show, _store, _mask, _handler) \
+	IIO_EVENT_ATTR(x_low, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_ATTR_ACCEL_X_LOW_SH(_evlist, _show, _store, _mask)\
+	IIO_EVENT_ATTR_SH(x_low, _evlist, _show, _store, _mask)
+
+#define IIO_EVENT_CODE_ACCEL_X_LOW 4
+
+#define IIO_EVENT_ATTR_ACCEL_Y_LOW(_show, _store, _mask, _handler) \
+	IIO_EVENT_ATTR(y_low, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_ATTR_ACCEL_Y_LOW_SH(_evlist, _show, _store, _mask)\
+	IIO_EVENT_ATTR_SH(y_low, _evlist, _show, _store, _mask)
+
+#define IIO_EVENT_CODE_ACCEL_Y_LOW 5
+
+#define IIO_EVENT_ATTR_ACCEL_Z_LOW(_show, _store, _mask, _handler)	\
+	IIO_EVENT_ATTR(z_low, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_ATTR_ACCEL_Z_LOW_SH(_evlist, _show, _store, _mask)	\
+	IIO_EVENT_ATTR_SH(z_low, _evlist, _show, _store, _mask)
+
+#define IIO_EVENT_CODE_ACCEL_Z_LOW 6
+
+#define IIO_EVENT_ATTR_FREE_FALL_DETECT(_show, _store, _mask, _handler)	\
+	IIO_EVENT_ATTR(free_fall, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_ATTR_FREE_FALL_DETECT_SH(_evlist, _show, _store, _mask) \
+	IIO_EVENT_ATTR_SH(free_fall, _evlist, _show, _store, _mask)
+
+#define IIO_EVENT_CODE_FREE_FALL 7
+
+/* These may be software or hardware events depending on type of ring buffer */
+
+#define IIO_EVENT_ATTR_RING_50_FULL(_show, _store, _mask, _handler)	\
+	IIO_EVENT_ATTR(ring_50_full, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_ATTR_RING_50_FULL_SH(_evlist, _show, _store, _mask)	\
+	IIO_EVENT_ATTR_SH(ring_50_full, _evlist, _show, _store, _mask)
+
+#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_ATTR_SW_RING_ENABLE(_show, _store, _mask, _handler)	\
+	IIO_EVENT_ATTR(sw_ring_enable, _show, _store, _mask, _handler)
+
+#define IIO_EVENT_CODE_RING_50_FULL 100
+#define IIO_EVENT_CODE_RING_75_FULL 101
+#define IIO_EVENT_CODE_RING_100_FULL 102
+/* HOW TO HANDLE COMPOSITE EVENTS? */
+
+#endif /* _INDUSTRIAL_IO_SYSFS_H_ */
--- a/drivers/industrialio/industrialio_ptimer_board_info.c	1970-01-01 01:00:00.000000000 +0100
+++ b/drivers/industrialio/industrialio_ptimer_board_info.c	2008-07-23 14:16:28.000000000 +0100
@@ -0,0 +1,44 @@
+/* The industrial I/O periodic timer registration code
+ *
+ * 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/init.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/industrialio_ptimer.h>
+
+LIST_HEAD(industrialio_ptimer_board_info_list);
+EXPORT_SYMBOL_GPL(industrialio_ptimer_board_info_list);
+
+DEFINE_MUTEX(industrialio_ptimer_board_lock);
+EXPORT_SYMBOL_GPL(industrialio_ptimer_board_lock);
+
+
+int __init
+industrialio_register_ptimer(struct ptimer_info const *info, unsigned n)
+{
+	int i;
+	struct ptimer_info_listel *pi;
+
+	mutex_lock(&industrialio_ptimer_board_lock);
+	for (i = 0; i < n; i++) {
+		pi = kzalloc(sizeof(*pi), GFP_KERNEL);
+		if (!pi) {
+			mutex_unlock(&industrialio_ptimer_board_lock);
+			return -ENOMEM;
+		}
+		strncpy(pi->info.name, info[i].name, IIO_PTIMER_NAME_SIZE);
+		list_add_tail(&pi->list, &industrialio_ptimer_board_info_list);
+	}
+	mutex_unlock(&industrialio_ptimer_board_lock);
+
+	return 0;
+}
--- a/drivers/industrialio/industrialio-core.c	1970-01-01 01:00:00.000000000 +0100
+++ b/drivers/industrialio/industrialio-core.c	2008-07-23 15:07:21.000000000 +0100
@@ -0,0 +1,787 @@
+/* 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/rtc.h>
+
+#include <linux/industrialio.h>
+#include <linux/industrialio_ptimer.h>
+
+MODULE_AUTHOR("Jonathan Cameron <jic23@xxxxxxxxx>");
+MODULE_DESCRIPTION("Industrial I/O core");
+MODULE_LICENSE("GPL");
+
+#define IIO_ID_PREFIX "industrialio"
+#define IIO_ID_FORMAT IIO_ID_PREFIX "%d"
+#define IIO_MAJOR 244
+
+/* Integer id  - used to assign each registered device a unique id*/
+static DEFINE_IDR(iio_idr);
+static DEFINE_SPINLOCK(iio_idr_lock);
+
+struct class iio_class = {
+	.name = "industrialio",
+};
+
+/* Struct used to maintain internal state about industrialio.
+ * This will be used to handle the character device accesses
+ * and redirect them to the relevant driver.
+ * Will reduce this to the included table if nothing else comes
+ * up that should go in here!
+ */
+struct __iio_state {
+	/* All initially set to NULL in init */
+	struct iio_handler *fhs[256];
+};
+
+static struct __iio_state iio_state;
+static DEFINE_SPINLOCK(iio_state_lock);
+
+/* Used to escalate shared event.
+ * Currently this is only used with ring buffer events.
+ */
+void __iio_change_event(struct iio_detected_event_list *ev,
+			int ev_code,
+			s64 timestamp)
+{
+	ev->ev.id = ev_code;
+	ev->ev.timestamp = timestamp;
+}
+
+/* Used both in the interrupt line put events and the ring buffer ones */
+ int
+__iio_put_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;
+
+	/* Does anyone care? */
+	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(struct iio_detected_event_list),
+			     GFP_KERNEL);
+		if (ev == NULL) {
+			ret = -ENOMEM;
+			goto error_ret;
+		}
+		ev->ev.id = ev_code;
+		ev->ev.timestamp = timestamp;
+		if (shared_pointer_p != NULL) {
+			ev->shared_pointer = shared_pointer_p;
+			shared_pointer_p->ev_p = ev;
+		} else
+			ev->shared_pointer = NULL;
+
+		mutex_lock(&ev_int->event_list_lock);
+		list_add_tail(&ev->list, &ev_int->det_events.list);
+		mutex_unlock(&ev_int->event_list_lock);
+
+		ev_int->current_events++;
+		wake_up_interruptible(&ev_int->wait);
+	}
+
+	return 0;
+error_ret:
+	return ret;
+
+}
+
+int iio_put_event(struct iio_dev *dev_info,
+		  int ev_line,
+		  int ev_code,
+		  s64 timestamp)
+{
+	return __iio_put_event(&dev_info->event_interfaces[ev_line],
+			       ev_code, timestamp, NULL);
+}
+EXPORT_SYMBOL(iio_put_event);
+
+/* 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] =
+		kmalloc(sizeof(struct iio_interrupt), GFP_KERNEL);
+	if (dev_info->interrupts[line_number] == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+
+	INIT_LIST_HEAD(&dev_info->interrupts[line_number]->ev_list.list);
+	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 end up handling lots of
+	 * events no-one cares about.*/
+	ret = request_irq(irq,
+			  &iio_interrupt_handler,
+			  type,
+			  name,
+			  dev_info->interrupts[line_number]);
+	if (ret < 0)
+		goto error_ret;
+
+	return 0;
+
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL(iio_register_interrupt_line);
+
+/* 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);
+
+/* 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;
+
+	if (list_empty(&int_info->ev_list.list))
+		return IRQ_NONE;
+
+	time_ns = iio_get_time_ns();
+	/* detect single element list*/
+	if (int_info->ev_list.list.next->next == &int_info->ev_list.list) {
+		disable_irq_nosync(irq);
+		p = list_first_entry(&int_info->ev_list.list,
+				     struct iio_event_handler_list,
+				     list);
+		p->handler(dev_info, 1, time_ns, 1);
+	} else
+		list_for_each_entry(p, &int_info->ev_list.list, list) {
+		       disable_irq_nosync(irq);
+		       p->handler(dev_info, 1, time_ns, 0);
+		}
+	return IRQ_HANDLED;
+}
+EXPORT_SYMBOL(iio_interrupt_handler);
+
+int iio_add_event_to_list(struct iio_event_handler_list *list,
+				   struct iio_event_handler_list *el)
+{
+	if (el->refcount == 0)
+		list_add(&list->list, &el->list);
+	el->refcount++;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iio_add_event_to_list);
+
+int iio_remove_event_from_list(struct iio_event_handler_list
+					*el)
+{
+	el->refcount--;
+	if (el->refcount == 0)
+		list_del_init(&el->list);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iio_remove_event_from_list);
+
+
+int iio_allocate_chrdev(struct iio_handler *handler)
+{
+	int id;
+
+	spin_lock(iio_state_lock);
+	for (id = 0; id <= 256; id++)
+		if (iio_state.fhs[id] == NULL)
+			break;
+	if (id == 256) {
+		spin_unlock(iio_state_lock);
+		return -ENOMEM;
+	}
+	iio_state.fhs[id] = handler;
+	spin_unlock(iio_state_lock);
+	handler->id = id;
+
+	return 0;
+}
+
+void iio_deallocate_chrdev(struct iio_handler *handler)
+{
+	spin_lock(iio_state_lock);
+	iio_state.fhs[handler->id] = NULL;
+	spin_unlock(iio_state_lock);
+}
+
+/* Upon open, switch in the correct file ops
+ * lifted directly from input subsystem */
+static int iio_open_file(struct inode *inode, struct file *file)
+{
+	struct iio_handler *handler;
+	const struct file_operations *old_fops, *new_fops = NULL;
+	int err;
+
+	/* This lock needed as unlike input we are dynamically allocating
+	 * chrdevs */
+	spin_lock(iio_state_lock);
+	handler = iio_state.fhs[iminor(inode)];
+	spin_unlock(iio_state_lock);
+
+	if (!handler) {
+		fops_put(file->f_op);
+		return -ENODEV;
+	}
+	new_fops = fops_get(handler->fops);
+	if (new_fops == NULL) {
+		fops_put(file->f_op);
+		return -ENODEV;
+	}
+
+	/* cribbed from lp.c */
+	if (test_and_set_bit(IIO_BUSY_BIT_POS, &handler->flags)) {
+		fops_put(file->f_op);
+		return -EBUSY;
+	}
+
+	if (!new_fops->open) {
+		fops_put(new_fops);
+		return -ENODEV;
+	}
+	old_fops = file->f_op;
+	file->f_op = new_fops;
+	/* use the private data pointer in file to give access to device
+	 * specific stuff */
+	file->private_data = handler->private;
+	err = new_fops->open(inode, file);
+
+	if (err) {
+		fops_put(file->f_op);
+		file->f_op = fops_get(old_fops);
+	}
+	fops_put(old_fops);
+
+	return err;
+}
+
+
+/* The main file ops structure. All open calls on the major number will
+ * be handled by this with fops for the actual minor number assigned by
+ * switching function above */
+static const struct file_operations iio_fops = {
+	.owner = THIS_MODULE,
+	.open = iio_open_file,
+};
+
+ssize_t iio_interrupt_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;
+
+	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);
+
+	if (copy_to_user(buf, &(el->ev),
+			 sizeof(struct iio_event_data))) {
+		ret = -EFAULT;
+		goto error_mutex_unlock;
+	}
+
+	list_del(&el->list);
+	ev_int->current_events--;
+	mutex_unlock(&ev_int->event_list_lock);
+
+	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 sizeof(struct iio_event_data);
+
+error_mutex_unlock:
+	mutex_unlock(&ev_int->event_list_lock);
+error_ret:
+
+	return ret;
+}
+
+int iio_interrupt_release(struct inode *inode, struct file *filep)
+{
+	struct iio_event_interface *ev_int = filep->private_data;
+
+	module_put(ev_int->owner);
+	clear_bit(IIO_BUSY_BIT_POS, &ev_int->handler.flags);
+
+	return 0;
+}
+
+int iio_interrupt_open(struct inode *inode, struct file *filep)
+{
+	struct iio_event_interface *ev_int = filep->private_data;
+
+	try_module_get(ev_int->owner);
+
+	return 0;
+}
+static const struct file_operations iio_interrupt_fileops = {
+	.read =  iio_interrupt_read,
+	.release = iio_interrupt_release,
+	.open = iio_interrupt_open,
+	.owner = THIS_MODULE,
+};
+
+
+ssize_t iio_show_attr_minor(struct device *dev,
+			    struct device_attribute *attr,
+			    char *buf)
+{
+	int len;
+
+	struct iio_chrdev_minor_attr *_attr
+		= to_iio_chrdev_minor_attr(attr);
+	len = sprintf(buf, "%d\n", _attr->minor);
+
+	return len;
+}
+
+void __init_iio_chrdev_minor_attr(struct iio_chrdev_minor_attr *minor_attr,
+				const char *name,
+				struct module *owner,
+				int id)
+{
+	minor_attr->dev_attr.attr.name = name;
+	minor_attr->dev_attr.attr.owner = owner;
+	minor_attr->dev_attr.attr.mode = S_IRUGO;
+	minor_attr->minor = id;
+	minor_attr->dev_attr.show = &iio_show_attr_minor;
+}
+
+int iio_setup_ev_int(struct iio_event_interface *ev_int,
+		     const char *name,
+		     struct module *owner,
+		     struct device *dev)
+{
+	int ret;
+
+	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.fops = &iio_interrupt_fileops;
+	ev_int->handler.private = ev_int;
+	ev_int->handler.flags = 0;
+	ret = iio_allocate_chrdev(&ev_int->handler);
+	if (ret)
+		goto error_ret;
+	__init_iio_chrdev_minor_attr(&ev_int->attr,
+				     (const char *)(name),
+				     owner,
+				     ev_int->handler.id);
+	ret = sysfs_create_file(&dev->kobj, &ev_int->attr.dev_attr.attr);
+	if (ret)
+		goto error_deallocate_chrdev;
+
+	return 0;
+error_deallocate_chrdev:
+	iio_deallocate_chrdev(&ev_int->handler);
+error_ret:
+	return ret;
+}
+
+void iio_free_ev_int(struct iio_event_interface *ev_int, struct device *dev)
+{
+	sysfs_remove_file(&dev->kobj, &ev_int->attr.dev_attr.attr);
+	iio_deallocate_chrdev(&ev_int->handler);
+}
+
+static int __init iio_init(void)
+{
+	int ret;
+
+	memset(iio_state.fhs,
+	       sizeof(struct iio_handler *)*256,
+	       0);
+
+	/* Create sysfs class */
+	ret  = class_register(&iio_class);
+	if (ret < 0) {
+		printk(KERN_ERR
+		       "industrialio.c: could not create sysfs class\n");
+		goto error_nothing;
+	}
+
+	ret = register_chrdev(IIO_MAJOR, "industrialio", &iio_fops);
+	if (ret) {
+		printk(KERN_ERR
+		       "industrialio: unable to register a char major %d",
+		       IIO_MAJOR);
+		goto error_unregister_class;
+	}
+
+	return 0;
+error_unregister_class:
+	class_unregister(&iio_class);
+error_nothing:
+	return ret;
+}
+
+static void __exit iio_exit(void)
+{
+	unregister_chrdev(IIO_MAJOR, "bob");
+	class_unregister(&iio_class);
+}
+
+int iio_device_register_sysfs(struct iio_dev *dev_info)
+{
+	int ret;
+
+	dev_info->sysfs_dev = device_create(&iio_class,
+					    dev_info->dev,
+					    MKDEV(0, 0),
+					    IIO_ID_FORMAT,
+					    dev_info->id);
+
+	if (IS_ERR(dev_info->sysfs_dev)) {
+		/* what would correct error here be?*/
+		ret = -EINVAL;
+		goto error_ret;
+	}
+	/* register attributes */
+	ret = sysfs_create_group(&dev_info->dev->kobj, dev_info->attrs);
+	if (ret) {
+		dev_err(dev_info->dev, "Failed to register sysfs hooks\n");
+		goto error_free_sysfs_device;
+	}
+
+	return 0;
+
+error_free_sysfs_device:
+	device_unregister(dev_info->dev);
+error_ret:
+	return ret;
+}
+
+void iio_device_unregister_sysfs(struct iio_dev *dev_info)
+{
+	sysfs_remove_group(&dev_info->dev->kobj, dev_info->attrs);
+	device_unregister(dev_info->sysfs_dev);
+}
+
+int iio_device_register_id(struct iio_dev *dev_info)
+{
+	int ret;
+
+idr_again:
+	if (unlikely(idr_pre_get(&iio_idr, GFP_KERNEL) == 0))
+		return -ENOMEM;
+
+	spin_lock(&iio_idr_lock);
+	ret = idr_get_new(&iio_idr, NULL, &dev_info->id);
+	spin_unlock(&iio_idr_lock);
+	if (unlikely(ret == -EAGAIN))
+		goto idr_again;
+	else if (unlikely(ret))
+		return ret;
+	dev_info->id = dev_info->id & MAX_ID_MASK;
+
+	return 0;
+}
+void iio_device_unregister_id(struct iio_dev *dev_info)
+{
+	/* Can I use the save id? */
+	int id;
+
+	if (likely(sscanf(dev_info->sysfs_dev->bus_id,
+			  IIO_ID_FORMAT, &id) == 1)) {
+		spin_lock(&iio_idr_lock);
+		idr_remove(&iio_idr, id);
+		spin_unlock(&iio_idr_lock);
+	} else
+		dev_dbg(dev_info->dev->parent,
+			"indio_device_unregister() failed: bad class ID!\n");
+}
+
+int iio_device_register_eventset(struct iio_dev *dev_info)
+{
+	int ret, i, j;
+
+	struct device_attribute *devattr;
+	struct iio_event_attr *indio_devattr;
+
+	if (dev_info->num_interrupt_lines == 0)
+		return 0;
+	dev_info->event_interfaces = (struct iio_event_interface *)
+		(kzalloc(sizeof(struct iio_event_interface)
+			 *dev_info->num_interrupt_lines,
+			 GFP_KERNEL));
+	if (dev_info->event_interfaces == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	/* assign id's to the event_interface elements */
+	for (i = 0; i < dev_info->num_interrupt_lines; i++) {
+		dev_info->event_interfaces[i].id = i;
+		dev_info->event_interfaces[i].owner = dev_info->driver_module;
+	}
+	dev_info->interrupts
+		= kzalloc(sizeof(struct iio_interrupt *)
+			  *dev_info->num_interrupt_lines,
+			  GFP_KERNEL);
+	if (dev_info->interrupts == NULL) {
+		dev_err(dev_info->dev,
+			"Failed to register sysfs hooks for events attributes");
+		ret = -ENOMEM;
+		goto error_free_event_interfaces;
+	}
+
+	for (i = 0; i < dev_info->num_interrupt_lines; i++) {
+
+		snprintf(dev_info->event_interfaces[i]._name, 20,
+			"event_line%d_minor", i);
+		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");
+			goto error_free_setup_ev_ints;
+		}
+	}
+	dev_info->event_attrs->name = "event_sources";
+	ret = sysfs_create_group(&dev_info->dev->kobj, dev_info->event_attrs);
+	if (ret) {
+		dev_err(dev_info->dev,
+			"Failed to register sysfs hooks for events attributes");
+		goto error_free_setup_ev_ints;
+	}
+	/* May double initialize lists in case of shared handlers,
+	   but other than a slight overhead that isn't a problem */
+	j = 0;
+	while (1) {
+		if (dev_info->event_attrs->attrs[j] == NULL)
+			break;
+		devattr = container_of(dev_info->event_attrs->attrs[j],
+				       struct device_attribute, attr);
+		indio_devattr = to_iio_event_attr(devattr);
+		INIT_LIST_HEAD(&indio_devattr->listel->list);
+		j++;
+	}
+	return 0;
+
+error_free_setup_ev_ints:
+	for (j = 0; j < i; j++)
+		iio_free_ev_int(&dev_info->event_interfaces[j],
+				dev_info->dev);
+	kfree(dev_info->interrupts);
+error_free_event_interfaces:
+	kfree(dev_info->event_interfaces);
+error_ret:
+	return ret;
+}
+
+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++)
+		iio_free_ev_int(&dev_info->event_interfaces[i],
+					 dev_info->dev);
+	if (dev_info->event_attrs)
+		sysfs_remove_group(&dev_info->dev->kobj, dev_info->event_attrs);
+	kfree(dev_info->event_interfaces);
+}
+
+int iio_get_ptimer(const char **name)
+{
+	struct ptimer_info_listel *ptimer_i;
+
+	*name = NULL;
+	mutex_lock(&industrialio_ptimer_board_lock);
+
+	list_for_each_entry(ptimer_i, &industrialio_ptimer_board_info_list,
+			    list)
+		if (ptimer_i->inuse == false) {
+			ptimer_i->inuse = true;
+			*name = ptimer_i->info.name;
+			break;
+		}
+	mutex_unlock(&industrialio_ptimer_board_lock);
+	if (*name == NULL)
+		return -EINVAL;
+
+	return 0;
+}
+int iio_free_ptimer(const char *name)
+{
+	struct ptimer_info_listel *ptimer_i;
+
+	mutex_lock(&industrialio_ptimer_board_lock);
+	list_for_each_entry(ptimer_i, &industrialio_ptimer_board_info_list,
+			    list)
+		if (ptimer_i->info.name == name) {
+			ptimer_i->inuse = false;
+			break;
+		}
+	mutex_unlock(&industrialio_ptimer_board_lock);
+
+	return 0;
+}
+
+int iio_device_register_ptimer(struct iio_dev *dev_info)
+{
+	int ret = 0;
+
+	if (dev_info->modes & INDIO_RING_POLLED) {
+		ret = iio_get_ptimer(&dev_info->ptimer_name);
+		if (ret)
+			goto error_ret;
+		ret = iio_ptimer_request_periodic_timer((char *)
+							(dev_info->ptimer_name),
+							dev_info);
+		if (ret)
+			goto error_release_ptimer;
+	}
+
+	return ret;
+
+error_release_ptimer:
+	iio_free_ptimer(dev_info->ptimer_name);
+error_ret:
+	return ret;
+
+}
+
+void iio_device_unregister_ptimer(struct iio_dev *dev_info)
+{
+	if (dev_info->ptimer) {
+		iio_ptimer_unrequest_periodic_timer(dev_info);
+		iio_free_ptimer(dev_info->ptimer_name);
+	}
+}
+
+int iio_device_register(struct iio_dev *dev_info)
+{
+	int ret;
+	mutex_init(&dev_info->mlock);
+	dev_set_drvdata(dev_info->dev, (void *)(dev_info));
+
+/*Get a unique id */
+	ret = iio_device_register_id(dev_info);
+	if (ret)
+		goto error_nothing;
+
+/* Create sysfs device */
+	ret = iio_device_register_sysfs(dev_info);
+	if (ret)
+		goto error_free_idr;
+
+/* Interrupt triggered events setup */
+	ret = iio_device_register_eventset(dev_info);
+	if (ret)
+		goto error_free_sysfs;
+
+/* Ring buffer init if relevant */
+	if (dev_info->modes & (INDIO_RING_POLLED | INDIO_RING_DATA_RDY)) {
+
+		ret = iio_device_register_sw_ring(dev_info, 0);
+		if (ret)
+			goto error_free_eventset;
+	}
+/* Register ptimer if relevant */
+	if (dev_info->modes & INDIO_RING_POLLED) {
+		ret = iio_device_register_ptimer(dev_info);
+		if (ret)
+			goto error_unregister_sw_ring;
+	}
+
+	return 0;
+
+error_unregister_sw_ring:
+	iio_device_unregister_sw_ring(dev_info);
+error_free_eventset:
+	iio_device_unregister_eventset(dev_info);
+error_free_sysfs:
+	iio_device_unregister_sysfs(dev_info);
+error_free_idr:
+	iio_device_unregister_id(dev_info);
+error_nothing:
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_device_register);
+
+void iio_device_unregister(struct iio_dev *dev_info)
+{
+	if (dev_info->modes & INDIO_RING_POLLED)
+		iio_device_unregister_ptimer(dev_info);
+	if (dev_info->modes & (INDIO_RING_POLLED | INDIO_RING_DATA_RDY))
+		iio_device_unregister_sw_ring(dev_info);
+	iio_device_unregister_eventset(dev_info);
+	iio_device_unregister_sysfs(dev_info);
+	iio_device_unregister_id(dev_info);
+
+}
+EXPORT_SYMBOL_GPL(iio_device_unregister);
+
+subsys_initcall(iio_init);
+module_exit(iio_exit);
--- a/drivers/industrialio/industrialio-rtc.c	1970-01-01 01:00:00.000000000 +0100
+++ b/drivers/industrialio/industrialio-rtc.c	2008-07-23 15:08:43.000000000 +0100
@@ -0,0 +1,134 @@
+/* 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.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/industrialio.h>
+#include <linux/industrialio_ptimer.h>
+/* This is a temporary stop gap until a more generic timer subsystem is in place
+ * within the kernel.
+ * See discussion (initial thoughts so far) on the rtc mailing list.
+ * Comments still welcomed though I may not do much about them!.
+ */
+int iio_ptimer_irq_set_state(struct iio_dev *indio_dev, bool state)
+{
+	return rtc_irq_set_state(indio_dev->ptimer->rtc,
+				 &indio_dev->ptimer->task,
+				 state);
+}
+EXPORT_SYMBOL(iio_ptimer_irq_set_state);
+
+int iio_ptimer_set_freq(struct iio_periodic *ptimer,
+			    unsigned frequency)
+{
+	int ret;
+
+	ret = rtc_irq_set_freq(ptimer->rtc, &ptimer->task, frequency);
+	if (ret == 0)
+		ptimer->frequency = frequency;
+
+	return ret;
+}
+EXPORT_SYMBOL(iio_ptimer_set_freq);
+
+static ssize_t iio_ptimer_show_samp_freq(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct iio_periodic *ptimer = dev_info->ptimer;
+	return sprintf(buf, "%u\n", ptimer->frequency);
+}
+
+static ssize_t iio_ptimer_store_samp_freq(struct device *dev,
+					  struct device_attribute *attr,
+					  const char *buf,
+					  size_t len)
+{
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	struct iio_periodic *ptimer = dev_info->ptimer;
+	int ret;
+	unsigned long val;
+
+	ret = strict_strtoul(buf, 10, &val);
+	if (ret)
+		goto error_ret;
+	ret = iio_ptimer_set_freq(ptimer, val);
+	if (ret)
+		goto error_ret;
+	return len;
+
+error_ret:
+	return ret;
+}
+
+
+IIO_DEV_ATTR_SAMP_FREQ(S_IRUGO | S_IWUSR,
+		       iio_ptimer_show_samp_freq,
+		       iio_ptimer_store_samp_freq);
+
+int iio_ptimer_request_periodic_timer(char *name,
+				      struct iio_dev *indio_dev)
+{
+	int ret;
+
+	indio_dev->ptimer = kmalloc(sizeof(struct iio_periodic), GFP_KERNEL);
+	indio_dev->ptimer->rtc = rtc_class_open(name);
+	if (indio_dev->ptimer == NULL) {
+		ret = -EINVAL;
+		goto error_free_ptimer;
+	}
+	indio_dev->ptimer->task.func = indio_dev->ring_poll_func;
+	indio_dev->ptimer->task.private_data = indio_dev;
+	ret = rtc_irq_register(indio_dev->ptimer->rtc,
+			       &indio_dev->ptimer->task);
+	if (ret)
+		goto error_close_class;
+
+	ret = sysfs_add_file_to_group(&indio_dev->dev->kobj,
+				      &iio_dev_attr_sampling_frequency
+				      .dev_attr.attr,
+				      "ring_buffer");
+	if (ret)
+		goto error_unregister_irq;
+
+	return 0;
+
+error_unregister_irq:
+	rtc_irq_unregister(indio_dev->ptimer->rtc, &indio_dev->ptimer->task);
+
+error_close_class:
+	rtc_class_close(indio_dev->ptimer->rtc);
+error_free_ptimer:
+	kfree(indio_dev->ptimer);
+	indio_dev->ptimer = NULL;
+	return ret;
+}
+EXPORT_SYMBOL(iio_ptimer_request_periodic_timer);
+
+void iio_ptimer_unrequest_periodic_timer(struct iio_dev *indio_dev)
+{
+
+	sysfs_remove_file_from_group(&indio_dev->dev->kobj,
+				      &iio_dev_attr_sampling_frequency
+				     .dev_attr.attr,
+				     "ring_buffer");
+
+	if (indio_dev->ptimer->rtc) {
+		rtc_irq_set_state(indio_dev->ptimer->rtc,
+				  &indio_dev->ptimer->task, 0);
+		rtc_irq_unregister(indio_dev->ptimer->rtc,
+				   &indio_dev->ptimer->task);
+				flush_scheduled_work();
+		rtc_class_close(indio_dev->ptimer->rtc);
+		flush_scheduled_work();
+	}
+	kfree(indio_dev->ptimer);
+}
+EXPORT_SYMBOL(iio_ptimer_unrequest_periodic_timer);
--- a/drivers/industrialio/industrialio-ring.c	1970-01-01 01:00:00.000000000 +0100
+++ b/drivers/industrialio/industrialio-ring.c	2008-07-23 15:10:39.000000000 +0100
@@ -0,0 +1,770 @@
+/* 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.
+ *
+ * Handling of ring allocation / resizing.
+ *
+ *
+ * Things to look at here.
+ * - Better memory allocation techniques?
+ * - Alternative access techniques?
+ */
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/industrialio.h>
+
+/* Prevent resizing of the ring if it might break anything */
+void iio_mark_sw_ring_buffer_in_use(struct iio_sw_ring_buffer *ring)
+{
+	spin_lock(ring->use_lock);
+	ring->use_count++;
+	spin_unlock(ring->use_lock);
+}
+EXPORT_SYMBOL_GPL(iio_mark_sw_ring_buffer_in_use);
+
+void iio_unmark_sw_ring_buffer_in_use(struct iio_sw_ring_buffer *ring)
+{
+	spin_lock(ring->use_lock);
+	ring->use_count--;
+	spin_unlock(ring->use_lock);
+}
+EXPORT_SYMBOL_GPL(iio_unmark_sw_ring_buffer_in_use);
+
+/* Mark that a resize is needed */
+static void iio_mark_sw_ring_buffer_need_update(struct iio_sw_ring_buffer *ring)
+{
+	spin_lock(ring->use_lock);
+	ring->update_needed = 1;
+	spin_unlock(ring->use_lock);
+}
+
+/* Event handling for the ring - allows escallation of events */
+int iio_put_ring_event(struct iio_ring_buffer *ring_buf,
+		       int event_code,
+		       s64 timestamp)
+{
+	return __iio_put_event(&ring_buf->ev_int,
+			       event_code,
+			       timestamp,
+			       &ring_buf->shared_ev_pointer);
+}
+EXPORT_SYMBOL(iio_put_ring_event);
+
+int iio_put_or_escallate_ring_event(struct iio_ring_buffer *ring_buf,
+				    int event_code,
+				    s64 timestamp)
+{
+	if (ring_buf->shared_ev_pointer.ev_p)
+		__iio_change_event(ring_buf->shared_ev_pointer.ev_p,
+				   event_code,
+				   timestamp);
+	else
+		return iio_put_ring_event(ring_buf,
+					  event_code,
+					  timestamp);
+	return 0;
+}
+EXPORT_SYMBOL(iio_put_or_escallate_ring_event);
+
+
+/* Ring buffer related functionality */
+/* Store to ring is typically called in the bh of a data ready interrupt handler
+ * in the device driver */
+/* Lock always held if their is a chance this may be called */
+int iio_store_to_sw_ring(struct iio_sw_ring_buffer *ring,
+			 unsigned char *data,
+			 s64 timestamp)
+{
+	bool init_read = true;
+	int ret;
+	int code;
+
+	/* initial store */
+	if (unlikely(ring->write_p == 0)) {
+		ring->write_p = ring->data;
+		/* doesn't actually matter if this is out of the set */
+		ring->half_p = ring->data - ring->buf.length*ring->buf.size/2;
+		init_read = false;
+	}
+	memcpy(ring->write_p, data, ring->buf.size);
+	barrier();
+	ring->last_written_p = ring->write_p;
+	barrier();
+	ring->write_p += ring->buf.size;
+	/* End of ring, back to the beginning */
+	if (ring->write_p == ring->data + ring->buf.length*ring->buf.size) {
+		ring->write_p = ring->data;
+		ring->buf.loopcount++;
+	}
+	if (ring->read_p == 0)
+		ring->read_p = ring->data;
+	/* Buffer full - move the read pointer and create / escalate
+	 * ring event */
+	else if (ring->write_p == ring->read_p) {
+		ring->read_p += ring->buf.size;
+		if (ring->read_p
+		    == ring->data + ring->buf.length*ring->buf.size)
+			ring->read_p = ring->data;
+
+		spin_lock(ring->buf.shared_ev_pointer.lock);
+		if (ring->buf.shared_ev_pointer.ev_p) {
+			/* Event escalation - probably quicker to let this
+			   keep running than check if it is necessary */
+			code = IIO_EVENT_CODE_RING_100_FULL;
+			__iio_change_event(ring
+					   ->buf.shared_ev_pointer.ev_p,
+					   code,
+					   timestamp);
+		} else {
+			code = IIO_EVENT_CODE_RING_100_FULL;
+			ret = __iio_put_event(&ring->buf.ev_int,
+					      code,
+					      timestamp,
+					      &ring
+					      ->buf.shared_ev_pointer);
+			if (ret) {
+				spin_unlock(ring->buf.shared_ev_pointer.lock);
+				goto error_ret;
+			}
+		}
+		spin_unlock(ring->buf.shared_ev_pointer.lock);
+	}
+	/* investigate if our event barrier has been passed */
+	/* There are definite 'issues' with this and chances of
+	 * simultaneous read */
+	/* Also need to use loop count to ensure this only happens once */
+	ring->half_p += ring->buf.size;
+	if (ring->half_p == ring->data + ring->buf.length*ring->buf.size)
+		ring->half_p = ring->data;
+	if (ring->half_p == ring->read_p) {
+		spin_lock(ring->buf.shared_ev_pointer.lock);
+		code = IIO_EVENT_CODE_RING_50_FULL;
+		ret = __iio_put_event(&ring->buf.ev_int,
+				      code,
+				      timestamp,
+				      &ring->buf.shared_ev_pointer);
+		spin_unlock(ring->buf.shared_ev_pointer.lock);
+
+		if (ret)
+			goto error_ret;
+	}
+	return 0;
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_store_to_sw_ring);
+
+
+/*doesn't currently read the timestamp */
+/* For software ring buffers this function is needed to get the latest
+ * reading without preventing it from ending up in the ring buffer.
+*/
+int iio_read_last_from_sw_ring(struct iio_sw_ring_buffer *ring,
+			       unsigned char *data)
+{
+	int loopcount_copy;
+	unsigned char *last_written_p_copy;
+	iio_mark_sw_ring_buffer_in_use(ring);
+again:
+	loopcount_copy = ring->buf.loopcount;
+	barrier();
+	last_written_p_copy = ring->last_written_p;
+	barrier(); /*unnessecary? */
+
+	memcpy(data, last_written_p_copy, ring->buf.size);
+
+	if (unlikely(loopcount_copy != ring->buf.loopcount)) {
+		if (unlikely(ring->last_written_p >= last_written_p_copy))
+			goto again;
+	}
+	iio_unmark_sw_ring_buffer_in_use(ring);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iio_read_last_from_sw_ring);
+
+/* Ring buffer access fileops */
+int iio_ring_open(struct inode *inode, struct file *filp)
+{
+	struct iio_sw_ring_buffer *ring = filp->private_data;
+
+	iio_mark_sw_ring_buffer_in_use(ring);
+	try_module_get(ring->buf.access_minor_attr.dev_attr.attr.owner);
+
+	return 0;
+}
+
+int iio_ring_release(struct inode *inode, struct file *filp)
+{
+	struct iio_sw_ring_buffer *ring = filp->private_data;
+
+	module_put(ring->buf.access_minor_attr.dev_attr.attr.owner);
+	clear_bit(IIO_BUSY_BIT_POS, &ring->buf.access_handler.flags);
+	iio_unmark_sw_ring_buffer_in_use(ring);
+
+	return 0;
+}
+
+/* no point in ripping more than nearest number of whole records below count */
+/* Depending on movement of pointers in the meantime this may return a lot
+ * less than count*/
+/* Also, we aren't going to wait for enough data to be available */
+
+/* Can only occur currently when the ring buffer is marked
+   - from userspace call */
+ssize_t iio_ring_rip(struct file *filp,
+		     char *buf,
+		     size_t count,
+		     loff_t *f_ps)
+{
+	unsigned char *initial_read_p, *initial_write_p,
+		*current_read_p, *end_read_p;
+
+	struct iio_sw_ring_buffer *ring = filp->private_data;
+	unsigned char *data_cpy;
+	int ret;
+	int dead_offset;
+	int bytes_to_rip = 0;
+	int max_copied;
+	/* Round down to nearest datum boundary */
+	bytes_to_rip = (count - count % ring->buf.size);
+	/* Limit size to whole of ring buffer */
+	if (bytes_to_rip > ring->buf.size*ring->buf.length)
+		bytes_to_rip = ring->buf.size*ring->buf.length;
+	data_cpy = kmalloc(bytes_to_rip, GFP_KERNEL);
+	if (data_cpy == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+
+	/* build local copy */
+	initial_read_p = ring->read_p;
+	if (unlikely(initial_read_p == 0)) {
+		/* No data here as yet */
+		ret = 0;
+		goto error_free_data_cpy;
+	}
+	initial_write_p = ring->write_p;
+
+	/* Need a consistent pair */
+	while (initial_read_p != ring->read_p
+	      || initial_write_p != ring->write_p) {
+		initial_read_p = ring->read_p;
+		initial_write_p = ring->write_p;
+	}
+	if (initial_write_p == initial_read_p) {
+		/* No new data available.*/
+		ret = 0;
+		goto error_free_data_cpy;
+	}
+
+	if (initial_write_p > initial_read_p + bytes_to_rip) {
+		/* write_p is greater than necessary, all is easy */
+		max_copied = bytes_to_rip;
+		memcpy(data_cpy, initial_read_p, max_copied);
+		end_read_p = initial_read_p + max_copied;
+	} else if (initial_write_p > initial_read_p) {
+		/*not enough data to cpy */
+		max_copied = initial_write_p - initial_read_p;
+		memcpy(data_cpy, initial_read_p, max_copied);
+		end_read_p = initial_write_p;
+	} else { /* going through 'end' of ring buffer */
+		max_copied = ring->data
+			+ ring->buf.length*ring->buf.size - initial_read_p;
+		memcpy(data_cpy, initial_read_p, max_copied);
+		if (initial_write_p > ring->data + bytes_to_rip - max_copied) {
+			/* enough data to finish */
+			memcpy(data_cpy + max_copied, ring->data,
+			       bytes_to_rip - max_copied);
+			max_copied = bytes_to_rip;
+			end_read_p = ring->data + (bytes_to_rip - max_copied);
+		} else {  /* not enough data */
+			memcpy(data_cpy + max_copied, ring->data,
+			       initial_write_p - ring->data);
+			max_copied += initial_write_p - ring->data;
+			end_read_p = initial_write_p;
+		}
+	}
+	/* Now to verify which section was cleanly copied - i.e. how far
+	 * read pointer has been pushed */
+	current_read_p = ring->read_p;
+
+	if (initial_read_p <= current_read_p)
+		dead_offset = current_read_p - initial_read_p;
+	else
+		dead_offset = ring->buf.length*ring->buf.size
+			- (initial_read_p - current_read_p);
+
+	/* possible issue if the initial write has been lapped or indeed
+	 * the point we were reading to has been passed */
+	/* No valid data read.
+	 * In this case the read pointer is already correct having been
+	 * pushed further than we would look. */
+	if (max_copied - dead_offset < 0) {
+		ret = 0;
+		goto error_free_data_cpy;
+	}
+
+	/* setup the next read position */
+	ring->read_p = end_read_p;
+
+	if (copy_to_user(buf, data_cpy + dead_offset,
+			 max_copied - dead_offset))  {
+		ret =  -EFAULT;
+		goto error_free_data_cpy;
+	}
+	kfree(data_cpy);
+
+	return max_copied - dead_offset;
+
+error_free_data_cpy:
+	kfree(data_cpy);
+error_ret:
+	return 0;
+}
+
+static const struct file_operations iio_ring_fileops = {
+	.read = iio_ring_rip,
+	.release = iio_ring_release,
+	.open = iio_ring_open,
+	.owner = THIS_MODULE,
+};
+
+inline int __iio_request_ring_buffer_event_chrdev(struct iio_ring_buffer *buf,
+						  int id,
+						  struct module *owner,
+						  struct device *dev)
+{
+	int ret;
+
+/* Create and register the event character device */
+	buf->event_minor_name = kmalloc(20, GFP_KERNEL);
+	if (buf->event_minor_name == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	sprintf(buf->event_minor_name, "ring_buffer%d_ev_minor", id);
+	ret = iio_setup_ev_int(&(buf->ev_int),
+			       (const char *)(buf->event_minor_name),
+			       owner,
+			       dev);
+	if (ret)
+		goto error_free_event_minor_name;
+
+	return 0;
+
+error_free_event_minor_name:
+	kfree(buf->event_minor_name);
+error_ret:
+	return ret;
+}
+
+inline void __iio_free_ring_buffer_event_chrdev(struct iio_ring_buffer *buf,
+						struct device *dev)
+{
+	iio_free_ev_int(&(buf->ev_int), dev);
+	kfree(buf->event_minor_name);
+}
+
+inline int
+__iio_request_ring_buffer_access_chrdev(struct iio_ring_buffer *buf,
+					int id,
+					struct module *owner,
+					struct device *dev,
+					const struct file_operations *fops)
+{
+	int ret;
+/* Create and register the access character device */
+	buf->access_minor_name = kmalloc(20, GFP_KERNEL);
+	if (buf->access_minor_name == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	sprintf(buf->access_minor_name, "ring_buffer%d_access_minor", id);
+
+	ret = iio_allocate_chrdev(&buf->access_handler);
+	if (ret)
+		goto error_free_access_minor_name;
+	buf->access_handler.fops = fops;
+	buf->access_handler.flags = 0;
+
+	__init_iio_chrdev_minor_attr(&buf->access_minor_attr,
+				   (const char *)(buf->access_minor_name),
+				   owner,
+				   buf->access_handler.id);
+
+	ret = sysfs_create_file(&dev->kobj,
+				&(buf->access_minor_attr.dev_attr.attr));
+	if (ret)
+		goto error_deallocate_chrdev;
+	return 0;
+
+error_deallocate_chrdev:
+	iio_deallocate_chrdev(&buf->access_handler);
+error_free_access_minor_name:
+	kfree(buf->access_minor_name);
+error_ret:
+	return ret;
+}
+
+inline void __iio_free_ring_buffer_access_chrdev(struct iio_ring_buffer *buf,
+						 struct device *dev)
+{
+	sysfs_remove_file(&dev->kobj,
+			  &buf->access_minor_attr.dev_attr.attr);
+	iio_deallocate_chrdev(&buf->access_handler);
+	kfree(buf->access_minor_name);
+}
+
+int iio_request_hw_ring_buffer(int bytes_per_datum,
+			       int length,
+			       struct iio_hw_ring_buffer **ring,
+			       int id,
+			       struct module *owner,
+			       struct device *dev,
+			       const struct file_operations *fops,
+			       void *private)
+{
+	int ret;
+
+	*ring = kmalloc(sizeof(struct iio_hw_ring_buffer),
+			GFP_KERNEL);
+
+	if (*ring == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	(*ring)->private = private;
+	INIT_IIO_RING_BUFFER(&((*ring)->buf), bytes_per_datum, length);
+	ret = __iio_request_ring_buffer_event_chrdev(&(*ring)->buf,
+						     id,
+						     owner,
+						     dev);
+
+	if (ret)
+		goto error_free_ring_data;
+	ret = __iio_request_ring_buffer_access_chrdev(&(*ring)->buf,
+						      id,
+						      owner,
+						      dev,
+						      fops);
+	if (ret)
+		goto error_free_ring_buffer_event_chrdev;
+	(*ring)->buf.ev_int.private = (*ring);
+	(*ring)->buf.access_handler.private = (*ring);
+
+	return 0;
+
+error_free_ring_buffer_event_chrdev:
+	__iio_free_ring_buffer_event_chrdev(&(*ring)->buf, dev);
+error_free_ring_data:
+	/* there isn't any!*/
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_request_hw_ring_buffer);
+
+void iio_free_hw_ring_buffer(struct iio_hw_ring_buffer *ring,
+			     struct device *dev)
+{
+	__iio_free_ring_buffer_access_chrdev(&(ring->buf), dev);
+	__iio_free_ring_buffer_event_chrdev(&(ring->buf), dev);
+	kfree(ring);
+}
+EXPORT_SYMBOL_GPL(iio_free_hw_ring_buffer);
+
+
+/* Resize the ring if requested - run whenever ring buffer mode entered */
+int __iio_request_update_sw_ring_buffer(int bytes_per_datum,
+					int length,
+					struct iio_sw_ring_buffer *ring,
+					int id,
+					struct module *owner,
+					struct device *dev)
+{
+/* Reference count the ring - if anyone is using it this will fail!*/
+	int ret = 0;
+/* Need to sanity check if this is necessary? */
+	spin_lock(ring->use_lock);
+
+	if (ring->use_count || !ring->update_needed) {
+		ret = -EAGAIN;
+		goto error_ret;
+	}
+	kfree(ring->data);
+	/* keeps clear of chr devs etc - so fine to use here - I THINK!*/
+	INIT_IIO_SW_RING_BUFFER(ring, bytes_per_datum, length);
+	if (ring->data == NULL)
+		ret = -ENOMEM;
+
+error_ret:
+	spin_unlock(ring->use_lock);
+	return ret;
+}
+
+int iio_request_update_sw_ring_buffer(struct iio_dev *dev_info, int id)
+{
+	return __iio_request_update_sw_ring_buffer(dev_info
+						   ->ring_bytes_per_datum,
+						   dev_info->ring_length,
+						   dev_info->ring,
+						   id,
+						   dev_info->driver_module,
+						   dev_info->dev);
+}
+EXPORT_SYMBOL_GPL(iio_request_update_sw_ring_buffer);
+
+/* Should only occur on init so no locking needed */
+int iio_request_sw_ring_buffer(int bytes_per_datum,
+			       int length,
+			       struct iio_sw_ring_buffer **ring,
+			       int id,
+			       struct module *owner,
+			       struct device *dev)
+{
+	int ret;
+
+	/* Actually do the ring buffer initialization */
+	*ring = kzalloc(sizeof(struct iio_sw_ring_buffer),
+			GFP_KERNEL);
+	if (*ring == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	/* Moved to an allocation on demand model.*/
+	iio_mark_sw_ring_buffer_need_update(*ring);
+	ret = __iio_request_ring_buffer_event_chrdev(&(*ring)->buf,
+						     id,
+						     owner,
+						     dev);
+	if (ret)
+		goto error_free_ring_data;
+
+	ret = __iio_request_ring_buffer_access_chrdev(&(*ring)->buf,
+						      id,
+						      owner,
+						      dev,
+						      &iio_ring_fileops);
+	if (ret)
+		goto error_free_ring_buffer_event_chrdev;
+
+	/* Setup the private pointer so the fileoperations will work */
+	(*ring)->buf.ev_int.private = (*ring);
+	(*ring)->buf.access_handler.private = (*ring);
+
+	return 0;
+
+error_free_ring_buffer_event_chrdev:
+	__iio_free_ring_buffer_event_chrdev(&(*ring)->buf, dev);
+error_free_ring_data:
+	FREE_IIO_SW_RING_BUFFER(*ring);
+	kfree(*ring);
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_request_sw_ring_buffer);
+
+void iio_free_sw_ring_buffer(struct iio_sw_ring_buffer *ring,
+			  struct device *dev)
+{
+	__iio_free_ring_buffer_access_chrdev(&(ring->buf), dev);
+	__iio_free_ring_buffer_event_chrdev(&(ring->buf), dev);
+	FREE_IIO_SW_RING_BUFFER(ring);
+	kfree(ring);
+}
+EXPORT_SYMBOL_GPL(iio_free_sw_ring_buffer);
+
+static ssize_t iio_read_ring_length(struct device *dev,
+					     struct device_attribute *attr,
+					     char *buf)
+{
+	int len;
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+
+	len = sprintf(buf, "%d\n", dev_info->ring_length);
+
+	return len;
+}
+
+static ssize_t iio_write_ring_length(struct device *dev,
+					      struct device_attribute *attr,
+					      const char *buf,
+					      size_t len)
+{
+	int ret;
+	long val;
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+	ret = strict_strtol(buf, 10, &val);
+	if (ret)
+		goto error_ret;
+	/* Ring length stored here and in ring? */
+	if (val != dev_info->ring_length) {
+		dev_info->ring_length = val;
+		iio_mark_sw_ring_buffer_need_update(dev_info->ring);
+	}
+
+	return len;
+error_ret:
+	return ret;
+}
+
+static ssize_t iio_read_ring_bps(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	int len;
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+
+	len = sprintf(buf, "%d\n", dev_info->ring_bytes_per_datum);
+
+	return len;
+}
+
+
+DEVICE_ATTR(length, S_IRUGO | S_IWUSR,
+	    iio_read_ring_length,
+	    iio_write_ring_length);
+/* The software ring buffers aren't currently capable of changing the
+ * storage accuracy so this is read only.
+ */
+DEVICE_ATTR(bps, S_IRUGO,
+	    iio_read_ring_bps,
+	    NULL);
+
+ssize_t iio_store_ring_enable(struct device *dev,
+			      struct device_attribute *attr,
+			      const char *buf,
+			      size_t len)
+{
+	int ret;
+	bool requested_state, current_state;
+	struct iio_dev *dev_info = dev_get_drvdata(dev);
+
+	mutex_lock(&dev_info->mlock);
+	requested_state = (buf[0] == '0') ? 0 : 1;
+	current_state = (dev_info->currentmode
+			 & (INDIO_RING_DATA_RDY | INDIO_RING_POLLED))
+			 ? 1: 0;
+	if (current_state == requested_state)
+		goto done;
+	if (requested_state) {
+		if (dev_info->ring_preenable) {
+			ret = dev_info->ring_preenable(dev_info);
+			if (ret)
+				goto error_ret;
+		}
+		ret = iio_request_update_sw_ring_buffer(dev_info, 0);
+		if (ret)
+			goto error_ret;
+		iio_mark_sw_ring_buffer_in_use(dev_info->ring);
+		if (dev_info->modes & INDIO_RING_DATA_RDY)
+			dev_info->currentmode = INDIO_RING_DATA_RDY;
+		else if (dev_info->modes & INDIO_RING_POLLED)
+			dev_info->currentmode = INDIO_RING_POLLED;
+		else { /* should never be reached */
+			ret = -EINVAL;
+			goto error_ret;
+		}
+
+		if (dev_info->ring_postenable) {
+			ret = dev_info->ring_postenable(dev_info);
+			if (ret)
+				goto error_ret;
+		}
+	} else {
+		if (dev_info->ring_predisable) {
+			ret = dev_info->ring_predisable(dev_info);
+			if (ret)
+				goto error_ret;
+		}
+		iio_unmark_sw_ring_buffer_in_use(dev_info->ring);
+		dev_info->currentmode = INDIO_DIRECT_MODE;
+		if (dev_info->ring_postdisable) {
+			ret = dev_info->ring_postdisable(dev_info);
+			if (ret)
+				goto error_ret;
+		}
+	}
+done:
+	mutex_unlock(&dev_info->mlock);
+	return len;
+error_ret:
+	mutex_unlock(&dev_info->mlock);
+	return ret;
+}
+
+static ssize_t iio_show_ring_enable(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+
+	int len;
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+
+	if (indio_dev->currentmode & (INDIO_RING_DATA_RDY | INDIO_RING_POLLED))
+		len = sprintf(buf, "1\n");
+	else
+		len = sprintf(buf, "0\n");
+
+	return len;
+}
+
+DEVICE_ATTR(sw_ring_enable, S_IRUGO | S_IWUSR,
+	    iio_show_ring_enable,
+	    iio_store_ring_enable);
+
+static struct attribute *iio_ring_attributes[] = {
+	&dev_attr_length.attr,
+	&dev_attr_bps.attr,
+	&dev_attr_sw_ring_enable.attr,
+	NULL,
+};
+
+static const struct attribute_group iio_ring_attribute_group = {
+	.name = "ring_buffer",
+	.attrs = iio_ring_attributes,
+};
+
+int iio_device_register_sw_ring(struct iio_dev *dev_info, int id)
+{
+	int ret;
+
+	ret = iio_request_sw_ring_buffer(dev_info->ring_bytes_per_datum,
+					 dev_info->ring_length,
+					 &dev_info->ring,
+					 id,
+					 dev_info->driver_module,
+					 dev_info->dev);
+	if (ret < 0)
+		goto error_ret;
+
+	ret = sysfs_create_group(&dev_info->dev->kobj,
+				 &iio_ring_attribute_group);
+	if (ret)
+		goto error_free_ring;
+
+	return 0;
+
+error_free_ring:
+	iio_free_sw_ring_buffer(dev_info->ring, dev_info->dev);
+error_ret:
+	return ret;
+}
+
+void iio_device_unregister_sw_ring(struct iio_dev *dev_info)
+{
+	sysfs_remove_group(&dev_info->dev->kobj,
+			   &iio_ring_attribute_group);
+	/* deallocate ring buffer related stuff */
+	if (dev_info->modes & (INDIO_RING_POLLED | INDIO_RING_DATA_RDY))
+		iio_free_sw_ring_buffer(dev_info->ring, dev_info->dev);
+
+}
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/