Commit beafc54c authored by Hans J. Koch's avatar Hans J. Koch Committed by Greg Kroah-Hartman
Browse files

UIO: Add the User IO core code 



This interface allows the ability to write the majority of a driver in
userspace with only a very small shell of a driver in the kernel itself.
It uses a char device and sysfs to interact with a userspace process to
process interrupts and control memory accesses.

See the docbook documentation for more details on how to use this
interface.

From: Hans J. Koch <hjk@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Benedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 5bae7ac9

drivers/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -84,4 +84,5 @@ source "drivers/auxdisplay/Kconfig" 


source "drivers/kvm/Kconfig"



source "drivers/uio/Kconfig"

endmenu

drivers/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ obj-$(CONFIG_ATA) += ata/ 
obj-$(CONFIG_FUSION)		+= message/

obj-$(CONFIG_FIREWIRE)		+= firewire/

obj-$(CONFIG_IEEE1394)		+= ieee1394/

obj-$(CONFIG_UIO)		+= uio/

obj-y				+= cdrom/

obj-y				+= auxdisplay/

obj-$(CONFIG_MTD)		+= mtd/

drivers/uio/Kconfig

0 → 100644
+16 −0
Original line number Diff line number Diff line 
menu "Userspace I/O"

	depends on !S390



config UIO

	tristate "Userspace I/O drivers"

	default n

	help

	  Enable this to allow the userspace driver core code to be

	  built.  This code allows userspace programs easy access to

	  kernel interrupts and memory locations, allowing some drivers

	  to be written in userspace.  Note that a small kernel driver

	  is also required for interrupt handling to work properly.



	  If you don't know what to do here, say N.



endmenu

drivers/uio/Makefile

0 → 100644
+1 −0
Original line number Diff line number Diff line 
obj-$(CONFIG_UIO) += uio.o

drivers/uio/uio.c

0 → 100644
+701 −0
Original line number Diff line number Diff line 
/*

 * drivers/uio/uio.c

 *

 * Copyright(C) 2005, Benedikt Spranger <b.spranger@linutronix.de>

 * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>

 * Copyright(C) 2006, Hans J. Koch <hjk@linutronix.de>

 * Copyright(C) 2006, Greg Kroah-Hartman <greg@kroah.com>

 *

 * Userspace IO

 *

 * Base Functions

 *

 * Licensed under the GPLv2 only.

 */



#include <linux/module.h>

#include <linux/init.h>

#include <linux/poll.h>

#include <linux/device.h>

#include <linux/mm.h>

#include <linux/idr.h>

#include <linux/string.h>

#include <linux/kobject.h>

#include <linux/uio_driver.h>



#define UIO_MAX_DEVICES 255



struct uio_device {

	struct module		*owner;

	struct device		*dev;

	int			minor;

	atomic_t		event;

	struct fasync_struct	*async_queue;

	wait_queue_head_t	wait;

	int			vma_count;

	struct uio_info		*info;

	struct kset 		map_attr_kset;

};



static int uio_major;

static DEFINE_IDR(uio_idr);

static struct file_operations uio_fops;



/* UIO class infrastructure */

static struct uio_class {

	struct kref kref;

	struct class *class;

} *uio_class;



/*

 * attributes

 */



static struct attribute attr_addr = {

	.name  = "addr",

	.mode  = S_IRUGO,

};



static struct attribute attr_size = {

	.name  = "size",

	.mode  = S_IRUGO,

};



static struct attribute* map_attrs[] = {

	&attr_addr, &attr_size, NULL

};



static ssize_t map_attr_show(struct kobject *kobj, struct attribute *attr,

			     char *buf)

{

	struct uio_mem *mem = container_of(kobj, struct uio_mem, kobj);



	if (strncmp(attr->name,"addr",4) == 0)

		return sprintf(buf, "0x%lx\n", mem->addr);



	if (strncmp(attr->name,"size",4) == 0)

		return sprintf(buf, "0x%lx\n", mem->size);



	return -ENODEV;

}



static void map_attr_release(struct kobject *kobj)

{

	/* TODO ??? */

}



static struct sysfs_ops map_attr_ops = {

	.show  = map_attr_show,

};



static struct kobj_type map_attr_type = {

	.release	= map_attr_release,

	.sysfs_ops	= &map_attr_ops,

	.default_attrs	= map_attrs,

};



static ssize_t show_name(struct device *dev,

			 struct device_attribute *attr, char *buf)

{

	struct uio_device *idev = dev_get_drvdata(dev);

	if (idev)

		return sprintf(buf, "%s\n", idev->info->name);

	else

		return -ENODEV;

}

static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);



static ssize_t show_version(struct device *dev,

			    struct device_attribute *attr, char *buf)

{

	struct uio_device *idev = dev_get_drvdata(dev);

	if (idev)

		return sprintf(buf, "%s\n", idev->info->version);

	else

		return -ENODEV;

}

static DEVICE_ATTR(version, S_IRUGO, show_version, NULL);



static ssize_t show_event(struct device *dev,

			  struct device_attribute *attr, char *buf)

{

	struct uio_device *idev = dev_get_drvdata(dev);

	if (idev)

		return sprintf(buf, "%u\n",

				(unsigned int)atomic_read(&idev->event));

	else

		return -ENODEV;

}

static DEVICE_ATTR(event, S_IRUGO, show_event, NULL);



static struct attribute *uio_attrs[] = {

	&dev_attr_name.attr,

	&dev_attr_version.attr,

	&dev_attr_event.attr,

	NULL,

};



static struct attribute_group uio_attr_grp = {

	.attrs = uio_attrs,

};



/*

 * device functions

 */

static int uio_dev_add_attributes(struct uio_device *idev)

{

	int ret;

	int mi;

	int map_found = 0;

	struct uio_mem *mem;



	ret = sysfs_create_group(&idev->dev->kobj, &uio_attr_grp);

	if (ret)

		goto err_group;



	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {

		mem = &idev->info->mem[mi];

		if (mem->size == 0)

			break;

		if (!map_found) {

			map_found = 1;

			kobject_set_name(&idev->map_attr_kset.kobj,"maps");

			idev->map_attr_kset.ktype = &map_attr_type;

			idev->map_attr_kset.kobj.parent = &idev->dev->kobj;

			ret = kset_register(&idev->map_attr_kset);

			if (ret)

				goto err_remove_group;

		}

		kobject_init(&mem->kobj);

		kobject_set_name(&mem->kobj,"map%d",mi);

		mem->kobj.parent = &idev->map_attr_kset.kobj;

		mem->kobj.kset = &idev->map_attr_kset;

		ret = kobject_add(&mem->kobj);

		if (ret)

			goto err_remove_maps;

	}



	return 0;



err_remove_maps:

	for (mi--; mi>=0; mi--) {

		mem = &idev->info->mem[mi];

		kobject_unregister(&mem->kobj);

	}

	kset_unregister(&idev->map_attr_kset); /* Needed ? */

err_remove_group:

	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);

err_group:

	dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);

	return ret;

}



static void uio_dev_del_attributes(struct uio_device *idev)

{

	int mi;

	struct uio_mem *mem;

	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {

		mem = &idev->info->mem[mi];

		if (mem->size == 0)

			break;

		kobject_unregister(&mem->kobj);

	}

	kset_unregister(&idev->map_attr_kset);

	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);

}



static int uio_get_minor(struct uio_device *idev)

{

	static DEFINE_MUTEX(minor_lock);

	int retval = -ENOMEM;

	int id;



	mutex_lock(&minor_lock);

	if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)

		goto exit;



	retval = idr_get_new(&uio_idr, idev, &id);

	if (retval < 0) {

		if (retval == -EAGAIN)

			retval = -ENOMEM;

		goto exit;

	}

	idev->minor = id & MAX_ID_MASK;

exit:

	mutex_unlock(&minor_lock);

	return retval;

}



static void uio_free_minor(struct uio_device *idev)

{

	idr_remove(&uio_idr, idev->minor);

}



/**

 * uio_event_notify - trigger an interrupt event

 * @info: UIO device capabilities

 */

void uio_event_notify(struct uio_info *info)

{

	struct uio_device *idev = info->uio_dev;



	atomic_inc(&idev->event);

	wake_up_interruptible(&idev->wait);

	kill_fasync(&idev->async_queue, SIGIO, POLL_IN);

}

EXPORT_SYMBOL_GPL(uio_event_notify);



/**

 * uio_interrupt - hardware interrupt handler

 * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer

 * @dev_id: Pointer to the devices uio_device structure

 */

static irqreturn_t uio_interrupt(int irq, void *dev_id)

{

	struct uio_device *idev = (struct uio_device *)dev_id;

	irqreturn_t ret = idev->info->handler(irq, idev->info);



	if (ret == IRQ_HANDLED)

		uio_event_notify(idev->info);



	return ret;

}



struct uio_listener {

	struct uio_device *dev;

	s32 event_count;

};



static int uio_open(struct inode *inode, struct file *filep)

{

	struct uio_device *idev;

	struct uio_listener *listener;

	int ret = 0;



	idev = idr_find(&uio_idr, iminor(inode));

	if (!idev)

		return -ENODEV;



	listener = kmalloc(sizeof(*listener), GFP_KERNEL);

	if (!listener)

		return -ENOMEM;



	listener->dev = idev;

	listener->event_count = atomic_read(&idev->event);

	filep->private_data = listener;



	if (idev->info->open) {

		if (!try_module_get(idev->owner))

			return -ENODEV;

		ret = idev->info->open(idev->info, inode);

		module_put(idev->owner);

	}



	if (ret)

		kfree(listener);



	return ret;

}



static int uio_fasync(int fd, struct file *filep, int on)

{

	struct uio_listener *listener = filep->private_data;

	struct uio_device *idev = listener->dev;



	return fasync_helper(fd, filep, on, &idev->async_queue);

}



static int uio_release(struct inode *inode, struct file *filep)

{

	int ret = 0;

	struct uio_listener *listener = filep->private_data;

	struct uio_device *idev = listener->dev;



	if (idev->info->release) {

		if (!try_module_get(idev->owner))

			return -ENODEV;

		ret = idev->info->release(idev->info, inode);

		module_put(idev->owner);

	}

	if (filep->f_flags & FASYNC)

		ret = uio_fasync(-1, filep, 0);

	kfree(listener);

	return ret;

}



static unsigned int uio_poll(struct file *filep, poll_table *wait)

{

	struct uio_listener *listener = filep->private_data;

	struct uio_device *idev = listener->dev;



	if (idev->info->irq == UIO_IRQ_NONE)

		return -EIO;



	poll_wait(filep, &idev->wait, wait);

	if (listener->event_count != atomic_read(&idev->event))

		return POLLIN | POLLRDNORM;

	return 0;

}



static ssize_t uio_read(struct file *filep, char __user *buf,

			size_t count, loff_t *ppos)

{

	struct uio_listener *listener = filep->private_data;

	struct uio_device *idev = listener->dev;

	DECLARE_WAITQUEUE(wait, current);

	ssize_t retval;

	s32 event_count;



	if (idev->info->irq == UIO_IRQ_NONE)

		return -EIO;



	if (count != sizeof(s32))

		return -EINVAL;



	add_wait_queue(&idev->wait, &wait);



	do {

		set_current_state(TASK_INTERRUPTIBLE);



		event_count = atomic_read(&idev->event);

		if (event_count != listener->event_count) {

			if (copy_to_user(buf, &event_count, count))

				retval = -EFAULT;

			else {

				listener->event_count = event_count;

				retval = count;

			}

			break;

		}



		if (filep->f_flags & O_NONBLOCK) {

			retval = -EAGAIN;

			break;

		}



		if (signal_pending(current)) {

			retval = -ERESTARTSYS;

			break;

		}

		schedule();

	} while (1);



	__set_current_state(TASK_RUNNING);

	remove_wait_queue(&idev->wait, &wait);



	return retval;

}



static int uio_find_mem_index(struct vm_area_struct *vma)

{

	int mi;

	struct uio_device *idev = vma->vm_private_data;



	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {

		if (idev->info->mem[mi].size == 0)

			return -1;

		if (vma->vm_pgoff == mi)

			return mi;

	}

	return -1;

}



static void uio_vma_open(struct vm_area_struct *vma)

{

	struct uio_device *idev = vma->vm_private_data;

	idev->vma_count++;

}



static void uio_vma_close(struct vm_area_struct *vma)

{

	struct uio_device *idev = vma->vm_private_data;

	idev->vma_count--;

}



static struct page *uio_vma_nopage(struct vm_area_struct *vma,

				   unsigned long address, int *type)

{

	struct uio_device *idev = vma->vm_private_data;

	struct page* page = NOPAGE_SIGBUS;



	int mi = uio_find_mem_index(vma);

	if (mi < 0)

		return page;



	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)

		page = virt_to_page(idev->info->mem[mi].addr);

	else

		page = vmalloc_to_page((void*)idev->info->mem[mi].addr);

	get_page(page);

	if (type)

		*type = VM_FAULT_MINOR;

	return page;

}



static struct vm_operations_struct uio_vm_ops = {

	.open = uio_vma_open,

	.close = uio_vma_close,

	.nopage = uio_vma_nopage,

};



static int uio_mmap_physical(struct vm_area_struct *vma)

{

	struct uio_device *idev = vma->vm_private_data;

	int mi = uio_find_mem_index(vma);

	if (mi < 0)

		return -EINVAL;



	vma->vm_flags |= VM_IO | VM_RESERVED;



	return remap_pfn_range(vma,

			       vma->vm_start,

			       idev->info->mem[mi].addr >> PAGE_SHIFT,

			       vma->vm_end - vma->vm_start,

			       vma->vm_page_prot);

}



static int uio_mmap_logical(struct vm_area_struct *vma)

{

	vma->vm_flags |= VM_RESERVED;

	vma->vm_ops = &uio_vm_ops;

	uio_vma_open(vma);

	return 0;

}



static int uio_mmap(struct file *filep, struct vm_area_struct *vma)

{

	struct uio_listener *listener = filep->private_data;

	struct uio_device *idev = listener->dev;

	int mi;

	unsigned long requested_pages, actual_pages;

	int ret = 0;



	if (vma->vm_end < vma->vm_start)

		return -EINVAL;



	vma->vm_private_data = idev;



	mi = uio_find_mem_index(vma);

	if (mi < 0)

		return -EINVAL;



	requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;

	actual_pages = (idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;

	if (requested_pages > actual_pages)

		return -EINVAL;



	if (idev->info->mmap) {

		if (!try_module_get(idev->owner))

			return -ENODEV;

		ret = idev->info->mmap(idev->info, vma);

		module_put(idev->owner);

		return ret;

	}



	switch (idev->info->mem[mi].memtype) {

		case UIO_MEM_PHYS:

			return uio_mmap_physical(vma);

		case UIO_MEM_LOGICAL:

		case UIO_MEM_VIRTUAL:

			return uio_mmap_logical(vma);

		default:

			return -EINVAL;

	}

}



static struct file_operations uio_fops = {

	.owner		= THIS_MODULE,

	.open		= uio_open,

	.release	= uio_release,

	.read		= uio_read,

	.mmap		= uio_mmap,

	.poll		= uio_poll,

	.fasync		= uio_fasync,

};



static int uio_major_init(void)

{

	uio_major = register_chrdev(0, "uio", &uio_fops);

	if (uio_major < 0)

		return uio_major;

	return 0;

}



static void uio_major_cleanup(void)

{

	unregister_chrdev(uio_major, "uio");

}



static int init_uio_class(void)

{

	int ret = 0;



	if (uio_class != NULL) {

		kref_get(&uio_class->kref);

		goto exit;

	}



	/* This is the first time in here, set everything up properly */

	ret = uio_major_init();

	if (ret)

		goto exit;



	uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);

	if (!uio_class) {

		ret = -ENOMEM;

		goto err_kzalloc;

	}



	kref_init(&uio_class->kref);

	uio_class->class = class_create(THIS_MODULE, "uio");

	if (IS_ERR(uio_class->class)) {

		ret = IS_ERR(uio_class->class);

		printk(KERN_ERR "class_create failed for uio\n");

		goto err_class_create;

	}

	return 0;



err_class_create:

	kfree(uio_class);

	uio_class = NULL;

err_kzalloc:

	uio_major_cleanup();

exit:

	return ret;

}



static void release_uio_class(struct kref *kref)

{

	/* Ok, we cheat as we know we only have one uio_class */

	class_destroy(uio_class->class);

	kfree(uio_class);

	uio_major_cleanup();

	uio_class = NULL;

}



static void uio_class_destroy(void)

{

	if (uio_class)

		kref_put(&uio_class->kref, release_uio_class);

}



/**

 * uio_register_device - register a new userspace IO device

 * @owner:	module that creates the new device

 * @parent:	parent device

 * @info:	UIO device capabilities

 *

 * returns zero on success or a negative error code.

 */

int __uio_register_device(struct module *owner,

			  struct device *parent,

			  struct uio_info *info)

{

	struct uio_device *idev;

	int ret = 0;



	if (!parent || !info || !info->name || !info->version)

		return -EINVAL;



	info->uio_dev = NULL;



	ret = init_uio_class();

	if (ret)

		return ret;



	idev = kzalloc(sizeof(*idev), GFP_KERNEL);

	if (!idev) {

		ret = -ENOMEM;

		goto err_kzalloc;

	}



	idev->owner = owner;

	idev->info = info;

	init_waitqueue_head(&idev->wait);

	atomic_set(&idev->event, 0);



	ret = uio_get_minor(idev);

	if (ret)

		goto err_get_minor;



	idev->dev = device_create(uio_class->class, parent,

				  MKDEV(uio_major, idev->minor),

				  "uio%d", idev->minor);

	if (IS_ERR(idev->dev)) {

		printk(KERN_ERR "UIO: device register failed\n");

		ret = PTR_ERR(idev->dev);

		goto err_device_create;

	}

	dev_set_drvdata(idev->dev, idev);



	ret = uio_dev_add_attributes(idev);

	if (ret)

		goto err_uio_dev_add_attributes;



	info->uio_dev = idev;



	if (idev->info->irq >= 0) {

		ret = request_irq(idev->info->irq, uio_interrupt,

				  idev->info->irq_flags, idev->info->name, idev);

		if (ret)

			goto err_request_irq;

	}



	return 0;



err_request_irq:

	uio_dev_del_attributes(idev);

err_uio_dev_add_attributes:

	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));

err_device_create:

	uio_free_minor(idev);

err_get_minor:

	kfree(idev);

err_kzalloc:

	uio_class_destroy();

	return ret;

}

EXPORT_SYMBOL_GPL(__uio_register_device);



/**

 * uio_unregister_device - unregister a industrial IO device

 * @info:	UIO device capabilities

 *

 */

void uio_unregister_device(struct uio_info *info)

{

	struct uio_device *idev;



	if (!info || !info->uio_dev)

		return;



	idev = info->uio_dev;



	uio_free_minor(idev);



	if (info->irq >= 0)

		free_irq(info->irq, idev);



	uio_dev_del_attributes(idev);



	dev_set_drvdata(idev->dev, NULL);

	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));

	kfree(idev);

	uio_class_destroy();



	return;

}

EXPORT_SYMBOL_GPL(uio_unregister_device);



static int __init uio_init(void)

{

	return 0;

}



static void __exit uio_exit(void)

{

}



module_init(uio_init)

module_exit(uio_exit)

MODULE_LICENSE("GPL v2");

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