xen: Add xenbus_backend device

xenbus-be-objs-$(CONFIG_XEN_BACKEND) += xenbus_probe_backend.o

xenbus-objs += $(xenbus-be-objs-y)

obj-$(CONFIG_XEN_BACKEND) += xenbus_dev_backend.o

obj-$(CONFIG_XEN_XENBUS_FRONTEND) += xenbus_probe_frontend.o

#include <linux/slab.h>

#include <linux/types.h>

#include <linux/mm.h>

#include <linux/fs.h>

#include <linux/miscdevice.h>

#include <linux/module.h>

#include <linux/capability.h>

#include <xen/page.h>

#include <xen/xenbus_dev.h>

#include "xenbus_comms.h"

MODULE_LICENSE("GPL");

static int xenbus_backend_open(struct inode *inode, struct file *filp)

{

	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;

	return nonseekable_open(inode, filp);

}

static long xenbus_backend_ioctl(struct file *file, unsigned int cmd, unsigned long data)

{

	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;

	switch (cmd) {

		case IOCTL_XENBUS_BACKEND_EVTCHN:

			if (xen_store_evtchn > 0)

				return xen_store_evtchn;

			return -ENODEV;

		default:

			return -ENOTTY;

	}

}

static int xenbus_backend_mmap(struct file *file, struct vm_area_struct *vma)

{

	size_t size = vma->vm_end - vma->vm_start;

	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;

	if ((size > PAGE_SIZE) || (vma->vm_pgoff != 0))

		return -EINVAL;

	if (remap_pfn_range(vma, vma->vm_start,

			    virt_to_pfn(xen_store_interface),

			    size, vma->vm_page_prot))

		return -EAGAIN;

	return 0;

}

const struct file_operations xenbus_backend_fops = {

	.open = xenbus_backend_open,

	.mmap = xenbus_backend_mmap,

	.unlocked_ioctl = xenbus_backend_ioctl,

};

static struct miscdevice xenbus_backend_dev = {

	.minor = MISC_DYNAMIC_MINOR,

	.name = "xen/xenbus_backend",

	.fops = &xenbus_backend_fops,

};

static int __init xenbus_backend_init(void)

{

	int err;

	if (!xen_initial_domain())

		return -ENODEV;

	err = misc_register(&xenbus_backend_dev);

	if (err)

		printk(KERN_ERR "Could not register xenbus backend device\n");

	return err;

}

static void __exit xenbus_backend_exit(void)

{

	misc_deregister(&xenbus_backend_dev);

}

module_init(xenbus_backend_init);

module_exit(xenbus_backend_exit);

/******************************************************************************

 * evtchn.h

 *

 * Interface to /dev/xen/xenbus_backend.

 *

 * Copyright (c) 2011 Bastian Blank <waldi@debian.org>

 *

 * 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; or, when distributed

 * separately from the Linux kernel or incorporated into other

 * software packages, subject to the following license:

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this source file (the "Software"), to deal in the Software without

 * restriction, including without limitation the rights to use, copy, modify,

 * merge, publish, distribute, sublicense, and/or sell copies of the Software,

 * and to permit persons to whom the Software is furnished to do so, subject to

 * the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 */

#ifndef __LINUX_XEN_XENBUS_DEV_H__

#define __LINUX_XEN_XENBUS_DEV_H__

#include <linux/ioctl.h>

#define IOCTL_XENBUS_BACKEND_EVTCHN			\

	_IOC(_IOC_NONE, 'B', 0, 0)

#endif /* __LINUX_XEN_XENBUS_DEV_H__ */