source: trunk/packages/xen-3.1/xen-3.1/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe_backend.c @ 34

/******************************************************************************
 * Talks to Xen Store to figure out what devices we have (backend half).
 *
 * Copyright (C) 2005 Rusty Russell, IBM Corporation
 * Copyright (C) 2005 Mike Wray, Hewlett-Packard
 * Copyright (C) 2005, 2006 XenSource Ltd
 * 
 * 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.
 */

#define DPRINTK(fmt, args...)                           \
        pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
                 __FUNCTION__, __LINE__, ##args)

#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/notifier.h>
#include <linux/kthread.h>

#include <asm/io.h>
#include <asm/page.h>
#include <asm/maddr.h>
#include <asm/pgtable.h>
#include <asm/hypervisor.h>
#include <xen/xenbus.h>
#include <xen/xen_proc.h>
#include <xen/evtchn.h>
#include <xen/features.h>
#include <xen/hvm.h>

#include "xenbus_comms.h"
#include "xenbus_probe.h"

#ifdef HAVE_XEN_PLATFORM_COMPAT_H
#include <xen/platform-compat.h>
#endif

static int xenbus_uevent_backend(struct device *dev, char **envp,
                                 int num_envp, char *buffer, int buffer_size);
static int xenbus_probe_backend(const char *type, const char *domid);

extern int read_otherend_details(struct xenbus_device *xendev,
                                 char *id_node, char *path_node);

static int read_frontend_details(struct xenbus_device *xendev)
{
        return read_otherend_details(xendev, "frontend-id", "frontend");
}

/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
static int backend_bus_id(char bus_id[BUS_ID_SIZE], const char *nodename)
{
        int domid, err;
        const char *devid, *type, *frontend;
        unsigned int typelen;

        type = strchr(nodename, '/');
        if (!type)
                return -EINVAL;
        type++;
        typelen = strcspn(type, "/");
        if (!typelen || type[typelen] != '/')
                return -EINVAL;

        devid = strrchr(nodename, '/') + 1;

        err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
                            "frontend", NULL, &frontend,
                            NULL);
        if (err)
                return err;
        if (strlen(frontend) == 0)
                err = -ERANGE;
        if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
                err = -ENOENT;
        kfree(frontend);

        if (err)
                return err;

        if (snprintf(bus_id, BUS_ID_SIZE,
                     "%.*s-%i-%s", typelen, type, domid, devid) >= BUS_ID_SIZE)
                return -ENOSPC;
        return 0;
}

static struct xen_bus_type xenbus_backend = {
        .root = "backend",
        .levels = 3,            /* backend/type/<frontend>/<id> */
        .get_bus_id = backend_bus_id,
        .probe = xenbus_probe_backend,
        .bus = {
                .name     = "xen-backend",
                .match    = xenbus_match,
                .probe    = xenbus_dev_probe,
                .remove   = xenbus_dev_remove,
//              .shutdown = xenbus_dev_shutdown,
                .uevent   = xenbus_uevent_backend,
        },
        .dev = {
                .bus_id = "xen-backend",
        },
};

static int xenbus_uevent_backend(struct device *dev, char **envp,
                                 int num_envp, char *buffer, int buffer_size)
{
        struct xenbus_device *xdev;
        struct xenbus_driver *drv;
        int i = 0;
        int length = 0;

        DPRINTK("");

        if (dev == NULL)
                return -ENODEV;

        xdev = to_xenbus_device(dev);
        if (xdev == NULL)
                return -ENODEV;

        /* stuff we want to pass to /sbin/hotplug */
        add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
                       "XENBUS_TYPE=%s", xdev->devicetype);

        add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
                       "XENBUS_PATH=%s", xdev->nodename);

        add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
                       "XENBUS_BASE_PATH=%s", xenbus_backend.root);

        /* terminate, set to next free slot, shrink available space */
        envp[i] = NULL;
        envp = &envp[i];
        num_envp -= i;
        buffer = &buffer[length];
        buffer_size -= length;

        if (dev->driver) {
                drv = to_xenbus_driver(dev->driver);
                if (drv && drv->uevent)
                        return drv->uevent(xdev, envp, num_envp, buffer,
                                           buffer_size);
        }

        return 0;
}

int xenbus_register_backend(struct xenbus_driver *drv)
{
        drv->read_otherend_details = read_frontend_details;

        return xenbus_register_driver_common(drv, &xenbus_backend);
}
EXPORT_SYMBOL_GPL(xenbus_register_backend);

/* backend/<typename>/<frontend-uuid>/<name> */
static int xenbus_probe_backend_unit(const char *dir,
                                     const char *type,
                                     const char *name)
{
        char *nodename;
        int err;

        nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
        if (!nodename)
                return -ENOMEM;

        DPRINTK("%s\n", nodename);

        err = xenbus_probe_node(&xenbus_backend, type, nodename);
        kfree(nodename);
        return err;
}

/* backend/<typename>/<frontend-domid> */
static int xenbus_probe_backend(const char *type, const char *domid)
{
        char *nodename;
        int err = 0;
        char **dir;
        unsigned int i, dir_n = 0;

        DPRINTK("");

        nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", xenbus_backend.root, type, domid);
        if (!nodename)
                return -ENOMEM;

        dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
        if (IS_ERR(dir)) {
                kfree(nodename);
                return PTR_ERR(dir);
        }

        for (i = 0; i < dir_n; i++) {
                err = xenbus_probe_backend_unit(nodename, type, dir[i]);
                if (err)
                        break;
        }
        kfree(dir);
        kfree(nodename);
        return err;
}

static void backend_changed(struct xenbus_watch *watch,
                            const char **vec, unsigned int len)
{
        DPRINTK("");

        dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
}

static struct xenbus_watch be_watch = {
        .node = "backend",
        .callback = backend_changed,
};

void xenbus_backend_suspend(int (*fn)(struct device *, void *))
{
        DPRINTK("");
        if (!xenbus_backend.error)
                bus_for_each_dev(&xenbus_backend.bus, NULL, NULL, fn);
}

void xenbus_backend_resume(int (*fn)(struct device *, void *))
{
        DPRINTK("");
        if (!xenbus_backend.error)
                bus_for_each_dev(&xenbus_backend.bus, NULL, NULL, fn);
}

void xenbus_backend_probe_and_watch(void)
{
        xenbus_probe_devices(&xenbus_backend);
        register_xenbus_watch(&be_watch);
}

void xenbus_backend_bus_register(void)
{
        xenbus_backend.error = bus_register(&xenbus_backend.bus);
        if (xenbus_backend.error)
                printk(KERN_WARNING
                       "XENBUS: Error registering backend bus: %i\n",
                       xenbus_backend.error);
}

void xenbus_backend_device_register(void)
{
        if (xenbus_backend.error)
                return;

        xenbus_backend.error = device_register(&xenbus_backend.dev);
        if (xenbus_backend.error) {
                bus_unregister(&xenbus_backend.bus);
                printk(KERN_WARNING
                       "XENBUS: Error registering backend device: %i\n",
                       xenbus_backend.error);
        }
}