1/******************************************************************************
2 * Talks to Xen Store to figure out what devices we have (backend half).
3 *
4 * Copyright (C) 2005 Rusty Russell, IBM Corporation
5 * Copyright (C) 2005 Mike Wray, Hewlett-Packard
6 * Copyright (C) 2005, 2006 XenSource Ltd
7 * Copyright (C) 2007 Solarflare Communications, Inc.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version 2
11 * as published by the Free Software Foundation; or, when distributed
12 * separately from the Linux kernel or incorporated into other
13 * software packages, subject to the following license:
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining a copy
16 * of this source file (the "Software"), to deal in the Software without
17 * restriction, including without limitation the rights to use, copy, modify,
18 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
19 * and to permit persons to whom the Software is furnished to do so, subject to
20 * the following conditions:
21 *
22 * The above copyright notice and this permission notice shall be included in
23 * all copies or substantial portions of the Software.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
31 * IN THE SOFTWARE.
32 */
33
34#define DPRINTK(fmt, args...)				\
35	pr_debug("xenbus_probe (%s:%d) " fmt ".\n",	\
36		 __func__, __LINE__, ##args)
37
38#include <linux/kernel.h>
39#include <linux/err.h>
40#include <linux/string.h>
41#include <linux/ctype.h>
42#include <linux/fcntl.h>
43#include <linux/mm.h>
44#include <linux/notifier.h>
45#include <linux/export.h>
46
47#include <asm/page.h>
48#include <asm/pgtable.h>
49#include <asm/xen/hypervisor.h>
50#include <asm/hypervisor.h>
51#include <xen/xenbus.h>
52#include <xen/features.h>
53
54#include "xenbus_comms.h"
55#include "xenbus_probe.h"
56
57/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
58static int backend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
59{
60	int domid, err;
61	const char *devid, *type, *frontend;
62	unsigned int typelen;
63
64	type = strchr(nodename, '/');
65	if (!type)
66		return -EINVAL;
67	type++;
68	typelen = strcspn(type, "/");
69	if (!typelen || type[typelen] != '/')
70		return -EINVAL;
71
72	devid = strrchr(nodename, '/') + 1;
73
74	err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
75			    "frontend", NULL, &frontend,
76			    NULL);
77	if (err)
78		return err;
79	if (strlen(frontend) == 0)
80		err = -ERANGE;
81	if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
82		err = -ENOENT;
83	kfree(frontend);
84
85	if (err)
86		return err;
87
88	if (snprintf(bus_id, XEN_BUS_ID_SIZE, "%.*s-%i-%s",
89		     typelen, type, domid, devid) >= XEN_BUS_ID_SIZE)
90		return -ENOSPC;
91	return 0;
92}
93
94static int xenbus_uevent_backend(struct device *dev,
95				 struct kobj_uevent_env *env)
96{
97	struct xenbus_device *xdev;
98	struct xenbus_driver *drv;
99	struct xen_bus_type *bus;
100
101	DPRINTK("");
102
103	if (dev == NULL)
104		return -ENODEV;
105
106	xdev = to_xenbus_device(dev);
107	bus = container_of(xdev->dev.bus, struct xen_bus_type, bus);
108
109	if (add_uevent_var(env, "MODALIAS=xen-backend:%s", xdev->devicetype))
110		return -ENOMEM;
111
112	/* stuff we want to pass to /sbin/hotplug */
113	if (add_uevent_var(env, "XENBUS_TYPE=%s", xdev->devicetype))
114		return -ENOMEM;
115
116	if (add_uevent_var(env, "XENBUS_PATH=%s", xdev->nodename))
117		return -ENOMEM;
118
119	if (add_uevent_var(env, "XENBUS_BASE_PATH=%s", bus->root))
120		return -ENOMEM;
121
122	if (dev->driver) {
123		drv = to_xenbus_driver(dev->driver);
124		if (drv && drv->uevent)
125			return drv->uevent(xdev, env);
126	}
127
128	return 0;
129}
130
131/* backend/<typename>/<frontend-uuid>/<name> */
132static int xenbus_probe_backend_unit(struct xen_bus_type *bus,
133				     const char *dir,
134				     const char *type,
135				     const char *name)
136{
137	char *nodename;
138	int err;
139
140	nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
141	if (!nodename)
142		return -ENOMEM;
143
144	DPRINTK("%s\n", nodename);
145
146	err = xenbus_probe_node(bus, type, nodename);
147	kfree(nodename);
148	return err;
149}
150
151/* backend/<typename>/<frontend-domid> */
152static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type,
153				const char *domid)
154{
155	char *nodename;
156	int err = 0;
157	char **dir;
158	unsigned int i, dir_n = 0;
159
160	DPRINTK("");
161
162	nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, domid);
163	if (!nodename)
164		return -ENOMEM;
165
166	dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
167	if (IS_ERR(dir)) {
168		kfree(nodename);
169		return PTR_ERR(dir);
170	}
171
172	for (i = 0; i < dir_n; i++) {
173		err = xenbus_probe_backend_unit(bus, nodename, type, dir[i]);
174		if (err)
175			break;
176	}
177	kfree(dir);
178	kfree(nodename);
179	return err;
180}
181
182static void frontend_changed(struct xenbus_watch *watch,
183			    const char **vec, unsigned int len)
184{
185	xenbus_otherend_changed(watch, vec, len, 0);
186}
187
188static struct xen_bus_type xenbus_backend = {
189	.root = "backend",
190	.levels = 3,		/* backend/type/<frontend>/<id> */
191	.get_bus_id = backend_bus_id,
192	.probe = xenbus_probe_backend,
193	.otherend_changed = frontend_changed,
194	.bus = {
195		.name		= "xen-backend",
196		.match		= xenbus_match,
197		.uevent		= xenbus_uevent_backend,
198		.probe		= xenbus_dev_probe,
199		.remove		= xenbus_dev_remove,
200		.shutdown	= xenbus_dev_shutdown,
201		.dev_attrs	= xenbus_dev_attrs,
202	},
203};
204
205static void backend_changed(struct xenbus_watch *watch,
206			    const char **vec, unsigned int len)
207{
208	DPRINTK("");
209
210	xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
211}
212
213static struct xenbus_watch be_watch = {
214	.node = "backend",
215	.callback = backend_changed,
216};
217
218static int read_frontend_details(struct xenbus_device *xendev)
219{
220	return xenbus_read_otherend_details(xendev, "frontend-id", "frontend");
221}
222
223int xenbus_dev_is_online(struct xenbus_device *dev)
224{
225	int rc, val;
226
227	rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val);
228	if (rc != 1)
229		val = 0; /* no online node present */
230
231	return val;
232}
233EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
234
235int xenbus_register_backend(struct xenbus_driver *drv)
236{
237	drv->read_otherend_details = read_frontend_details;
238
239	return xenbus_register_driver_common(drv, &xenbus_backend);
240}
241EXPORT_SYMBOL_GPL(xenbus_register_backend);
242
243static int backend_probe_and_watch(struct notifier_block *notifier,
244				   unsigned long event,
245				   void *data)
246{
247	/* Enumerate devices in xenstore and watch for changes. */
248	xenbus_probe_devices(&xenbus_backend);
249	register_xenbus_watch(&be_watch);
250
251	return NOTIFY_DONE;
252}
253
254static int __init xenbus_probe_backend_init(void)
255{
256	static struct notifier_block xenstore_notifier = {
257		.notifier_call = backend_probe_and_watch
258	};
259	int err;
260
261	DPRINTK("");
262
263	/* Register ourselves with the kernel bus subsystem */
264	err = bus_register(&xenbus_backend.bus);
265	if (err)
266		return err;
267
268	register_xenstore_notifier(&xenstore_notifier);
269
270	return 0;
271}
272subsys_initcall(xenbus_probe_backend_init);
273