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/drivers/xen/xenbus/xenbus_probe_backend.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 275 lines | 190 code | 47 blank | 38 comment | 30 complexity | 2563200b896b112425c53763f70df131 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  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
 46#include <asm/page.h>
 47#include <asm/pgtable.h>
 48#include <asm/xen/hypervisor.h>
 49#include <asm/hypervisor.h>
 50#include <xen/xenbus.h>
 51#include <xen/features.h>
 52
 53#include "xenbus_comms.h"
 54#include "xenbus_probe.h"
 55
 56/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
 57static int backend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
 58{
 59	int domid, err;
 60	const char *devid, *type, *frontend;
 61	unsigned int typelen;
 62
 63	type = strchr(nodename, '/');
 64	if (!type)
 65		return -EINVAL;
 66	type++;
 67	typelen = strcspn(type, "/");
 68	if (!typelen || type[typelen] != '/')
 69		return -EINVAL;
 70
 71	devid = strrchr(nodename, '/') + 1;
 72
 73	err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
 74			    "frontend", NULL, &frontend,
 75			    NULL);
 76	if (err)
 77		return err;
 78	if (strlen(frontend) == 0)
 79		err = -ERANGE;
 80	if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
 81		err = -ENOENT;
 82	kfree(frontend);
 83
 84	if (err)
 85		return err;
 86
 87	if (snprintf(bus_id, XEN_BUS_ID_SIZE, "%.*s-%i-%s",
 88		     typelen, type, domid, devid) >= XEN_BUS_ID_SIZE)
 89		return -ENOSPC;
 90	return 0;
 91}
 92
 93static int xenbus_uevent_backend(struct device *dev,
 94				 struct kobj_uevent_env *env)
 95{
 96	struct xenbus_device *xdev;
 97	struct xenbus_driver *drv;
 98	struct xen_bus_type *bus;
 99
100	DPRINTK("");
101
102	if (dev == NULL)
103		return -ENODEV;
104
105	xdev = to_xenbus_device(dev);
106	bus = container_of(xdev->dev.bus, struct xen_bus_type, bus);
107	if (xdev == NULL)
108		return -ENODEV;
109
110	if (add_uevent_var(env, "MODALIAS=xen-backend:%s", xdev->devicetype))
111		return -ENOMEM;
112
113	/* stuff we want to pass to /sbin/hotplug */
114	if (add_uevent_var(env, "XENBUS_TYPE=%s", xdev->devicetype))
115		return -ENOMEM;
116
117	if (add_uevent_var(env, "XENBUS_PATH=%s", xdev->nodename))
118		return -ENOMEM;
119
120	if (add_uevent_var(env, "XENBUS_BASE_PATH=%s", bus->root))
121		return -ENOMEM;
122
123	if (dev->driver) {
124		drv = to_xenbus_driver(dev->driver);
125		if (drv && drv->uevent)
126			return drv->uevent(xdev, env);
127	}
128
129	return 0;
130}
131
132/* backend/<typename>/<frontend-uuid>/<name> */
133static int xenbus_probe_backend_unit(struct xen_bus_type *bus,
134				     const char *dir,
135				     const char *type,
136				     const char *name)
137{
138	char *nodename;
139	int err;
140
141	nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
142	if (!nodename)
143		return -ENOMEM;
144
145	DPRINTK("%s\n", nodename);
146
147	err = xenbus_probe_node(bus, type, nodename);
148	kfree(nodename);
149	return err;
150}
151
152/* backend/<typename>/<frontend-domid> */
153static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type,
154				const char *domid)
155{
156	char *nodename;
157	int err = 0;
158	char **dir;
159	unsigned int i, dir_n = 0;
160
161	DPRINTK("");
162
163	nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, domid);
164	if (!nodename)
165		return -ENOMEM;
166
167	dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
168	if (IS_ERR(dir)) {
169		kfree(nodename);
170		return PTR_ERR(dir);
171	}
172
173	for (i = 0; i < dir_n; i++) {
174		err = xenbus_probe_backend_unit(bus, nodename, type, dir[i]);
175		if (err)
176			break;
177	}
178	kfree(dir);
179	kfree(nodename);
180	return err;
181}
182
183static void frontend_changed(struct xenbus_watch *watch,
184			    const char **vec, unsigned int len)
185{
186	xenbus_otherend_changed(watch, vec, len, 0);
187}
188
189static struct xen_bus_type xenbus_backend = {
190	.root = "backend",
191	.levels = 3,		/* backend/type/<frontend>/<id> */
192	.get_bus_id = backend_bus_id,
193	.probe = xenbus_probe_backend,
194	.otherend_changed = frontend_changed,
195	.bus = {
196		.name		= "xen-backend",
197		.match		= xenbus_match,
198		.uevent		= xenbus_uevent_backend,
199		.probe		= xenbus_dev_probe,
200		.remove		= xenbus_dev_remove,
201		.shutdown	= xenbus_dev_shutdown,
202		.dev_attrs	= xenbus_dev_attrs,
203	},
204};
205
206static void backend_changed(struct xenbus_watch *watch,
207			    const char **vec, unsigned int len)
208{
209	DPRINTK("");
210
211	xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
212}
213
214static struct xenbus_watch be_watch = {
215	.node = "backend",
216	.callback = backend_changed,
217};
218
219static int read_frontend_details(struct xenbus_device *xendev)
220{
221	return xenbus_read_otherend_details(xendev, "frontend-id", "frontend");
222}
223
224int xenbus_dev_is_online(struct xenbus_device *dev)
225{
226	int rc, val;
227
228	rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val);
229	if (rc != 1)
230		val = 0; /* no online node present */
231
232	return val;
233}
234EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
235
236int __xenbus_register_backend(struct xenbus_driver *drv,
237			      struct module *owner, const char *mod_name)
238{
239	drv->read_otherend_details = read_frontend_details;
240
241	return xenbus_register_driver_common(drv, &xenbus_backend,
242					     owner, mod_name);
243}
244EXPORT_SYMBOL_GPL(__xenbus_register_backend);
245
246static int backend_probe_and_watch(struct notifier_block *notifier,
247				   unsigned long event,
248				   void *data)
249{
250	/* Enumerate devices in xenstore and watch for changes. */
251	xenbus_probe_devices(&xenbus_backend);
252	register_xenbus_watch(&be_watch);
253
254	return NOTIFY_DONE;
255}
256
257static int __init xenbus_probe_backend_init(void)
258{
259	static struct notifier_block xenstore_notifier = {
260		.notifier_call = backend_probe_and_watch
261	};
262	int err;
263
264	DPRINTK("");
265
266	/* Register ourselves with the kernel bus subsystem */
267	err = bus_register(&xenbus_backend.bus);
268	if (err)
269		return err;
270
271	register_xenstore_notifier(&xenstore_notifier);
272
273	return 0;
274}
275subsys_initcall(xenbus_probe_backend_init);