xenbus_probe.c revision 8863:94039d51dda4 
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*
28 * Talks to Xen Store to figure out what devices we have.
29 *
30 * Copyright (C) 2005 Rusty Russell, IBM Corporation
31 * Copyright (C) 2005 Mike Wray, Hewlett-Packard
32 * Copyright (C) 2005 XenSource Ltd
33 *
34 * This file may be distributed separately from the Linux kernel, or
35 * incorporated into other software packages, subject to the following license:
36 *
37 * Permission is hereby granted, free of charge, to any person obtaining a copy
38 * of this source file (the "Software"), to deal in the Software without
39 * restriction, including without limitation the rights to use, copy, modify,
40 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
41 * and to permit persons to whom the Software is furnished to do so, subject to
42 * the following conditions:
43 *
44 * The above copyright notice and this permission notice shall be included in
45 * all copies or substantial portions of the Software.
46 *
47 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
48 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
49 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
50 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
51 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
52 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
53 * IN THE SOFTWARE.
54 */
55
56#ifdef XPV_HVM_DRIVER
57#include <sys/xpv_support.h>
58#endif
59#include <sys/hypervisor.h>
60#include <xen/sys/xenbus_impl.h>
61#include <xen/sys/xenbus_comms.h>
62#include <xen/public/io/xs_wire.h>
63
64static int
65read_otherend_details(struct xenbus_device *xendev,
66			char *id_node, char *path_node)
67{
68	int err = xenbus_gather(XBT_NULL, xendev->nodename,
69	    id_node, "%i", &xendev->otherend_id, path_node, NULL,
70	    &xendev->otherend, NULL);
71	if (err) {
72		xenbus_dev_fatal(xendev, err,
73		    "reading other end details from %s", xendev->nodename);
74		return (err);
75	}
76	if (strlen(xendev->otherend) == 0 ||
77	    !xenbus_exists_dir(xendev->otherend, "")) {
78		xenbus_dev_fatal(xendev, X_ENOENT, "missing other end from %s",
79		    xendev->nodename);
80		kmem_free((void *)xendev->otherend,
81		    strlen(xendev->otherend) + 1);
82		xendev->otherend = NULL;
83		return (X_ENOENT);
84	}
85
86	return (0);
87}
88
89
90static int
91read_backend_details(struct xenbus_device *xendev)
92{
93	return (read_otherend_details(xendev, "backend-id", "backend"));
94}
95
96
97static int
98read_frontend_details(struct xenbus_device *xendev)
99{
100	return (read_otherend_details(xendev, "frontend-id", "frontend"));
101}
102
103
104static void
105free_otherend_details(struct xenbus_device *dev)
106{
107	if (dev->otherend != NULL) {
108		kmem_free((void *)dev->otherend, strlen(dev->otherend) + 1);
109		dev->otherend = NULL;
110	}
111}
112
113
114static void
115free_otherend_watch(struct xenbus_device *dev)
116{
117	if (dev->otherend_watch.node) {
118		unregister_xenbus_watch(&dev->otherend_watch);
119		kmem_free((void *)dev->otherend_watch.node,
120		    strlen(dev->otherend_watch.node) + 1);
121		dev->otherend_watch.node = NULL;
122	}
123}
124
125
126/*ARGSUSED2*/
127static void
128otherend_changed(struct xenbus_watch *watch, const char **vec, unsigned int len)
129{
130	struct xenbus_device *dev = watch->dev;
131	XenbusState state;
132
133	/*
134	 * Protect us against watches firing on old details when the otherend
135	 * details change, say immediately after a resume.
136	 */
137	if (!dev->otherend ||
138	    strncmp(dev->otherend, vec[XS_WATCH_PATH], strlen(dev->otherend))) {
139#if 0
140		printf("Ignoring watch at %s", vec[XS_WATCH_PATH]);
141#endif
142		return;
143	}
144
145	state = xenbus_read_driver_state(dev->otherend);
146
147#if 0
148	printf("state is %d, %s, %s",
149	    state, dev->otherend_watch.node, vec[XS_WATCH_PATH]);
150#endif
151	if (dev->otherend_changed)
152		dev->otherend_changed(dev, state);
153}
154
155
156int
157talk_to_otherend(struct xenbus_device *dev)
158{
159	int err;
160
161	free_otherend_watch(dev);
162	free_otherend_details(dev);
163
164	if (dev->frontend)
165		err = read_backend_details(dev);
166	else
167		err = read_frontend_details(dev);
168	if (err)
169		return (err);
170
171	dev->otherend_watch.dev = dev;
172	return (xenbus_watch_path2(dev, dev->otherend, "state",
173	    &dev->otherend_watch, otherend_changed));
174}
175
176
177/*
178 * Local variables:
179 *  c-file-style: "solaris"
180 *  indent-tabs-mode: t
181 *  c-indent-level: 8
182 *  c-basic-offset: 8
183 *  tab-width: 8
184 * End:
185 */
186