1 /******************************************************************************
2 * Client-facing interface for the Xenbus driver. In other words, the
3 * interface between the Xenbus and the device-specific code, be it the
4 * frontend or the backend of that driver.
6 * Copyright (C) 2005 XenSource Ltd
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License version 2
10 * as published by the Free Software Foundation; or, when distributed
11 * separately from the Linux kernel or incorporated into other
12 * software packages, subject to the following license:
14 * Permission is hereby granted, free of charge, to any person obtaining a copy
15 * of this source file (the "Software"), to deal in the Software without
16 * restriction, including without limitation the rights to use, copy, modify,
17 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
18 * and to permit persons to whom the Software is furnished to do so, subject to
19 * the following conditions:
21 * The above copyright notice and this permission notice shall be included in
22 * all copies or substantial portions of the Software.
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
26 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
28 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
29 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
33 #include <xen/evtchn.h>
34 #include <xen/gnttab.h>
35 #include <xen/xenbus.h>
36 #include <xen/driver_util.h>
38 #define DPRINTK(fmt, args...) \
39 pr_debug("xenbus_client (%s:%d) " fmt ".\n", __FUNCTION__, __LINE__, ##args)
41 char *xenbus_strstate(enum xenbus_state state)
43 static char *name[] = {
44 [ XenbusStateUnknown ] = "Unknown",
45 [ XenbusStateInitialising ] = "Initialising",
46 [ XenbusStateInitWait ] = "InitWait",
47 [ XenbusStateInitialised ] = "Initialised",
48 [ XenbusStateConnected ] = "Connected",
49 [ XenbusStateClosing ] = "Closing",
50 [ XenbusStateClosed ] = "Closed",
52 return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID";
55 int xenbus_watch_path(struct xenbus_device *dev, const char *path,
56 struct xenbus_watch *watch,
57 void (*callback)(struct xenbus_watch *,
58 const char **, unsigned int))
63 watch->callback = callback;
65 err = register_xenbus_watch(watch);
69 watch->callback = NULL;
70 xenbus_dev_fatal(dev, err, "adding watch on %s", path);
75 EXPORT_SYMBOL_GPL(xenbus_watch_path);
78 int xenbus_watch_path2(struct xenbus_device *dev, const char *path,
79 const char *path2, struct xenbus_watch *watch,
80 void (*callback)(struct xenbus_watch *,
81 const char **, unsigned int))
84 char *state = kasprintf(GFP_KERNEL, "%s/%s", path, path2);
86 xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch");
89 err = xenbus_watch_path(dev, state, watch, callback);
95 EXPORT_SYMBOL_GPL(xenbus_watch_path2);
98 int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
100 /* We check whether the state is currently set to the given value, and
101 if not, then the state is set. We don't want to unconditionally
102 write the given state, because we don't want to fire watches
103 unnecessarily. Furthermore, if the node has gone, we don't write
104 to it, as the device will be tearing down, and we don't want to
105 resurrect that directory.
107 Note that, because of this cached value of our state, this function
108 will not work inside a Xenstore transaction (something it was
109 trying to in the past) because dev->state would not get reset if
110 the transaction was aborted.
117 if (state == dev->state)
120 err = xenbus_scanf(XBT_NIL, dev->nodename, "state", "%d",
125 err = xenbus_printf(XBT_NIL, dev->nodename, "state", "%d", state);
127 if (state != XenbusStateClosing) /* Avoid looping */
128 xenbus_dev_fatal(dev, err, "writing new state");
136 EXPORT_SYMBOL_GPL(xenbus_switch_state);
138 int xenbus_frontend_closed(struct xenbus_device *dev)
140 xenbus_switch_state(dev, XenbusStateClosed);
141 complete(&dev->down);
144 EXPORT_SYMBOL_GPL(xenbus_frontend_closed);
147 * Return the path to the error node for the given device, or NULL on failure.
148 * If the value returned is non-NULL, then it is the caller's to kfree.
150 static char *error_path(struct xenbus_device *dev)
152 return kasprintf(GFP_KERNEL, "error/%s", dev->nodename);
156 void _dev_error(struct xenbus_device *dev, int err, const char *fmt,
161 char *printf_buffer = NULL, *path_buffer = NULL;
163 #define PRINTF_BUFFER_SIZE 4096
164 printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL);
165 if (printf_buffer == NULL)
168 len = sprintf(printf_buffer, "%i ", -err);
169 ret = vsnprintf(printf_buffer+len, PRINTF_BUFFER_SIZE-len, fmt, ap);
171 BUG_ON(len + ret > PRINTF_BUFFER_SIZE-1);
173 dev_err(&dev->dev, "%s\n", printf_buffer);
175 path_buffer = error_path(dev);
177 if (path_buffer == NULL) {
178 printk("xenbus: failed to write error node for %s (%s)\n",
179 dev->nodename, printf_buffer);
183 if (xenbus_write(XBT_NIL, path_buffer, "error", printf_buffer) != 0) {
184 printk("xenbus: failed to write error node for %s (%s)\n",
185 dev->nodename, printf_buffer);
191 kfree(printf_buffer);
197 void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt,
203 _dev_error(dev, err, fmt, ap);
206 EXPORT_SYMBOL_GPL(xenbus_dev_error);
209 void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt,
215 _dev_error(dev, err, fmt, ap);
218 xenbus_switch_state(dev, XenbusStateClosing);
220 EXPORT_SYMBOL_GPL(xenbus_dev_fatal);
223 int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn)
225 int err = gnttab_grant_foreign_access(dev->otherend_id, ring_mfn, 0);
227 xenbus_dev_fatal(dev, err, "granting access to ring page");
230 EXPORT_SYMBOL_GPL(xenbus_grant_ring);
233 int xenbus_alloc_evtchn(struct xenbus_device *dev, int *port)
235 struct evtchn_alloc_unbound alloc_unbound;
238 alloc_unbound.dom = DOMID_SELF;
239 alloc_unbound.remote_dom = dev->otherend_id;
241 err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
244 xenbus_dev_fatal(dev, err, "allocating event channel");
246 *port = alloc_unbound.port;
250 EXPORT_SYMBOL_GPL(xenbus_alloc_evtchn);
253 int xenbus_bind_evtchn(struct xenbus_device *dev, int remote_port, int *port)
255 struct evtchn_bind_interdomain bind_interdomain;
258 bind_interdomain.remote_dom = dev->otherend_id;
259 bind_interdomain.remote_port = remote_port,
261 err = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
264 xenbus_dev_fatal(dev, err,
265 "binding to event channel %d from domain %d",
266 remote_port, dev->otherend_id);
268 *port = bind_interdomain.local_port;
272 EXPORT_SYMBOL_GPL(xenbus_bind_evtchn);
275 int xenbus_free_evtchn(struct xenbus_device *dev, int port)
277 struct evtchn_close close;
282 err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
284 xenbus_dev_error(dev, err, "freeing event channel %d", port);
290 enum xenbus_state xenbus_read_driver_state(const char *path)
292 enum xenbus_state result;
293 int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL);
295 result = XenbusStateUnknown;
299 EXPORT_SYMBOL_GPL(xenbus_read_driver_state);