sys/arch/xen/xenbus/xenbus_client.c

   1 /* $NetBSD: xenbus_client.c,v 1.9 2008/09/05 13:37:24 tron Exp $ */
   2 /******************************************************************************
   3  * Client-facing interface for the Xenbus driver.  In other words, the
   4  * interface between the Xenbus and the device-specific code, be it the
   5  * frontend or the backend of that driver.
   6  *
   7  * Copyright (C) 2005 XenSource Ltd
   8  *
   9  * This file may be distributed separately from the Linux kernel, or
  10  * incorporated into other software packages, subject to the following license:
  11  *
  12  * Permission is hereby granted, free of charge, to any person obtaining a copy
  13  * of this source file (the "Software"), to deal in the Software without
  14  * restriction, including without limitation the rights to use, copy, modify,
  15  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  16  * and to permit persons to whom the Software is furnished to do so, subject to
  17  * the following conditions:
  18  *
  19  * The above copyright notice and this permission notice shall be included in
  20  * all copies or substantial portions of the Software.
  21  *
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  25  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  26  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  27  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  28  * IN THE SOFTWARE.
  29  */
  30
  31 #include <sys/cdefs.h>
  32 __KERNEL_RCSID(0, "$NetBSD: xenbus_client.c,v 1.9 2008/09/05 13:37:24 tron Exp $");
  33
  34 #if 0
  35 #define DPRINTK(fmt, args...) \
  36     printk("xenbus_client (%s:%d) " fmt ".\n", __func__, __LINE__, ##args)
  37 #else
  38 #define DPRINTK(fmt, args...) ((void)0)
  39 #endif
  40
  41 #include <sys/types.h>
  42 #include <sys/null.h>
  43 #include <sys/errno.h>
  44 #include <sys/malloc.h>
  45 #include <sys/systm.h>
  46
  47 #include <machine/stdarg.h>
  48
  49 #include <xen/xen.h>
  50 #include <xen/hypervisor.h>
  51 #include <xen/evtchn.h>
  52 #include <xen/xenbus.h>
  53 #include <xen/granttables.h>
  54
  55
  56 int
  57 xenbus_watch_path(struct xenbus_device *dev, char *path,
  58                       struct xenbus_watch *watch,
  59                       void (*callback)(struct xenbus_watch *,
  60                                        const char **, unsigned int))
  61 {
  62         int err;
  63
  64         watch->node = path;
  65         watch->xbw_callback = callback;
  66
  67         err = register_xenbus_watch(watch);
  68
  69         if (err) {
  70                 watch->node = NULL;
  71                 watch->xbw_callback = NULL;
  72                 xenbus_dev_fatal(dev, err, "adding watch on %s", path);
  73         }
  74         err = 0;
  75
  76         return err;
  77 }
  78
  79 int
  80 xenbus_watch_path2(struct xenbus_device *dev, const char *path,
  81                        const char *path2, struct xenbus_watch *watch,
  82                        void (*callback)(struct xenbus_watch *,
  83                                         const char **, unsigned int))
  84 {
  85         int err;
  86         char *state;
  87
  88         DPRINTK("xenbus_watch_path2 path %s path2 %s\n", path, path2);
  89         state =
  90                 malloc(strlen(path) + 1 + strlen(path2) + 1, M_DEVBUF,
  91                     M_NOWAIT);
  92         if (!state) {
  93                 xenbus_dev_fatal(dev, ENOMEM, "allocating path for watch");
  94                 return ENOMEM;
  95         }
  96         strcpy(state, path);
  97         strcat(state, "/");
  98         strcat(state, path2);
  99
 100         err = xenbus_watch_path(dev, state, watch, callback);
 101
 102         if (err) {
 103                 free(state, M_DEVBUF);
 104         }
 105         return err;
 106 }
 107
 108
 109 int
 110 xenbus_switch_state(struct xenbus_device *dev,
 111                         struct xenbus_transaction *xbt,
 112                         XenbusState state)
 113 {
 114         /* We check whether the state is currently set to the given value, and
 115            if not, then the state is set.  We don't want to unconditionally
 116            write the given state, because we don't want to fire watches
 117            unnecessarily.  Furthermore, if the node has gone, we don't write
 118            to it, as the device will be tearing down, and we don't want to
 119            resurrect that directory.
 120          */
 121
 122         u_long current_state;
 123
 124         int err = xenbus_read_ul(xbt, dev->xbusd_path, "state",
 125             &current_state, 10);
 126         if (err)
 127                 return 0;
 128
 129         if ((XenbusState)current_state == state)
 130                 return 0;
 131
 132         err = xenbus_printf(xbt, dev->xbusd_path, "state", "%d", state);
 133         if (err) {
 134                 xenbus_dev_fatal(dev, err, "writing new state");
 135                 return err;
 136         }
 137         return 0;
 138 }
 139
 140 /**
 141  * Return the path to the error node for the given device, or NULL on failure.
 142  * If the value returned is non-NULL, then it is the caller's to kfree.
 143  */
 144 static char *
 145 error_path(struct xenbus_device *dev)
 146 {
 147         char *path_buffer = malloc(strlen("error/") + strlen(dev->xbusd_path) +
 148                                     1, M_DEVBUF, M_NOWAIT);
 149         if (path_buffer == NULL) {
 150                 return NULL;
 151         }
 152
 153         strcpy(path_buffer, "error/");
 154         strcpy(path_buffer + strlen("error/"), dev->xbusd_path);
 155
 156         return path_buffer;
 157 }
 158
 159
 160 static void
 161 _dev_error(struct xenbus_device *dev, int err, const char *fmt,
 162                 va_list ap)
 163 {
 164         int ret;
 165         unsigned int len;
 166         char *printf_buffer = NULL, *path_buffer = NULL;
 167
 168 #define PRINTF_BUFFER_SIZE 4096
 169         printf_buffer = malloc(PRINTF_BUFFER_SIZE, M_DEVBUF, M_NOWAIT);
 170         if (printf_buffer == NULL)
 171                 goto fail;
 172
 173         len = snprintf(printf_buffer, PRINTF_BUFFER_SIZE, "%i ", -err);
 174         ret = vsnprintf(printf_buffer+len, PRINTF_BUFFER_SIZE-len, fmt, ap);
 175
 176         KASSERT(len + ret < PRINTF_BUFFER_SIZE);
 177         dev->xbusd_has_error = 1;
 178
 179         path_buffer = error_path(dev);
 180
 181         if (path_buffer == NULL) {
 182                 printk("xenbus: failed to write error node for %s (%s)\n",
 183                        dev->xbusd_path, printf_buffer);
 184                 goto fail;
 185         }
 186
 187         if (xenbus_write(NULL, path_buffer, "error", printf_buffer) != 0) {
 188                 printk("xenbus: failed to write error node for %s (%s)\n",
 189                        dev->xbusd_path, printf_buffer);
 190                 goto fail;
 191         }
 192
 193 fail:
 194         if (printf_buffer)
 195                 free(printf_buffer, M_DEVBUF);
 196         if (path_buffer)
 197                 free(path_buffer, M_DEVBUF);
 198 }
 199
 200
 201 void
 202 xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt,
 203                       ...)
 204 {
 205         va_list ap;
 206
 207         va_start(ap, fmt);
 208         _dev_error(dev, err, fmt, ap);
 209         va_end(ap);
 210 }
 211
 212
 213 void
 214 xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt,
 215                       ...)
 216 {
 217         va_list ap;
 218
 219         va_start(ap, fmt);
 220         _dev_error(dev, err, fmt, ap);
 221         va_end(ap);
 222
 223         xenbus_switch_state(dev, NULL, XenbusStateClosing);
 224 }
 225
 226
 227 int
 228 xenbus_grant_ring(struct xenbus_device *dev, paddr_t ring_pa,
 229     grant_ref_t *entryp)
 230 {
 231         int err = xengnt_grant_access(dev->xbusd_otherend_id, ring_pa,
 232             0, entryp);
 233         if (err != 0)
 234                 xenbus_dev_fatal(dev, err, "granting access to ring page");
 235         return err;
 236 }
 237
 238
 239 int
 240 xenbus_alloc_evtchn(struct xenbus_device *dev, int *port)
 241 {
 242         evtchn_op_t op = {
 243                 .cmd = EVTCHNOP_alloc_unbound,
 244                 .u.alloc_unbound = {
 245                         .dom = DOMID_SELF,
 246                         .remote_dom = dev->xbusd_otherend_id,
 247                         .port = 0
 248                 }
 249         };
 250
 251         int err = HYPERVISOR_event_channel_op(&op);
 252         if (err)
 253                 xenbus_dev_fatal(dev, err, "allocating event channel");
 254         else
 255                 *port = op.u.alloc_unbound.port;
 256         return err;
 257 }
 258
 259
 260 XenbusState
 261 xenbus_read_driver_state(const char *path)
 262 {
 263         u_long result;
 264
 265         int err = xenbus_read_ul(NULL, path, "state", &result, 10);
 266         if (err)
 267                 result = XenbusStateClosed;
 268
 269         return result;
 270 }
 271
 272
 273 /*
 274  * Local variables:
 275  *  c-file-style: "linux"
 276  *  indent-tabs-mode: t
 277  *  c-indent-level: 8
 278  *  c-basic-offset: 8
 279  *  tab-width: 8
 280  * End:
 281  */