drivers/uwb/uwbd.c

   1 /*
   2  * Ultra Wide Band
   3  * Neighborhood Management Daemon
   4  *
   5  * Copyright (C) 2005-2006 Intel Corporation
   6  * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
   7  *
   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
  10  * 2 as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20  * 02110-1301, USA.
  21  *
  22  *
  23  * This daemon takes care of maintaing information that describes the
  24  * UWB neighborhood that the radios in this machine can see. It also
  25  * keeps a tab of which devices are visible, makes sure each HC sits
  26  * on a different channel to avoid interfering, etc.
  27  *
  28  * Different drivers (radio controller, device, any API in general)
  29  * communicate with this daemon through an event queue. Daemon wakes
  30  * up, takes a list of events and handles them one by one; handling
  31  * function is extracted from a table based on the event's type and
  32  * subtype. Events are freed only if the handling function says so.
  33  *
  34  *   . Lock protecting the event list has to be an spinlock and locked
  35  *     with IRQSAVE because it might be called from an interrupt
  36  *     context (ie: when events arrive and the notification drops
  37  *     down from the ISR).
  38  *
  39  *   . UWB radio controller drivers queue events to the daemon using
  40  *     uwbd_event_queue(). They just get the event, chew it to make it
  41  *     look like UWBD likes it and pass it in a buffer allocated with
  42  *     uwb_event_alloc().
  43  *
  44  * EVENTS
  45  *
  46  * Events have a type, a subtype, a lenght, some other stuff and the
  47  * data blob, which depends on the event. The header is 'struct
  48  * uwb_event'; for payloads, see 'struct uwbd_evt_*'.
  49  *
  50  * EVENT HANDLER TABLES
  51  *
  52  * To find a handling function for an event, the type is used to index
  53  * a subtype-table in the type-table. The subtype-table is indexed
  54  * with the subtype to get the function that handles the event. Start
  55  * with the main type-table 'uwbd_evt_type_handler'.
  56  *
  57  * DEVICES
  58  *
  59  * Devices are created when a bunch of beacons have been received and
  60  * it is stablished that the device has stable radio presence. CREATED
  61  * only, not configured. Devices are ONLY configured when an
  62  * Application-Specific IE Probe is receieved, in which the device
  63  * declares which Protocol ID it groks. Then the device is CONFIGURED
  64  * (and the driver->probe() stuff of the device model is invoked).
  65  *
  66  * Devices are considered disconnected when a certain number of
  67  * beacons are not received in an amount of time.
  68  *
  69  * Handler functions are called normally uwbd_evt_handle_*().
  70  */
  71 #include <linux/kthread.h>
  72 #include <linux/module.h>
  73 #include <linux/freezer.h>
  74
  75 #include "uwb-internal.h"
  76
  77 /*
  78  * UWBD Event handler function signature
  79  *
  80  * Return !0 if the event needs not to be freed (ie the handler
  81  * takes/took care of it). 0 means the daemon code will free the
  82  * event.
  83  *
  84  * @evt->rc is already referenced and guaranteed to exist. See
  85  * uwb_evt_handle().
  86  */
  87 typedef int (*uwbd_evt_handler_f)(struct uwb_event *);
  88
  89 /**
  90  * Properties of a UWBD event
  91  *
  92  * @handler:    the function that will handle this event
  93  * @name:       text name of event
  94  */
  95 struct uwbd_event {
  96         uwbd_evt_handler_f handler;
  97         const char *name;
  98 };
  99
 100 /* Table of handlers for and properties of the UWBD Radio Control Events */
 101 static struct uwbd_event uwbd_urc_events[] = {
 102         [UWB_RC_EVT_IE_RCV] = {
 103                 .handler = uwbd_evt_handle_rc_ie_rcv,
 104                 .name = "IE_RECEIVED"
 105         },
 106         [UWB_RC_EVT_BEACON] = {
 107                 .handler = uwbd_evt_handle_rc_beacon,
 108                 .name = "BEACON_RECEIVED"
 109         },
 110         [UWB_RC_EVT_BEACON_SIZE] = {
 111                 .handler = uwbd_evt_handle_rc_beacon_size,
 112                 .name = "BEACON_SIZE_CHANGE"
 113         },
 114         [UWB_RC_EVT_BPOIE_CHANGE] = {
 115                 .handler = uwbd_evt_handle_rc_bpoie_change,
 116                 .name = "BPOIE_CHANGE"
 117         },
 118         [UWB_RC_EVT_BP_SLOT_CHANGE] = {
 119                 .handler = uwbd_evt_handle_rc_bp_slot_change,
 120                 .name = "BP_SLOT_CHANGE"
 121         },
 122         [UWB_RC_EVT_DRP_AVAIL] = {
 123                 .handler = uwbd_evt_handle_rc_drp_avail,
 124                 .name = "DRP_AVAILABILITY_CHANGE"
 125         },
 126         [UWB_RC_EVT_DRP] = {
 127                 .handler = uwbd_evt_handle_rc_drp,
 128                 .name = "DRP"
 129         },
 130         [UWB_RC_EVT_DEV_ADDR_CONFLICT] = {
 131                 .handler = uwbd_evt_handle_rc_dev_addr_conflict,
 132                 .name = "DEV_ADDR_CONFLICT",
 133         },
 134 };
 135
 136
 137
 138 struct uwbd_evt_type_handler {
 139         const char *name;
 140         struct uwbd_event *uwbd_events;
 141         size_t size;
 142 };
 143
 144 /* Table of handlers for each UWBD Event type. */
 145 static struct uwbd_evt_type_handler uwbd_urc_evt_type_handlers[] = {
 146         [UWB_RC_CET_GENERAL] = {
 147                 .name        = "URC",
 148                 .uwbd_events = uwbd_urc_events,
 149                 .size        = ARRAY_SIZE(uwbd_urc_events),
 150         },
 151 };
 152
 153 static const struct uwbd_event uwbd_message_handlers[] = {
 154         [UWB_EVT_MSG_RESET] = {
 155                 .handler = uwbd_msg_handle_reset,
 156                 .name = "reset",
 157         },
 158 };
 159
 160 /*
 161  * Handle an URC event passed to the UWB Daemon
 162  *
 163  * @evt: the event to handle
 164  * @returns: 0 if the event can be kfreed, !0 on the contrary
 165  *           (somebody else took ownership) [coincidentally, returning
 166  *           a <0 errno code will free it :)].
 167  *
 168  * Looks up the two indirection tables (one for the type, one for the
 169  * subtype) to decide which function handles it and then calls the
 170  * handler.
 171  *
 172  * The event structure passed to the event handler has the radio
 173  * controller in @evt->rc referenced. The reference will be dropped
 174  * once the handler returns, so if it needs it for longer (async),
 175  * it'll need to take another one.
 176  */
 177 static
 178 int uwbd_event_handle_urc(struct uwb_event *evt)
 179 {
 180         int result = -EINVAL;
 181         struct uwbd_evt_type_handler *type_table;
 182         uwbd_evt_handler_f handler;
 183         u8 type, context;
 184         u16 event;
 185
 186         type = evt->notif.rceb->bEventType;
 187         event = le16_to_cpu(evt->notif.rceb->wEvent);
 188         context = evt->notif.rceb->bEventContext;
 189
 190         if (type >= ARRAY_SIZE(uwbd_urc_evt_type_handlers))
 191                 goto out;
 192         type_table = &uwbd_urc_evt_type_handlers[type];
 193         if (type_table->uwbd_events == NULL)
 194                 goto out;
 195         if (event >= type_table->size)
 196                 goto out;
 197         handler = type_table->uwbd_events[event].handler;
 198         if (handler == NULL)
 199                 goto out;
 200
 201         result = (*handler)(evt);
 202 out:
 203         if (result < 0)
 204                 dev_err(&evt->rc->uwb_dev.dev,
 205                         "UWBD: event 0x%02x/%04x/%02x, handling failed: %d\n",
 206                         type, event, context, result);
 207         return result;
 208 }
 209
 210 static void uwbd_event_handle_message(struct uwb_event *evt)
 211 {
 212         struct uwb_rc *rc;
 213         int result;
 214
 215         rc = evt->rc;
 216
 217         if (evt->message < 0 || evt->message >= ARRAY_SIZE(uwbd_message_handlers)) {
 218                 dev_err(&rc->uwb_dev.dev, "UWBD: invalid message type %d\n", evt->message);
 219                 return;
 220         }
 221
 222         result = uwbd_message_handlers[evt->message].handler(evt);
 223         if (result < 0)
 224                 dev_err(&rc->uwb_dev.dev, "UWBD: '%s' message failed: %d\n",
 225                         uwbd_message_handlers[evt->message].name, result);
 226 }
 227
 228 static void uwbd_event_handle(struct uwb_event *evt)
 229 {
 230         struct uwb_rc *rc;
 231         int should_keep;
 232
 233         rc = evt->rc;
 234
 235         if (rc->ready) {
 236                 switch (evt->type) {
 237                 case UWB_EVT_TYPE_NOTIF:
 238                         should_keep = uwbd_event_handle_urc(evt);
 239                         if (should_keep <= 0)
 240                                 kfree(evt->notif.rceb);
 241                         break;
 242                 case UWB_EVT_TYPE_MSG:
 243                         uwbd_event_handle_message(evt);
 244                         break;
 245                 default:
 246                         dev_err(&rc->uwb_dev.dev, "UWBD: invalid event type %d\n", evt->type);
 247                         break;
 248                 }
 249         }
 250
 251         __uwb_rc_put(rc);       /* for the __uwb_rc_get() in uwb_rc_notif_cb() */
 252 }
 253
 254 /**
 255  * UWB Daemon
 256  *
 257  * Listens to all UWB notifications and takes care to track the state
 258  * of the UWB neighboorhood for the kernel. When we do a run, we
 259  * spinlock, move the list to a private copy and release the
 260  * lock. Hold it as little as possible. Not a conflict: it is
 261  * guaranteed we own the events in the private list.
 262  *
 263  * FIXME: should change so we don't have a 1HZ timer all the time, but
 264  *        only if there are devices.
 265  */
 266 static int uwbd(void *param)
 267 {
 268         struct uwb_rc *rc = param;
 269         unsigned long flags;
 270         struct uwb_event *evt;
 271         int should_stop = 0;
 272
 273         while (1) {
 274                 wait_event_interruptible_timeout(
 275                         rc->uwbd.wq,
 276                         !list_empty(&rc->uwbd.event_list)
 277                           || (should_stop = kthread_should_stop()),
 278                         HZ);
 279                 if (should_stop)
 280                         break;
 281                 try_to_freeze();
 282
 283                 spin_lock_irqsave(&rc->uwbd.event_list_lock, flags);
 284                 if (!list_empty(&rc->uwbd.event_list)) {
 285                         evt = list_first_entry(&rc->uwbd.event_list, struct uwb_event, list_node);
 286                         list_del(&evt->list_node);
 287                 } else
 288                         evt = NULL;
 289                 spin_unlock_irqrestore(&rc->uwbd.event_list_lock, flags);
 290
 291                 if (evt) {
 292                         uwbd_event_handle(evt);
 293                         kfree(evt);
 294                 }
 295
 296                 uwb_beca_purge(rc);     /* Purge devices that left */
 297         }
 298         return 0;
 299 }
 300
 301
 302 /** Start the UWB daemon */
 303 void uwbd_start(struct uwb_rc *rc)
 304 {
 305         rc->uwbd.task = kthread_run(uwbd, rc, "uwbd");
 306         if (rc->uwbd.task == NULL)
 307                 printk(KERN_ERR "UWB: Cannot start management daemon; "
 308                        "UWB won't work\n");
 309         else
 310                 rc->uwbd.pid = rc->uwbd.task->pid;
 311 }
 312
 313 /* Stop the UWB daemon and free any unprocessed events */
 314 void uwbd_stop(struct uwb_rc *rc)
 315 {
 316         kthread_stop(rc->uwbd.task);
 317         uwbd_flush(rc);
 318 }
 319
 320 /*
 321  * Queue an event for the management daemon
 322  *
 323  * When some lower layer receives an event, it uses this function to
 324  * push it forward to the UWB daemon.
 325  *
 326  * Once you pass the event, you don't own it any more, but the daemon
 327  * does. It will uwb_event_free() it when done, so make sure you
 328  * uwb_event_alloc()ed it or bad things will happen.
 329  *
 330  * If the daemon is not running, we just free the event.
 331  */
 332 void uwbd_event_queue(struct uwb_event *evt)
 333 {
 334         struct uwb_rc *rc = evt->rc;
 335         unsigned long flags;
 336
 337         spin_lock_irqsave(&rc->uwbd.event_list_lock, flags);
 338         if (rc->uwbd.pid != 0) {
 339                 list_add(&evt->list_node, &rc->uwbd.event_list);
 340                 wake_up_all(&rc->uwbd.wq);
 341         } else {
 342                 __uwb_rc_put(evt->rc);
 343                 if (evt->type == UWB_EVT_TYPE_NOTIF)
 344                         kfree(evt->notif.rceb);
 345                 kfree(evt);
 346         }
 347         spin_unlock_irqrestore(&rc->uwbd.event_list_lock, flags);
 348         return;
 349 }
 350
 351 void uwbd_flush(struct uwb_rc *rc)
 352 {
 353         struct uwb_event *evt, *nxt;
 354
 355         spin_lock_irq(&rc->uwbd.event_list_lock);
 356         list_for_each_entry_safe(evt, nxt, &rc->uwbd.event_list, list_node) {
 357                 if (evt->rc == rc) {
 358                         __uwb_rc_put(rc);
 359                         list_del(&evt->list_node);
 360                         if (evt->type == UWB_EVT_TYPE_NOTIF)
 361                                 kfree(evt->notif.rceb);
 362                         kfree(evt);
 363                 }
 364         }
 365         spin_unlock_irq(&rc->uwbd.event_list_lock);
 366 }