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 length, 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/slab.h>
  73 #include <linux/module.h>
  74 #include <linux/freezer.h>
  75
  76 #include "uwb-internal.h"
  77
  78 /*
  79  * UWBD Event handler function signature
  80  *
  81  * Return !0 if the event needs not to be freed (ie the handler
  82  * takes/took care of it). 0 means the daemon code will free the
  83  * event.
  84  *
  85  * @evt->rc is already referenced and guaranteed to exist. See
  86  * uwb_evt_handle().
  87  */
  88 typedef int (*uwbd_evt_handler_f)(struct uwb_event *);
  89
  90 /**
  91  * Properties of a UWBD event
  92  *
  93  * @handler:    the function that will handle this event
  94  * @name:       text name of event
  95  */
  96 struct uwbd_event {
  97         uwbd_evt_handler_f handler;
  98         const char *name;
  99 };
 100
 101 /* Table of handlers for and properties of the UWBD Radio Control Events */
 102 static struct uwbd_event uwbd_urc_events[] = {
 103         [UWB_RC_EVT_IE_RCV] = {
 104                 .handler = uwbd_evt_handle_rc_ie_rcv,
 105                 .name = "IE_RECEIVED"
 106         },
 107         [UWB_RC_EVT_BEACON] = {
 108                 .handler = uwbd_evt_handle_rc_beacon,
 109                 .name = "BEACON_RECEIVED"
 110         },
 111         [UWB_RC_EVT_BEACON_SIZE] = {
 112                 .handler = uwbd_evt_handle_rc_beacon_size,
 113                 .name = "BEACON_SIZE_CHANGE"
 114         },
 115         [UWB_RC_EVT_BPOIE_CHANGE] = {
 116                 .handler = uwbd_evt_handle_rc_bpoie_change,
 117                 .name = "BPOIE_CHANGE"
 118         },
 119         [UWB_RC_EVT_BP_SLOT_CHANGE] = {
 120                 .handler = uwbd_evt_handle_rc_bp_slot_change,
 121                 .name = "BP_SLOT_CHANGE"
 122         },
 123         [UWB_RC_EVT_DRP_AVAIL] = {
 124                 .handler = uwbd_evt_handle_rc_drp_avail,
 125                 .name = "DRP_AVAILABILITY_CHANGE"
 126         },
 127         [UWB_RC_EVT_DRP] = {
 128                 .handler = uwbd_evt_handle_rc_drp,
 129                 .name = "DRP"
 130         },
 131         [UWB_RC_EVT_DEV_ADDR_CONFLICT] = {
 132                 .handler = uwbd_evt_handle_rc_dev_addr_conflict,
 133                 .name = "DEV_ADDR_CONFLICT",
 134         },
 135 };
 136
 137
 138
 139 struct uwbd_evt_type_handler {
 140         const char *name;
 141         struct uwbd_event *uwbd_events;
 142         size_t size;
 143 };
 144
 145 /* Table of handlers for each UWBD Event type. */
 146 static struct uwbd_evt_type_handler uwbd_urc_evt_type_handlers[] = {
 147         [UWB_RC_CET_GENERAL] = {
 148                 .name        = "URC",
 149                 .uwbd_events = uwbd_urc_events,
 150                 .size        = ARRAY_SIZE(uwbd_urc_events),
 151         },
 152 };
 153
 154 static const struct uwbd_event uwbd_message_handlers[] = {
 155         [UWB_EVT_MSG_RESET] = {
 156                 .handler = uwbd_msg_handle_reset,
 157                 .name = "reset",
 158         },
 159 };
 160
 161 /*
 162  * Handle an URC event passed to the UWB Daemon
 163  *
 164  * @evt: the event to handle
 165  * @returns: 0 if the event can be kfreed, !0 on the contrary
 166  *           (somebody else took ownership) [coincidentally, returning
 167  *           a <0 errno code will free it :)].
 168  *
 169  * Looks up the two indirection tables (one for the type, one for the
 170  * subtype) to decide which function handles it and then calls the
 171  * handler.
 172  *
 173  * The event structure passed to the event handler has the radio
 174  * controller in @evt->rc referenced. The reference will be dropped
 175  * once the handler returns, so if it needs it for longer (async),
 176  * it'll need to take another one.
 177  */
 178 static
 179 int uwbd_event_handle_urc(struct uwb_event *evt)
 180 {
 181         int result = -EINVAL;
 182         struct uwbd_evt_type_handler *type_table;
 183         uwbd_evt_handler_f handler;
 184         u8 type, context;
 185         u16 event;
 186
 187         type = evt->notif.rceb->bEventType;
 188         event = le16_to_cpu(evt->notif.rceb->wEvent);
 189         context = evt->notif.rceb->bEventContext;
 190
 191         if (type >= ARRAY_SIZE(uwbd_urc_evt_type_handlers))
 192                 goto out;
 193         type_table = &uwbd_urc_evt_type_handlers[type];
 194         if (type_table->uwbd_events == NULL)
 195                 goto out;
 196         if (event >= type_table->size)
 197                 goto out;
 198         handler = type_table->uwbd_events[event].handler;
 199         if (handler == NULL)
 200                 goto out;
 201
 202         result = (*handler)(evt);
 203 out:
 204         if (result < 0)
 205                 dev_err(&evt->rc->uwb_dev.dev,
 206                         "UWBD: event 0x%02x/%04x/%02x, handling failed: %d\n",
 207                         type, event, context, result);
 208         return result;
 209 }
 210
 211 static void uwbd_event_handle_message(struct uwb_event *evt)
 212 {
 213         struct uwb_rc *rc;
 214         int result;
 215
 216         rc = evt->rc;
 217
 218         if (evt->message < 0 || evt->message >= ARRAY_SIZE(uwbd_message_handlers)) {
 219                 dev_err(&rc->uwb_dev.dev, "UWBD: invalid message type %d\n", evt->message);
 220                 return;
 221         }
 222
 223         result = uwbd_message_handlers[evt->message].handler(evt);
 224         if (result < 0)
 225                 dev_err(&rc->uwb_dev.dev, "UWBD: '%s' message failed: %d\n",
 226                         uwbd_message_handlers[evt->message].name, result);
 227 }
 228
 229 static void uwbd_event_handle(struct uwb_event *evt)
 230 {
 231         struct uwb_rc *rc;
 232         int should_keep;
 233
 234         rc = evt->rc;
 235
 236         if (rc->ready) {
 237                 switch (evt->type) {
 238                 case UWB_EVT_TYPE_NOTIF:
 239                         should_keep = uwbd_event_handle_urc(evt);
 240                         if (should_keep <= 0)
 241                                 kfree(evt->notif.rceb);
 242                         break;
 243                 case UWB_EVT_TYPE_MSG:
 244                         uwbd_event_handle_message(evt);
 245                         break;
 246                 default:
 247                         dev_err(&rc->uwb_dev.dev, "UWBD: invalid event type %d\n", evt->type);
 248                         break;
 249                 }
 250         }
 251
 252         __uwb_rc_put(rc);       /* for the __uwb_rc_get() in uwb_rc_notif_cb() */
 253 }
 254
 255 /**
 256  * UWB Daemon
 257  *
 258  * Listens to all UWB notifications and takes care to track the state
 259  * of the UWB neighbourhood for the kernel. When we do a run, we
 260  * spinlock, move the list to a private copy and release the
 261  * lock. Hold it as little as possible. Not a conflict: it is
 262  * guaranteed we own the events in the private list.
 263  *
 264  * FIXME: should change so we don't have a 1HZ timer all the time, but
 265  *        only if there are devices.
 266  */
 267 static int uwbd(void *param)
 268 {
 269         struct uwb_rc *rc = param;
 270         unsigned long flags;
 271         struct uwb_event *evt;
 272         int should_stop = 0;
 273
 274         while (1) {
 275                 wait_event_interruptible_timeout(
 276                         rc->uwbd.wq,
 277                         !list_empty(&rc->uwbd.event_list)
 278                           || (should_stop = kthread_should_stop()),
 279                         HZ);
 280                 if (should_stop)
 281                         break;
 282                 try_to_freeze();
 283
 284                 spin_lock_irqsave(&rc->uwbd.event_list_lock, flags);
 285                 if (!list_empty(&rc->uwbd.event_list)) {
 286                         evt = list_first_entry(&rc->uwbd.event_list, struct uwb_event, list_node);
 287                         list_del(&evt->list_node);
 288                 } else
 289                         evt = NULL;
 290                 spin_unlock_irqrestore(&rc->uwbd.event_list_lock, flags);
 291
 292                 if (evt) {
 293                         uwbd_event_handle(evt);
 294                         kfree(evt);
 295                 }
 296
 297                 uwb_beca_purge(rc);     /* Purge devices that left */
 298         }
 299         return 0;
 300 }
 301
 302
 303 /** Start the UWB daemon */
 304 void uwbd_start(struct uwb_rc *rc)
 305 {
 306         rc->uwbd.task = kthread_run(uwbd, rc, "uwbd");
 307         if (rc->uwbd.task == NULL)
 308                 printk(KERN_ERR "UWB: Cannot start management daemon; "
 309                        "UWB won't work\n");
 310         else
 311                 rc->uwbd.pid = rc->uwbd.task->pid;
 312 }
 313
 314 /* Stop the UWB daemon and free any unprocessed events */
 315 void uwbd_stop(struct uwb_rc *rc)
 316 {
 317         kthread_stop(rc->uwbd.task);
 318         uwbd_flush(rc);
 319 }
 320
 321 /*
 322  * Queue an event for the management daemon
 323  *
 324  * When some lower layer receives an event, it uses this function to
 325  * push it forward to the UWB daemon.
 326  *
 327  * Once you pass the event, you don't own it any more, but the daemon
 328  * does. It will uwb_event_free() it when done, so make sure you
 329  * uwb_event_alloc()ed it or bad things will happen.
 330  *
 331  * If the daemon is not running, we just free the event.
 332  */
 333 void uwbd_event_queue(struct uwb_event *evt)
 334 {
 335         struct uwb_rc *rc = evt->rc;
 336         unsigned long flags;
 337
 338         spin_lock_irqsave(&rc->uwbd.event_list_lock, flags);
 339         if (rc->uwbd.pid != 0) {
 340                 list_add(&evt->list_node, &rc->uwbd.event_list);
 341                 wake_up_all(&rc->uwbd.wq);
 342         } else {
 343                 __uwb_rc_put(evt->rc);
 344                 if (evt->type == UWB_EVT_TYPE_NOTIF)
 345                         kfree(evt->notif.rceb);
 346                 kfree(evt);
 347         }
 348         spin_unlock_irqrestore(&rc->uwbd.event_list_lock, flags);
 349         return;
 350 }
 351
 352 void uwbd_flush(struct uwb_rc *rc)
 353 {
 354         struct uwb_event *evt, *nxt;
 355
 356         spin_lock_irq(&rc->uwbd.event_list_lock);
 357         list_for_each_entry_safe(evt, nxt, &rc->uwbd.event_list, list_node) {
 358                 if (evt->rc == rc) {
 359                         __uwb_rc_put(rc);
 360                         list_del(&evt->list_node);
 361                         if (evt->type == UWB_EVT_TYPE_NOTIF)
 362                                 kfree(evt->notif.rceb);
 363                         kfree(evt);
 364                 }
 365         }
 366         spin_unlock_irq(&rc->uwbd.event_list_lock);
 367 }