Root/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 */
88typedef 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 */
96struct 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 */
102static 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
139struct 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. */
146static 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
154static 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 */
178static
179int 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);
203out:
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
211static 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
229static 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 */
267static 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 */
304void 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 */
315void 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 */
333void 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
352void 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}
368

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