Root/drivers/uwb/radio.c

1/*
2 * UWB radio (channel) management.
3 *
4 * Copyright (C) 2008 Cambridge Silicon Radio Ltd.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License version
8 * 2 as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
17 */
18#include <linux/kernel.h>
19#include <linux/uwb.h>
20#include <linux/export.h>
21
22#include "uwb-internal.h"
23
24
25static int uwb_radio_select_channel(struct uwb_rc *rc)
26{
27    /*
28     * Default to channel 9 (BG1, TFC1) unless the user has
29     * selected a specific channel or there are no active PALs.
30     */
31    if (rc->active_pals == 0)
32        return -1;
33    if (rc->beaconing_forced)
34        return rc->beaconing_forced;
35    return 9;
36}
37
38
39/*
40 * Notify all active PALs that the channel has changed.
41 */
42static void uwb_radio_channel_changed(struct uwb_rc *rc, int channel)
43{
44    struct uwb_pal *pal;
45
46    list_for_each_entry(pal, &rc->pals, node) {
47        if (pal->channel && channel != pal->channel) {
48            pal->channel = channel;
49            if (pal->channel_changed)
50                pal->channel_changed(pal, pal->channel);
51        }
52    }
53}
54
55/*
56 * Change to a new channel and notify any active PALs of the new
57 * channel.
58 *
59 * When stopping the radio, PALs need to be notified first so they can
60 * terminate any active reservations.
61 */
62static int uwb_radio_change_channel(struct uwb_rc *rc, int channel)
63{
64    int ret = 0;
65
66    if (channel == -1)
67        uwb_radio_channel_changed(rc, channel);
68
69    if (channel != rc->beaconing) {
70        if (rc->beaconing != -1 && channel != -1) {
71            /*
72             * FIXME: should signal the channel change
73             * with a Channel Change IE.
74             */
75            ret = uwb_radio_change_channel(rc, -1);
76            if (ret < 0)
77                return ret;
78        }
79        ret = uwb_rc_beacon(rc, channel, 0);
80    }
81
82    if (channel != -1)
83        uwb_radio_channel_changed(rc, rc->beaconing);
84
85    return ret;
86}
87
88/**
89 * uwb_radio_start - request that the radio be started
90 * @pal: the PAL making the request.
91 *
92 * If the radio is not already active, aa suitable channel is selected
93 * and beacons are started.
94 */
95int uwb_radio_start(struct uwb_pal *pal)
96{
97    struct uwb_rc *rc = pal->rc;
98    int ret = 0;
99
100    mutex_lock(&rc->uwb_dev.mutex);
101
102    if (!pal->channel) {
103        pal->channel = -1;
104        rc->active_pals++;
105        ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
106    }
107
108    mutex_unlock(&rc->uwb_dev.mutex);
109    return ret;
110}
111EXPORT_SYMBOL_GPL(uwb_radio_start);
112
113/**
114 * uwb_radio_stop - request tha the radio be stopped.
115 * @pal: the PAL making the request.
116 *
117 * Stops the radio if no other PAL is making use of it.
118 */
119void uwb_radio_stop(struct uwb_pal *pal)
120{
121    struct uwb_rc *rc = pal->rc;
122
123    mutex_lock(&rc->uwb_dev.mutex);
124
125    if (pal->channel) {
126        rc->active_pals--;
127        uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
128        pal->channel = 0;
129    }
130
131    mutex_unlock(&rc->uwb_dev.mutex);
132}
133EXPORT_SYMBOL_GPL(uwb_radio_stop);
134
135/*
136 * uwb_radio_force_channel - force a specific channel to be used
137 * @rc: the radio controller.
138 * @channel: the channel to use; -1 to force the radio to stop; 0 to
139 * use the default channel selection algorithm.
140 */
141int uwb_radio_force_channel(struct uwb_rc *rc, int channel)
142{
143    int ret = 0;
144
145    mutex_lock(&rc->uwb_dev.mutex);
146
147    rc->beaconing_forced = channel;
148    ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
149
150    mutex_unlock(&rc->uwb_dev.mutex);
151    return ret;
152}
153
154/*
155 * uwb_radio_setup - setup the radio manager
156 * @rc: the radio controller.
157 *
158 * The radio controller is reset to ensure it's in a known state
159 * before it's used.
160 */
161int uwb_radio_setup(struct uwb_rc *rc)
162{
163    return uwb_rc_reset(rc);
164}
165
166/*
167 * uwb_radio_reset_state - reset any radio manager state
168 * @rc: the radio controller.
169 *
170 * All internal radio manager state is reset to values corresponding
171 * to a reset radio controller.
172 */
173void uwb_radio_reset_state(struct uwb_rc *rc)
174{
175    struct uwb_pal *pal;
176
177    mutex_lock(&rc->uwb_dev.mutex);
178
179    list_for_each_entry(pal, &rc->pals, node) {
180        if (pal->channel) {
181            pal->channel = -1;
182            if (pal->channel_changed)
183                pal->channel_changed(pal, -1);
184        }
185    }
186
187    rc->beaconing = -1;
188    rc->scanning = -1;
189
190    mutex_unlock(&rc->uwb_dev.mutex);
191}
192
193/*
194 * uwb_radio_shutdown - shutdown the radio manager
195 * @rc: the radio controller.
196 *
197 * The radio controller is reset.
198 */
199void uwb_radio_shutdown(struct uwb_rc *rc)
200{
201    uwb_radio_reset_state(rc);
202    uwb_rc_reset(rc);
203}
204

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