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}