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
 21#include "uwb-internal.h"
 22
 23
 24static int uwb_radio_select_channel(struct uwb_rc *rc)
 25{
 26	/*
 27	 * Default to channel 9 (BG1, TFC1) unless the user has
 28	 * selected a specific channel or there are no active PALs.
 29	 */
 30	if (rc->active_pals == 0)
 31		return -1;
 32	if (rc->beaconing_forced)
 33		return rc->beaconing_forced;
 34	return 9;
 35}
 36
 37
 38/*
 39 * Notify all active PALs that the channel has changed.
 40 */
 41static void uwb_radio_channel_changed(struct uwb_rc *rc, int channel)
 42{
 43	struct uwb_pal *pal;
 44
 45	list_for_each_entry(pal, &rc->pals, node) {
 46		if (pal->channel && channel != pal->channel) {
 47			pal->channel = channel;
 48			if (pal->channel_changed)
 49				pal->channel_changed(pal, pal->channel);
 50		}
 51	}
 52}
 53
 54/*
 55 * Change to a new channel and notify any active PALs of the new
 56 * channel.
 57 *
 58 * When stopping the radio, PALs need to be notified first so they can
 59 * terminate any active reservations.
 60 */
 61static int uwb_radio_change_channel(struct uwb_rc *rc, int channel)
 62{
 63	int ret = 0;
 64
 65	if (channel == -1)
 66		uwb_radio_channel_changed(rc, channel);
 67
 68	if (channel != rc->beaconing) {
 69		if (rc->beaconing != -1 && channel != -1) {
 70			/*
 71			 * FIXME: should signal the channel change
 72			 * with a Channel Change IE.
 73			 */
 74			ret = uwb_radio_change_channel(rc, -1);
 75			if (ret < 0)
 76				return ret;
 77		}
 78		ret = uwb_rc_beacon(rc, channel, 0);
 79	}
 80
 81	if (channel != -1)
 82		uwb_radio_channel_changed(rc, rc->beaconing);
 83
 84	return ret;
 85}
 86
 87/**
 88 * uwb_radio_start - request that the radio be started
 89 * @pal: the PAL making the request.
 90 *
 91 * If the radio is not already active, aa suitable channel is selected
 92 * and beacons are started.
 93 */
 94int uwb_radio_start(struct uwb_pal *pal)
 95{
 96	struct uwb_rc *rc = pal->rc;
 97	int ret = 0;
 98
 99	mutex_lock(&rc->uwb_dev.mutex);
100
101	if (!pal->channel) {
102		pal->channel = -1;
103		rc->active_pals++;
104		ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
105	}
106
107	mutex_unlock(&rc->uwb_dev.mutex);
108	return ret;
109}
110EXPORT_SYMBOL_GPL(uwb_radio_start);
111
112/**
113 * uwb_radio_stop - request tha the radio be stopped.
114 * @pal: the PAL making the request.
115 *
116 * Stops the radio if no other PAL is making use of it.
117 */
118void uwb_radio_stop(struct uwb_pal *pal)
119{
120	struct uwb_rc *rc = pal->rc;
121
122	mutex_lock(&rc->uwb_dev.mutex);
123
124	if (pal->channel) {
125		rc->active_pals--;
126		uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
127		pal->channel = 0;
128	}
129
130	mutex_unlock(&rc->uwb_dev.mutex);
131}
132EXPORT_SYMBOL_GPL(uwb_radio_stop);
133
134/*
135 * uwb_radio_force_channel - force a specific channel to be used
136 * @rc: the radio controller.
137 * @channel: the channel to use; -1 to force the radio to stop; 0 to
138 *   use the default channel selection algorithm.
139 */
140int uwb_radio_force_channel(struct uwb_rc *rc, int channel)
141{
142	int ret = 0;
143
144	mutex_lock(&rc->uwb_dev.mutex);
145
146	rc->beaconing_forced = channel;
147	ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
148
149	mutex_unlock(&rc->uwb_dev.mutex);
150	return ret;
151}
152
153/*
154 * uwb_radio_setup - setup the radio manager
155 * @rc: the radio controller.
156 *
157 * The radio controller is reset to ensure it's in a known state
158 * before it's used.
159 */
160int uwb_radio_setup(struct uwb_rc *rc)
161{
162	return uwb_rc_reset(rc);
163}
164
165/*
166 * uwb_radio_reset_state - reset any radio manager state
167 * @rc: the radio controller.
168 *
169 * All internal radio manager state is reset to values corresponding
170 * to a reset radio controller.
171 */
172void uwb_radio_reset_state(struct uwb_rc *rc)
173{
174	struct uwb_pal *pal;
175
176	mutex_lock(&rc->uwb_dev.mutex);
177
178	list_for_each_entry(pal, &rc->pals, node) {
179		if (pal->channel) {
180			pal->channel = -1;
181			if (pal->channel_changed)
182				pal->channel_changed(pal, -1);
183		}
184	}
185
186	rc->beaconing = -1;
187	rc->scanning = -1;
188
189	mutex_unlock(&rc->uwb_dev.mutex);
190}
191
192/*
193 * uwb_radio_shutdown - shutdown the radio manager
194 * @rc: the radio controller.
195 *
196 * The radio controller is reset.
197 */
198void uwb_radio_shutdown(struct uwb_rc *rc)
199{
200	uwb_radio_reset_state(rc);
201	uwb_rc_reset(rc);
202}