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	struct device *dev = &rc->uwb_dev.dev;
 66
 67	dev_dbg(dev, "%s: channel = %d, rc->beaconing = %d\n", __func__,
 68		channel, rc->beaconing);
 69
 70	if (channel == -1)
 71		uwb_radio_channel_changed(rc, channel);
 72
 73	if (channel != rc->beaconing) {
 74		if (rc->beaconing != -1 && channel != -1) {
 75			/*
 76			 * FIXME: should signal the channel change
 77			 * with a Channel Change IE.
 78			 */
 79			ret = uwb_radio_change_channel(rc, -1);
 80			if (ret < 0)
 81				return ret;
 82		}
 83		ret = uwb_rc_beacon(rc, channel, 0);
 84	}
 85
 86	if (channel != -1)
 87		uwb_radio_channel_changed(rc, rc->beaconing);
 88
 89	return ret;
 90}
 91
 92/**
 93 * uwb_radio_start - request that the radio be started
 94 * @pal: the PAL making the request.
 95 *
 96 * If the radio is not already active, a suitable channel is selected
 97 * and beacons are started.
 98 */
 99int uwb_radio_start(struct uwb_pal *pal)
100{
101	struct uwb_rc *rc = pal->rc;
102	int ret = 0;
103
104	mutex_lock(&rc->uwb_dev.mutex);
105
106	if (!pal->channel) {
107		pal->channel = -1;
108		rc->active_pals++;
109		ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
110	}
111
112	mutex_unlock(&rc->uwb_dev.mutex);
113	return ret;
114}
115EXPORT_SYMBOL_GPL(uwb_radio_start);
116
117/**
118 * uwb_radio_stop - request that the radio be stopped.
119 * @pal: the PAL making the request.
120 *
121 * Stops the radio if no other PAL is making use of it.
122 */
123void uwb_radio_stop(struct uwb_pal *pal)
124{
125	struct uwb_rc *rc = pal->rc;
126
127	mutex_lock(&rc->uwb_dev.mutex);
128
129	if (pal->channel) {
130		rc->active_pals--;
131		uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
132		pal->channel = 0;
133	}
134
135	mutex_unlock(&rc->uwb_dev.mutex);
136}
137EXPORT_SYMBOL_GPL(uwb_radio_stop);
138
139/*
140 * uwb_radio_force_channel - force a specific channel to be used
141 * @rc: the radio controller.
142 * @channel: the channel to use; -1 to force the radio to stop; 0 to
143 *   use the default channel selection algorithm.
144 */
145int uwb_radio_force_channel(struct uwb_rc *rc, int channel)
146{
147	int ret = 0;
148
149	mutex_lock(&rc->uwb_dev.mutex);
150
151	rc->beaconing_forced = channel;
152	ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
153
154	mutex_unlock(&rc->uwb_dev.mutex);
155	return ret;
156}
157
158/*
159 * uwb_radio_setup - setup the radio manager
160 * @rc: the radio controller.
161 *
162 * The radio controller is reset to ensure it's in a known state
163 * before it's used.
164 */
165int uwb_radio_setup(struct uwb_rc *rc)
166{
167	return uwb_rc_reset(rc);
168}
169
170/*
171 * uwb_radio_reset_state - reset any radio manager state
172 * @rc: the radio controller.
173 *
174 * All internal radio manager state is reset to values corresponding
175 * to a reset radio controller.
176 */
177void uwb_radio_reset_state(struct uwb_rc *rc)
178{
179	struct uwb_pal *pal;
180
181	mutex_lock(&rc->uwb_dev.mutex);
182
183	list_for_each_entry(pal, &rc->pals, node) {
184		if (pal->channel) {
185			pal->channel = -1;
186			if (pal->channel_changed)
187				pal->channel_changed(pal, -1);
188		}
189	}
190
191	rc->beaconing = -1;
192	rc->scanning = -1;
193
194	mutex_unlock(&rc->uwb_dev.mutex);
195}
196
197/*
198 * uwb_radio_shutdown - shutdown the radio manager
199 * @rc: the radio controller.
200 *
201 * The radio controller is reset.
202 */
203void uwb_radio_shutdown(struct uwb_rc *rc)
204{
205	uwb_radio_reset_state(rc);
206	uwb_rc_reset(rc);
207}