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
  25 static 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  */
  42 static 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  */
  62 static 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  */
  95 int 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 }
 111 EXPORT_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  */
 119 void 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 }
 133 EXPORT_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  */
 141 int 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  */
 161 int 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  */
 173 void 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  */
 199 void uwb_radio_shutdown(struct uwb_rc *rc)
 200 {
 201         uwb_radio_reset_state(rc);
 202         uwb_rc_reset(rc);
 203 }