release/src-rt-6.x.4708/linux/linux-2.6.36/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
  21 #include "uwb-internal.h"
  22
  23
  24 static 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  */
  41 static 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  */
  61 static 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                         ret = uwb_radio_change_channel(rc, -1);
  71                         if (ret < 0)
  72                                 return ret;
  73                 }
  74                 ret = uwb_rc_beacon(rc, channel, 0);
  75         }
  76
  77         if (channel != -1)
  78                 uwb_radio_channel_changed(rc, rc->beaconing);
  79
  80         return ret;
  81 }
  82
  83 /**
  84  * uwb_radio_start - request that the radio be started
  85  * @pal: the PAL making the request.
  86  *
  87  * If the radio is not already active, aa suitable channel is selected
  88  * and beacons are started.
  89  */
  90 int uwb_radio_start(struct uwb_pal *pal)
  91 {
  92         struct uwb_rc *rc = pal->rc;
  93         int ret = 0;
  94
  95         mutex_lock(&rc->uwb_dev.mutex);
  96
  97         if (!pal->channel) {
  98                 pal->channel = -1;
  99                 rc->active_pals++;
 100                 ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
 101         }
 102
 103         mutex_unlock(&rc->uwb_dev.mutex);
 104         return ret;
 105 }
 106 EXPORT_SYMBOL_GPL(uwb_radio_start);
 107
 108 /**
 109  * uwb_radio_stop - request tha the radio be stopped.
 110  * @pal: the PAL making the request.
 111  *
 112  * Stops the radio if no other PAL is making use of it.
 113  */
 114 void uwb_radio_stop(struct uwb_pal *pal)
 115 {
 116         struct uwb_rc *rc = pal->rc;
 117
 118         mutex_lock(&rc->uwb_dev.mutex);
 119
 120         if (pal->channel) {
 121                 rc->active_pals--;
 122                 uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
 123                 pal->channel = 0;
 124         }
 125
 126         mutex_unlock(&rc->uwb_dev.mutex);
 127 }
 128 EXPORT_SYMBOL_GPL(uwb_radio_stop);
 129
 130 /*
 131  * uwb_radio_force_channel - force a specific channel to be used
 132  * @rc: the radio controller.
 133  * @channel: the channel to use; -1 to force the radio to stop; 0 to
 134  *   use the default channel selection algorithm.
 135  */
 136 int uwb_radio_force_channel(struct uwb_rc *rc, int channel)
 137 {
 138         int ret = 0;
 139
 140         mutex_lock(&rc->uwb_dev.mutex);
 141
 142         rc->beaconing_forced = channel;
 143         ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
 144
 145         mutex_unlock(&rc->uwb_dev.mutex);
 146         return ret;
 147 }
 148
 149 /*
 150  * uwb_radio_setup - setup the radio manager
 151  * @rc: the radio controller.
 152  *
 153  * The radio controller is reset to ensure it's in a known state
 154  * before it's used.
 155  */
 156 int uwb_radio_setup(struct uwb_rc *rc)
 157 {
 158         return uwb_rc_reset(rc);
 159 }
 160
 161 /*
 162  * uwb_radio_reset_state - reset any radio manager state
 163  * @rc: the radio controller.
 164  *
 165  * All internal radio manager state is reset to values corresponding
 166  * to a reset radio controller.
 167  */
 168 void uwb_radio_reset_state(struct uwb_rc *rc)
 169 {
 170         struct uwb_pal *pal;
 171
 172         mutex_lock(&rc->uwb_dev.mutex);
 173
 174         list_for_each_entry(pal, &rc->pals, node) {
 175                 if (pal->channel) {
 176                         pal->channel = -1;
 177                         if (pal->channel_changed)
 178                                 pal->channel_changed(pal, -1);
 179                 }
 180         }
 181
 182         rc->beaconing = -1;
 183         rc->scanning = -1;
 184
 185         mutex_unlock(&rc->uwb_dev.mutex);
 186 }
 187
 188 /*
 189  * uwb_radio_shutdown - shutdown the radio manager
 190  * @rc: the radio controller.
 191  *
 192  * The radio controller is reset.
 193  */
 194 void uwb_radio_shutdown(struct uwb_rc *rc)
 195 {
 196         uwb_radio_reset_state(rc);
 197         uwb_rc_reset(rc);
 198 }