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                         /*
  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  */
  94 int 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 }
 110 EXPORT_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  */
 118 void 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 }
 132 EXPORT_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  */
 140 int 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  */
 160 int 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  */
 172 void 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  */
 198 void uwb_radio_shutdown(struct uwb_rc *rc)
 199 {
 200         uwb_radio_reset_state(rc);
 201         uwb_rc_reset(rc);
 202 }