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         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  */
  99 int 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 }
 115 EXPORT_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  */
 123 void 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 }
 137 EXPORT_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  */
 145 int 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  */
 165 int 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  */
 177 void 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  */
 203 void uwb_radio_shutdown(struct uwb_rc *rc)
 204 {
 205         uwb_radio_reset_state(rc);
 206         uwb_rc_reset(rc);
 207 }