Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
radio.c
Go to the documentation of this file.
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 
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 }
112 
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 }
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 
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  */
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 {
202  uwb_rc_reset(rc);
203 }