uwb: add basic radio manager

The UWB radio manager coordinates the use of the radio between the
PALs that may be using it.  PALs request use of the radio with
uwb_radio_start() and the radio manager will start beaconing if its
not already doing so.  When the last PAL has called uwb_radio_stop()
beaconing will be stopped.

In the future, the radio manager will have a more sophisticated channel
selection algorithm, probably following the Channel Selection Policy
from the WiMedia Alliance when it is finalized.  For now, channel 9
(BG1, TFC1) is selected.

The user may override the channel selected by the radio manager and may
force the radio to stop beaconing.

The WUSB Host Controller PAL makes use of this and there are two new
debug PAL commands that can be used for testing.

Signed-off-by: David Vrabel <david.vrabel@csr.com>

1 files changed, 202 insertions, 0 deletions

diff --git a/drivers/uwb/radio.c b/drivers/uwb/radio.c
new file mode 100644
index 0000000..f0d5549
--- /dev/null
+++ b/drivers/uwb/radio.c
@@ -0,0 +1,202 @@
+/*
+ * UWB radio (channel) management.
+ *
+ * Copyright (C) 2008 Cambridge Silicon Radio Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/kernel.h>
+#include <linux/uwb.h>
+
+#include "uwb-internal.h"
+
+
+static int uwb_radio_select_channel(struct uwb_rc *rc)
+{
+	/*
+	 * Default to channel 9 (BG1, TFC1) unless the user has
+	 * selected a specific channel or there are no active PALs.
+	 */
+	if (rc->active_pals == 0)
+		return -1;
+	if (rc->beaconing_forced)
+		return rc->beaconing_forced;
+	return 9;
+}
+
+
+/*
+ * Notify all active PALs that the channel has changed.
+ */
+static void uwb_radio_channel_changed(struct uwb_rc *rc, int channel)
+{
+	struct uwb_pal *pal;
+
+	list_for_each_entry(pal, &rc->pals, node) {
+		if (pal->channel && channel != pal->channel) {
+			pal->channel = channel;
+			if (pal->channel_changed)
+				pal->channel_changed(pal, pal->channel);
+		}
+	}
+}
+
+/*
+ * Change to a new channel and notify any active PALs of the new
+ * channel.
+ *
+ * When stopping the radio, PALs need to be notified first so they can
+ * terminate any active reservations.
+ */
+static int uwb_radio_change_channel(struct uwb_rc *rc, int channel)
+{
+	int ret = 0;
+
+	if (channel == -1)
+		uwb_radio_channel_changed(rc, channel);
+
+	if (channel != rc->beaconing) {
+		if (rc->beaconing != -1 && channel != -1) {
+			/*
+			 * FIXME: should signal the channel change
+			 * with a Channel Change IE.
+			 */
+			ret = uwb_radio_change_channel(rc, -1);
+			if (ret < 0)
+				return ret;
+		}
+		ret = uwb_rc_beacon(rc, channel, 0);
+	}
+
+	if (channel != -1)
+		uwb_radio_channel_changed(rc, rc->beaconing);
+
+	return ret;
+}
+
+/**
+ * uwb_radio_start - request that the radio be started
+ * @pal: the PAL making the request.
+ *
+ * If the radio is not already active, aa suitable channel is selected
+ * and beacons are started.
+ */
+int uwb_radio_start(struct uwb_pal *pal)
+{
+	struct uwb_rc *rc = pal->rc;
+	int ret = 0;
+
+	mutex_lock(&rc->uwb_dev.mutex);
+
+	if (!pal->channel) {
+		pal->channel = -1;
+		rc->active_pals++;
+		ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
+	}
+
+	mutex_unlock(&rc->uwb_dev.mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(uwb_radio_start);
+
+/**
+ * uwb_radio_stop - request tha the radio be stopped.
+ * @pal: the PAL making the request.
+ *
+ * Stops the radio if no other PAL is making use of it.
+ */
+void uwb_radio_stop(struct uwb_pal *pal)
+{
+	struct uwb_rc *rc = pal->rc;
+
+	mutex_lock(&rc->uwb_dev.mutex);
+
+	if (pal->channel) {
+		rc->active_pals--;
+		uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
+		pal->channel = 0;
+	}
+
+	mutex_unlock(&rc->uwb_dev.mutex);
+}
+EXPORT_SYMBOL_GPL(uwb_radio_stop);
+
+/*
+ * uwb_radio_force_channel - force a specific channel to be used
+ * @rc: the radio controller.
+ * @channel: the channel to use; -1 to force the radio to stop; 0 to
+ *   use the default channel selection algorithm.
+ */
+int uwb_radio_force_channel(struct uwb_rc *rc, int channel)
+{
+	int ret = 0;
+
+	mutex_lock(&rc->uwb_dev.mutex);
+
+	rc->beaconing_forced = channel;
+	ret = uwb_radio_change_channel(rc, uwb_radio_select_channel(rc));
+
+	mutex_unlock(&rc->uwb_dev.mutex);
+	return ret;
+}
+
+/*
+ * uwb_radio_setup - setup the radio manager
+ * @rc: the radio controller.
+ *
+ * The radio controller is reset to ensure it's in a known state
+ * before it's used.
+ */
+int uwb_radio_setup(struct uwb_rc *rc)
+{
+	return uwb_rc_reset(rc);
+}
+
+/*
+ * uwb_radio_reset_state - reset any radio manager state
+ * @rc: the radio controller.
+ *
+ * All internal radio manager state is reset to values corresponding
+ * to a reset radio controller.
+ */
+void uwb_radio_reset_state(struct uwb_rc *rc)
+{
+	struct uwb_pal *pal;
+
+	mutex_lock(&rc->uwb_dev.mutex);
+
+	list_for_each_entry(pal, &rc->pals, node) {
+		if (pal->channel) {
+			pal->channel = -1;
+			if (pal->channel_changed)
+				pal->channel_changed(pal, -1);
+		}
+	}
+
+	rc->beaconing = -1;
+	rc->scanning = -1;
+
+	mutex_unlock(&rc->uwb_dev.mutex);
+}
+
+/*
+ * uwb_radio_shutdown - shutdown the radio manager
+ * @rc: the radio controller.
+ *
+ * The radio controller is reset.
+ */
+void uwb_radio_shutdown(struct uwb_rc *rc)
+{
+	uwb_radio_reset_state(rc);
+	uwb_rc_reset(rc);
+}