uwb: add the UWB stack (core files)

UWB device and radio controller device and event management.

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

1 files changed, 427 insertions, 0 deletions

diff --git a/drivers/uwb/uwbd.c b/drivers/uwb/uwbd.c
new file mode 100644
index 0000000..b3673d6
--- /dev/null
+++ b/drivers/uwb/uwbd.c
@@ -0,0 +1,427 @@
+/*
+ * Ultra Wide Band
+ * Neighborhood Management Daemon
+ *
+ * Copyright (C) 2005-2006 Intel Corporation
+ * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ *
+ * This daemon takes care of maintaing information that describes the
+ * UWB neighborhood that the radios in this machine can see. It also
+ * keeps a tab of which devices are visible, makes sure each HC sits
+ * on a different channel to avoid interfering, etc.
+ *
+ * Different drivers (radio controller, device, any API in general)
+ * communicate with this daemon through an event queue. Daemon wakes
+ * up, takes a list of events and handles them one by one; handling
+ * function is extracted from a table based on the event's type and
+ * subtype. Events are freed only if the handling function says so.
+ *
+ *   . Lock protecting the event list has to be an spinlock and locked
+ *     with IRQSAVE because it might be called from an interrupt
+ *     context (ie: when events arrive and the notification drops
+ *     down from the ISR).
+ *
+ *   . UWB radio controller drivers queue events to the daemon using
+ *     uwbd_event_queue(). They just get the event, chew it to make it
+ *     look like UWBD likes it and pass it in a buffer allocated with
+ *     uwb_event_alloc().
+ *
+ * EVENTS
+ *
+ * Events have a type, a subtype, a lenght, some other stuff and the
+ * data blob, which depends on the event. The header is 'struct
+ * uwb_event'; for payloads, see 'struct uwbd_evt_*'.
+ *
+ * EVENT HANDLER TABLES
+ *
+ * To find a handling function for an event, the type is used to index
+ * a subtype-table in the type-table. The subtype-table is indexed
+ * with the subtype to get the function that handles the event. Start
+ * with the main type-table 'uwbd_evt_type_handler'.
+ *
+ * DEVICES
+ *
+ * Devices are created when a bunch of beacons have been received and
+ * it is stablished that the device has stable radio presence. CREATED
+ * only, not configured. Devices are ONLY configured when an
+ * Application-Specific IE Probe is receieved, in which the device
+ * declares which Protocol ID it groks. Then the device is CONFIGURED
+ * (and the driver->probe() stuff of the device model is invoked).
+ *
+ * Devices are considered disconnected when a certain number of
+ * beacons are not received in an amount of time.
+ *
+ * Handler functions are called normally uwbd_evt_handle_*().
+ */
+
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/freezer.h>
+#include "uwb-internal.h"
+
+#define D_LOCAL 1
+#include <linux/uwb/debug.h>
+
+
+/**
+ * UWBD Event handler function signature
+ *
+ * Return !0 if the event needs not to be freed (ie the handler
+ * takes/took care of it). 0 means the daemon code will free the
+ * event.
+ *
+ * @evt->rc is already referenced and guaranteed to exist. See
+ * uwb_evt_handle().
+ */
+typedef int (*uwbd_evt_handler_f)(struct uwb_event *);
+
+/**
+ * Properties of a UWBD event
+ *
+ * @handler:    the function that will handle this event
+ * @name:       text name of event
+ */
+struct uwbd_event {
+	uwbd_evt_handler_f handler;
+	const char *name;
+};
+
+/** Table of handlers for and properties of the UWBD Radio Control Events */
+static
+struct uwbd_event uwbd_events[] = {
+	[UWB_RC_EVT_BEACON] = {
+		.handler = uwbd_evt_handle_rc_beacon,
+		.name = "BEACON_RECEIVED"
+	},
+	[UWB_RC_EVT_BEACON_SIZE] = {
+		.handler = uwbd_evt_handle_rc_beacon_size,
+		.name = "BEACON_SIZE_CHANGE"
+	},
+	[UWB_RC_EVT_BPOIE_CHANGE] = {
+		.handler = uwbd_evt_handle_rc_bpoie_change,
+		.name = "BPOIE_CHANGE"
+	},
+	[UWB_RC_EVT_BP_SLOT_CHANGE] = {
+		.handler = uwbd_evt_handle_rc_bp_slot_change,
+		.name = "BP_SLOT_CHANGE"
+	},
+	[UWB_RC_EVT_DRP_AVAIL] = {
+		.handler = uwbd_evt_handle_rc_drp_avail,
+		.name = "DRP_AVAILABILITY_CHANGE"
+	},
+	[UWB_RC_EVT_DRP] = {
+		.handler = uwbd_evt_handle_rc_drp,
+		.name = "DRP"
+	},
+	[UWB_RC_EVT_DEV_ADDR_CONFLICT] = {
+		.handler = uwbd_evt_handle_rc_dev_addr_conflict,
+		.name = "DEV_ADDR_CONFLICT",
+	},
+};
+
+
+
+struct uwbd_evt_type_handler {
+	const char *name;
+	struct uwbd_event *uwbd_events;
+	size_t size;
+};
+
+#define UWBD_EVT_TYPE_HANDLER(n,a) {		\
+	.name = (n),				\
+	.uwbd_events = (a),			\
+	.size = sizeof(a)/sizeof((a)[0])	\
+}
+
+
+/** Table of handlers for each UWBD Event type. */
+static
+struct uwbd_evt_type_handler uwbd_evt_type_handlers[] = {
+	[UWB_RC_CET_GENERAL] = UWBD_EVT_TYPE_HANDLER("RC", uwbd_events)
+};
+
+static const
+size_t uwbd_evt_type_handlers_len =
+	sizeof(uwbd_evt_type_handlers) / sizeof(uwbd_evt_type_handlers[0]);
+
+static const struct uwbd_event uwbd_message_handlers[] = {
+	[UWB_EVT_MSG_RESET] = {
+		.handler = uwbd_msg_handle_reset,
+		.name = "reset",
+	},
+};
+
+static DEFINE_MUTEX(uwbd_event_mutex);
+
+/**
+ * Handle an URC event passed to the UWB Daemon
+ *
+ * @evt: the event to handle
+ * @returns: 0 if the event can be kfreed, !0 on the contrary
+ *           (somebody else took ownership) [coincidentally, returning
+ *           a <0 errno code will free it :)].
+ *
+ * Looks up the two indirection tables (one for the type, one for the
+ * subtype) to decide which function handles it and then calls the
+ * handler.
+ *
+ * The event structure passed to the event handler has the radio
+ * controller in @evt->rc referenced. The reference will be dropped
+ * once the handler returns, so if it needs it for longer (async),
+ * it'll need to take another one.
+ */
+static
+int uwbd_event_handle_urc(struct uwb_event *evt)
+{
+	int result;
+	struct uwbd_evt_type_handler *type_table;
+	uwbd_evt_handler_f handler;
+	u8 type, context;
+	u16 event;
+
+	type = evt->notif.rceb->bEventType;
+	event = le16_to_cpu(evt->notif.rceb->wEvent);
+	context = evt->notif.rceb->bEventContext;
+
+	if (type > uwbd_evt_type_handlers_len) {
+		if (printk_ratelimit())
+			printk(KERN_ERR "UWBD: event type %u: unknown "
+			       "(too high)\n", type);
+		return -EINVAL;
+	}
+	type_table = &uwbd_evt_type_handlers[type];
+	if (type_table->uwbd_events == NULL) {
+		if (printk_ratelimit())
+			printk(KERN_ERR "UWBD: event type %u: unknown\n", type);
+		return -EINVAL;
+	}
+	if (event > type_table->size) {
+		if (printk_ratelimit())
+			printk(KERN_ERR "UWBD: event %s[%u]: "
+			       "unknown (too high)\n", type_table->name, event);
+		return -EINVAL;
+	}
+	handler = type_table->uwbd_events[event].handler;
+	if (handler == NULL) {
+		if (printk_ratelimit())
+			printk(KERN_ERR "UWBD: event %s[%u]: unknown\n",
+			       type_table->name, event);
+		return -EINVAL;
+	}
+	d_printf(3, NULL, "processing 0x%02x/%04x/%02x, %zu bytes\n",
+		 type, event, context, evt->notif.size);
+	result = (*handler)(evt);
+	if (result < 0) {
+		if (printk_ratelimit())
+			printk(KERN_ERR "UWBD: event 0x%02x/%04x/%02x, "
+			       "table %s[%u]: handling failed: %d\n",
+			       type, event, context, type_table->name,
+			       event, result);
+	}
+	return result;
+}
+
+static void uwbd_event_handle_message(struct uwb_event *evt)
+{
+	struct uwb_rc *rc;
+	int result;
+
+	rc = evt->rc;
+
+	if (evt->message < 0 || evt->message >= ARRAY_SIZE(uwbd_message_handlers)) {
+		dev_err(&rc->uwb_dev.dev, "UWBD: invalid message type %d\n", evt->message);
+		return;
+	}
+
+	/* If this is a reset event we need to drop the
+	 * uwbd_event_mutex or it deadlocks when the reset handler
+	 * attempts to flush the uwbd events. */
+	if (evt->message == UWB_EVT_MSG_RESET)
+		mutex_unlock(&uwbd_event_mutex);
+
+	result = uwbd_message_handlers[evt->message].handler(evt);
+	if (result < 0)
+		dev_err(&rc->uwb_dev.dev, "UWBD: '%s' message failed: %d\n",
+			uwbd_message_handlers[evt->message].name, result);
+
+	if (evt->message == UWB_EVT_MSG_RESET)
+		mutex_lock(&uwbd_event_mutex);
+}
+
+static void uwbd_event_handle(struct uwb_event *evt)
+{
+	struct uwb_rc *rc;
+	int should_keep;
+
+	rc = evt->rc;
+
+	if (rc->ready) {
+		switch (evt->type) {
+		case UWB_EVT_TYPE_NOTIF:
+			should_keep = uwbd_event_handle_urc(evt);
+			if (should_keep <= 0)
+				kfree(evt->notif.rceb);
+			break;
+		case UWB_EVT_TYPE_MSG:
+			uwbd_event_handle_message(evt);
+			break;
+		default:
+			dev_err(&rc->uwb_dev.dev, "UWBD: invalid event type %d\n", evt->type);
+			break;
+		}
+	}
+
+	__uwb_rc_put(rc);	/* for the __uwb_rc_get() in uwb_rc_notif_cb() */
+}
+/* The UWB Daemon */
+
+
+/** Daemon's PID: used to decide if we can queue or not */
+static int uwbd_pid;
+/** Daemon's task struct for managing the kthread */
+static struct task_struct *uwbd_task;
+/** Daemon's waitqueue for waiting for new events */
+static DECLARE_WAIT_QUEUE_HEAD(uwbd_wq);
+/** Daemon's list of events; we queue/dequeue here */
+static struct list_head uwbd_event_list = LIST_HEAD_INIT(uwbd_event_list);
+/** Daemon's list lock to protect concurent access */
+static DEFINE_SPINLOCK(uwbd_event_list_lock);
+
+
+/**
+ * UWB Daemon
+ *
+ * Listens to all UWB notifications and takes care to track the state
+ * of the UWB neighboorhood for the kernel. When we do a run, we
+ * spinlock, move the list to a private copy and release the
+ * lock. Hold it as little as possible. Not a conflict: it is
+ * guaranteed we own the events in the private list.
+ *
+ * FIXME: should change so we don't have a 1HZ timer all the time, but
+ *        only if there are devices.
+ */
+static int uwbd(void *unused)
+{
+	unsigned long flags;
+	struct list_head list = LIST_HEAD_INIT(list);
+	struct uwb_event *evt, *nxt;
+	int should_stop = 0;
+	while (1) {
+		wait_event_interruptible_timeout(
+			uwbd_wq,
+			!list_empty(&uwbd_event_list)
+			  || (should_stop = kthread_should_stop()),
+			HZ);
+		if (should_stop)
+			break;
+		try_to_freeze();
+
+		mutex_lock(&uwbd_event_mutex);
+		spin_lock_irqsave(&uwbd_event_list_lock, flags);
+		list_splice_init(&uwbd_event_list, &list);
+		spin_unlock_irqrestore(&uwbd_event_list_lock, flags);
+		list_for_each_entry_safe(evt, nxt, &list, list_node) {
+			list_del(&evt->list_node);
+			uwbd_event_handle(evt);
+			kfree(evt);
+		}
+		mutex_unlock(&uwbd_event_mutex);
+
+		uwb_beca_purge();	/* Purge devices that left */
+	}
+	return 0;
+}
+
+
+/** Start the UWB daemon */
+void uwbd_start(void)
+{
+	uwbd_task = kthread_run(uwbd, NULL, "uwbd");
+	if (uwbd_task == NULL)
+		printk(KERN_ERR "UWB: Cannot start management daemon; "
+		       "UWB won't work\n");
+	else
+		uwbd_pid = uwbd_task->pid;
+}
+
+/* Stop the UWB daemon and free any unprocessed events */
+void uwbd_stop(void)
+{
+	unsigned long flags;
+	struct uwb_event *evt, *nxt;
+	kthread_stop(uwbd_task);
+	spin_lock_irqsave(&uwbd_event_list_lock, flags);
+	uwbd_pid = 0;
+	list_for_each_entry_safe(evt, nxt, &uwbd_event_list, list_node) {
+		if (evt->type == UWB_EVT_TYPE_NOTIF)
+			kfree(evt->notif.rceb);
+		kfree(evt);
+	}
+	spin_unlock_irqrestore(&uwbd_event_list_lock, flags);
+	uwb_beca_release();
+}
+
+/*
+ * Queue an event for the management daemon
+ *
+ * When some lower layer receives an event, it uses this function to
+ * push it forward to the UWB daemon.
+ *
+ * Once you pass the event, you don't own it any more, but the daemon
+ * does. It will uwb_event_free() it when done, so make sure you
+ * uwb_event_alloc()ed it or bad things will happen.
+ *
+ * If the daemon is not running, we just free the event.
+ */
+void uwbd_event_queue(struct uwb_event *evt)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&uwbd_event_list_lock, flags);
+	if (uwbd_pid != 0) {
+		list_add(&evt->list_node, &uwbd_event_list);
+		wake_up_all(&uwbd_wq);
+	} else {
+		__uwb_rc_put(evt->rc);
+		if (evt->type == UWB_EVT_TYPE_NOTIF)
+			kfree(evt->notif.rceb);
+		kfree(evt);
+	}
+	spin_unlock_irqrestore(&uwbd_event_list_lock, flags);
+	return;
+}
+
+void uwbd_flush(struct uwb_rc *rc)
+{
+	struct uwb_event *evt, *nxt;
+
+	mutex_lock(&uwbd_event_mutex);
+
+	spin_lock_irq(&uwbd_event_list_lock);
+	list_for_each_entry_safe(evt, nxt, &uwbd_event_list, list_node) {
+		if (evt->rc == rc) {
+			__uwb_rc_put(rc);
+			list_del(&evt->list_node);
+			if (evt->type == UWB_EVT_TYPE_NOTIF)
+				kfree(evt->notif.rceb);
+			kfree(evt);
+		}
+	}
+	spin_unlock_irq(&uwbd_event_list_lock);
+
+	mutex_unlock(&uwbd_event_mutex);
+}