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