- 根目录:
- drivers
- uwb
- neh.c
/*
* WUSB Wire Adapter: Radio Control Interface (WUSB[8])
* Notification and Event Handling
*
* 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.
*
*
* The RC interface of the Host Wire Adapter (USB dongle) or WHCI PCI
* card delivers a stream of notifications and events to the
* notification end event endpoint or area. This code takes care of
* getting a buffer with that data, breaking it up in separate
* notifications and events and then deliver those.
*
* Events are answers to commands and they carry a context ID that
* associates them to the command. Notifications are that,
* notifications, they come out of the blue and have a context ID of
* zero. Think of the context ID kind of like a handler. The
* uwb_rc_neh_* code deals with managing context IDs.
*
* This is why you require a handle to operate on a UWB host. When you
* open a handle a context ID is assigned to you.
*
* So, as it is done is:
*
* 1. Add an event handler [uwb_rc_neh_add()] (assigns a ctx id)
* 2. Issue command [rc->cmd(rc, ...)]
* 3. Arm the timeout timer [uwb_rc_neh_arm()]
* 4, Release the reference to the neh [uwb_rc_neh_put()]
* 5. Wait for the callback
* 6. Command result (RCEB) is passed to the callback
*
* If (2) fails, you should remove the handle [uwb_rc_neh_rm()]
* instead of arming the timer.
*
* Handles are for using in *serialized* code, single thread.
*
* When the notification/event comes, the IRQ handler/endpoint
* callback passes the data read to uwb_rc_neh_grok() which will break
* it up in a discrete series of events, look up who is listening for
* them and execute the pertinent callbacks.
*
* If the reader detects an error while reading the data stream, call
* uwb_rc_neh_error().
*
* CONSTRAINTS/ASSUMPTIONS:
*
* - Most notifications/events are small (less thank .5k), copying
* around is ok.
*
* - Notifications/events are ALWAYS smaller than PAGE_SIZE
*
* - Notifications/events always come in a single piece (ie: a buffer
* will always contain entire notifications/events).
*
* - we cannot know in advance how long each event is (because they
* lack a length field in their header--smart move by the standards
* body, btw). So we need a facility to get the event size given the
* header. This is what the EST code does (notif/Event Size
* Tables), check nest.c--as well, you can associate the size to
* the handle [w/ neh->extra_size()].
*
* - Most notifications/events are fixed size; only a few are variable
* size (NEST takes care of that).
*
* - Listeners of events expect them, so they usually provide a
* buffer, as they know the size. Listeners to notifications don't,
* so we allocate their buffers dynamically.
*/
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/err.h>
#include "uwb-internal.h"
/*
* UWB Radio Controller Notification/Event Handle
*
* Represents an entity waiting for an event coming from the UWB Radio
* Controller with a given context id (context) and type (evt_type and
* evt). On reception of the notification/event, the callback (cb) is
* called with the event.
*
* If the timer expires before the event is received, the callback is
* called with -ETIMEDOUT as the event size.
*/
struct uwb_rc_neh {
struct kref kref;
struct uwb_rc *rc;
u8 evt_type;
__le16 evt;
u8 context;
uwb_rc_cmd_cb_f cb;
void *arg;
struct timer_list timer;
struct list_head list_node;
};
static void uwb_rc_neh_timer(unsigned long arg);
static void uwb_rc_neh_release(struct kref *kref)
{
struct uwb_rc_neh *neh = container_of(kref, struct uwb_rc_neh, kref);
kfree(neh);
}
static void uwb_rc_neh_get(struct uwb_rc_neh *neh)
{
kref_get(&neh->kref);
}
/**
* uwb_rc_neh_put - release reference to a neh
* @neh: the neh
*/
void uwb_rc_neh_put(struct uwb_rc_neh *neh)
{
kref_put(&neh->kref, uwb_rc_neh_release);
}
/**
* Assigns @neh a context id from @rc's pool
*
* @rc: UWB Radio Controller descriptor; @rc->neh_lock taken
* @neh: Notification/Event Handle
* @returns 0 if context id was assigned ok; < 0 errno on error (if
* all the context IDs are taken).
*
* (assumes @wa is locked).
*
* NOTE: WUSB spec reserves context ids 0x00 for notifications and
* 0xff is invalid, so they must not be used. Initialization
* fills up those two in the bitmap so they are not allocated.
*
* We spread the allocation around to reduce the possibility of two
* consecutive opened @neh's getting the same context ID assigned (to
* avoid surprises with late events that timed out long time ago). So
* first we search from where @rc->ctx_roll is, if not found, we
* search from zero.
*/
static
int __uwb_rc_ctx_get(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
int result;
result = find_next_zero_bit(rc->ctx_bm, UWB_RC_CTX_MAX,
rc->ctx_roll++);
if (result < UWB_RC_CTX_MAX)
goto found;
result = find_first_zero_bit(rc->ctx_bm, UWB_RC_CTX_MAX);
if (result < UWB_RC_CTX_MAX)
goto found;
return -ENFILE;
found:
set_bit(result, rc->ctx_bm);
neh->context = result;
return 0;
}
/** Releases @neh's context ID back to @rc (@rc->neh_lock is locked). */
static
void __uwb_rc_ctx_put(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
struct device *dev = &rc->uwb_dev.dev;
if (neh->context == 0)
return;
if (test_bit(neh->context, rc->ctx_bm) == 0) {
dev_err(dev, "context %u not set in bitmap\n",
neh->context);
WARN_ON(1);
}
clear_bit(neh->context, rc->ctx_bm);
neh->context = 0;
}
/**
* uwb_rc_neh_add - add a neh for a radio controller command
* @rc: the radio controller
* @cmd: the radio controller command
* @expected_type: the type of the expected response event
* @expected_event: the expected event ID
* @cb: callback for when the event is received
* @arg: argument for the callback
*
* Creates a neh and adds it to the list of those waiting for an
* event. A context ID will be assigned to the command.
*/
struct uwb_rc_neh *uwb_rc_neh_add(struct uwb_rc *rc, struct uwb_rccb *cmd,
u8 expected_type, u16 expected_event,
uwb_rc_cmd_cb_f cb, void *arg)
{
int result;
unsigned long flags;
struct device *dev = &rc->uwb_dev.dev;
struct uwb_rc_neh *neh;
neh = kzalloc(sizeof(*neh), GFP_KERNEL);
if (neh == NULL) {
result = -ENOMEM;
goto error_kzalloc;
}
kref_init(&neh->kref);
INIT_LIST_HEAD(&neh->list_node);
init_timer(&neh->timer);
neh->timer.function = uwb_rc_neh_timer;
neh->timer.data = (unsigned long)neh;
neh->rc = rc;
neh->evt_type = expected_type;
neh->evt = cpu_to_le16(expected_event);
neh->cb = cb;
neh->arg = arg;
spin_lock_irqsave(&rc->neh_lock, flags);
result = __uwb_rc_ctx_get(rc, neh);
if (result >= 0) {
cmd->bCommandContext = neh->context;
list_add_tail(&neh->list_node, &rc->neh_list);
uwb_rc_neh_get(neh);
}
spin_unlock_irqrestore(&rc->neh_lock, flags);
if (result < 0)
goto error_ctx_get;
return neh;
error_ctx_get:
kfree(neh);
error_kzalloc:
dev_err(dev, "cannot open handle to radio controller: %d\n", result);
return ERR_PTR(result);
}
static void __uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
__uwb_rc_ctx_put(rc, neh);
list_del(&neh->list_node);
}
/**
* uwb_rc_neh_rm - remove a neh.
* @rc: the radio controller
* @neh: the neh to remove
*
* Remove an active neh immediately instead of waiting for the event
* (or a time out).
*/
void uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
unsigned long flags;
spin_lock_irqsave(&rc->neh_lock, flags);
__uwb_rc_neh_rm(rc, neh);
spin_unlock_irqrestore(&rc->neh_lock, flags);
del_timer_sync(&neh->timer);
uwb_rc_neh_put(neh);
}
/**
* uwb_rc_neh_arm - arm an event handler timeout timer
*
* @rc: UWB Radio Controller
* @neh: Notification/event handler for @rc
*
* The timer is only armed if the neh is active.
*/
void uwb_rc_neh_arm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
unsigned long flags;
spin_lock_irqsave(&rc->neh_lock, flags);
if (neh->context)
mod_timer(&neh->timer,
jiffies + msecs_to_jiffies(UWB_RC_CMD_TIMEOUT_MS));
spin_unlock_irqrestore(&rc->neh_lock, flags);
}
static void uwb_rc_neh_cb(struct uwb_rc_neh *neh, struct uwb_rceb *rceb, size_t size)
{
(*neh->cb)(neh->rc, neh->arg, rceb, size);
uwb_rc_neh_put(neh);
}
static bool uwb_rc_neh_match(struct uwb_rc_neh *neh, const struct uwb_rceb *rceb)
{
return neh->evt_type == rceb->bEventType
&& neh->evt == rceb->wEvent
&& neh->context == rceb->bEventContext;
}
/**
* Find the handle waiting for a RC Radio Control Event
*
* @rc: UWB Radio Controller
* @rceb: Pointer to the RCEB buffer
* @event_size: Pointer to the size of the RCEB buffer. Might be
* adjusted to take into account the @neh->extra_size
* settings.
*
* If the listener has no buffer (NULL buffer), one is allocated for
* the right size (the amount of data received). @neh->ptr will point
* to the event payload, which always starts with a 'struct
* uwb_rceb'. kfree() it when done.
*/
static
struct uwb_rc_neh *uwb_rc_neh_lookup(struct uwb_rc *rc,
const struct uwb_rceb *rceb)
{
struct uwb_rc_neh *neh = NULL, *h;
unsigned long flags;
spin_lock_irqsave(&rc->neh_lock, flags);
list_for_each_entry(h, &rc->neh_list, list_node) {
if (uwb_rc_neh_match(h, rceb)) {
neh = h;
break;
}
}
if (neh)
__uwb_rc_neh_rm(rc, neh);
spin_unlock_irqrestore(&rc->neh_lock, flags);
return neh;
}
/*
* Process notifications coming from the radio control interface
*
* @rc: UWB Radio Control Interface descriptor
* @neh: Notification/Event Handler @neh->ptr points to
* @uwb_evt->buffer.
*
* This function is called by the event/notif handling subsystem when
* notifications arrive (hwarc_probe() arms a notification/event handle
* that calls back this function for every received notification; this
* function then will rearm itself).
*
* Notification data buffers are dynamically allocated by the NEH
* handling code in neh.c [uwb_rc_neh_lookup()]. What is actually
* allocated is space to contain the notification data.
*
* Buffers are prefixed with a Radio Control Event Block (RCEB) as
* defined by the WUSB Wired-Adapter Radio Control interface. We
* just use it for the notification code.
*
* On each case statement we just transcode endianess of the different
* fields. We declare a pointer to a RCI definition of an event, and
* then to a UWB definition of the same event (which are the same,
* remember). Event if we use different pointers
*/
static
void uwb_rc_notif(struct uwb_rc *rc, struct uwb_rceb *rceb, ssize_t size)
{
struct device *dev = &rc->uwb_dev.dev;
struct uwb_event *uwb_evt;
if (size == -ESHUTDOWN)
return;
if (size < 0) {
dev_err(dev, "ignoring event with error code %zu\n",
size);
return;
}
uwb_evt = kzalloc(sizeof(*uwb_evt), GFP_ATOMIC);
if (unlikely(uwb_evt == NULL)) {
dev_err(dev, "no memory to queue event 0x%02x/%04x/%02x\n",
rceb->bEventType, le16_to_cpu(rceb->wEvent),
rceb->bEventContext);
return;
}
uwb_evt->rc = __uwb_rc_get(rc); /* will be put by uwbd's uwbd_event_handle() */
uwb_evt->ts_jiffies = jiffies;
uwb_evt->type = UWB_EVT_TYPE_NOTIF;
uwb_evt->notif.size = size;
uwb_evt->notif.rceb = rceb;
uwbd_event_queue(uwb_evt);
}
static void uwb_rc_neh_grok_event(struct uwb_rc *rc, struct uwb_rceb *rceb, size_t size)
{
struct device *dev = &rc->uwb_dev.dev;
struct uwb_rc_neh *neh;
struct uwb_rceb *notif;
if (rceb->bEventContext == 0) {
notif = kmalloc(size, GFP_ATOMIC);
if (notif) {
memcpy(notif, rceb, size);
uwb_rc_notif(rc, notif, size);
} else
dev_err(dev, "event 0x%02x/%04x/%02x (%zu bytes): no memory\n",
rceb->bEventType, le16_to_cpu(rceb->wEvent),
rceb->bEventContext, size);
} else {
neh = uwb_rc_neh_lookup(rc, rceb);
if (neh) {
del_timer_sync(&neh->timer);
uwb_rc_neh_cb(neh, rceb, size);
} else
dev_warn(dev, "event 0x%02x/%04x/%02x (%zu bytes): nobody cared\n",
rceb->bEventType, le16_to_cpu(rceb->wEvent),
rceb->bEventContext, size);
}
}
/**
* Given a buffer with one or more UWB RC events/notifications, break
* them up and dispatch them.
*
* @rc: UWB Radio Controller
* @buf: Buffer with the stream of notifications/events
* @buf_size: Amount of data in the buffer
*
* Note each notification/event starts always with a 'struct
* uwb_rceb', so the minimum size if 4 bytes.
*
* The device may pass us events formatted differently than expected.
* These are first filtered, potentially creating a new event in a new
* memory location. If a new event is created by the filter it is also
* freed here.
*
* For each notif/event, tries to guess the size looking at the EST
* tables, then looks for a neh that is waiting for that event and if
* found, copies the payload to the neh's buffer and calls it back. If
* not, the data is ignored.
*
* Note that if we can't find a size description in the EST tables, we
* still might find a size in the 'neh' handle in uwb_rc_neh_lookup().
*
* Assumptions:
*
* @rc->neh_lock is NOT taken
*
* We keep track of various sizes here:
* size: contains the size of the buffer that is processed for the
* incoming event. this buffer may contain events that are not
* formatted as WHCI.
* real_size: the actual space taken by this event in the buffer.
* We need to keep track of the real size of an event to be able to
* advance the buffer correctly.
* event_size: the size of the event as expected by the core layer
* [OR] the size of the event after filtering. if the filtering
* created a new event in a new memory location then this is
* effectively the size of a new event buffer
*/
void uwb_rc_neh_grok(struct uwb_rc *rc, void *buf, size_t buf_size)
{
struct device *dev = &rc->uwb_dev.dev;
void *itr;
struct uwb_rceb *rceb;
size_t size, real_size, event_size;
int needtofree;
itr = buf;
size = buf_size;
while (size > 0) {
if (size < sizeof(*rceb)) {
dev_err(dev, "not enough data in event buffer to "
"process incoming events (%zu left, minimum is "
"%zu)\n", size, sizeof(*rceb));
break;
}
rceb = itr;
if (rc->filter_event) {
needtofree = rc->filter_event(rc, &rceb, size,
&real_size, &event_size);
if (needtofree < 0 && needtofree != -ENOANO) {
dev_err(dev, "BUG: Unable to filter event "
"(0x%02x/%04x/%02x) from "
"device. \n", rceb->bEventType,
le16_to_cpu(rceb->wEvent),
rceb->bEventContext);
break;
}
} else
needtofree = -ENOANO;
/* do real processing if there was no filtering or the
* filtering didn't act */
if (needtofree == -ENOANO) {
ssize_t ret = uwb_est_find_size(rc, rceb, size);
if (ret < 0)
break;
if (ret > size) {
dev_err(dev, "BUG: hw sent incomplete event "
"0x%02x/%04x/%02x (%zd bytes), only got "
"%zu bytes. We don't handle that.\n",
rceb->bEventType, le16_to_cpu(rceb->wEvent),
rceb->bEventContext, ret, size);
break;
}
real_size = event_size = ret;
}
uwb_rc_neh_grok_event(rc, rceb, event_size);
if (needtofree == 1)
kfree(rceb);
itr += real_size;
size -= real_size;
}
}
EXPORT_SYMBOL_GPL(uwb_rc_neh_grok);
/**
* The entity that reads from the device notification/event channel has
* detected an error.
*
* @rc: UWB Radio Controller
* @error: Errno error code
*
*/
void uwb_rc_neh_error(struct uwb_rc *rc, int error)
{
struct uwb_rc_neh *neh;
unsigned long flags;
for (;;) {
spin_lock_irqsave(&rc->neh_lock, flags);
if (list_empty(&rc->neh_list)) {
spin_unlock_irqrestore(&rc->neh_lock, flags);
break;
}
neh = list_first_entry(&rc->neh_list, struct uwb_rc_neh, list_node);
__uwb_rc_neh_rm(rc, neh);
spin_unlock_irqrestore(&rc->neh_lock, flags);
del_timer_sync(&neh->timer);
uwb_rc_neh_cb(neh, NULL, error);
}
}
EXPORT_SYMBOL_GPL(uwb_rc_neh_error);
static void uwb_rc_neh_timer(unsigned long arg)
{
struct uwb_rc_neh *neh = (struct uwb_rc_neh *)arg;
struct uwb_rc *rc = neh->rc;
unsigned long flags;
spin_lock_irqsave(&rc->neh_lock, flags);
if (neh->context)
__uwb_rc_neh_rm(rc, neh);
else
neh = NULL;
spin_unlock_irqrestore(&rc->neh_lock, flags);
if (neh)
uwb_rc_neh_cb(neh, NULL, -ETIMEDOUT);
}
/** Initializes the @rc's neh subsystem
*/
void uwb_rc_neh_create(struct uwb_rc *rc)
{
spin_lock_init(&rc->neh_lock);
INIT_LIST_HEAD(&rc->neh_list);
set_bit(0, rc->ctx_bm); /* 0 is reserved (see [WUSB] table 8-65) */
set_bit(0xff, rc->ctx_bm); /* and 0xff is invalid */
rc->ctx_roll = 1;
}
/** Release's the @rc's neh subsystem */
void uwb_rc_neh_destroy(struct uwb_rc *rc)
{
unsigned long flags;
struct uwb_rc_neh *neh;
for (;;) {
spin_lock_irqsave(&rc->neh_lock, flags);
if (list_empty(&rc->neh_list)) {
spin_unlock_irqrestore(&rc->neh_lock, flags);
break;
}
neh = list_first_entry(&rc->neh_list, struct uwb_rc_neh, list_node);
__uwb_rc_neh_rm(rc, neh);
spin_unlock_irqrestore(&rc->neh_lock, flags);
del_timer_sync(&neh->timer);
uwb_rc_neh_put(neh);
}
}