/* * 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/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); } }