5 * Copyright (C) 2005-2006 Intel Corporation
6 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License version
10 * 2 as published by the Free Software Foundation.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
23 * FIXME: doc: overview of the API, different parts and pointers
26 #ifndef __LINUX__UWB_H__
27 #define __LINUX__UWB_H__
29 #include <linux/limits.h>
30 #include <linux/device.h>
31 #include <linux/mutex.h>
32 #include <linux/timer.h>
33 #include <linux/wait.h>
34 #include <linux/workqueue.h>
35 #include <linux/uwb/spec.h>
44 * struct uwb_dev - a UWB Device
45 * @rc: UWB Radio Controller that discovered the device (kind of its
47 * @bce: a beacon cache entry for this device; or NULL if the device
48 * is a local radio controller.
49 * @mac_addr: the EUI-48 address of this device.
50 * @dev_addr: the current DevAddr used by this device.
51 * @beacon_slot: the slot number the beacon is using.
52 * @streams: bitmap of streams allocated to reservations targeted at
53 * this device. For an RC, this is the streams allocated for
54 * reservations targeted at DevAddrs.
56 * A UWB device may either by a neighbor or part of a local radio
61 struct list_head list_node;
63 struct uwb_rc *rc; /* radio controller */
64 struct uwb_beca_e *bce; /* Beacon Cache Entry */
66 struct uwb_mac_addr mac_addr;
67 struct uwb_dev_addr dev_addr;
69 DECLARE_BITMAP(streams, UWB_NUM_STREAMS);
70 DECLARE_BITMAP(last_availability_bm, UWB_NUM_MAS);
72 #define to_uwb_dev(d) container_of(d, struct uwb_dev, dev)
75 * UWB HWA/WHCI Radio Control {Command|Event} Block context IDs
77 * RC[CE]Bs have a 'context ID' field that matches the command with
78 * the event received to confirm it.
80 * Maximum number of context IDs
82 enum { UWB_RC_CTX_MAX = 256 };
85 /** Notification chain head for UWB generated events to listeners */
86 struct uwb_notifs_chain {
87 struct list_head list;
91 /* Beacon cache list */
93 struct list_head list;
98 /* Event handling thread. */
101 struct task_struct *task;
102 wait_queue_head_t wq;
103 struct list_head event_list;
104 spinlock_t event_list_lock;
108 * struct uwb_mas_bm - a bitmap of all MAS in a superframe
109 * @bm: a bitmap of length #UWB_NUM_MAS
112 DECLARE_BITMAP(bm, UWB_NUM_MAS);
113 DECLARE_BITMAP(unsafe_bm, UWB_NUM_MAS);
119 * uwb_rsv_state - UWB Reservation state.
121 * NONE - reservation is not active (no DRP IE being transmitted).
123 * Owner reservation states:
125 * INITIATED - owner has sent an initial DRP request.
126 * PENDING - target responded with pending Reason Code.
127 * MODIFIED - reservation manager is modifying an established
128 * reservation with a different MAS allocation.
129 * ESTABLISHED - the reservation has been successfully negotiated.
131 * Target reservation states:
133 * DENIED - request is denied.
134 * ACCEPTED - request is accepted.
135 * PENDING - PAL has yet to make a decision to whether to accept or
138 * FIXME: further target states TBD.
141 UWB_RSV_STATE_NONE = 0,
142 UWB_RSV_STATE_O_INITIATED,
143 UWB_RSV_STATE_O_PENDING,
144 UWB_RSV_STATE_O_MODIFIED,
145 UWB_RSV_STATE_O_ESTABLISHED,
146 UWB_RSV_STATE_O_TO_BE_MOVED,
147 UWB_RSV_STATE_O_MOVE_EXPANDING,
148 UWB_RSV_STATE_O_MOVE_COMBINING,
149 UWB_RSV_STATE_O_MOVE_REDUCING,
150 UWB_RSV_STATE_T_ACCEPTED,
151 UWB_RSV_STATE_T_DENIED,
152 UWB_RSV_STATE_T_CONFLICT,
153 UWB_RSV_STATE_T_PENDING,
154 UWB_RSV_STATE_T_EXPANDING_ACCEPTED,
155 UWB_RSV_STATE_T_EXPANDING_CONFLICT,
156 UWB_RSV_STATE_T_EXPANDING_PENDING,
157 UWB_RSV_STATE_T_EXPANDING_DENIED,
158 UWB_RSV_STATE_T_RESIZED,
163 enum uwb_rsv_target_type {
165 UWB_RSV_TARGET_DEVADDR,
169 * struct uwb_rsv_target - the target of a reservation.
171 * Reservations unicast and targeted at a single device
172 * (UWB_RSV_TARGET_DEV); or (e.g., in the case of WUSB) targeted at a
173 * specific (private) DevAddr (UWB_RSV_TARGET_DEVADDR).
175 struct uwb_rsv_target {
176 enum uwb_rsv_target_type type;
179 struct uwb_dev_addr devaddr;
183 struct uwb_rsv_move {
184 struct uwb_mas_bm final_mas;
185 struct uwb_ie_drp *companion_drp_ie;
186 struct uwb_mas_bm companion_mas;
190 * Number of streams reserved for reservations targeted at DevAddrs.
192 #define UWB_NUM_GLOBAL_STREAMS 1
194 typedef void (*uwb_rsv_cb_f)(struct uwb_rsv *rsv);
197 * struct uwb_rsv - a DRP reservation
199 * Data structure management:
201 * @rc: the radio controller this reservation is for
202 * (as target or owner)
203 * @rc_node: a list node for the RC
204 * @pal_node: a list node for the PAL
206 * Owner and target parameters:
208 * @owner: the UWB device owning this reservation
209 * @target: the target UWB device
210 * @type: reservation type
214 * @max_mas: maxiumum number of MAS
215 * @min_mas: minimum number of MAS
216 * @sparsity: owner selected sparsity
217 * @is_multicast: true iff multicast
219 * @callback: callback function when the reservation completes
220 * @pal_priv: private data for the PAL making the reservation
222 * Reservation status:
224 * @status: negotiation status
225 * @stream: stream index allocated for this reservation
226 * @tiebreaker: conflict tiebreaker for this reservation
228 * @drp_ie: the DRP IE
229 * @ie_valid: true iff the DRP IE matches the reservation parameters
231 * DRP reservations are uniquely identified by the owner, target and
232 * stream index. However, when using a DevAddr as a target (e.g., for
233 * a WUSB cluster reservation) the responses may be received from
234 * devices with different DevAddrs. In this case, reservations are
235 * uniquely identified by just the stream index. A number of stream
236 * indexes (UWB_NUM_GLOBAL_STREAMS) are reserved for this.
240 struct list_head rc_node;
241 struct list_head pal_node;
244 struct uwb_dev *owner;
245 struct uwb_rsv_target target;
246 enum uwb_drp_type type;
252 uwb_rsv_cb_f callback;
255 enum uwb_rsv_state state;
256 bool needs_release_companion_mas;
259 struct uwb_mas_bm mas;
260 struct uwb_ie_drp *drp_ie;
261 struct uwb_rsv_move mv;
263 struct timer_list timer;
264 struct work_struct handle_timeout_work;
268 struct uwb_mas_bm uwb_mas_bm_zero = { .bm = { 0 } };
270 static inline void uwb_mas_bm_copy_le(void *dst, const struct uwb_mas_bm *mas)
272 bitmap_copy_le(dst, mas->bm, UWB_NUM_MAS);
276 * struct uwb_drp_avail - a radio controller's view of MAS usage
277 * @global: MAS unused by neighbors (excluding reservations targeted
278 * or owned by the local radio controller) or the beaon period
279 * @local: MAS unused by local established reservations
280 * @pending: MAS unused by local pending reservations
281 * @ie: DRP Availability IE to be included in the beacon
282 * @ie_valid: true iff @ie is valid and does not need to regenerated from
285 * Each radio controller maintains a view of MAS usage or
286 * availability. MAS available for a new reservation are determined
287 * from the intersection of @global, @local, and @pending.
289 * The radio controller must transmit a DRP Availability IE that's the
290 * intersection of @global and @local.
292 * A set bit indicates the MAS is unused and available.
294 * rc->rsvs_mutex should be held before accessing this data structure.
296 * [ECMA-368] section 17.4.3.
298 struct uwb_drp_avail {
299 DECLARE_BITMAP(global, UWB_NUM_MAS);
300 DECLARE_BITMAP(local, UWB_NUM_MAS);
301 DECLARE_BITMAP(pending, UWB_NUM_MAS);
302 struct uwb_ie_drp_avail ie;
306 struct uwb_drp_backoff_win {
310 struct timer_list timer;
311 bool can_reserve_extra_mases;
314 const char *uwb_rsv_state_str(enum uwb_rsv_state state);
315 const char *uwb_rsv_type_str(enum uwb_drp_type type);
317 struct uwb_rsv *uwb_rsv_create(struct uwb_rc *rc, uwb_rsv_cb_f cb,
319 void uwb_rsv_destroy(struct uwb_rsv *rsv);
321 int uwb_rsv_establish(struct uwb_rsv *rsv);
322 int uwb_rsv_modify(struct uwb_rsv *rsv,
323 int max_mas, int min_mas, int sparsity);
324 void uwb_rsv_terminate(struct uwb_rsv *rsv);
326 void uwb_rsv_accept(struct uwb_rsv *rsv, uwb_rsv_cb_f cb, void *pal_priv);
328 void uwb_rsv_get_usable_mas(struct uwb_rsv *orig_rsv, struct uwb_mas_bm *mas);
331 * Radio Control Interface instance
334 * Life cycle rules: those of the UWB Device.
336 * @index: an index number for this radio controller, as used in the
338 * @version: version of protocol supported by this device
339 * @priv: Backend implementation; rw with uwb_dev.dev.sem taken.
340 * @cmd: Backend implementation to execute commands; rw and call
341 * only with uwb_dev.dev.sem taken.
342 * @reset: Hardware reset of radio controller and any PAL controllers.
343 * @filter: Backend implementation to manipulate data to and from device
344 * to be compliant to specification assumed by driver (WHCI
347 * uwb_dev.dev.mutex is used to execute commands and update
348 * the corresponding structures; can't use a spinlock
349 * because rc->cmd() can sleep.
350 * @ies: This is a dynamically allocated array cacheing the
351 * IEs (settable by the host) that the beacon of this
352 * radio controller is currently sending.
354 * In reality, we store here the full command we set to
355 * the radio controller (which is basically a command
356 * prefix followed by all the IEs the beacon currently
357 * contains). This way we don't have to realloc and
358 * memcpy when setting it.
360 * We set this up in uwb_rc_ie_setup(), where we alloc
361 * this struct, call get_ie() [so we know which IEs are
362 * currently being sent, if any].
364 * @ies_capacity:Amount of space (in bytes) allocated in @ies. The
365 * amount used is given by sizeof(*ies) plus ies->wIELength
366 * (which is a little endian quantity all the time).
367 * @ies_mutex: protect the IE cache
368 * @dbg: information for the debug interface
371 struct uwb_dev uwb_dev;
375 struct module *owner;
377 int (*start)(struct uwb_rc *rc);
378 void (*stop)(struct uwb_rc *rc);
379 int (*cmd)(struct uwb_rc *, const struct uwb_rccb *, size_t);
380 int (*reset)(struct uwb_rc *rc);
381 int (*filter_cmd)(struct uwb_rc *, struct uwb_rccb **, size_t *);
382 int (*filter_event)(struct uwb_rc *, struct uwb_rceb **, const size_t,
385 spinlock_t neh_lock; /* protects neh_* and ctx_* */
386 struct list_head neh_list; /* Open NE handles */
387 unsigned long ctx_bm[UWB_RC_CTX_MAX / 8 / sizeof(unsigned long)];
390 int beaconing; /* Beaconing state [channel number] */
391 int beaconing_forced;
393 enum uwb_scan_type scan_type:3;
395 struct uwb_notifs_chain notifs_chain;
396 struct uwb_beca uwb_beca;
400 struct uwb_drp_backoff_win bow;
401 struct uwb_drp_avail drp_avail;
402 struct list_head reservations;
403 struct list_head cnflt_alien_list;
404 struct uwb_mas_bm cnflt_alien_bitmap;
405 struct mutex rsvs_mutex;
406 spinlock_t rsvs_lock;
407 struct workqueue_struct *rsv_workq;
409 struct delayed_work rsv_update_work;
410 struct delayed_work rsv_alien_bp_work;
411 int set_drp_ie_pending;
412 struct mutex ies_mutex;
413 struct uwb_rc_cmd_set_ie *ies;
416 struct list_head pals;
424 * struct uwb_pal - a UWB PAL
425 * @name: descriptive name for this PAL (wusbhc, wlp, etc.).
426 * @device: a device for the PAL. Used to link the PAL and the radio
427 * controller in sysfs.
428 * @rc: the radio controller the PAL uses.
429 * @channel_changed: called when the channel used by the radio changes.
430 * A channel of -1 means the channel has been stopped.
431 * @new_rsv: called when a peer requests a reservation (may be NULL if
432 * the PAL cannot accept reservation requests).
433 * @channel: channel being used by the PAL; 0 if the PAL isn't using
434 * the radio; -1 if the PAL wishes to use the radio but
436 * @debugfs_dir: a debugfs directory which the PAL can use for its own
439 * A Protocol Adaptation Layer (PAL) is a user of the WiMedia UWB
440 * radio platform (e.g., WUSB, WLP or Bluetooth UWB AMP).
442 * The PALs using a radio controller must register themselves to
443 * permit the UWB stack to coordinate usage of the radio between the
444 * various PALs or to allow PALs to response to certain requests from
447 * A struct uwb_pal should be embedded in a containing structure
448 * belonging to the PAL and initialized with uwb_pal_init()). Fields
449 * should be set appropriately by the PAL before registering the PAL
450 * with uwb_pal_register().
453 struct list_head node;
455 struct device *device;
458 void (*channel_changed)(struct uwb_pal *pal, int channel);
459 void (*new_rsv)(struct uwb_pal *pal, struct uwb_rsv *rsv);
462 struct dentry *debugfs_dir;
465 void uwb_pal_init(struct uwb_pal *pal);
466 int uwb_pal_register(struct uwb_pal *pal);
467 void uwb_pal_unregister(struct uwb_pal *pal);
469 int uwb_radio_start(struct uwb_pal *pal);
470 void uwb_radio_stop(struct uwb_pal *pal);
475 * This API can be used by UWB device drivers or by those implementing
476 * UWB Radio Controllers
478 struct uwb_dev *uwb_dev_get_by_devaddr(struct uwb_rc *rc,
479 const struct uwb_dev_addr *devaddr);
480 struct uwb_dev *uwb_dev_get_by_rc(struct uwb_dev *, struct uwb_rc *);
481 static inline void uwb_dev_get(struct uwb_dev *uwb_dev)
483 get_device(&uwb_dev->dev);
485 static inline void uwb_dev_put(struct uwb_dev *uwb_dev)
487 put_device(&uwb_dev->dev);
489 struct uwb_dev *uwb_dev_try_get(struct uwb_rc *rc, struct uwb_dev *uwb_dev);
492 * Callback function for 'uwb_{dev,rc}_foreach()'.
494 * @dev: Linux device instance
495 * 'uwb_dev = container_of(dev, struct uwb_dev, dev)'
496 * @priv: Data passed by the caller to 'uwb_{dev,rc}_foreach()'.
498 * @returns: 0 to continue the iterations, any other val to stop
499 * iterating and return the value to the caller of
502 typedef int (*uwb_dev_for_each_f)(struct device *dev, void *priv);
503 int uwb_dev_for_each(struct uwb_rc *rc, uwb_dev_for_each_f func, void *priv);
505 struct uwb_rc *uwb_rc_alloc(void);
506 struct uwb_rc *uwb_rc_get_by_dev(const struct uwb_dev_addr *);
507 struct uwb_rc *uwb_rc_get_by_grandpa(const struct device *);
508 void uwb_rc_put(struct uwb_rc *rc);
510 typedef void (*uwb_rc_cmd_cb_f)(struct uwb_rc *rc, void *arg,
511 struct uwb_rceb *reply, ssize_t reply_size);
513 int uwb_rc_cmd_async(struct uwb_rc *rc, const char *cmd_name,
514 struct uwb_rccb *cmd, size_t cmd_size,
515 u8 expected_type, u16 expected_event,
516 uwb_rc_cmd_cb_f cb, void *arg);
517 ssize_t uwb_rc_cmd(struct uwb_rc *rc, const char *cmd_name,
518 struct uwb_rccb *cmd, size_t cmd_size,
519 struct uwb_rceb *reply, size_t reply_size);
520 ssize_t uwb_rc_vcmd(struct uwb_rc *rc, const char *cmd_name,
521 struct uwb_rccb *cmd, size_t cmd_size,
522 u8 expected_type, u16 expected_event,
523 struct uwb_rceb **preply);
525 size_t __uwb_addr_print(char *, size_t, const unsigned char *, int);
527 int uwb_rc_dev_addr_set(struct uwb_rc *, const struct uwb_dev_addr *);
528 int uwb_rc_dev_addr_get(struct uwb_rc *, struct uwb_dev_addr *);
529 int uwb_rc_mac_addr_set(struct uwb_rc *, const struct uwb_mac_addr *);
530 int uwb_rc_mac_addr_get(struct uwb_rc *, struct uwb_mac_addr *);
531 int __uwb_mac_addr_assigned_check(struct device *, void *);
532 int __uwb_dev_addr_assigned_check(struct device *, void *);
534 /* Print in @buf a pretty repr of @addr */
535 static inline size_t uwb_dev_addr_print(char *buf, size_t buf_size,
536 const struct uwb_dev_addr *addr)
538 return __uwb_addr_print(buf, buf_size, addr->data, 0);
541 /* Print in @buf a pretty repr of @addr */
542 static inline size_t uwb_mac_addr_print(char *buf, size_t buf_size,
543 const struct uwb_mac_addr *addr)
545 return __uwb_addr_print(buf, buf_size, addr->data, 1);
548 /* @returns 0 if device addresses @addr2 and @addr1 are equal */
549 static inline int uwb_dev_addr_cmp(const struct uwb_dev_addr *addr1,
550 const struct uwb_dev_addr *addr2)
552 return memcmp(addr1, addr2, sizeof(*addr1));
555 /* @returns 0 if MAC addresses @addr2 and @addr1 are equal */
556 static inline int uwb_mac_addr_cmp(const struct uwb_mac_addr *addr1,
557 const struct uwb_mac_addr *addr2)
559 return memcmp(addr1, addr2, sizeof(*addr1));
562 /* @returns !0 if a MAC @addr is a broadcast address */
563 static inline int uwb_mac_addr_bcast(const struct uwb_mac_addr *addr)
565 struct uwb_mac_addr bcast = {
566 .data = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }
568 return !uwb_mac_addr_cmp(addr, &bcast);
571 /* @returns !0 if a MAC @addr is all zeroes*/
572 static inline int uwb_mac_addr_unset(const struct uwb_mac_addr *addr)
574 struct uwb_mac_addr unset = {
575 .data = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
577 return !uwb_mac_addr_cmp(addr, &unset);
580 /* @returns !0 if the address is in use. */
581 static inline unsigned __uwb_dev_addr_assigned(struct uwb_rc *rc,
582 struct uwb_dev_addr *addr)
584 return uwb_dev_for_each(rc, __uwb_dev_addr_assigned_check, addr);
588 * UWB Radio Controller API
590 * This API is used (in addition to the general API) to implement UWB
593 void uwb_rc_init(struct uwb_rc *);
594 int uwb_rc_add(struct uwb_rc *, struct device *dev, void *rc_priv);
595 void uwb_rc_rm(struct uwb_rc *);
596 void uwb_rc_neh_grok(struct uwb_rc *, void *, size_t);
597 void uwb_rc_neh_error(struct uwb_rc *, int);
598 void uwb_rc_reset_all(struct uwb_rc *rc);
599 void uwb_rc_pre_reset(struct uwb_rc *rc);
600 int uwb_rc_post_reset(struct uwb_rc *rc);
603 * uwb_rsv_is_owner - is the owner of this reservation the RC?
604 * @rsv: the reservation
606 static inline bool uwb_rsv_is_owner(struct uwb_rsv *rsv)
608 return rsv->owner == &rsv->rc->uwb_dev;
612 * enum uwb_notifs - UWB events that can be passed to any listeners
613 * @UWB_NOTIF_ONAIR: a new neighbour has joined the beacon group.
614 * @UWB_NOTIF_OFFAIR: a neighbour has left the beacon group.
616 * Higher layers can register callback functions with the radio
617 * controller using uwb_notifs_register(). The radio controller
618 * maintains a list of all registered handlers and will notify all
619 * nodes when an event occurs.
626 /* Callback function registered with UWB */
627 struct uwb_notifs_handler {
628 struct list_head list_node;
629 void (*cb)(void *, struct uwb_dev *, enum uwb_notifs);
633 int uwb_notifs_register(struct uwb_rc *, struct uwb_notifs_handler *);
634 int uwb_notifs_deregister(struct uwb_rc *, struct uwb_notifs_handler *);
638 * UWB radio controller Event Size Entry (for creating entry tables)
640 * WUSB and WHCI define events and notifications, and they might have
641 * fixed or variable size.
643 * Each event/notification has a size which is not necessarily known
644 * in advance based on the event code. As well, vendor specific
645 * events/notifications will have a size impossible to determine
646 * unless we know about the device's specific details.
648 * It was way too smart of the spec writers not to think that it would
649 * be impossible for a generic driver to skip over vendor specific
650 * events/notifications if there are no LENGTH fields in the HEADER of
651 * each message...the transaction size cannot be counted on as the
652 * spec does not forbid to pack more than one event in a single
655 * Thus, we guess sizes with tables (or for events, when you know the
656 * size ahead of time you can use uwb_rc_neh_extra_size*()). We
657 * register tables with the known events and their sizes, and then we
658 * traverse those tables. For those with variable length, we provide a
659 * way to lookup the size inside the event/notification's
660 * payload. This allows device-specific event size tables to be
663 * @size: Size of the payload
665 * @offset: if != 0, at offset @offset-1 starts a field with a length
666 * that has to be added to @size. The format of the field is
669 * @type: Type and length of the offset field. Most common is LE 16
670 * bits (that's why that is zero); others are there mostly to
671 * cover for bugs and weirdos.
673 struct uwb_est_entry {
676 enum { UWB_EST_16 = 0, UWB_EST_8 = 1 } type;
679 int uwb_est_register(u8 type, u8 code_high, u16 vendor, u16 product,
680 const struct uwb_est_entry *, size_t entries);
681 int uwb_est_unregister(u8 type, u8 code_high, u16 vendor, u16 product,
682 const struct uwb_est_entry *, size_t entries);
683 ssize_t uwb_est_find_size(struct uwb_rc *rc, const struct uwb_rceb *rceb,
690 EDC_ERROR_TIMEFRAME = HZ,
693 /* error density counter */
695 unsigned long timestart;
700 void edc_init(struct edc *edc)
702 edc->timestart = jiffies;
705 /* Called when an error occurred.
706 * This is way to determine if the number of acceptable errors per time
707 * period has been exceeded. It is not accurate as there are cases in which
708 * this scheme will not work, for example if there are periodic occurrences
709 * of errors that straddle updates to the start time. This scheme is
710 * sufficient for our usage.
712 * @returns 1 if maximum acceptable errors per timeframe has been exceeded.
714 static inline int edc_inc(struct edc *err_hist, u16 max_err, u16 timeframe)
719 if (now - err_hist->timestart > timeframe) {
720 err_hist->errorcount = 1;
721 err_hist->timestart = now;
722 } else if (++err_hist->errorcount > max_err) {
723 err_hist->errorcount = 0;
724 err_hist->timestart = now;
731 /* Information Element handling */
733 struct uwb_ie_hdr *uwb_ie_next(void **ptr, size_t *len);
734 int uwb_rc_ie_add(struct uwb_rc *uwb_rc, const struct uwb_ie_hdr *ies, size_t size);
735 int uwb_rc_ie_rm(struct uwb_rc *uwb_rc, enum uwb_ie element_id);
738 * Transmission statistics
740 * UWB uses LQI and RSSI (one byte values) for reporting radio signal
741 * strength and line quality indication. We do quick and dirty
742 * averages of those. They are signed values, btw.
744 * For 8 bit quantities, we keep the min, the max, an accumulator
745 * (@sigma) and a # of samples. When @samples gets to 255, we compute
746 * the average (@sigma / @samples), place it in @sigma and reset
747 * @samples to 1 (so we use it as the first sample).
749 * Now, statistically speaking, probably I am kicking the kidneys of
750 * some books I have in my shelves collecting dust, but I just want to
751 * get an approx, not the Nobel.
753 * LOCKING: there is no locking per se, but we try to keep a lockless
754 * schema. Only _add_samples() modifies the values--as long as you
755 * have other locking on top that makes sure that no two calls of
756 * _add_sample() happen at the same time, then we are fine. Now, for
757 * resetting the values we just set @samples to 0 and that makes the
758 * next _add_sample() to start with defaults. Reading the values in
759 * _show() currently can race, so you need to make sure the calls are
760 * under the same lock that protects calls to _add_sample(). FIXME:
761 * currently unlocked (It is not ultraprecise but does the trick. Bite
771 void stats_init(struct stats *stats)
773 atomic_set(&stats->samples, 0);
778 void stats_add_sample(struct stats *stats, s8 sample)
782 unsigned samples = atomic_read(&stats->samples);
783 if (samples == 0) { /* it was zero before, so we initialize */
790 sigma = stats->sigma;
793 if (sample < min) /* compute new values */
795 else if (sample > max)
799 stats->min = min; /* commit */
801 stats->sigma = sigma;
802 if (atomic_add_return(1, &stats->samples) > 255) {
803 /* wrapped around! reset */
804 stats->sigma = sigma / 256;
805 atomic_set(&stats->samples, 1);
809 static inline ssize_t stats_show(struct stats *stats, char *buf)
812 int samples = atomic_read(&stats->samples);
818 avg = stats->sigma / samples;
820 return scnprintf(buf, PAGE_SIZE, "%d %d %d\n", min, max, avg);
823 static inline ssize_t stats_store(struct stats *stats, const char *buf,
830 #endif /* #ifndef __LINUX__UWB_H__ */