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Diffstat (limited to 'include/linux/uwb.h')
| -rw-r--r-- | include/linux/uwb.h | 765 |
1 files changed, 765 insertions, 0 deletions
diff --git a/include/linux/uwb.h b/include/linux/uwb.h new file mode 100644 index 000000000000..f9ccbd9a2ced --- /dev/null +++ b/include/linux/uwb.h @@ -0,0 +1,765 @@ +/* + * Ultra Wide Band + * UWB API + * + * 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. + * + * + * FIXME: doc: overview of the API, different parts and pointers + */ + +#ifndef __LINUX__UWB_H__ +#define __LINUX__UWB_H__ + +#include <linux/limits.h> +#include <linux/device.h> +#include <linux/mutex.h> +#include <linux/timer.h> +#include <linux/workqueue.h> +#include <linux/uwb/spec.h> + +struct uwb_dev; +struct uwb_beca_e; +struct uwb_rc; +struct uwb_rsv; +struct uwb_dbg; + +/** + * struct uwb_dev - a UWB Device + * @rc: UWB Radio Controller that discovered the device (kind of its + * parent). + * @bce: a beacon cache entry for this device; or NULL if the device + * is a local radio controller. + * @mac_addr: the EUI-48 address of this device. + * @dev_addr: the current DevAddr used by this device. + * @beacon_slot: the slot number the beacon is using. + * @streams: bitmap of streams allocated to reservations targeted at + * this device. For an RC, this is the streams allocated for + * reservations targeted at DevAddrs. + * + * A UWB device may either by a neighbor or part of a local radio + * controller. + */ +struct uwb_dev { + struct mutex mutex; + struct list_head list_node; + struct device dev; + struct uwb_rc *rc; /* radio controller */ + struct uwb_beca_e *bce; /* Beacon Cache Entry */ + + struct uwb_mac_addr mac_addr; + struct uwb_dev_addr dev_addr; + int beacon_slot; + DECLARE_BITMAP(streams, UWB_NUM_STREAMS); +}; +#define to_uwb_dev(d) container_of(d, struct uwb_dev, dev) + +/** + * UWB HWA/WHCI Radio Control {Command|Event} Block context IDs + * + * RC[CE]Bs have a 'context ID' field that matches the command with + * the event received to confirm it. + * + * Maximum number of context IDs + */ +enum { UWB_RC_CTX_MAX = 256 }; + + +/** Notification chain head for UWB generated events to listeners */ +struct uwb_notifs_chain { + struct list_head list; + struct mutex mutex; +}; + +/** + * struct uwb_mas_bm - a bitmap of all MAS in a superframe + * @bm: a bitmap of length #UWB_NUM_MAS + */ +struct uwb_mas_bm { + DECLARE_BITMAP(bm, UWB_NUM_MAS); +}; + +/** + * uwb_rsv_state - UWB Reservation state. + * + * NONE - reservation is not active (no DRP IE being transmitted). + * + * Owner reservation states: + * + * INITIATED - owner has sent an initial DRP request. + * PENDING - target responded with pending Reason Code. + * MODIFIED - reservation manager is modifying an established + * reservation with a different MAS allocation. + * ESTABLISHED - the reservation has been successfully negotiated. + * + * Target reservation states: + * + * DENIED - request is denied. + * ACCEPTED - request is accepted. + * PENDING - PAL has yet to make a decision to whether to accept or + * deny. + * + * FIXME: further target states TBD. + */ +enum uwb_rsv_state { + UWB_RSV_STATE_NONE, + UWB_RSV_STATE_O_INITIATED, + UWB_RSV_STATE_O_PENDING, + UWB_RSV_STATE_O_MODIFIED, + UWB_RSV_STATE_O_ESTABLISHED, + UWB_RSV_STATE_T_ACCEPTED, + UWB_RSV_STATE_T_DENIED, + UWB_RSV_STATE_T_PENDING, + + UWB_RSV_STATE_LAST, +}; + +enum uwb_rsv_target_type { + UWB_RSV_TARGET_DEV, + UWB_RSV_TARGET_DEVADDR, +}; + +/** + * struct uwb_rsv_target - the target of a reservation. + * + * Reservations unicast and targeted at a single device + * (UWB_RSV_TARGET_DEV); or (e.g., in the case of WUSB) targeted at a + * specific (private) DevAddr (UWB_RSV_TARGET_DEVADDR). + */ +struct uwb_rsv_target { + enum uwb_rsv_target_type type; + union { + struct uwb_dev *dev; + struct uwb_dev_addr devaddr; + }; +}; + +/* + * Number of streams reserved for reservations targeted at DevAddrs. + */ +#define UWB_NUM_GLOBAL_STREAMS 1 + +typedef void (*uwb_rsv_cb_f)(struct uwb_rsv *rsv); + +/** + * struct uwb_rsv - a DRP reservation + * + * Data structure management: + * + * @rc: the radio controller this reservation is for + * (as target or owner) + * @rc_node: a list node for the RC + * @pal_node: a list node for the PAL + * + * Owner and target parameters: + * + * @owner: the UWB device owning this reservation + * @target: the target UWB device + * @type: reservation type + * + * Owner parameters: + * + * @max_mas: maxiumum number of MAS + * @min_mas: minimum number of MAS + * @sparsity: owner selected sparsity + * @is_multicast: true iff multicast + * + * @callback: callback function when the reservation completes + * @pal_priv: private data for the PAL making the reservation + * + * Reservation status: + * + * @status: negotiation status + * @stream: stream index allocated for this reservation + * @mas: reserved MAS + * @drp_ie: the DRP IE + * @ie_valid: true iff the DRP IE matches the reservation parameters + * + * DRP reservations are uniquely identified by the owner, target and + * stream index. However, when using a DevAddr as a target (e.g., for + * a WUSB cluster reservation) the responses may be received from + * devices with different DevAddrs. In this case, reservations are + * uniquely identified by just the stream index. A number of stream + * indexes (UWB_NUM_GLOBAL_STREAMS) are reserved for this. + */ +struct uwb_rsv { + struct uwb_rc *rc; + struct list_head rc_node; + struct list_head pal_node; + + struct uwb_dev *owner; + struct uwb_rsv_target target; + enum uwb_drp_type type; + int max_mas; + int min_mas; + int sparsity; + bool is_multicast; + + uwb_rsv_cb_f callback; + void *pal_priv; + + enum uwb_rsv_state state; + u8 stream; + struct uwb_mas_bm mas; + struct uwb_ie_drp *drp_ie; + bool ie_valid; + struct timer_list timer; + bool expired; +}; + +static const +struct uwb_mas_bm uwb_mas_bm_zero = { .bm = { 0 } }; + +static inline void uwb_mas_bm_copy_le(void *dst, const struct uwb_mas_bm *mas) +{ + bitmap_copy_le(dst, mas->bm, UWB_NUM_MAS); +} + +/** + * struct uwb_drp_avail - a radio controller's view of MAS usage + * @global: MAS unused by neighbors (excluding reservations targetted + * or owned by the local radio controller) or the beaon period + * @local: MAS unused by local established reservations + * @pending: MAS unused by local pending reservations + * @ie: DRP Availability IE to be included in the beacon + * @ie_valid: true iff @ie is valid and does not need to regenerated from + * @global and @local + * + * Each radio controller maintains a view of MAS usage or + * availability. MAS available for a new reservation are determined + * from the intersection of @global, @local, and @pending. + * + * The radio controller must transmit a DRP Availability IE that's the + * intersection of @global and @local. + * + * A set bit indicates the MAS is unused and available. + * + * rc->rsvs_mutex should be held before accessing this data structure. + * + * [ECMA-368] section 17.4.3. + */ +struct uwb_drp_avail { + DECLARE_BITMAP(global, UWB_NUM_MAS); + DECLARE_BITMAP(local, UWB_NUM_MAS); + DECLARE_BITMAP(pending, UWB_NUM_MAS); + struct uwb_ie_drp_avail ie; + bool ie_valid; +}; + + +const char *uwb_rsv_state_str(enum uwb_rsv_state state); +const char *uwb_rsv_type_str(enum uwb_drp_type type); + +struct uwb_rsv *uwb_rsv_create(struct uwb_rc *rc, uwb_rsv_cb_f cb, + void *pal_priv); +void uwb_rsv_destroy(struct uwb_rsv *rsv); + +int uwb_rsv_establish(struct uwb_rsv *rsv); +int uwb_rsv_modify(struct uwb_rsv *rsv, + int max_mas, int min_mas, int sparsity); +void uwb_rsv_terminate(struct uwb_rsv *rsv); + +void uwb_rsv_accept(struct uwb_rsv *rsv, uwb_rsv_cb_f cb, void *pal_priv); + +/** + * Radio Control Interface instance + * + * + * Life cycle rules: those of the UWB Device. + * + * @index: an index number for this radio controller, as used in the + * device name. + * @version: version of protocol supported by this device + * @priv: Backend implementation; rw with uwb_dev.dev.sem taken. + * @cmd: Backend implementation to execute commands; rw and call + * only with uwb_dev.dev.sem taken. + * @reset: Hardware reset of radio controller and any PAL controllers. + * @filter: Backend implementation to manipulate data to and from device + * to be compliant to specification assumed by driver (WHCI + * 0.95). + * + * uwb_dev.dev.mutex is used to execute commands and update + * the corresponding structures; can't use a spinlock + * because rc->cmd() can sleep. + * @ies: This is a dynamically allocated array cacheing the + * IEs (settable by the host) that the beacon of this + * radio controller is currently sending. + * + * In reality, we store here the full command we set to + * the radio controller (which is basically a command + * prefix followed by all the IEs the beacon currently + * contains). This way we don't have to realloc and + * memcpy when setting it. + * + * We set this up in uwb_rc_ie_setup(), where we alloc + * this struct, call get_ie() [so we know which IEs are + * currently being sent, if any]. + * + * @ies_capacity:Amount of space (in bytes) allocated in @ies. The + * amount used is given by sizeof(*ies) plus ies->wIELength + * (which is a little endian quantity all the time). + * @ies_mutex: protect the IE cache + * @dbg: information for the debug interface + */ +struct uwb_rc { + struct uwb_dev uwb_dev; + int index; + u16 version; + + struct module *owner; + void *priv; + int (*start)(struct uwb_rc *rc); + void (*stop)(struct uwb_rc *rc); + int (*cmd)(struct uwb_rc *, const struct uwb_rccb *, size_t); + int (*reset)(struct uwb_rc *rc); + int (*filter_cmd)(struct uwb_rc *, struct uwb_rccb **, size_t *); + int (*filter_event)(struct uwb_rc *, struct uwb_rceb **, const size_t, + size_t *, size_t *); + + spinlock_t neh_lock; /* protects neh_* and ctx_* */ + struct list_head neh_list; /* Open NE handles */ + unsigned long ctx_bm[UWB_RC_CTX_MAX / 8 / sizeof(unsigned long)]; + u8 ctx_roll; + + int beaconing; /* Beaconing state [channel number] */ + int scanning; + enum uwb_scan_type scan_type:3; + unsigned ready:1; + struct uwb_notifs_chain notifs_chain; + + struct uwb_drp_avail drp_avail; + struct list_head reservations; + struct mutex rsvs_mutex; + struct workqueue_struct *rsv_workq; + struct work_struct rsv_update_work; + + struct mutex ies_mutex; + struct uwb_rc_cmd_set_ie *ies; + size_t ies_capacity; + + spinlock_t pal_lock; + struct list_head pals; + + struct uwb_dbg *dbg; +}; + + +/** + * struct uwb_pal - a UWB PAL + * @name: descriptive name for this PAL (wushc, wlp, etc.). + * @device: a device for the PAL. Used to link the PAL and the radio + * controller in sysfs. + * @new_rsv: called when a peer requests a reservation (may be NULL if + * the PAL cannot accept reservation requests). + * + * A Protocol Adaptation Layer (PAL) is a user of the WiMedia UWB + * radio platform (e.g., WUSB, WLP or Bluetooth UWB AMP). + * + * The PALs using a radio controller must register themselves to + * permit the UWB stack to coordinate usage of the radio between the + * various PALs or to allow PALs to response to certain requests from + * peers. + * + * A struct uwb_pal should be embedded in a containing structure + * belonging to the PAL and initialized with uwb_pal_init()). Fields + * should be set appropriately by the PAL before registering the PAL + * with uwb_pal_register(). + */ +struct uwb_pal { + struct list_head node; + const char *name; + struct device *device; + void (*new_rsv)(struct uwb_rsv *rsv); +}; + +void uwb_pal_init(struct uwb_pal *pal); +int uwb_pal_register(struct uwb_rc *rc, struct uwb_pal *pal); +void uwb_pal_unregister(struct uwb_rc *rc, struct uwb_pal *pal); + +/* + * General public API + * + * This API can be used by UWB device drivers or by those implementing + * UWB Radio Controllers + */ +struct uwb_dev *uwb_dev_get_by_devaddr(struct uwb_rc *rc, + const struct uwb_dev_addr *devaddr); +struct uwb_dev *uwb_dev_get_by_rc(struct uwb_dev *, struct uwb_rc *); +static inline void uwb_dev_get(struct uwb_dev *uwb_dev) +{ + get_device(&uwb_dev->dev); +} +static inline void uwb_dev_put(struct uwb_dev *uwb_dev) +{ + put_device(&uwb_dev->dev); +} +struct uwb_dev *uwb_dev_try_get(struct uwb_rc *rc, struct uwb_dev *uwb_dev); + +/** + * Callback function for 'uwb_{dev,rc}_foreach()'. + * + * @dev: Linux device instance + * 'uwb_dev = container_of(dev, struct uwb_dev, dev)' + * @priv: Data passed by the caller to 'uwb_{dev,rc}_foreach()'. + * + * @returns: 0 to continue the iterations, any other val to stop + * iterating and return the value to the caller of + * _foreach(). + */ +typedef int (*uwb_dev_for_each_f)(struct device *dev, void *priv); +int uwb_dev_for_each(struct uwb_rc *rc, uwb_dev_for_each_f func, void *priv); + +struct uwb_rc *uwb_rc_alloc(void); +struct uwb_rc *uwb_rc_get_by_dev(const struct uwb_dev_addr *); +struct uwb_rc *uwb_rc_get_by_grandpa(const struct device *); +void uwb_rc_put(struct uwb_rc *rc); + +typedef void (*uwb_rc_cmd_cb_f)(struct uwb_rc *rc, void *arg, + struct uwb_rceb *reply, ssize_t reply_size); + +int uwb_rc_cmd_async(struct uwb_rc *rc, const char *cmd_name, + struct uwb_rccb *cmd, size_t cmd_size, + u8 expected_type, u16 expected_event, + uwb_rc_cmd_cb_f cb, void *arg); +ssize_t uwb_rc_cmd(struct uwb_rc *rc, const char *cmd_name, + struct uwb_rccb *cmd, size_t cmd_size, + struct uwb_rceb *reply, size_t reply_size); +ssize_t uwb_rc_vcmd(struct uwb_rc *rc, const char *cmd_name, + struct uwb_rccb *cmd, size_t cmd_size, + u8 expected_type, u16 expected_event, + struct uwb_rceb **preply); +ssize_t uwb_rc_get_ie(struct uwb_rc *, struct uwb_rc_evt_get_ie **); +int uwb_bg_joined(struct uwb_rc *rc); + +size_t __uwb_addr_print(char *, size_t, const unsigned char *, int); + +int uwb_rc_dev_addr_set(struct uwb_rc *, const struct uwb_dev_addr *); +int uwb_rc_dev_addr_get(struct uwb_rc *, struct uwb_dev_addr *); +int uwb_rc_mac_addr_set(struct uwb_rc *, const struct uwb_mac_addr *); +int uwb_rc_mac_addr_get(struct uwb_rc *, struct uwb_mac_addr *); +int __uwb_mac_addr_assigned_check(struct device *, void *); +int __uwb_dev_addr_assigned_check(struct device *, void *); + +/* Print in @buf a pretty repr of @addr */ +static inline size_t uwb_dev_addr_print(char *buf, size_t buf_size, + const struct uwb_dev_addr *addr) +{ + return __uwb_addr_print(buf, buf_size, addr->data, 0); +} + +/* Print in @buf a pretty repr of @addr */ +static inline size_t uwb_mac_addr_print(char *buf, size_t buf_size, + const struct uwb_mac_addr *addr) +{ + return __uwb_addr_print(buf, buf_size, addr->data, 1); +} + +/* @returns 0 if device addresses @addr2 and @addr1 are equal */ +static inline int uwb_dev_addr_cmp(const struct uwb_dev_addr *addr1, + const struct uwb_dev_addr *addr2) +{ + return memcmp(addr1, addr2, sizeof(*addr1)); +} + +/* @returns 0 if MAC addresses @addr2 and @addr1 are equal */ +static inline int uwb_mac_addr_cmp(const struct uwb_mac_addr *addr1, + const struct uwb_mac_addr *addr2) +{ + return memcmp(addr1, addr2, sizeof(*addr1)); +} + +/* @returns !0 if a MAC @addr is a broadcast address */ +static inline int uwb_mac_addr_bcast(const struct uwb_mac_addr *addr) +{ + struct uwb_mac_addr bcast = { + .data = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff } + }; + return !uwb_mac_addr_cmp(addr, &bcast); +} + +/* @returns !0 if a MAC @addr is all zeroes*/ +static inline int uwb_mac_addr_unset(const struct uwb_mac_addr *addr) +{ + struct uwb_mac_addr unset = { + .data = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } + }; + return !uwb_mac_addr_cmp(addr, &unset); +} + +/* @returns !0 if the address is in use. */ +static inline unsigned __uwb_dev_addr_assigned(struct uwb_rc *rc, + struct uwb_dev_addr *addr) +{ + return uwb_dev_for_each(rc, __uwb_dev_addr_assigned_check, addr); +} + +/* + * UWB Radio Controller API + * + * This API is used (in addition to the general API) to implement UWB + * Radio Controllers. + */ +void uwb_rc_init(struct uwb_rc *); +int uwb_rc_add(struct uwb_rc *, struct device *dev, void *rc_priv); +void uwb_rc_rm(struct uwb_rc *); +void uwb_rc_neh_grok(struct uwb_rc *, void *, size_t); +void uwb_rc_neh_error(struct uwb_rc *, int); +void uwb_rc_reset_all(struct uwb_rc *rc); + +/** + * uwb_rsv_is_owner - is the owner of this reservation the RC? + * @rsv: the reservation + */ +static inline bool uwb_rsv_is_owner(struct uwb_rsv *rsv) +{ + return rsv->owner == &rsv->rc->uwb_dev; +} + +/** + * Events generated by UWB that can be passed to any listeners + * + * Higher layers can register callback functions with the radio + * controller using uwb_notifs_register(). The radio controller + * maintains a list of all registered handlers and will notify all + * nodes when an event occurs. + */ +enum uwb_notifs { + UWB_NOTIF_BG_JOIN = 0, /* radio controller joined a beacon group */ + UWB_NOTIF_BG_LEAVE = 1, /* radio controller left a beacon group */ + UWB_NOTIF_ONAIR, + UWB_NOTIF_OFFAIR, +}; + +/* Callback function registered with UWB */ +struct uwb_notifs_handler { + struct list_head list_node; + void (*cb)(void *, struct uwb_dev *, enum uwb_notifs); + void *data; +}; + +int uwb_notifs_register(struct uwb_rc *, struct uwb_notifs_handler *); +int uwb_notifs_deregister(struct uwb_rc *, struct uwb_notifs_handler *); + + +/** + * UWB radio controller Event Size Entry (for creating entry tables) + * + * WUSB and WHCI define events and notifications, and they might have + * fixed or variable size. + * + * Each event/notification has a size which is not necessarily known + * in advance based on the event code. As well, vendor specific + * events/notifications will have a size impossible to determine + * unless we know about the device's specific details. + * + * It was way too smart of the spec writers not to think that it would + * be impossible for a generic driver to skip over vendor specific + * events/notifications if there are no LENGTH fields in the HEADER of + * each message...the transaction size cannot be counted on as the + * spec does not forbid to pack more than one event in a single + * transaction. + * + * Thus, we guess sizes with tables (or for events, when you know the + * size ahead of time you can use uwb_rc_neh_extra_size*()). We + * register tables with the known events and their sizes, and then we + * traverse those tables. For those with variable length, we provide a + * way to lookup the size inside the event/notification's + * payload. This allows device-specific event size tables to be + * registered. + * + * @size: Size of the payload + * + * @offset: if != 0, at offset @offset-1 starts a field with a length + * that has to be added to @size. The format of the field is + * given by @type. + * + * @type: Type and length of the offset field. Most common is LE 16 + * bits (that's why that is zero); others are there mostly to + * cover for bugs and weirdos. + */ +struct uwb_est_entry { + size_t size; + unsigned offset; + enum { UWB_EST_16 = 0, UWB_EST_8 = 1 } type; +}; + +int uwb_est_register(u8 type, u8 code_high, u16 vendor, u16 product, + const struct uwb_est_entry *, size_t entries); +int uwb_est_unregister(u8 type, u8 code_high, u16 vendor, u16 product, + const struct uwb_est_entry *, size_t entries); +ssize_t uwb_est_find_size(struct uwb_rc *rc, const struct uwb_rceb *rceb, + size_t len); + +/* -- Misc */ + +enum { + EDC_MAX_ERRORS = 10, + EDC_ERROR_TIMEFRAME = HZ, +}; + +/* error density counter */ +struct edc { + unsigned long timestart; + u16 errorcount; +}; + +static inline +void edc_init(struct edc *edc) +{ + edc->timestart = jiffies; +} + +/* Called when an error occured. + * This is way to determine if the number of acceptable errors per time + * period has been exceeded. It is not accurate as there are cases in which + * this scheme will not work, for example if there are periodic occurences + * of errors that straddle updates to the start time. This scheme is + * sufficient for our usage. + * + * @returns 1 if maximum acceptable errors per timeframe has been exceeded. + */ +static inline int edc_inc(struct edc *err_hist, u16 max_err, u16 timeframe) +{ + unsigned long now; + + now = jiffies; + if (now - err_hist->timestart > timeframe) { + err_hist->errorcount = 1; + err_hist->timestart = now; + } else if (++err_hist->errorcount > max_err) { + err_hist->errorcount = 0; + err_hist->timestart = now; + return 1; + } + return 0; +} + + +/* Information Element handling */ + +/* For representing the state of writing to a buffer when iterating */ +struct uwb_buf_ctx { + char *buf; + size_t bytes, size; +}; + +typedef int (*uwb_ie_f)(struct uwb_dev *, const struct uwb_ie_hdr *, + size_t, void *); +struct uwb_ie_hdr *uwb_ie_next(void **ptr, size_t *len); +ssize_t uwb_ie_for_each(struct uwb_dev *uwb_dev, uwb_ie_f fn, void *data, + const void *buf, size_t size); +int uwb_ie_dump_hex(struct uwb_dev *, const struct uwb_ie_hdr *, + size_t, void *); +int uwb_rc_set_ie(struct uwb_rc *, struct uwb_rc_cmd_set_ie *); +struct uwb_ie_hdr *uwb_ie_next(void **ptr, size_t *len); + + +/* + * Transmission statistics + * + * UWB uses LQI and RSSI (one byte values) for reporting radio signal + * strength and line quality indication. We do quick and dirty + * averages of those. They are signed values, btw. + * + * For 8 bit quantities, we keep the min, the max, an accumulator + * (@sigma) and a # of samples. When @samples gets to 255, we compute + * the average (@sigma / @samples), place it in @sigma and reset + * @samples to 1 (so we use it as the first sample). + * + * Now, statistically speaking, probably I am kicking the kidneys of + * some books I have in my shelves collecting dust, but I just want to + * get an approx, not the Nobel. + * + * LOCKING: there is no locking per se, but we try to keep a lockless + * schema. Only _add_samples() modifies the values--as long as you + * have other locking on top that makes sure that no two calls of + * _add_sample() happen at the same time, then we are fine. Now, for + * resetting the values we just set @samples to 0 and that makes the + * next _add_sample() to start with defaults. Reading the values in + * _show() currently can race, so you need to make sure the calls are + * under the same lock that protects calls to _add_sample(). FIXME: + * currently unlocked (It is not ultraprecise but does the trick. Bite + * me). + */ +struct stats { + s8 min, max; + s16 sigma; + atomic_t samples; +}; + +static inline +void stats_init(struct stats *stats) +{ + atomic_set(&stats->samples, 0); + wmb(); +} + +static inline +void stats_add_sample(struct stats *stats, s8 sample) +{ + s8 min, max; + s16 sigma; + unsigned samples = atomic_read(&stats->samples); + if (samples == 0) { /* it was zero before, so we initialize */ + min = 127; + max = -128; + sigma = 0; + } else { + min = stats->min; + max = stats->max; + sigma = stats->sigma; + } + + if (sample < min) /* compute new values */ + min = sample; + else if (sample > max) + max = sample; + sigma += sample; + + stats->min = min; /* commit */ + stats->max = max; + stats->sigma = sigma; + if (atomic_add_return(1, &stats->samples) > 255) { + /* wrapped around! reset */ + stats->sigma = sigma / 256; + atomic_set(&stats->samples, 1); + } +} + +static inline ssize_t stats_show(struct stats *stats, char *buf) +{ + int min, max, avg; + int samples = atomic_read(&stats->samples); + if (samples == 0) + min = max = avg = 0; + else { + min = stats->min; + max = stats->max; + avg = stats->sigma / samples; + } + return scnprintf(buf, PAGE_SIZE, "%d %d %d\n", min, max, avg); +} + +static inline ssize_t stats_store(struct stats *stats, const char *buf, + size_t size) +{ + stats_init(stats); + return size; +} + +#endif /* #ifndef __LINUX__UWB_H__ */ |