diff options
| -rw-r--r-- | drivers/firmware/arm_scmi/notify.c | 367 | ||||
| -rw-r--r-- | drivers/firmware/arm_scmi/notify.h | 10 |
2 files changed, 373 insertions, 4 deletions
diff --git a/drivers/firmware/arm_scmi/notify.c b/drivers/firmware/arm_scmi/notify.c index 79615eef0148..c4d006cfde88 100644 --- a/drivers/firmware/arm_scmi/notify.c +++ b/drivers/firmware/arm_scmi/notify.c @@ -47,6 +47,27 @@ * as described in the SCMI Protocol specification, while src_id represents an * optional, protocol dependent, source identifier (like domain_id, perf_id * or sensor_id and so forth). + * + * Upon reception of a notification message from the platform the SCMI RX ISR + * passes the received message payload and some ancillary information (including + * an arrival timestamp in nanoseconds) to the core via @scmi_notify() which + * pushes the event-data itself on a protocol-dedicated kfifo queue for further + * deferred processing as specified in @scmi_events_dispatcher(). + * + * Each protocol has it own dedicated work_struct and worker which, once kicked + * by the ISR, takes care to empty its own dedicated queue, deliverying the + * queued items into the proper notification-chain: notifications processing can + * proceed concurrently on distinct workers only between events belonging to + * different protocols while delivery of events within the same protocol is + * still strictly sequentially ordered by time of arrival. + * + * Events' information is then extracted from the SCMI Notification messages and + * conveyed, converted into a custom per-event report struct, as the void *data + * param to the user callback provided by the registered notifier_block, so that + * from the user perspective his callback will look invoked like: + * + * int user_cb(struct notifier_block *nb, unsigned long event_id, void *report) + * */ #define dev_fmt(fmt) "SCMI Notifications - " fmt @@ -67,6 +88,7 @@ #include <linux/scmi_protocol.h> #include <linux/slab.h> #include <linux/types.h> +#include <linux/workqueue.h> #include "notify.h" @@ -164,6 +186,13 @@ #define REVT_NOTIFY_DISABLE(revt, eid, sid) \ REVT_NOTIFY_SET_STATUS((revt), (eid), (sid), false) +#define REVT_FILL_REPORT(revt, ...) \ +({ \ + typeof(revt) r = revt; \ + r->proto->ops->fill_custom_report(r->proto->ni->handle, \ + __VA_ARGS__); \ +}) + #define SCMI_PENDING_HASH_SZ 4 #define SCMI_REGISTERED_HASH_SZ 6 @@ -175,6 +204,7 @@ struct scmi_registered_events_desc; * @gid: GroupID used for devres * @handle: A reference to the platform instance * @init_work: A work item to perform final initializations of pending handlers + * @notify_wq: A reference to the allocated Kernel cmwq * @pending_mtx: A mutex to protect @pending_events_handlers * @registered_protocols: A statically allocated array containing pointers to * all the registered protocol-level specific information @@ -189,6 +219,7 @@ struct scmi_notify_instance { void *gid; struct scmi_handle *handle; struct work_struct init_work; + struct workqueue_struct *notify_wq; /* lock to protect pending_events_handlers */ struct mutex pending_mtx; struct scmi_registered_events_desc **registered_protocols; @@ -199,12 +230,16 @@ struct scmi_notify_instance { * struct events_queue - Describes a queue and its associated worker * @sz: Size in bytes of the related kfifo * @kfifo: A dedicated Kernel kfifo descriptor + * @notify_work: A custom work item bound to this queue + * @wq: A reference to the associated workqueue * * Each protocol has its own dedicated events_queue descriptor. */ struct events_queue { - size_t sz; - struct kfifo kfifo; + size_t sz; + struct kfifo kfifo; + struct work_struct notify_work; + struct workqueue_struct *wq; }; /** @@ -328,10 +363,271 @@ struct scmi_event_handler { #define IS_HNDL_PENDING(hndl) (!(hndl)->r_evt) +static struct scmi_event_handler * +scmi_get_active_handler(struct scmi_notify_instance *ni, u32 evt_key); +static void scmi_put_active_handler(struct scmi_notify_instance *ni, + struct scmi_event_handler *hndl); static void scmi_put_handler_unlocked(struct scmi_notify_instance *ni, struct scmi_event_handler *hndl); /** + * scmi_lookup_and_call_event_chain() - Lookup the proper chain and call it + * @ni: A reference to the notification instance to use + * @evt_key: The key to use to lookup the related notification chain + * @report: The customized event-specific report to pass down to the callbacks + * as their *data parameter. + */ +static inline void +scmi_lookup_and_call_event_chain(struct scmi_notify_instance *ni, + u32 evt_key, void *report) +{ + int ret; + struct scmi_event_handler *hndl; + + /* + * Here ensure the event handler cannot vanish while using it. + * It is legitimate, though, for an handler not to be found at all here, + * e.g. when it has been unregistered by the user after some events had + * already been queued. + */ + hndl = scmi_get_active_handler(ni, evt_key); + if (!hndl) + return; + + ret = blocking_notifier_call_chain(&hndl->chain, + KEY_XTRACT_EVT_ID(evt_key), + report); + /* Notifiers are NOT supposed to cut the chain ... */ + WARN_ON_ONCE(ret & NOTIFY_STOP_MASK); + + scmi_put_active_handler(ni, hndl); +} + +/** + * scmi_process_event_header() - Dequeue and process an event header + * @eq: The queue to use + * @pd: The protocol descriptor to use + * + * Read an event header from the protocol queue into the dedicated scratch + * buffer and looks for a matching registered event; in case an anomalously + * sized read is detected just flush the queue. + * + * Return: + * * a reference to the matching registered event when found + * * ERR_PTR(-EINVAL) when NO registered event could be found + * * NULL when the queue is empty + */ +static inline struct scmi_registered_event * +scmi_process_event_header(struct events_queue *eq, + struct scmi_registered_events_desc *pd) +{ + unsigned int outs; + struct scmi_registered_event *r_evt; + + outs = kfifo_out(&eq->kfifo, pd->eh, + sizeof(struct scmi_event_header)); + if (!outs) + return NULL; + if (outs != sizeof(struct scmi_event_header)) { + dev_err(pd->ni->handle->dev, "corrupted EVT header. Flush.\n"); + kfifo_reset_out(&eq->kfifo); + return NULL; + } + + r_evt = SCMI_GET_REVT_FROM_PD(pd, pd->eh->evt_id); + if (!r_evt) + r_evt = ERR_PTR(-EINVAL); + + return r_evt; +} + +/** + * scmi_process_event_payload() - Dequeue and process an event payload + * @eq: The queue to use + * @pd: The protocol descriptor to use + * @r_evt: The registered event descriptor to use + * + * Read an event payload from the protocol queue into the dedicated scratch + * buffer, fills a custom report and then look for matching event handlers and + * call them; skip any unknown event (as marked by scmi_process_event_header()) + * and in case an anomalously sized read is detected just flush the queue. + * + * Return: False when the queue is empty + */ +static inline bool +scmi_process_event_payload(struct events_queue *eq, + struct scmi_registered_events_desc *pd, + struct scmi_registered_event *r_evt) +{ + u32 src_id, key; + unsigned int outs; + void *report = NULL; + + outs = kfifo_out(&eq->kfifo, pd->eh->payld, pd->eh->payld_sz); + if (!outs) + return false; + + /* Any in-flight event has now been officially processed */ + pd->in_flight = NULL; + + if (outs != pd->eh->payld_sz) { + dev_err(pd->ni->handle->dev, "corrupted EVT Payload. Flush.\n"); + kfifo_reset_out(&eq->kfifo); + return false; + } + + if (IS_ERR(r_evt)) { + dev_warn(pd->ni->handle->dev, + "SKIP UNKNOWN EVT - proto:%X evt:%d\n", + pd->id, pd->eh->evt_id); + return true; + } + + report = REVT_FILL_REPORT(r_evt, pd->eh->evt_id, pd->eh->timestamp, + pd->eh->payld, pd->eh->payld_sz, + r_evt->report, &src_id); + if (!report) { + dev_err(pd->ni->handle->dev, + "report not available - proto:%X evt:%d\n", + pd->id, pd->eh->evt_id); + return true; + } + + /* At first search for a generic ALL src_ids handler... */ + key = MAKE_ALL_SRCS_KEY(pd->id, pd->eh->evt_id); + scmi_lookup_and_call_event_chain(pd->ni, key, report); + + /* ...then search for any specific src_id */ + key = MAKE_HASH_KEY(pd->id, pd->eh->evt_id, src_id); + scmi_lookup_and_call_event_chain(pd->ni, key, report); + + return true; +} + +/** + * scmi_events_dispatcher() - Common worker logic for all work items. + * @work: The work item to use, which is associated to a dedicated events_queue + * + * Logic: + * 1. dequeue one pending RX notification (queued in SCMI RX ISR context) + * 2. generate a custom event report from the received event message + * 3. lookup for any registered ALL_SRC_IDs handler: + * - > call the related notification chain passing in the report + * 4. lookup for any registered specific SRC_ID handler: + * - > call the related notification chain passing in the report + * + * Note that: + * * a dedicated per-protocol kfifo queue is used: in this way an anomalous + * flood of events cannot saturate other protocols' queues. + * * each per-protocol queue is associated to a distinct work_item, which + * means, in turn, that: + * + all protocols can process their dedicated queues concurrently + * (since notify_wq:max_active != 1) + * + anyway at most one worker instance is allowed to run on the same queue + * concurrently: this ensures that we can have only one concurrent + * reader/writer on the associated kfifo, so that we can use it lock-less + * + * Context: Process context. + */ +static void scmi_events_dispatcher(struct work_struct *work) +{ + struct events_queue *eq; + struct scmi_registered_events_desc *pd; + struct scmi_registered_event *r_evt; + + eq = container_of(work, struct events_queue, notify_work); + pd = container_of(eq, struct scmi_registered_events_desc, equeue); + /* + * In order to keep the queue lock-less and the number of memcopies + * to the bare minimum needed, the dispatcher accounts for the + * possibility of per-protocol in-flight events: i.e. an event whose + * reception could end up being split across two subsequent runs of this + * worker, first the header, then the payload. + */ + do { + if (!pd->in_flight) { + r_evt = scmi_process_event_header(eq, pd); + if (!r_evt) + break; + pd->in_flight = r_evt; + } else { + r_evt = pd->in_flight; + } + } while (scmi_process_event_payload(eq, pd, r_evt)); +} + +/** + * scmi_notify() - Queues a notification for further deferred processing + * @handle: The handle identifying the platform instance from which the + * dispatched event is generated + * @proto_id: Protocol ID + * @evt_id: Event ID (msgID) + * @buf: Event Message Payload (without the header) + * @len: Event Message Payload size + * @ts: RX Timestamp in nanoseconds (boottime) + * + * Context: Called in interrupt context to queue a received event for + * deferred processing. + * + * Return: 0 on Success + */ +int scmi_notify(const struct scmi_handle *handle, u8 proto_id, u8 evt_id, + const void *buf, size_t len, u64 ts) +{ + struct scmi_registered_event *r_evt; + struct scmi_event_header eh; + struct scmi_notify_instance *ni; + + /* Ensure notify_priv is updated */ + smp_rmb(); + if (!handle->notify_priv) + return 0; + ni = handle->notify_priv; + + r_evt = SCMI_GET_REVT(ni, proto_id, evt_id); + if (!r_evt) + return -EINVAL; + + if (len > r_evt->evt->max_payld_sz) { + dev_err(handle->dev, "discard badly sized message\n"); + return -EINVAL; + } + if (kfifo_avail(&r_evt->proto->equeue.kfifo) < sizeof(eh) + len) { + dev_warn(handle->dev, + "queue full, dropping proto_id:%d evt_id:%d ts:%lld\n", + proto_id, evt_id, ts); + return -ENOMEM; + } + + eh.timestamp = ts; + eh.evt_id = evt_id; + eh.payld_sz = len; + /* + * Header and payload are enqueued with two distinct kfifo_in() (so non + * atomic), but this situation is handled properly on the consumer side + * with in-flight events tracking. + */ + kfifo_in(&r_evt->proto->equeue.kfifo, &eh, sizeof(eh)); + kfifo_in(&r_evt->proto->equeue.kfifo, buf, len); + /* + * Don't care about return value here since we just want to ensure that + * a work is queued all the times whenever some items have been pushed + * on the kfifo: + * - if work was already queued it will simply fail to queue a new one + * since it is not needed + * - if work was not queued already it will be now, even in case work + * was in fact already running: this behavior avoids any possible race + * when this function pushes new items onto the kfifos after the + * related executing worker had already determined the kfifo to be + * empty and it was terminating. + */ + queue_work(r_evt->proto->equeue.wq, + &r_evt->proto->equeue.notify_work); + + return 0; +} + +/** * scmi_kfifo_free() - Devres action helper to free the kfifo * @kfifo: The kfifo to free */ @@ -353,13 +649,22 @@ static void scmi_kfifo_free(void *kfifo) static int scmi_initialize_events_queue(struct scmi_notify_instance *ni, struct events_queue *equeue, size_t sz) { + int ret; + if (kfifo_alloc(&equeue->kfifo, sz, GFP_KERNEL)) return -ENOMEM; /* Size could have been roundup to power-of-two */ equeue->sz = kfifo_size(&equeue->kfifo); - return devm_add_action_or_reset(ni->handle->dev, scmi_kfifo_free, - &equeue->kfifo); + ret = devm_add_action_or_reset(ni->handle->dev, scmi_kfifo_free, + &equeue->kfifo); + if (ret) + return ret; + + INIT_WORK(&equeue->notify_work, scmi_events_dispatcher); + equeue->wq = ni->notify_wq; + + return ret; } /** @@ -759,6 +1064,37 @@ scmi_get_or_create_handler(struct scmi_notify_instance *ni, u32 evt_key) } /** + * scmi_get_active_handler() - Helper to get active handlers only + * @ni: A reference to the notification instance to use + * @evt_key: The event key to use + * + * Search for the desired handler matching the key only in the per-protocol + * table of registered handlers: this is called only from the dispatching path + * so want to be as quick as possible and do not care about pending. + * + * Return: A properly refcounted active handler + */ +static struct scmi_event_handler * +scmi_get_active_handler(struct scmi_notify_instance *ni, u32 evt_key) +{ + struct scmi_registered_event *r_evt; + struct scmi_event_handler *hndl = NULL; + + r_evt = SCMI_GET_REVT(ni, KEY_XTRACT_PROTO_ID(evt_key), + KEY_XTRACT_EVT_ID(evt_key)); + if (r_evt) { + mutex_lock(&r_evt->proto->registered_mtx); + hndl = KEY_FIND(r_evt->proto->registered_events_handlers, + hndl, evt_key); + if (hndl) + refcount_inc(&hndl->users); + mutex_unlock(&r_evt->proto->registered_mtx); + } + + return hndl; +} + +/** * __scmi_enable_evt() - Enable/disable events generation * @r_evt: The registered event to act upon * @src_id: The src_id to act upon @@ -883,6 +1219,16 @@ static void scmi_put_handler(struct scmi_notify_instance *ni, mutex_unlock(&ni->pending_mtx); } +static void scmi_put_active_handler(struct scmi_notify_instance *ni, + struct scmi_event_handler *hndl) +{ + struct scmi_registered_event *r_evt = hndl->r_evt; + + mutex_lock(&r_evt->proto->registered_mtx); + scmi_put_handler_unlocked(ni, hndl); + mutex_unlock(&r_evt->proto->registered_mtx); +} + /** * scmi_event_handler_enable_events() - Enable events associated to an handler * @hndl: The Event handler to act upon @@ -1121,6 +1467,12 @@ int scmi_notification_init(struct scmi_handle *handle) ni->gid = gid; ni->handle = handle; + ni->notify_wq = alloc_workqueue("scmi_notify", + WQ_UNBOUND | WQ_FREEZABLE | WQ_SYSFS, + 0); + if (!ni->notify_wq) + goto err; + ni->registered_protocols = devm_kcalloc(handle->dev, SCMI_MAX_PROTO, sizeof(char *), GFP_KERNEL); if (!ni->registered_protocols) @@ -1162,5 +1514,12 @@ void scmi_notification_exit(struct scmi_handle *handle) return; ni = handle->notify_priv; + handle->notify_priv = NULL; + /* Ensure handle is up to date */ + smp_wmb(); + + /* Destroy while letting pending work complete */ + destroy_workqueue(ni->notify_wq); + devres_release_group(ni->handle->dev, ni->gid); } diff --git a/drivers/firmware/arm_scmi/notify.h b/drivers/firmware/arm_scmi/notify.h index 48702e42995f..3791bb7aa79b 100644 --- a/drivers/firmware/arm_scmi/notify.h +++ b/drivers/firmware/arm_scmi/notify.h @@ -35,6 +35,11 @@ struct scmi_event { * @set_notify_enabled: Enable/disable the required evt_id/src_id notifications * using the proper custom protocol commands. * Return 0 on Success + * @fill_custom_report: fills a custom event report from the provided + * event message payld identifying the event + * specific src_id. + * Return NULL on failure otherwise @report now fully + * populated * * Context: Helpers described in &struct scmi_event_ops are called only in * process context. @@ -42,6 +47,9 @@ struct scmi_event { struct scmi_event_ops { int (*set_notify_enabled)(const struct scmi_handle *handle, u8 evt_id, u32 src_id, bool enabled); + void *(*fill_custom_report)(const struct scmi_handle *handle, + u8 evt_id, u64 timestamp, const void *payld, + size_t payld_sz, void *report, u32 *src_id); }; int scmi_notification_init(struct scmi_handle *handle); @@ -52,5 +60,7 @@ int scmi_register_protocol_events(const struct scmi_handle *handle, const struct scmi_event_ops *ops, const struct scmi_event *evt, int num_events, int num_sources); +int scmi_notify(const struct scmi_handle *handle, u8 proto_id, u8 evt_id, + const void *buf, size_t len, u64 ts); #endif /* _SCMI_NOTIFY_H */ |