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Diffstat (limited to 'drivers/firmware/arm_scmi/notify.c')
| -rw-r--r-- | drivers/firmware/arm_scmi/notify.c | 1712 |
1 files changed, 1712 insertions, 0 deletions
diff --git a/drivers/firmware/arm_scmi/notify.c b/drivers/firmware/arm_scmi/notify.c new file mode 100644 index 000000000..0efd20cd9 --- /dev/null +++ b/drivers/firmware/arm_scmi/notify.c @@ -0,0 +1,1712 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * System Control and Management Interface (SCMI) Notification support + * + * Copyright (C) 2020-2021 ARM Ltd. + */ +/** + * DOC: Theory of operation + * + * SCMI Protocol specification allows the platform to signal events to + * interested agents via notification messages: this is an implementation + * of the dispatch and delivery of such notifications to the interested users + * inside the Linux kernel. + * + * An SCMI Notification core instance is initialized for each active platform + * instance identified by the means of the usual &struct scmi_handle. + * + * Each SCMI Protocol implementation, during its initialization, registers with + * this core its set of supported events using scmi_register_protocol_events(): + * all the needed descriptors are stored in the &struct registered_protocols and + * &struct registered_events arrays. + * + * Kernel users interested in some specific event can register their callbacks + * providing the usual notifier_block descriptor, since this core implements + * events' delivery using the standard Kernel notification chains machinery. + * + * Given the number of possible events defined by SCMI and the extensibility + * of the SCMI Protocol itself, the underlying notification chains are created + * and destroyed dynamically on demand depending on the number of users + * effectively registered for an event, so that no support structures or chains + * are allocated until at least one user has registered a notifier_block for + * such event. Similarly, events' generation itself is enabled at the platform + * level only after at least one user has registered, and it is shutdown after + * the last user for that event has gone. + * + * All users provided callbacks and allocated notification-chains are stored in + * the @registered_events_handlers hashtable. Callbacks' registration requests + * for still to be registered events are instead kept in the dedicated common + * hashtable @pending_events_handlers. + * + * An event is identified univocally by the tuple (proto_id, evt_id, src_id) + * and is served by its own dedicated notification chain; information contained + * in such tuples is used, in a few different ways, to generate the needed + * hash-keys. + * + * Here proto_id and evt_id are simply the protocol_id and message_id numbers + * 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 +#define pr_fmt(fmt) "SCMI Notifications - " fmt + +#include <linux/bitfield.h> +#include <linux/bug.h> +#include <linux/compiler.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/hashtable.h> +#include <linux/kernel.h> +#include <linux/ktime.h> +#include <linux/kfifo.h> +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/notifier.h> +#include <linux/refcount.h> +#include <linux/scmi_protocol.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <linux/workqueue.h> + +#include "common.h" +#include "notify.h" + +#define SCMI_MAX_PROTO 256 + +#define PROTO_ID_MASK GENMASK(31, 24) +#define EVT_ID_MASK GENMASK(23, 16) +#define SRC_ID_MASK GENMASK(15, 0) + +/* + * Builds an unsigned 32bit key from the given input tuple to be used + * as a key in hashtables. + */ +#define MAKE_HASH_KEY(p, e, s) \ + (FIELD_PREP(PROTO_ID_MASK, (p)) | \ + FIELD_PREP(EVT_ID_MASK, (e)) | \ + FIELD_PREP(SRC_ID_MASK, (s))) + +#define MAKE_ALL_SRCS_KEY(p, e) MAKE_HASH_KEY((p), (e), SRC_ID_MASK) + +/* + * Assumes that the stored obj includes its own hash-key in a field named 'key': + * with this simplification this macro can be equally used for all the objects' + * types hashed by this implementation. + * + * @__ht: The hashtable name + * @__obj: A pointer to the object type to be retrieved from the hashtable; + * it will be used as a cursor while scanning the hastable and it will + * be possibly left as NULL when @__k is not found + * @__k: The key to search for + */ +#define KEY_FIND(__ht, __obj, __k) \ +({ \ + typeof(__k) k_ = __k; \ + typeof(__obj) obj_; \ + \ + hash_for_each_possible((__ht), obj_, hash, k_) \ + if (obj_->key == k_) \ + break; \ + __obj = obj_; \ +}) + +#define KEY_XTRACT_PROTO_ID(key) FIELD_GET(PROTO_ID_MASK, (key)) +#define KEY_XTRACT_EVT_ID(key) FIELD_GET(EVT_ID_MASK, (key)) +#define KEY_XTRACT_SRC_ID(key) FIELD_GET(SRC_ID_MASK, (key)) + +/* + * A set of macros used to access safely @registered_protocols and + * @registered_events arrays; these are fixed in size and each entry is possibly + * populated at protocols' registration time and then only read but NEVER + * modified or removed. + */ +#define SCMI_GET_PROTO(__ni, __pid) \ +({ \ + typeof(__ni) ni_ = __ni; \ + struct scmi_registered_events_desc *__pd = NULL; \ + \ + if (ni_) \ + __pd = READ_ONCE(ni_->registered_protocols[(__pid)]); \ + __pd; \ +}) + +#define SCMI_GET_REVT_FROM_PD(__pd, __eid) \ +({ \ + typeof(__pd) pd_ = __pd; \ + typeof(__eid) eid_ = __eid; \ + struct scmi_registered_event *__revt = NULL; \ + \ + if (pd_ && eid_ < pd_->num_events) \ + __revt = READ_ONCE(pd_->registered_events[eid_]); \ + __revt; \ +}) + +#define SCMI_GET_REVT(__ni, __pid, __eid) \ +({ \ + struct scmi_registered_event *__revt; \ + struct scmi_registered_events_desc *__pd; \ + \ + __pd = SCMI_GET_PROTO((__ni), (__pid)); \ + __revt = SCMI_GET_REVT_FROM_PD(__pd, (__eid)); \ + __revt; \ +}) + +/* A couple of utility macros to limit cruft when calling protocols' helpers */ +#define REVT_NOTIFY_SET_STATUS(revt, eid, sid, state) \ +({ \ + typeof(revt) r = revt; \ + r->proto->ops->set_notify_enabled(r->proto->ph, \ + (eid), (sid), (state)); \ +}) + +#define REVT_NOTIFY_ENABLE(revt, eid, sid) \ + REVT_NOTIFY_SET_STATUS((revt), (eid), (sid), true) + +#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->ph, \ + __VA_ARGS__); \ +}) + +#define SCMI_PENDING_HASH_SZ 4 +#define SCMI_REGISTERED_HASH_SZ 6 + +struct scmi_registered_events_desc; + +/** + * struct scmi_notify_instance - Represents an instance of the notification + * core + * @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 + * related to events' handling + * @pending_events_handlers: An hashtable containing all pending events' + * handlers descriptors + * + * Each platform instance, represented by a handle, has its own instance of + * the notification subsystem represented by this structure. + */ +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; + DECLARE_HASHTABLE(pending_events_handlers, SCMI_PENDING_HASH_SZ); +}; + +/** + * 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; + struct work_struct notify_work; + struct workqueue_struct *wq; +}; + +/** + * struct scmi_event_header - A utility header + * @timestamp: The timestamp, in nanoseconds (boottime), which was associated + * to this event as soon as it entered the SCMI RX ISR + * @payld_sz: Effective size of the embedded message payload which follows + * @evt_id: Event ID (corresponds to the Event MsgID for this Protocol) + * @payld: A reference to the embedded event payload + * + * This header is prepended to each received event message payload before + * queueing it on the related &struct events_queue. + */ +struct scmi_event_header { + ktime_t timestamp; + size_t payld_sz; + unsigned char evt_id; + unsigned char payld[]; +}; + +struct scmi_registered_event; + +/** + * struct scmi_registered_events_desc - Protocol Specific information + * @id: Protocol ID + * @ops: Protocol specific and event-related operations + * @equeue: The embedded per-protocol events_queue + * @ni: A reference to the initialized instance descriptor + * @eh: A reference to pre-allocated buffer to be used as a scratch area by the + * deferred worker when fetching data from the kfifo + * @eh_sz: Size of the pre-allocated buffer @eh + * @in_flight: A reference to an in flight &struct scmi_registered_event + * @num_events: Number of events in @registered_events + * @registered_events: A dynamically allocated array holding all the registered + * events' descriptors, whose fixed-size is determined at + * compile time. + * @registered_mtx: A mutex to protect @registered_events_handlers + * @ph: SCMI protocol handle reference + * @registered_events_handlers: An hashtable containing all events' handlers + * descriptors registered for this protocol + * + * All protocols that register at least one event have their protocol-specific + * information stored here, together with the embedded allocated events_queue. + * These descriptors are stored in the @registered_protocols array at protocol + * registration time. + * + * Once these descriptors are successfully registered, they are NEVER again + * removed or modified since protocols do not unregister ever, so that, once + * we safely grab a NON-NULL reference from the array we can keep it and use it. + */ +struct scmi_registered_events_desc { + u8 id; + const struct scmi_event_ops *ops; + struct events_queue equeue; + struct scmi_notify_instance *ni; + struct scmi_event_header *eh; + size_t eh_sz; + void *in_flight; + int num_events; + struct scmi_registered_event **registered_events; + /* mutex to protect registered_events_handlers */ + struct mutex registered_mtx; + const struct scmi_protocol_handle *ph; + DECLARE_HASHTABLE(registered_events_handlers, SCMI_REGISTERED_HASH_SZ); +}; + +/** + * struct scmi_registered_event - Event Specific Information + * @proto: A reference to the associated protocol descriptor + * @evt: A reference to the associated event descriptor (as provided at + * registration time) + * @report: A pre-allocated buffer used by the deferred worker to fill a + * customized event report + * @num_sources: The number of possible sources for this event as stated at + * events' registration time + * @sources: A reference to a dynamically allocated array used to refcount the + * events' enable requests for all the existing sources + * @sources_mtx: A mutex to serialize the access to @sources + * + * All registered events are represented by one of these structures that are + * stored in the @registered_events array at protocol registration time. + * + * Once these descriptors are successfully registered, they are NEVER again + * removed or modified since protocols do not unregister ever, so that once we + * safely grab a NON-NULL reference from the table we can keep it and use it. + */ +struct scmi_registered_event { + struct scmi_registered_events_desc *proto; + const struct scmi_event *evt; + void *report; + u32 num_sources; + refcount_t *sources; + /* locking to serialize the access to sources */ + struct mutex sources_mtx; +}; + +/** + * struct scmi_event_handler - Event handler information + * @key: The used hashkey + * @users: A reference count for number of active users for this handler + * @r_evt: A reference to the associated registered event; when this is NULL + * this handler is pending, which means that identifies a set of + * callbacks intended to be attached to an event which is still not + * known nor registered by any protocol at that point in time + * @chain: The notification chain dedicated to this specific event tuple + * @hash: The hlist_node used for collision handling + * @enabled: A boolean which records if event's generation has been already + * enabled for this handler as a whole + * + * This structure collects all the information needed to process a received + * event identified by the tuple (proto_id, evt_id, src_id). + * These descriptors are stored in a per-protocol @registered_events_handlers + * table using as a key a value derived from that tuple. + */ +struct scmi_event_handler { + u32 key; + refcount_t users; + struct scmi_registered_event *r_evt; + struct blocking_notifier_head chain; + struct hlist_node hash; + bool enabled; +}; + +#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 bool 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, ktime_t ts) +{ + struct scmi_registered_event *r_evt; + struct scmi_event_header eh; + struct scmi_notify_instance *ni; + + ni = scmi_notification_instance_data_get(handle); + if (!ni) + return 0; + + 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, ktime_to_ns(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 + */ +static void scmi_kfifo_free(void *kfifo) +{ + kfifo_free((struct kfifo *)kfifo); +} + +/** + * scmi_initialize_events_queue() - Allocate/Initialize a kfifo buffer + * @ni: A reference to the notification instance to use + * @equeue: The events_queue to initialize + * @sz: Size of the kfifo buffer to allocate + * + * Allocate a buffer for the kfifo and initialize it. + * + * Return: 0 on Success + */ +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); + + 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; +} + +/** + * scmi_allocate_registered_events_desc() - Allocate a registered events' + * descriptor + * @ni: A reference to the &struct scmi_notify_instance notification instance + * to use + * @proto_id: Protocol ID + * @queue_sz: Size of the associated queue to allocate + * @eh_sz: Size of the event header scratch area to pre-allocate + * @num_events: Number of events to support (size of @registered_events) + * @ops: Pointer to a struct holding references to protocol specific helpers + * needed during events handling + * + * It is supposed to be called only once for each protocol at protocol + * initialization time, so it warns if the requested protocol is found already + * registered. + * + * Return: The allocated and registered descriptor on Success + */ +static struct scmi_registered_events_desc * +scmi_allocate_registered_events_desc(struct scmi_notify_instance *ni, + u8 proto_id, size_t queue_sz, size_t eh_sz, + int num_events, + const struct scmi_event_ops *ops) +{ + int ret; + struct scmi_registered_events_desc *pd; + + /* Ensure protocols are up to date */ + smp_rmb(); + if (WARN_ON(ni->registered_protocols[proto_id])) + return ERR_PTR(-EINVAL); + + pd = devm_kzalloc(ni->handle->dev, sizeof(*pd), GFP_KERNEL); + if (!pd) + return ERR_PTR(-ENOMEM); + pd->id = proto_id; + pd->ops = ops; + pd->ni = ni; + + ret = scmi_initialize_events_queue(ni, &pd->equeue, queue_sz); + if (ret) + return ERR_PTR(ret); + + pd->eh = devm_kzalloc(ni->handle->dev, eh_sz, GFP_KERNEL); + if (!pd->eh) + return ERR_PTR(-ENOMEM); + pd->eh_sz = eh_sz; + + pd->registered_events = devm_kcalloc(ni->handle->dev, num_events, + sizeof(char *), GFP_KERNEL); + if (!pd->registered_events) + return ERR_PTR(-ENOMEM); + pd->num_events = num_events; + + /* Initialize per protocol handlers table */ + mutex_init(&pd->registered_mtx); + hash_init(pd->registered_events_handlers); + + return pd; +} + +/** + * scmi_register_protocol_events() - Register Protocol Events with the core + * @handle: The handle identifying the platform instance against which the + * protocol's events are registered + * @proto_id: Protocol ID + * @ph: SCMI protocol handle. + * @ee: A structure describing the events supported by this protocol. + * + * Used by SCMI Protocols initialization code to register with the notification + * core the list of supported events and their descriptors: takes care to + * pre-allocate and store all needed descriptors, scratch buffers and event + * queues. + * + * Return: 0 on Success + */ +int scmi_register_protocol_events(const struct scmi_handle *handle, u8 proto_id, + const struct scmi_protocol_handle *ph, + const struct scmi_protocol_events *ee) +{ + int i; + unsigned int num_sources; + size_t payld_sz = 0; + struct scmi_registered_events_desc *pd; + struct scmi_notify_instance *ni; + const struct scmi_event *evt; + + if (!ee || !ee->ops || !ee->evts || !ph || + (!ee->num_sources && !ee->ops->get_num_sources)) + return -EINVAL; + + ni = scmi_notification_instance_data_get(handle); + if (!ni) + return -ENOMEM; + + /* num_sources cannot be <= 0 */ + if (ee->num_sources) { + num_sources = ee->num_sources; + } else { + int nsrc = ee->ops->get_num_sources(ph); + + if (nsrc <= 0) + return -EINVAL; + num_sources = nsrc; + } + + evt = ee->evts; + for (i = 0; i < ee->num_events; i++) + payld_sz = max_t(size_t, payld_sz, evt[i].max_payld_sz); + payld_sz += sizeof(struct scmi_event_header); + + pd = scmi_allocate_registered_events_desc(ni, proto_id, ee->queue_sz, + payld_sz, ee->num_events, + ee->ops); + if (IS_ERR(pd)) + return PTR_ERR(pd); + + pd->ph = ph; + for (i = 0; i < ee->num_events; i++, evt++) { + struct scmi_registered_event *r_evt; + + r_evt = devm_kzalloc(ni->handle->dev, sizeof(*r_evt), + GFP_KERNEL); + if (!r_evt) + return -ENOMEM; + r_evt->proto = pd; + r_evt->evt = evt; + + r_evt->sources = devm_kcalloc(ni->handle->dev, num_sources, + sizeof(refcount_t), GFP_KERNEL); + if (!r_evt->sources) + return -ENOMEM; + r_evt->num_sources = num_sources; + mutex_init(&r_evt->sources_mtx); + + r_evt->report = devm_kzalloc(ni->handle->dev, + evt->max_report_sz, GFP_KERNEL); + if (!r_evt->report) + return -ENOMEM; + + pd->registered_events[i] = r_evt; + /* Ensure events are updated */ + smp_wmb(); + dev_dbg(handle->dev, "registered event - %lX\n", + MAKE_ALL_SRCS_KEY(r_evt->proto->id, r_evt->evt->id)); + } + + /* Register protocol and events...it will never be removed */ + ni->registered_protocols[proto_id] = pd; + /* Ensure protocols are updated */ + smp_wmb(); + + /* + * Finalize any pending events' handler which could have been waiting + * for this protocol's events registration. + */ + schedule_work(&ni->init_work); + + return 0; +} + +/** + * scmi_deregister_protocol_events - Deregister protocol events with the core + * @handle: The handle identifying the platform instance against which the + * protocol's events are registered + * @proto_id: Protocol ID + */ +void scmi_deregister_protocol_events(const struct scmi_handle *handle, + u8 proto_id) +{ + struct scmi_notify_instance *ni; + struct scmi_registered_events_desc *pd; + + ni = scmi_notification_instance_data_get(handle); + if (!ni) + return; + + pd = ni->registered_protocols[proto_id]; + if (!pd) + return; + + ni->registered_protocols[proto_id] = NULL; + /* Ensure protocols are updated */ + smp_wmb(); + + cancel_work_sync(&pd->equeue.notify_work); +} + +/** + * scmi_allocate_event_handler() - Allocate Event handler + * @ni: A reference to the notification instance to use + * @evt_key: 32bit key uniquely bind to the event identified by the tuple + * (proto_id, evt_id, src_id) + * + * Allocate an event handler and related notification chain associated with + * the provided event handler key. + * Note that, at this point, a related registered_event is still to be + * associated to this handler descriptor (hndl->r_evt == NULL), so the handler + * is initialized as pending. + * + * Context: Assumes to be called with @pending_mtx already acquired. + * Return: the freshly allocated structure on Success + */ +static struct scmi_event_handler * +scmi_allocate_event_handler(struct scmi_notify_instance *ni, u32 evt_key) +{ + struct scmi_event_handler *hndl; + + hndl = kzalloc(sizeof(*hndl), GFP_KERNEL); + if (!hndl) + return NULL; + hndl->key = evt_key; + BLOCKING_INIT_NOTIFIER_HEAD(&hndl->chain); + refcount_set(&hndl->users, 1); + /* New handlers are created pending */ + hash_add(ni->pending_events_handlers, &hndl->hash, hndl->key); + + return hndl; +} + +/** + * scmi_free_event_handler() - Free the provided Event handler + * @hndl: The event handler structure to free + * + * Context: Assumes to be called with proper locking acquired depending + * on the situation. + */ +static void scmi_free_event_handler(struct scmi_event_handler *hndl) +{ + hash_del(&hndl->hash); + kfree(hndl); +} + +/** + * scmi_bind_event_handler() - Helper to attempt binding an handler to an event + * @ni: A reference to the notification instance to use + * @hndl: The event handler to bind + * + * If an associated registered event is found, move the handler from the pending + * into the registered table. + * + * Context: Assumes to be called with @pending_mtx already acquired. + * + * Return: 0 on Success + */ +static inline int scmi_bind_event_handler(struct scmi_notify_instance *ni, + struct scmi_event_handler *hndl) +{ + struct scmi_registered_event *r_evt; + + r_evt = SCMI_GET_REVT(ni, KEY_XTRACT_PROTO_ID(hndl->key), + KEY_XTRACT_EVT_ID(hndl->key)); + if (!r_evt) + return -EINVAL; + + /* + * Remove from pending and insert into registered while getting hold + * of protocol instance. + */ + hash_del(&hndl->hash); + /* + * Acquire protocols only for NON pending handlers, so as NOT to trigger + * protocol initialization when a notifier is registered against a still + * not registered protocol, since it would make little sense to force init + * protocols for which still no SCMI driver user exists: they wouldn't + * emit any event anyway till some SCMI driver starts using it. + */ + scmi_protocol_acquire(ni->handle, KEY_XTRACT_PROTO_ID(hndl->key)); + hndl->r_evt = r_evt; + + mutex_lock(&r_evt->proto->registered_mtx); + hash_add(r_evt->proto->registered_events_handlers, + &hndl->hash, hndl->key); + mutex_unlock(&r_evt->proto->registered_mtx); + + return 0; +} + +/** + * scmi_valid_pending_handler() - Helper to check pending status of handlers + * @ni: A reference to the notification instance to use + * @hndl: The event handler to check + * + * An handler is considered pending when its r_evt == NULL, because the related + * event was still unknown at handler's registration time; anyway, since all + * protocols register their supported events once for all at protocols' + * initialization time, a pending handler cannot be considered valid anymore if + * the underlying event (which it is waiting for), belongs to an already + * initialized and registered protocol. + * + * Return: 0 on Success + */ +static inline int scmi_valid_pending_handler(struct scmi_notify_instance *ni, + struct scmi_event_handler *hndl) +{ + struct scmi_registered_events_desc *pd; + + if (!IS_HNDL_PENDING(hndl)) + return -EINVAL; + + pd = SCMI_GET_PROTO(ni, KEY_XTRACT_PROTO_ID(hndl->key)); + if (pd) + return -EINVAL; + + return 0; +} + +/** + * scmi_register_event_handler() - Register whenever possible an Event handler + * @ni: A reference to the notification instance to use + * @hndl: The event handler to register + * + * At first try to bind an event handler to its associated event, then check if + * it was at least a valid pending handler: if it was not bound nor valid return + * false. + * + * Valid pending incomplete bindings will be periodically retried by a dedicated + * worker which is kicked each time a new protocol completes its own + * registration phase. + * + * Context: Assumes to be called with @pending_mtx acquired. + * + * Return: 0 on Success + */ +static int scmi_register_event_handler(struct scmi_notify_instance *ni, + struct scmi_event_handler *hndl) +{ + int ret; + + ret = scmi_bind_event_handler(ni, hndl); + if (!ret) { + dev_dbg(ni->handle->dev, "registered NEW handler - key:%X\n", + hndl->key); + } else { + ret = scmi_valid_pending_handler(ni, hndl); + if (!ret) + dev_dbg(ni->handle->dev, + "registered PENDING handler - key:%X\n", + hndl->key); + } + + return ret; +} + +/** + * __scmi_event_handler_get_ops() - Utility to get or create an event handler + * @ni: A reference to the notification instance to use + * @evt_key: The event key to use + * @create: A boolean flag to specify if a handler must be created when + * not already existent + * + * Search for the desired handler matching the key in both the per-protocol + * registered table and the common pending table: + * * if found adjust users refcount + * * if not found and @create is true, create and register the new handler: + * handler could end up being registered as pending if no matching event + * could be found. + * + * An handler is guaranteed to reside in one and only one of the tables at + * any one time; to ensure this the whole search and create is performed + * holding the @pending_mtx lock, with @registered_mtx additionally acquired + * if needed. + * + * Note that when a nested acquisition of these mutexes is needed the locking + * order is always (same as in @init_work): + * 1. pending_mtx + * 2. registered_mtx + * + * Events generation is NOT enabled right after creation within this routine + * since at creation time we usually want to have all setup and ready before + * events really start flowing. + * + * Return: A properly refcounted handler on Success, NULL on Failure + */ +static inline struct scmi_event_handler * +__scmi_event_handler_get_ops(struct scmi_notify_instance *ni, + u32 evt_key, bool create) +{ + 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)); + + mutex_lock(&ni->pending_mtx); + /* Search registered events at first ... if possible at all */ + 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); + } + + /* ...then amongst pending. */ + if (!hndl) { + hndl = KEY_FIND(ni->pending_events_handlers, hndl, evt_key); + if (hndl) + refcount_inc(&hndl->users); + } + + /* Create if still not found and required */ + if (!hndl && create) { + hndl = scmi_allocate_event_handler(ni, evt_key); + if (hndl && scmi_register_event_handler(ni, hndl)) { + dev_dbg(ni->handle->dev, + "purging UNKNOWN handler - key:%X\n", + hndl->key); + /* this hndl can be only a pending one */ + scmi_put_handler_unlocked(ni, hndl); + hndl = NULL; + } + } + mutex_unlock(&ni->pending_mtx); + + return hndl; +} + +static struct scmi_event_handler * +scmi_get_handler(struct scmi_notify_instance *ni, u32 evt_key) +{ + return __scmi_event_handler_get_ops(ni, evt_key, false); +} + +static struct scmi_event_handler * +scmi_get_or_create_handler(struct scmi_notify_instance *ni, u32 evt_key) +{ + return __scmi_event_handler_get_ops(ni, evt_key, true); +} + +/** + * 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 + * @enable: The action to perform: true->Enable, false->Disable + * + * Takes care of proper refcounting while performing enable/disable: handles + * the special case of ALL sources requests by itself. + * Returns successfully if at least one of the required src_id has been + * successfully enabled/disabled. + * + * Return: 0 on Success + */ +static inline int __scmi_enable_evt(struct scmi_registered_event *r_evt, + u32 src_id, bool enable) +{ + int retvals = 0; + u32 num_sources; + refcount_t *sid; + + if (src_id == SRC_ID_MASK) { + src_id = 0; + num_sources = r_evt->num_sources; + } else if (src_id < r_evt->num_sources) { + num_sources = 1; + } else { + return -EINVAL; + } + + mutex_lock(&r_evt->sources_mtx); + if (enable) { + for (; num_sources; src_id++, num_sources--) { + int ret = 0; + + sid = &r_evt->sources[src_id]; + if (refcount_read(sid) == 0) { + ret = REVT_NOTIFY_ENABLE(r_evt, r_evt->evt->id, + src_id); + if (!ret) + refcount_set(sid, 1); + } else { + refcount_inc(sid); + } + retvals += !ret; + } + } else { + for (; num_sources; src_id++, num_sources--) { + sid = &r_evt->sources[src_id]; + if (refcount_dec_and_test(sid)) + REVT_NOTIFY_DISABLE(r_evt, + r_evt->evt->id, src_id); + } + retvals = 1; + } + mutex_unlock(&r_evt->sources_mtx); + + return retvals ? 0 : -EINVAL; +} + +static int scmi_enable_events(struct scmi_event_handler *hndl) +{ + int ret = 0; + + if (!hndl->enabled) { + ret = __scmi_enable_evt(hndl->r_evt, + KEY_XTRACT_SRC_ID(hndl->key), true); + if (!ret) + hndl->enabled = true; + } + + return ret; +} + +static int scmi_disable_events(struct scmi_event_handler *hndl) +{ + int ret = 0; + + if (hndl->enabled) { + ret = __scmi_enable_evt(hndl->r_evt, + KEY_XTRACT_SRC_ID(hndl->key), false); + if (!ret) + hndl->enabled = false; + } + + return ret; +} + +/** + * scmi_put_handler_unlocked() - Put an event handler + * @ni: A reference to the notification instance to use + * @hndl: The event handler to act upon + * + * After having got exclusive access to the registered handlers hashtable, + * update the refcount and if @hndl is no more in use by anyone: + * * ask for events' generation disabling + * * unregister and free the handler itself + * + * Context: Assumes all the proper locking has been managed by the caller. + * + * Return: True if handler was freed (users dropped to zero) + */ +static bool scmi_put_handler_unlocked(struct scmi_notify_instance *ni, + struct scmi_event_handler *hndl) +{ + bool freed = false; + + if (refcount_dec_and_test(&hndl->users)) { + if (!IS_HNDL_PENDING(hndl)) + scmi_disable_events(hndl); + scmi_free_event_handler(hndl); + freed = true; + } + + return freed; +} + +static void scmi_put_handler(struct scmi_notify_instance *ni, + struct scmi_event_handler *hndl) +{ + bool freed; + u8 protocol_id; + struct scmi_registered_event *r_evt = hndl->r_evt; + + mutex_lock(&ni->pending_mtx); + if (r_evt) { + protocol_id = r_evt->proto->id; + mutex_lock(&r_evt->proto->registered_mtx); + } + + freed = scmi_put_handler_unlocked(ni, hndl); + + if (r_evt) { + mutex_unlock(&r_evt->proto->registered_mtx); + /* + * Only registered handler acquired protocol; must be here + * released only AFTER unlocking registered_mtx, since + * releasing a protocol can trigger its de-initialization + * (ie. including r_evt and registered_mtx) + */ + if (freed) + scmi_protocol_release(ni->handle, protocol_id); + } + mutex_unlock(&ni->pending_mtx); +} + +static void scmi_put_active_handler(struct scmi_notify_instance *ni, + struct scmi_event_handler *hndl) +{ + bool freed; + struct scmi_registered_event *r_evt = hndl->r_evt; + u8 protocol_id = r_evt->proto->id; + + mutex_lock(&r_evt->proto->registered_mtx); + freed = scmi_put_handler_unlocked(ni, hndl); + mutex_unlock(&r_evt->proto->registered_mtx); + if (freed) + scmi_protocol_release(ni->handle, protocol_id); +} + +/** + * scmi_event_handler_enable_events() - Enable events associated to an handler + * @hndl: The Event handler to act upon + * + * Return: 0 on Success + */ +static int scmi_event_handler_enable_events(struct scmi_event_handler *hndl) +{ + if (scmi_enable_events(hndl)) { + pr_err("Failed to ENABLE events for key:%X !\n", hndl->key); + return -EINVAL; + } + + return 0; +} + +/** + * scmi_notifier_register() - Register a notifier_block for an event + * @handle: The handle identifying the platform instance against which the + * callback is registered + * @proto_id: Protocol ID + * @evt_id: Event ID + * @src_id: Source ID, when NULL register for events coming form ALL possible + * sources + * @nb: A standard notifier block to register for the specified event + * + * Generic helper to register a notifier_block against a protocol event. + * + * A notifier_block @nb will be registered for each distinct event identified + * by the tuple (proto_id, evt_id, src_id) on a dedicated notification chain + * so that: + * + * (proto_X, evt_Y, src_Z) --> chain_X_Y_Z + * + * @src_id meaning is protocol specific and identifies the origin of the event + * (like domain_id, sensor_id and so forth). + * + * @src_id can be NULL to signify that the caller is interested in receiving + * notifications from ALL the available sources for that protocol OR simply that + * the protocol does not support distinct sources. + * + * As soon as one user for the specified tuple appears, an handler is created, + * and that specific event's generation is enabled at the platform level, unless + * an associated registered event is found missing, meaning that the needed + * protocol is still to be initialized and the handler has just been registered + * as still pending. + * + * Return: 0 on Success + */ +static int scmi_notifier_register(const struct scmi_handle *handle, + u8 proto_id, u8 evt_id, const u32 *src_id, + struct notifier_block *nb) +{ + int ret = 0; + u32 evt_key; + struct scmi_event_handler *hndl; + struct scmi_notify_instance *ni; + + ni = scmi_notification_instance_data_get(handle); + if (!ni) + return -ENODEV; + + evt_key = MAKE_HASH_KEY(proto_id, evt_id, + src_id ? *src_id : SRC_ID_MASK); + hndl = scmi_get_or_create_handler(ni, evt_key); + if (!hndl) + return -EINVAL; + + blocking_notifier_chain_register(&hndl->chain, nb); + + /* Enable events for not pending handlers */ + if (!IS_HNDL_PENDING(hndl)) { + ret = scmi_event_handler_enable_events(hndl); + if (ret) + scmi_put_handler(ni, hndl); + } + + return ret; +} + +/** + * scmi_notifier_unregister() - Unregister a notifier_block for an event + * @handle: The handle identifying the platform instance against which the + * callback is unregistered + * @proto_id: Protocol ID + * @evt_id: Event ID + * @src_id: Source ID + * @nb: The notifier_block to unregister + * + * Takes care to unregister the provided @nb from the notification chain + * associated to the specified event and, if there are no more users for the + * event handler, frees also the associated event handler structures. + * (this could possibly cause disabling of event's generation at platform level) + * + * Return: 0 on Success + */ +static int scmi_notifier_unregister(const struct scmi_handle *handle, + u8 proto_id, u8 evt_id, const u32 *src_id, + struct notifier_block *nb) +{ + u32 evt_key; + struct scmi_event_handler *hndl; + struct scmi_notify_instance *ni; + + ni = scmi_notification_instance_data_get(handle); + if (!ni) + return -ENODEV; + + evt_key = MAKE_HASH_KEY(proto_id, evt_id, + src_id ? *src_id : SRC_ID_MASK); + hndl = scmi_get_handler(ni, evt_key); + if (!hndl) + return -EINVAL; + + /* + * Note that this chain unregistration call is safe on its own + * being internally protected by an rwsem. + */ + blocking_notifier_chain_unregister(&hndl->chain, nb); + scmi_put_handler(ni, hndl); + + /* + * This balances the initial get issued in @scmi_notifier_register. + * If this notifier_block happened to be the last known user callback + * for this event, the handler is here freed and the event's generation + * stopped. + * + * Note that, an ongoing concurrent lookup on the delivery workqueue + * path could still hold the refcount to 1 even after this routine + * completes: in such a case it will be the final put on the delivery + * path which will finally free this unused handler. + */ + scmi_put_handler(ni, hndl); + + return 0; +} + +struct scmi_notifier_devres { + const struct scmi_handle *handle; + u8 proto_id; + u8 evt_id; + u32 __src_id; + u32 *src_id; + struct notifier_block *nb; +}; + +static void scmi_devm_release_notifier(struct device *dev, void *res) +{ + struct scmi_notifier_devres *dres = res; + + scmi_notifier_unregister(dres->handle, dres->proto_id, dres->evt_id, + dres->src_id, dres->nb); +} + +/** + * scmi_devm_notifier_register() - Managed registration of a notifier_block + * for an event + * @sdev: A reference to an scmi_device whose embedded struct device is to + * be used for devres accounting. + * @proto_id: Protocol ID + * @evt_id: Event ID + * @src_id: Source ID, when NULL register for events coming form ALL possible + * sources + * @nb: A standard notifier block to register for the specified event + * + * Generic devres managed helper to register a notifier_block against a + * protocol event. + * + * Return: 0 on Success + */ +static int scmi_devm_notifier_register(struct scmi_device *sdev, + u8 proto_id, u8 evt_id, + const u32 *src_id, + struct notifier_block *nb) +{ + int ret; + struct scmi_notifier_devres *dres; + + dres = devres_alloc(scmi_devm_release_notifier, + sizeof(*dres), GFP_KERNEL); + if (!dres) + return -ENOMEM; + + ret = scmi_notifier_register(sdev->handle, proto_id, + evt_id, src_id, nb); + if (ret) { + devres_free(dres); + return ret; + } + + dres->handle = sdev->handle; + dres->proto_id = proto_id; + dres->evt_id = evt_id; + dres->nb = nb; + if (src_id) { + dres->__src_id = *src_id; + dres->src_id = &dres->__src_id; + } else { + dres->src_id = NULL; + } + devres_add(&sdev->dev, dres); + + return ret; +} + +static int scmi_devm_notifier_match(struct device *dev, void *res, void *data) +{ + struct scmi_notifier_devres *dres = res; + struct scmi_notifier_devres *xres = data; + + if (WARN_ON(!dres || !xres)) + return 0; + + return dres->proto_id == xres->proto_id && + dres->evt_id == xres->evt_id && + dres->nb == xres->nb && + ((!dres->src_id && !xres->src_id) || + (dres->src_id && xres->src_id && + dres->__src_id == xres->__src_id)); +} + +/** + * scmi_devm_notifier_unregister() - Managed un-registration of a + * notifier_block for an event + * @sdev: A reference to an scmi_device whose embedded struct device is to + * be used for devres accounting. + * @proto_id: Protocol ID + * @evt_id: Event ID + * @src_id: Source ID, when NULL register for events coming form ALL possible + * sources + * @nb: A standard notifier block to register for the specified event + * + * Generic devres managed helper to explicitly un-register a notifier_block + * against a protocol event, which was previously registered using the above + * @scmi_devm_notifier_register. + * + * Return: 0 on Success + */ +static int scmi_devm_notifier_unregister(struct scmi_device *sdev, + u8 proto_id, u8 evt_id, + const u32 *src_id, + struct notifier_block *nb) +{ + int ret; + struct scmi_notifier_devres dres; + + dres.handle = sdev->handle; + dres.proto_id = proto_id; + dres.evt_id = evt_id; + if (src_id) { + dres.__src_id = *src_id; + dres.src_id = &dres.__src_id; + } else { + dres.src_id = NULL; + } + + ret = devres_release(&sdev->dev, scmi_devm_release_notifier, + scmi_devm_notifier_match, &dres); + + WARN_ON(ret); + + return ret; +} + +/** + * scmi_protocols_late_init() - Worker for late initialization + * @work: The work item to use associated to the proper SCMI instance + * + * This kicks in whenever a new protocol has completed its own registration via + * scmi_register_protocol_events(): it is in charge of scanning the table of + * pending handlers (registered by users while the related protocol was still + * not initialized) and finalizing their initialization whenever possible; + * invalid pending handlers are purged at this point in time. + */ +static void scmi_protocols_late_init(struct work_struct *work) +{ + int bkt; + struct scmi_event_handler *hndl; + struct scmi_notify_instance *ni; + struct hlist_node *tmp; + + ni = container_of(work, struct scmi_notify_instance, init_work); + + /* Ensure protocols and events are up to date */ + smp_rmb(); + + mutex_lock(&ni->pending_mtx); + hash_for_each_safe(ni->pending_events_handlers, bkt, tmp, hndl, hash) { + int ret; + + ret = scmi_bind_event_handler(ni, hndl); + if (!ret) { + dev_dbg(ni->handle->dev, + "finalized PENDING handler - key:%X\n", + hndl->key); + ret = scmi_event_handler_enable_events(hndl); + if (ret) { + dev_dbg(ni->handle->dev, + "purging INVALID handler - key:%X\n", + hndl->key); + scmi_put_active_handler(ni, hndl); + } + } else { + ret = scmi_valid_pending_handler(ni, hndl); + if (ret) { + dev_dbg(ni->handle->dev, + "purging PENDING handler - key:%X\n", + hndl->key); + /* this hndl can be only a pending one */ + scmi_put_handler_unlocked(ni, hndl); + } + } + } + mutex_unlock(&ni->pending_mtx); +} + +/* + * notify_ops are attached to the handle so that can be accessed + * directly from an scmi_driver to register its own notifiers. + */ +static const struct scmi_notify_ops notify_ops = { + .devm_event_notifier_register = scmi_devm_notifier_register, + .devm_event_notifier_unregister = scmi_devm_notifier_unregister, + .event_notifier_register = scmi_notifier_register, + .event_notifier_unregister = scmi_notifier_unregister, +}; + +/** + * scmi_notification_init() - Initializes Notification Core Support + * @handle: The handle identifying the platform instance to initialize + * + * This function lays out all the basic resources needed by the notification + * core instance identified by the provided handle: once done, all of the + * SCMI Protocols can register their events with the core during their own + * initializations. + * + * Note that failing to initialize the core notifications support does not + * cause the whole SCMI Protocols stack to fail its initialization. + * + * SCMI Notification Initialization happens in 2 steps: + * * initialization: basic common allocations (this function) + * * registration: protocols asynchronously come into life and registers their + * own supported list of events with the core; this causes + * further per-protocol allocations + * + * Any user's callback registration attempt, referring a still not registered + * event, will be registered as pending and finalized later (if possible) + * by scmi_protocols_late_init() work. + * This allows for lazy initialization of SCMI Protocols due to late (or + * missing) SCMI drivers' modules loading. + * + * Return: 0 on Success + */ +int scmi_notification_init(struct scmi_handle *handle) +{ + void *gid; + struct scmi_notify_instance *ni; + + gid = devres_open_group(handle->dev, NULL, GFP_KERNEL); + if (!gid) + return -ENOMEM; + + ni = devm_kzalloc(handle->dev, sizeof(*ni), GFP_KERNEL); + if (!ni) + goto err; + + ni->gid = gid; + ni->handle = handle; + + ni->registered_protocols = devm_kcalloc(handle->dev, SCMI_MAX_PROTO, + sizeof(char *), GFP_KERNEL); + if (!ni->registered_protocols) + goto err; + + ni->notify_wq = alloc_workqueue(dev_name(handle->dev), + WQ_UNBOUND | WQ_FREEZABLE | WQ_SYSFS, + 0); + if (!ni->notify_wq) + goto err; + + mutex_init(&ni->pending_mtx); + hash_init(ni->pending_events_handlers); + + INIT_WORK(&ni->init_work, scmi_protocols_late_init); + + scmi_notification_instance_data_set(handle, ni); + handle->notify_ops = ¬ify_ops; + /* Ensure handle is up to date */ + smp_wmb(); + + dev_info(handle->dev, "Core Enabled.\n"); + + devres_close_group(handle->dev, ni->gid); + + return 0; + +err: + dev_warn(handle->dev, "Initialization Failed.\n"); + devres_release_group(handle->dev, gid); + return -ENOMEM; +} + +/** + * scmi_notification_exit() - Shutdown and clean Notification core + * @handle: The handle identifying the platform instance to shutdown + */ +void scmi_notification_exit(struct scmi_handle *handle) +{ + struct scmi_notify_instance *ni; + + ni = scmi_notification_instance_data_get(handle); + if (!ni) + return; + scmi_notification_instance_data_set(handle, NULL); + + /* Destroy while letting pending work complete */ + destroy_workqueue(ni->notify_wq); + + devres_release_group(ni->handle->dev, ni->gid); +} |