blob: 2754f9d01636ae711eb31d8ca3f6f83c5bac02d6 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* System Control and Management Interface (SCMI) Notification support
*
* Copyright (C) 2020 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 "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->ni->handle, \
(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->ni->handle, \
__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
* @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;
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 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, ktime_t 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, 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
* the protocol's events are registered
* @proto_id: Protocol ID
* @queue_sz: Size in bytes of the associated queue to be allocated
* @ops: Protocol specific event-related operations
* @evt: Event descriptor array
* @num_events: Number of events in @evt array
* @num_sources: Number of possible sources for this protocol on this
* platform.
*
* 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, size_t queue_sz,
const struct scmi_event_ops *ops,
const struct scmi_event *evt, int num_events,
int num_sources)
{
int i;
size_t payld_sz = 0;
struct scmi_registered_events_desc *pd;
struct scmi_notify_instance *ni;
if (!ops || !evt)
return -EINVAL;
/* Ensure notify_priv is updated */
smp_rmb();
if (!handle->notify_priv)
return -ENOMEM;
ni = handle->notify_priv;
/* Attach to the notification main devres group */
if (!devres_open_group(ni->handle->dev, ni->gid, GFP_KERNEL))
return -ENOMEM;
for (i = 0; i < 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, queue_sz,
payld_sz, num_events, ops);
if (IS_ERR(pd))
goto err;
for (i = 0; i < 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)
goto err;
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)
goto err;
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)
goto err;
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();
devres_close_group(ni->handle->dev, ni->gid);
/*
* Finalize any pending events' handler which could have been waiting
* for this protocol's events registration.
*/
schedule_work(&ni->init_work);
return 0;
err:
dev_warn(handle->dev, "Proto:%X - Registration Failed !\n", proto_id);
/* A failing protocol registration does not trigger full failure */
devres_close_group(ni->handle->dev, ni->gid);
return -ENOMEM;
}
/**
* 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 */
hash_del(&hndl->hash);
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.
*/
static void scmi_put_handler_unlocked(struct scmi_notify_instance *ni,
struct scmi_event_handler *hndl)
{
if (refcount_dec_and_test(&hndl->users)) {
if (!IS_HNDL_PENDING(hndl))
scmi_disable_events(hndl);
scmi_free_event_handler(hndl);
}
}
static void scmi_put_handler(struct scmi_notify_instance *ni,
struct scmi_event_handler *hndl)
{
struct scmi_registered_event *r_evt = hndl->r_evt;
mutex_lock(&ni->pending_mtx);
if (r_evt)
mutex_lock(&r_evt->proto->registered_mtx);
scmi_put_handler_unlocked(ni, hndl);
if (r_evt)
mutex_unlock(&r_evt->proto->registered_mtx);
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
*
* 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_register_notifier() - 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_register_notifier(const struct scmi_handle *handle,
u8 proto_id, u8 evt_id, u32 *src_id,
struct notifier_block *nb)
{
int ret = 0;
u32 evt_key;
struct scmi_event_handler *hndl;
struct scmi_notify_instance *ni;
/* Ensure notify_priv is updated */
smp_rmb();
if (!handle->notify_priv)
return -ENODEV;
ni = handle->notify_priv;
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_unregister_notifier() - 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_unregister_notifier(const struct scmi_handle *handle,
u8 proto_id, u8 evt_id, u32 *src_id,
struct notifier_block *nb)
{
u32 evt_key;
struct scmi_event_handler *hndl;
struct scmi_notify_instance *ni;
/* Ensure notify_priv is updated */
smp_rmb();
if (!handle->notify_priv)
return -ENODEV;
ni = handle->notify_priv;
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_register_notifier.
* 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;
}
/**
* 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);
} 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 = {
.register_event_notifier = scmi_register_notifier,
.unregister_event_notifier = scmi_unregister_notifier,
};
/**
* 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->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)
goto err;
mutex_init(&ni->pending_mtx);
hash_init(ni->pending_events_handlers);
INIT_WORK(&ni->init_work, scmi_protocols_late_init);
handle->notify_ops = &notify_ops;
handle->notify_priv = ni;
/* 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, NULL);
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;
/* Ensure notify_priv is updated */
smp_rmb();
if (!handle->notify_priv)
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);
}