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firmware: arm_scmi: Add notification callbacks-registration 

Add the core SCMI notifications callbacks-registration support: allow
users to register their own callbacks against the desired events.

Whenever a registration request is issued against a still non existent
event, mark such request as pending for later processing, in order to
account for possible late initializations of SCMI Protocols associated
to loadable drivers.

Link: https://lore.kernel.org/r/20200701155348.52864-3-cristian.marussi@arm.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
This commit is contained in:
Cristian Marussi 2020-07-01 16:53:41 +01:00 committed by Sudeep Holla
parent 1fc2dd1864
commit e7c215f358
2 changed files with 772 additions and 0 deletions
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726
drivers/firmware/arm_scmi/notify.c
View File

@ -19,18 +19,50 @@
* 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).
*/
#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/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>
@ -55,6 +87,86 @@
#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 SCMI_PENDING_HASH_SZ 4
#define SCMI_REGISTERED_HASH_SZ 6
struct scmi_registered_events_desc;
/**
@ -62,9 +174,13 @@ struct scmi_registered_events_desc;
* 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
* @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.
@ -72,7 +188,11 @@ struct scmi_registered_events_desc;
struct scmi_notify_instance {
void *gid;
struct scmi_handle *handle;
struct work_struct init_work;
/* 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);
};
/**
@ -121,6 +241,9 @@ struct scmi_registered_event;
* @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.
@ -141,6 +264,9 @@ struct scmi_registered_events_desc {
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);
};
/**
@ -173,6 +299,38 @@ struct scmi_registered_event {
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 void scmi_put_handler_unlocked(struct scmi_notify_instance *ni,
struct scmi_event_handler *hndl);
/**
* scmi_kfifo_free() - Devres action helper to free the kfifo
* @kfifo: The kfifo to free
@ -258,6 +416,10 @@ scmi_allocate_registered_events_desc(struct scmi_notify_instance *ni,
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;
}
@ -349,6 +511,12 @@ int scmi_register_protocol_events(const struct scmi_handle *handle,
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:
@ -359,6 +527,558 @@ err:
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_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);
}
/**
* 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 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
@ -406,6 +1126,12 @@ int scmi_notification_init(struct scmi_handle *handle)
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();

46
include/linux/scmi_protocol.h
View File

@ -9,6 +9,7 @@
#define _LINUX_SCMI_PROTOCOL_H
#include <linux/device.h>
#include <linux/notifier.h>
#include <linux/types.h>
#define SCMI_MAX_STR_SIZE 16
@ -213,6 +214,49 @@ struct scmi_reset_ops {
int (*deassert)(const struct scmi_handle *handle, u32 domain);
};
/**
* struct scmi_notify_ops - represents notifications' operations provided by
* SCMI core
* @register_event_notifier: Register a notifier_block for the requested event
* @unregister_event_notifier: Unregister a notifier_block for the requested
* event
*
* A user can register/unregister its own notifier_block against the wanted
* platform instance regarding the desired event identified by the
* tuple: (proto_id, evt_id, src_id) using the provided register/unregister
* interface where:
*
* @handle: The handle identifying the platform instance to use
* @proto_id: The protocol ID as in SCMI Specification
* @evt_id: The message ID of the desired event as in SCMI Specification
* @src_id: A pointer to the desired source ID if different sources are
* possible for the protocol (like domain_id, sensor_id...etc)
*
* @src_id can be provided as NULL if it simply does NOT make sense for
* the protocol at hand, OR if the user is explicitly interested in
* receiving notifications from ANY existent source associated to the
* specified proto_id / evt_id.
*
* Received notifications are finally delivered to the registered users,
* invoking the callback provided with the notifier_block *nb as follows:
*
* int user_cb(nb, evt_id, report)
*
* with:
*
* @nb: The notifier block provided by the user
* @evt_id: The message ID of the delivered event
* @report: A custom struct describing the specific event delivered
*/
struct scmi_notify_ops {
int (*register_event_notifier)(const struct scmi_handle *handle,
u8 proto_id, u8 evt_id, u32 *src_id,
struct notifier_block *nb);
int (*unregister_event_notifier)(const struct scmi_handle *handle,
u8 proto_id, u8 evt_id, u32 *src_id,
struct notifier_block *nb);
};
/**
* struct scmi_handle - Handle returned to ARM SCMI clients for usage.
*
@ -223,6 +267,7 @@ struct scmi_reset_ops {
* @clk_ops: pointer to set of clock protocol operations
* @sensor_ops: pointer to set of sensor protocol operations
* @reset_ops: pointer to set of reset protocol operations
* @notify_ops: pointer to set of notifications related operations
* @perf_priv: pointer to private data structure specific to performance
* protocol(for internal use only)
* @clk_priv: pointer to private data structure specific to clock
@ -244,6 +289,7 @@ struct scmi_handle {
struct scmi_power_ops *power_ops;
struct scmi_sensor_ops *sensor_ops;
struct scmi_reset_ops *reset_ops;
struct scmi_notify_ops *notify_ops;
/* for protocol internal use */
void *perf_priv;
void *clk_priv;