blob: 52011c1d9d809cbf80cd1f34497f2c10cd8caf76 [file] [log] [blame]
/*
* Copyright (c) 2021 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file event objects library
*
* Event objects are used to signal one or more threads that a custom set of
* events has occurred. Threads wait on event objects until another thread or
* ISR posts the desired set of events to the event object. Each time events
* are posted to an event object, all threads waiting on that event object are
* processed to determine if there is a match. All threads that whose wait
* conditions match the current set of events now belonging to the event object
* are awakened.
*
* Threads waiting on an event object have the option of either waking once
* any or all of the events it desires have been posted to the event object.
*
* @brief Kernel event object
*/
#include <kernel.h>
#include <kernel_structs.h>
#include <toolchain.h>
#include <wait_q.h>
#include <sys/dlist.h>
#include <ksched.h>
#include <init.h>
#include <syscall_handler.h>
#include <tracing/tracing.h>
#include <sys/check.h>
#define K_EVENT_WAIT_ANY 0x00 /* Wait for any events */
#define K_EVENT_WAIT_ALL 0x01 /* Wait for all events */
#define K_EVENT_WAIT_MASK 0x01
#define K_EVENT_WAIT_RESET 0x02 /* Reset events prior to waiting */
void z_impl_k_event_init(struct k_event *event)
{
event->events = 0;
event->lock = (struct k_spinlock) {};
SYS_PORT_TRACING_OBJ_INIT(k_event, event);
z_waitq_init(&event->wait_q);
z_object_init(event);
}
#ifdef CONFIG_USERSPACE
void z_vrfy_k_event_init(struct k_event *event)
{
Z_OOPS(Z_SYSCALL_OBJ_NEVER_INIT(event, K_OBJ_EVENT));
z_impl_k_event_init(event);
}
#include <syscalls/k_event_init_mrsh.c>
#endif
/**
* @brief determine if desired set of events been satisfied
*
* This routine determines if the current set of events satisfies the desired
* set of events. If @a wait_condition is K_EVENT_WAIT_ALL, then at least
* all the desired events must be present to satisfy the request. If @a
* wait_condition is not K_EVENT_WAIT_ALL, it is assumed to be K_EVENT_WAIT_ANY.
* In the K_EVENT_WAIT_ANY case, the request is satisfied when any of the
* current set of events are present in the desired set of events.
*/
static bool are_wait_conditions_met(uint32_t desired, uint32_t current,
unsigned int wait_condition)
{
uint32_t match = current & desired;
if (wait_condition == K_EVENT_WAIT_ALL) {
return match == desired;
}
/* wait_condition assumed to be K_EVENT_WAIT_ANY */
return match != 0;
}
static void k_event_post_internal(struct k_event *event, uint32_t events,
bool accumulate)
{
k_spinlock_key_t key;
struct k_thread *thread;
unsigned int wait_condition;
struct k_thread *head = NULL;
key = k_spin_lock(&event->lock);
SYS_PORT_TRACING_OBJ_FUNC_ENTER(k_event, post, event, events,
accumulate);
if (accumulate) {
events |= event->events;
}
event->events = events;
/*
* Posting an event has the potential to wake multiple pended threads.
* It is desirable to unpend all affected threads simultaneously. To
* do so, this must be done in three steps as it is unsafe to unpend
* threads from within the _WAIT_Q_FOR_EACH() loop.
*
* 1. Create a linked list of threads to unpend.
* 2. Unpend each of the threads in the linked list
* 3. Ready each of the threads in the linked list
*/
_WAIT_Q_FOR_EACH(&event->wait_q, thread) {
wait_condition = thread->event_options & K_EVENT_WAIT_MASK;
if (are_wait_conditions_met(thread->events, events,
wait_condition)) {
/*
* The wait conditions have been satisfied. Add this
* thread to the list of threads to unpend.
*/
thread->next_event_link = head;
head = thread;
}
}
if (head != NULL) {
thread = head;
do {
z_unpend_thread(thread);
arch_thread_return_value_set(thread, 0);
thread->events = events;
z_ready_thread(thread);
thread = thread->next_event_link;
} while (thread != NULL);
}
z_reschedule(&event->lock, key);
SYS_PORT_TRACING_OBJ_FUNC_EXIT(k_event, post, event, events,
accumulate);
}
void z_impl_k_event_post(struct k_event *event, uint32_t events)
{
k_event_post_internal(event, events, true);
}
#ifdef CONFIG_USERSPACE
void z_vrfy_k_event_post(struct k_event *event, uint32_t events)
{
Z_OOPS(Z_SYSCALL_OBJ(event, K_OBJ_EVENT));
z_impl_k_event_post(event, events);
}
#include <syscalls/k_event_post_mrsh.c>
#endif
void z_impl_k_event_set(struct k_event *event, uint32_t events)
{
k_event_post_internal(event, events, false);
}
#ifdef CONFIG_USERSPACE
void z_vrfy_k_event_set(struct k_event *event, uint32_t events)
{
Z_OOPS(Z_SYSCALL_OBJ(event, K_OBJ_EVENT));
z_impl_k_event_set(event, events);
}
#include <syscalls/k_event_set_mrsh.c>
#endif
static uint32_t k_event_wait_internal(struct k_event *event, uint32_t events,
unsigned int options, k_timeout_t timeout)
{
uint32_t rv = 0;
unsigned int wait_condition;
struct k_thread *thread;
__ASSERT(((arch_is_in_isr() == false) ||
K_TIMEOUT_EQ(timeout, K_NO_WAIT)), "");
SYS_PORT_TRACING_OBJ_FUNC_ENTER(k_event, wait, event, events,
options, timeout);
if (events == 0) {
SYS_PORT_TRACING_OBJ_FUNC_EXIT(k_event, wait, event, events, 0);
return 0;
}
wait_condition = options & K_EVENT_WAIT_MASK;
thread = z_current_get();
k_spinlock_key_t key = k_spin_lock(&event->lock);
if (options & K_EVENT_WAIT_RESET) {
event->events = 0;
}
/* Test if the wait conditions have already been met. */
if (are_wait_conditions_met(events, event->events, wait_condition)) {
rv = event->events;
k_spin_unlock(&event->lock, key);
goto out;
}
/* Match conditions have not been met. */
if (K_TIMEOUT_EQ(timeout, K_NO_WAIT)) {
k_spin_unlock(&event->lock, key);
goto out;
}
/*
* The caller must pend to wait for the match. Save the desired
* set of events in the k_thread structure.
*/
thread->events = events;
thread->event_options = options;
SYS_PORT_TRACING_OBJ_FUNC_BLOCKING(k_event, wait, event, events,
options, timeout);
if (z_pend_curr(&event->lock, key, &event->wait_q, timeout) == 0) {
/* Retrieve the set of events that woke the thread */
rv = thread->events;
}
out:
SYS_PORT_TRACING_OBJ_FUNC_EXIT(k_event, wait, event,
events, rv & events);
return rv & events;
}
/**
* Wait for any of the specified events
*/
uint32_t z_impl_k_event_wait(struct k_event *event, uint32_t events,
bool reset, k_timeout_t timeout)
{
uint32_t options = reset ? K_EVENT_WAIT_RESET : 0;
return k_event_wait_internal(event, events, options, timeout);
}
#ifdef CONFIG_USERSPACE
uint32_t z_vrfy_k_event_wait(struct k_event *event, uint32_t events,
bool reset, k_timeout_t timeout)
{
Z_OOPS(Z_SYSCALL_OBJ(event, K_OBJ_EVENT));
return z_impl_k_event_wait(event, events, reset, timeout);
}
#include <syscalls/k_event_wait_mrsh.c>
#endif
/**
* Wait for all of the specified events
*/
uint32_t z_impl_k_event_wait_all(struct k_event *event, uint32_t events,
bool reset, k_timeout_t timeout)
{
uint32_t options = reset ? (K_EVENT_WAIT_RESET | K_EVENT_WAIT_ALL)
: K_EVENT_WAIT_ALL;
return k_event_wait_internal(event, events, options, timeout);
}
#ifdef CONFIG_USERSPACE
uint32_t z_vrfy_k_event_wait_all(struct k_event *event, uint32_t events,
bool reset, k_timeout_t timeout)
{
Z_OOPS(Z_SYSCALL_OBJ(event, K_OBJ_EVENT));
return z_impl_k_event_wait_all(event, events, reset, timeout);
}
#include <syscalls/k_event_wait_all_mrsh.c>
#endif