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src/rp2_common/pico_async_context/async_context_freertos.c
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/*
* Copyright (c) 2022 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <string.h>
#include "pico/async_context_freertos.h"
#include "pico/async_context_base.h"
#include "pico/sync.h"
#include "hardware/irq.h"
#include "semphr.h"
#if configNUMBER_OF_CORES > 1 && !defined(configUSE_CORE_AFFINITY)
#error async_context_freertos requires configUSE_CORE_AFFINITY under SMP
#endif
static const async_context_type_t template;
static void async_context_freertos_acquire_lock_blocking(async_context_t *self_base);
static void async_context_freertos_release_lock(async_context_t *self_base);
static void async_context_freertos_lock_check(async_context_t *self_base);
static TickType_t sensible_ticks_until(absolute_time_t until) {
TickType_t ticks;
int64_t delay_us = absolute_time_diff_us(get_absolute_time(), until);
if (delay_us <= 0) {
ticks = 0;
} else {
static const uint32_t max_delay = 60000000;
uint32_t delay_us_32 = delay_us > max_delay ? max_delay : (uint32_t) delay_us;
ticks = pdMS_TO_TICKS((delay_us_32+999)/1000);
// we want to round up, as both rounding down to zero is wrong (may produce no delays
// where delays are needed), but also we don't want to wake up, and then realize there
// is no work to do yet!
ticks++;
}
return ticks;
}
static void process_under_lock(async_context_freertos_t *self) {
#ifndef NDEBUG
async_context_freertos_lock_check(&self->core);
#endif
bool repeat;
do {
repeat = false;
absolute_time_t next_time = async_context_base_execute_once(&self->core);
TickType_t ticks;
if (is_at_the_end_of_time(next_time)) {
ticks = portMAX_DELAY;
} else {
ticks = sensible_ticks_until(next_time);
}
if (ticks) {
// last parameter (timeout) is also 'ticks', since there is no point waiting to change the period
// for longer than the period itself!
repeat = pdFALSE == xTimerChangePeriod(self->timer_handle, ticks, ticks);
} else {
repeat = true;
}
} while (repeat);
}
static void async_context_task(__unused void *vself) {
async_context_freertos_t *self = (async_context_freertos_t *)vself;
do {
ulTaskNotifyTake(pdFALSE, portMAX_DELAY);
if (self->task_should_exit) break;
async_context_freertos_acquire_lock_blocking(&self->core);
process_under_lock(self);
async_context_freertos_release_lock(&self->core);
__sev(); // it is possible regular code is waiting on a WFE on the other core
} while (!self->task_should_exit);
vTaskDelete(NULL);
}
static void async_context_freertos_wake_up(async_context_t *self_base) {
async_context_freertos_t *self = (async_context_freertos_t *)self_base;
if (self->task_handle) {
if (portCHECK_IF_IN_ISR()) {
vTaskNotifyGiveFromISR(self->task_handle, NULL);
xSemaphoreGiveFromISR(self->work_needed_sem, NULL);
} else {
// we don't want to wake ourselves up (we will only ever be called
// from the async_context_task if we own the lock, in which case processing
// will already happen when the lock is finally unlocked
if (xTaskGetCurrentTaskHandle() != self->task_handle) {
xTaskNotifyGive(self->task_handle);
xSemaphoreGive(self->work_needed_sem);
} else {
#ifndef NDEBUG
async_context_freertos_lock_check(self_base);
#endif
}
}
}
}
static void timer_handler(__unused TimerHandle_t handle)
{
async_context_freertos_t *self = (async_context_freertos_t *)pvTimerGetTimerID(handle);
async_context_freertos_wake_up(&self->core);
}
bool async_context_freertos_init(async_context_freertos_t *self, async_context_freertos_config_t *config) {
memset(self, 0, sizeof(*self));
self->core.type = &template;
self->core.flags = ASYNC_CONTEXT_FLAG_CALLBACK_FROM_NON_IRQ;
self->core.core_num = get_core_num();
self->lock_mutex = xSemaphoreCreateRecursiveMutex();
self->work_needed_sem = xSemaphoreCreateBinary();
self->timer_handle = xTimerCreate( "async_context_timer", // Just a text name, not used by the kernel.
portMAX_DELAY,
pdFALSE, // The timers will auto-reload themselves when they expire.
self,
timer_handler);
if (!self->lock_mutex ||
!self->work_needed_sem ||
!self->timer_handle ||
pdPASS != xTaskCreate(async_context_task, "async_context_task", config->task_stack_size, self,
config->task_priority, &self->task_handle)) {
async_context_deinit(&self->core);
return false;
}
#if configNUMBER_OF_CORES > 1
UBaseType_t core_id = config->task_core_id;
if (core_id == (UBaseType_t)-1) {
core_id = portGET_CORE_ID();
}
// we must run on a single core
vTaskCoreAffinitySet(self->task_handle, 1u << core_id);
#endif
return true;
}
static uint32_t end_task_func(void *param) {
async_context_freertos_t *self = (async_context_freertos_t *)param;
// we will immediately exit
self->task_should_exit = true;
return 0;
}
void async_context_freertos_deinit(async_context_t *self_base) {
async_context_freertos_t *self = (async_context_freertos_t *)self_base;
if (self->task_handle) {
async_context_execute_sync(self_base, end_task_func, self_base);
}
if (self->timer_handle) {
xTimerDelete(self->timer_handle, 0);
}
if (self->lock_mutex) {
vSemaphoreDelete(self->lock_mutex);
}
if (self->work_needed_sem) {
vSemaphoreDelete(self->work_needed_sem);
}
memset(self, 0, sizeof(*self));
}
void async_context_freertos_acquire_lock_blocking(async_context_t *self_base) {
async_context_freertos_t *self = (async_context_freertos_t *)self_base;
// Lock the other core and stop low_prio_irq running
assert(!portCHECK_IF_IN_ISR());
xSemaphoreTakeRecursive(self->lock_mutex, portMAX_DELAY);
self->nesting++;
}
void async_context_freertos_lock_check(__unused async_context_t *self_base) {
#ifndef NDEBUG
async_context_freertos_t *self = (async_context_freertos_t *)self_base;
// Lock the other core and stop low_prio_irq running
assert(xSemaphoreGetMutexHolder(self->lock_mutex) == xTaskGetCurrentTaskHandle());
#endif
}
typedef struct sync_func_call{
async_when_pending_worker_t worker;
SemaphoreHandle_t sem;
uint32_t (*func)(void *param);
void *param;
uint32_t rc;
} sync_func_call_t;
static void handle_sync_func_call(async_context_t *context, async_when_pending_worker_t *worker) {
sync_func_call_t *call = (sync_func_call_t *)worker;
call->rc = call->func(call->param);
xSemaphoreGive(call->sem);
async_context_remove_when_pending_worker(context, worker);
}
uint32_t async_context_freertos_execute_sync(async_context_t *self_base, uint32_t (*func)(void *param), void *param) {
async_context_freertos_t *self = (async_context_freertos_t*)self_base;
hard_assert(xSemaphoreGetMutexHolder(self->lock_mutex) != xTaskGetCurrentTaskHandle());
sync_func_call_t call;
call.worker.do_work = handle_sync_func_call;
call.func = func;
call.param = param;
call.sem = xSemaphoreCreateBinary();
async_context_add_when_pending_worker(self_base, &call.worker);
async_context_set_work_pending(self_base, &call.worker);
xSemaphoreTake(call.sem, portMAX_DELAY);
vSemaphoreDelete(call.sem);
return call.rc;
}
void async_context_freertos_release_lock(async_context_t *self_base) {
async_context_freertos_t *self = (async_context_freertos_t *)self_base;
bool do_wakeup = false;
if (self->nesting == 1) {
// note that we always do a processing on outermost lock exit, to facilitate cases
// like lwIP where we have no notification when lwIP timers are added.
//
// this operation must be done from the right task
if (self->task_handle != xTaskGetCurrentTaskHandle()) {
// note we defer the wakeup until after we release the lock, otherwise it can be wasteful
// (waking up the task, but then having it block immediately on us)
do_wakeup = true;
} else {
process_under_lock(self);
}
}
--self->nesting;
xSemaphoreGiveRecursive(self->lock_mutex);
if (do_wakeup) {
async_context_freertos_wake_up(self_base);
}
}
static bool async_context_freertos_add_at_time_worker(async_context_t *self_base, async_at_time_worker_t *worker) {
async_context_freertos_acquire_lock_blocking(self_base);
bool rc = async_context_base_add_at_time_worker(self_base, worker);
async_context_freertos_release_lock(self_base);
return rc;
}
static bool async_context_freertos_remove_at_time_worker(async_context_t *self_base, async_at_time_worker_t *worker) {
async_context_freertos_acquire_lock_blocking(self_base);
bool rc = async_context_base_remove_at_time_worker(self_base, worker);
async_context_freertos_release_lock(self_base);
return rc;
}
static bool async_context_freertos_add_when_pending_worker(async_context_t *self_base, async_when_pending_worker_t *worker) {
async_context_freertos_acquire_lock_blocking(self_base);
bool rc = async_context_base_add_when_pending_worker(self_base, worker);
async_context_freertos_release_lock(self_base);
return rc;
}
static bool async_context_freertos_remove_when_pending_worker(async_context_t *self_base, async_when_pending_worker_t *worker) {
async_context_freertos_acquire_lock_blocking(self_base);
bool rc = async_context_base_remove_when_pending_worker(self_base, worker);
async_context_freertos_release_lock(self_base);
return rc;
}
static void async_context_freertos_set_work_pending(async_context_t *self_base, async_when_pending_worker_t *worker) {
worker->work_pending = true;
async_context_freertos_wake_up(self_base);
}
static void async_context_freertos_wait_until(__unused async_context_t *self_base, absolute_time_t until) {
assert(!portCHECK_IF_IN_ISR());
TickType_t ticks = sensible_ticks_until(until);
vTaskDelay(ticks);
}
static void async_context_freertos_wait_for_work_until(async_context_t *self_base, absolute_time_t until) {
async_context_freertos_t *self = (async_context_freertos_t *)self_base;
assert(!portCHECK_IF_IN_ISR());
while (!time_reached(until)) {
TickType_t ticks = sensible_ticks_until(until);
if (!ticks || xSemaphoreTake(self->work_needed_sem, ticks)) return;
}
}
static const async_context_type_t template = {
.type = ASYNC_CONTEXT_FREERTOS,
.acquire_lock_blocking = async_context_freertos_acquire_lock_blocking,
.release_lock = async_context_freertos_release_lock,
.lock_check = async_context_freertos_lock_check,
.execute_sync = async_context_freertos_execute_sync,
.add_at_time_worker = async_context_freertos_add_at_time_worker,
.remove_at_time_worker = async_context_freertos_remove_at_time_worker,
.add_when_pending_worker = async_context_freertos_add_when_pending_worker,
.remove_when_pending_worker = async_context_freertos_remove_when_pending_worker,
.set_work_pending = async_context_freertos_set_work_pending,
.poll = 0,
.wait_until = async_context_freertos_wait_until,
.wait_for_work_until = async_context_freertos_wait_for_work_until,
.deinit = async_context_freertos_deinit,
};
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