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/*
* SPDX-FileCopyrightText: 2015-2024 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#pragma once
#include "sdkconfig.h"
#include <stdint.h>
#include <stdbool.h>
#include "esp_cpu.h"
#if __XTENSA__
#include "xtensa/xtruntime.h"
#include "xt_utils.h"
#else
#include "riscv/rv_utils.h"
#endif
#ifdef __cplusplus
extern "C" {
#endif
#ifdef CONFIG_SPIRAM_WORKAROUND_NEED_VOLATILE_SPINLOCK
#define NEED_VOLATILE_MUX volatile
#else
#define NEED_VOLATILE_MUX
#endif
#define SPINLOCK_FREE 0xB33FFFFF
#define SPINLOCK_WAIT_FOREVER (-1)
#define SPINLOCK_NO_WAIT 0
#define SPINLOCK_INITIALIZER {.owner = SPINLOCK_FREE,.count = 0}
#define SPINLOCK_OWNER_ID_0 0xCDCD /* Use these values to avoid 0 being a valid lock owner, same as CORE_ID_REGVAL_PRO on Xtensa */
#define SPINLOCK_OWNER_ID_1 0xABAB /* Same as CORE_ID_REGVAL_APP on Xtensa*/
#define CORE_ID_REGVAL_XOR_SWAP (0xCDCD ^ 0xABAB)
#define SPINLOCK_OWNER_ID_XOR_SWAP CORE_ID_REGVAL_XOR_SWAP
typedef struct {
NEED_VOLATILE_MUX uint32_t owner;
NEED_VOLATILE_MUX uint32_t count;
} spinlock_t;
/**
* @brief Initialize a lock to its default state - unlocked
* @param lock - spinlock object to initialize
*/
static inline void __attribute__((always_inline)) spinlock_initialize(spinlock_t *lock)
{
assert(lock);
#if !CONFIG_ESP_SYSTEM_SINGLE_CORE_MODE
lock->owner = SPINLOCK_FREE;
lock->count = 0;
#endif
}
/**
* @brief Top level spinlock acquire function, spins until get the lock
*
* This function will:
* - Save current interrupt state, then disable interrupts
* - Spin until lock is acquired or until timeout occurs
* - Restore interrupt state
*
* @note Spinlocks alone do no constitute true critical sections (as this
* function reenables interrupts once the spinlock is acquired). For critical
* sections, use the interface provided by the operating system.
* @param lock - target spinlock object
* @param timeout - cycles to wait, passing SPINLOCK_WAIT_FOREVER blocks indefinitely
*/
static inline bool __attribute__((always_inline)) spinlock_acquire(spinlock_t *lock, int32_t timeout)
{
#if !CONFIG_ESP_SYSTEM_SINGLE_CORE_MODE && !BOOTLOADER_BUILD
uint32_t irq_status;
uint32_t core_owner_id;
// Unused if asserts are disabled
uint32_t __attribute__((unused)) other_core_owner_id;
bool lock_set;
esp_cpu_cycle_count_t start_count;
assert(lock);
#if __XTENSA__
irq_status = XTOS_SET_INTLEVEL(XCHAL_EXCM_LEVEL);
// Note: The core IDs are the full 32 bit (CORE_ID_REGVAL_PRO/CORE_ID_REGVAL_APP) values
core_owner_id = xt_utils_get_raw_core_id();
#else //__riscv
irq_status = rv_utils_set_intlevel_regval(RVHAL_EXCM_LEVEL_CLIC);
core_owner_id = rv_utils_get_core_id() == 0 ? SPINLOCK_OWNER_ID_0 : SPINLOCK_OWNER_ID_1;
#endif
other_core_owner_id = CORE_ID_REGVAL_XOR_SWAP ^ core_owner_id;
/* lock->owner should be one of SPINLOCK_FREE, CORE_ID_REGVAL_PRO,
* CORE_ID_REGVAL_APP:
* - If SPINLOCK_FREE, we want to atomically set to 'core_owner_id'.
* - If "our" core_owner_id, we can drop through immediately.
* - If "other_core_owner_id", we spin here.
*/
// The caller is already the owner of the lock. Simply increment the nesting count
if (lock->owner == core_owner_id) {
assert(lock->count > 0 && lock->count < 0xFF); // Bad count value implies memory corruption
lock->count++;
#if __XTENSA__
XTOS_RESTORE_INTLEVEL(irq_status);
#else
rv_utils_restore_intlevel_regval(irq_status);
#endif
return true;
}
/* First attempt to take the lock.
*
* Note: We do a first attempt separately (instead of putting this into a loop) in order to avoid call to
* esp_cpu_get_cycle_count(). This doing a first attempt separately makes acquiring a free lock quicker, which
* is the case for the majority of spinlock_acquire() calls (as spinlocks are free most of the time since they
* aren't meant to be held for long).
*/
lock_set = esp_cpu_compare_and_set(&lock->owner, SPINLOCK_FREE, core_owner_id);
if (lock_set || timeout == SPINLOCK_NO_WAIT) {
// We've successfully taken the lock, or we are not retrying
goto exit;
}
// First attempt to take the lock has failed. Retry until the lock is taken, or until we timeout.
start_count = esp_cpu_get_cycle_count();
do {
lock_set = esp_cpu_compare_and_set(&lock->owner, SPINLOCK_FREE, core_owner_id);
if (lock_set) {
break;
}
// Keep looping if we are waiting forever, or check if we have timed out
} while ((timeout == SPINLOCK_WAIT_FOREVER) || (esp_cpu_get_cycle_count() - start_count) <= (esp_cpu_cycle_count_t)timeout);
exit:
if (lock_set) {
assert(lock->owner == core_owner_id);
assert(lock->count == 0); // This is the first time the lock is set, so count should still be 0
lock->count++; // Finally, we increment the lock count
} else { // We timed out waiting for lock
assert(lock->owner == SPINLOCK_FREE || lock->owner == other_core_owner_id);
assert(lock->count < 0xFF); // Bad count value implies memory corruption
}
#if __XTENSA__
XTOS_RESTORE_INTLEVEL(irq_status);
#else
rv_utils_restore_intlevel_regval(irq_status);
#endif
return lock_set;
#else // !CONFIG_ESP_SYSTEM_SINGLE_CORE_MODE
return true;
#endif
}
/**
* @brief Top level spinlock unlock function, unlocks a previously locked spinlock
*
* This function will:
* - Save current interrupt state, then disable interrupts
* - Release the spinlock
* - Restore interrupt state
*
* @note Spinlocks alone do no constitute true critical sections (as this
* function reenables interrupts once the spinlock is acquired). For critical
* sections, use the interface provided by the operating system.
* @param lock - target, locked before, spinlock object
*/
static inline void __attribute__((always_inline)) spinlock_release(spinlock_t *lock)
{
#if !CONFIG_ESP_SYSTEM_SINGLE_CORE_MODE && !BOOTLOADER_BUILD
uint32_t irq_status;
// Return value unused if asserts are disabled
uint32_t __attribute__((unused)) core_owner_id;
assert(lock);
#if __XTENSA__
irq_status = XTOS_SET_INTLEVEL(XCHAL_EXCM_LEVEL);
core_owner_id = xt_utils_get_raw_core_id();
#else
irq_status = rv_utils_set_intlevel_regval(RVHAL_EXCM_LEVEL_CLIC);
core_owner_id = rv_utils_get_core_id() == 0 ? SPINLOCK_OWNER_ID_0 : SPINLOCK_OWNER_ID_1;
#endif
assert(core_owner_id == lock->owner); // This is a lock that we didn't acquire, or the lock is corrupt
lock->count--;
if (!lock->count) { // If this is the last recursive release of the lock, mark the lock as free
lock->owner = SPINLOCK_FREE;
} else {
assert(lock->count < 0x100); // Indicates memory corruption
}
#if __XTENSA__
XTOS_RESTORE_INTLEVEL(irq_status);
#else
rv_utils_restore_intlevel_regval(irq_status);
#endif //#if __XTENSA__
#endif //#if !CONFIG_ESP_SYSTEM_SINGLE_CORE_MODE && !BOOTLOADER_BUILD
}
#ifdef __cplusplus
}
#endif
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