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/*
* Copyright (C) 2018-2019, STMicroelectronics - All Rights Reserved
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#ifndef STM32MP_SHRES_HELPERS_H
#define STM32MP_SHRES_HELPERS_H
#include <stdint.h>
#include <common/debug.h>
/*
* Shared reference counter: increments by 2 on secure increment
* request, decrements by 2 on secure decrement request. Bit #0
* is set to 1 on non-secure increment request and reset to 0 on
* non-secure decrement request. The counter initializes to
* either 0, 1 or 2 upon their expect default state.
* Counters saturates once above UINT_MAX / 2.
*/
#define SHREFCNT_NONSECURE_FLAG 0x1UL
#define SHREFCNT_SECURE_STEP 0x2UL
#define SHREFCNT_MAX (UINT32_MAX / 2)
/* Return 1 if refcnt increments from 0, else return 0 */
static inline int stm32mp_incr_shrefcnt(unsigned int *refcnt, bool secure)
{
int rc = !*refcnt;
if (secure) {
*refcnt += SHREFCNT_SECURE_STEP;
if (*refcnt >= SHREFCNT_MAX) {
panic();
}
} else {
*refcnt |= SHREFCNT_NONSECURE_FLAG;
}
return rc;
}
/* Return 1 if refcnt decrements to 0, else return 0 */
static inline int stm32mp_decr_shrefcnt(unsigned int *refcnt, bool secure)
{
int rc = 0;
if (secure) {
if (*refcnt < SHREFCNT_MAX) {
if (*refcnt < SHREFCNT_SECURE_STEP) {
panic();
}
*refcnt -= SHREFCNT_SECURE_STEP;
rc = !*refcnt;
}
} else {
rc = (*refcnt == SHREFCNT_NONSECURE_FLAG) ? 1 : 0;
*refcnt &= ~SHREFCNT_NONSECURE_FLAG;
}
return rc;
}
static inline int stm32mp_incr_refcnt(unsigned int *refcnt)
{
return stm32mp_incr_shrefcnt(refcnt, true);
}
static inline int stm32mp_decr_refcnt(unsigned int *refcnt)
{
return stm32mp_decr_shrefcnt(refcnt, true);
}
#endif /* STM32MP_SHRES_HELPERS_H */
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