1 files changed, 74 insertions, 0 deletions
diff --git a/plat/st/common/include/stm32mp_shres_helpers.h b/plat/st/common/include/stm32mp_shres_helpers.h
new file mode 100644
index 000000000..8b786cc04
--- /dev/null
+++ b/plat/st/common/include/stm32mp_shres_helpers.h
@@ -0,0 +1,74 @@
+/*
+ * 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 */