1 files changed, 127 insertions, 0 deletions
diff --git a/FreeRTOS/Demo/RISC-V_RV32_SiFive_HiFive1-RevB_FreedomStudio/bsp/install/include/metal/lock.h b/FreeRTOS/Demo/RISC-V_RV32_SiFive_HiFive1-RevB_FreedomStudio/bsp/install/include/metal/lock.h
new file mode 100644
index 000000000..d863aa96e
--- /dev/null
+++ b/FreeRTOS/Demo/RISC-V_RV32_SiFive_HiFive1-RevB_FreedomStudio/bsp/install/include/metal/lock.h
@@ -0,0 +1,127 @@
+/* Copyright 2019 SiFive, Inc */
+/* SPDX-License-Identifier: Apache-2.0 */
+
+#ifndef METAL__LOCK_H
+#define METAL__LOCK_H
+
+#include <metal/memory.h>
+#include <metal/compiler.h>
+
+/*!
+ * @file lock.h
+ * @brief An API for creating and using a software lock/mutex
+ */
+
+/* TODO: How can we make the exception code platform-independant? */
+#define _METAL_STORE_AMO_ACCESS_FAULT 7
+
+/*!
+ * @def METAL_LOCK_DECLARE
+ * @brief Declare a lock
+ *
+ * Locks must be declared with METAL_LOCK_DECLARE to ensure that the lock
+ * is linked into a memory region which supports atomic memory operations.
+ */
+#define METAL_LOCK_DECLARE(name) \
+		__attribute__((section(".data.locks"))) \
+		struct metal_lock name
+
+/*!
+ * @brief A handle for a lock
+ */
+struct metal_lock {
+	int _state;
+};
+
+/*!
+ * @brief Initialize a lock
+ * @param lock The handle for a lock
+ * @return 0 if the lock is successfully initialized. A non-zero code indicates failure.
+ *
+ * If the lock cannot be initialized, attempts to take or give the lock
+ * will result in a Store/AMO access fault.
+ */
+inline int metal_lock_init(struct metal_lock *lock) {
+#ifdef __riscv_atomic
+    /* Get a handle for the memory which holds the lock state */
+    struct metal_memory *lock_mem = metal_get_memory_from_address((uintptr_t) &(lock->_state));
+    if(!lock_mem) {
+        return 1;
+    }
+
+    /* If the memory doesn't support atomics, report an error */
+    if(!metal_memory_supports_atomics(lock_mem)) {
+        return 2;
+    }
+
+    lock->_state = 0;
+
+    return 0;
+#else
+    return 3;
+#endif
+}
+
+/*!
+ * @brief Take a lock
+ * @param lock The handle for a lock
+ * @return 0 if the lock is successfully taken
+ *
+ * If the lock initialization failed, attempts to take a lock will result in
+ * a Store/AMO access fault.
+ */
+inline int metal_lock_take(struct metal_lock *lock) {
+#ifdef __riscv_atomic
+    int old = 1;
+    int new = 1;
+
+    while(old != 0) {
+        __asm__ volatile("amoswap.w.aq %[old], %[new], (%[state])"
+                         : [old] "=r" (old)
+                         : [new] "r" (new), [state] "r" (&(lock->_state))
+                         : "memory");
+    }
+
+    return 0;
+#else
+    /* Store the memory address in mtval like a normal store/amo access fault */
+    __asm__ ("csrw mtval, %[state]"
+             :: [state] "r" (&(lock->_state)));
+
+    /* Trigger a Store/AMO access fault */
+    _metal_trap(_METAL_STORE_AMO_ACCESS_FAULT);
+
+    /* If execution returns, indicate failure */
+    return 1;
+#endif
+}
+
+/*!
+ * @brief Give back a held lock
+ * @param lock The handle for a lock
+ * @return 0 if the lock is successfully given
+ *
+ * If the lock initialization failed, attempts to give a lock will result in
+ * a Store/AMO access fault.
+ */
+inline int metal_lock_give(struct metal_lock *lock) {
+#ifdef __riscv_atomic
+    __asm__ volatile("amoswap.w.rl x0, x0, (%[state])"
+                     :: [state] "r" (&(lock->_state))
+                     : "memory");
+
+    return 0;
+#else
+    /* Store the memory address in mtval like a normal store/amo access fault */
+    __asm__ ("csrw mtval, %[state]"
+             :: [state] "r" (&(lock->_state)));
+
+    /* Trigger a Store/AMO access fault */
+    _metal_trap(_METAL_STORE_AMO_ACCESS_FAULT);
+
+    /* If execution returns, indicate failure */
+    return 1;
+#endif
+}
+
+#endif /* METAL__LOCK_H */