core/cortex-m: add Zephyr compatible atomic functions

Add atomic functions with prototypes equal to the ones in Zephyr.

It is done as a part of porting to Zephyr, the next step is to use in
the code atomic_* instead of deprecated_atomic_*.

Some atomic functions in Zephyr return a value e.g. atomic_add - it
returns the value of the variable before the add operation.
The current state of ATOMIC_OP macro is not designed to return such value
so instead of reworking it or writing new custom asm code just use
builtin functions.

BUG=b:169151160
BRANCH=none
TEST=buildall

Signed-off-by: Dawid Niedzwiecki <dn@semihalf.com>
Change-Id: Iccd7a4d674601271f11f88834c8b2db08c537534
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2428945
Reviewed-by: Jett Rink <jettrink@chromium.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/core/cortex-m/atomic.h b/core/cortex-m/atomic.h
index 736d5887b4..1f432e8d1e 100644
--- a/core/cortex-m/atomic.h
+++ b/core/cortex-m/atomic.h
@@ -10,6 +10,9 @@
 
 #include "common.h"
 
+typedef int atomic_t;
+typedef atomic_t atomic_val_t;
+
 /**
  * Implements atomic arithmetic operations on 32-bit integers.
  *
@@ -42,23 +45,43 @@ static inline void deprecated_atomic_clear_bits(uint32_t volatile *addr,
 	ATOMIC_OP(bic, addr, bits);
 }
 
+static inline void atomic_clear_bits(atomic_t *addr, atomic_val_t bits)
+{
+	__atomic_fetch_and(addr, ~bits, __ATOMIC_SEQ_CST);
+}
+
 static inline void deprecated_atomic_or(uint32_t volatile *addr, uint32_t bits)
 {
 	ATOMIC_OP(orr, addr, bits);
 }
 
+static inline atomic_val_t atomic_or(atomic_t *addr, atomic_val_t bits)
+{
+	return __atomic_fetch_or(addr, bits, __ATOMIC_SEQ_CST);
+}
+
 static inline void deprecated_atomic_add(uint32_t volatile *addr,
 					 uint32_t value)
 {
 	ATOMIC_OP(add, addr, value);
 }
 
+static inline atomic_val_t atomic_add(atomic_t *addr, atomic_val_t value)
+{
+	return __atomic_fetch_add(addr, value, __ATOMIC_SEQ_CST);
+}
+
 static inline void deprecated_atomic_sub(uint32_t volatile *addr,
 					 uint32_t value)
 {
 	ATOMIC_OP(sub, addr, value);
 }
 
+static inline atomic_val_t atomic_sub(atomic_t *addr, atomic_val_t value)
+{
+	return __atomic_fetch_sub(addr, value, __ATOMIC_SEQ_CST);
+}
+
 static inline uint32_t deprecated_atomic_read_clear(uint32_t volatile *addr)
 {
 	uint32_t ret, tmp;
@@ -73,4 +96,10 @@ static inline uint32_t deprecated_atomic_read_clear(uint32_t volatile *addr)
 
 	return ret;
 }
+
+static inline atomic_val_t atomic_read_clear(atomic_t *addr)
+{
+	return __atomic_exchange_n(addr, 0, __ATOMIC_SEQ_CST);
+}
+
 #endif  /* __CROS_EC_ATOMIC_H */