lib: atomics: fix AMO test macros

The "RISC-V C API" [1] defines architecture extension test macros
says naming rule for the test macros is __riscv_<ext_name>, where
<ext_name> is all lower-case.

Three extensions dealing with atomics implementation are:
  "zaamo" consists of AMO instructions,
  "zalrsc" - LR/SC,
  "a" extension means both "zaamo" and "zalrsc"
Built-in test macros are __riscv_a, __riscv_zaamo and __riscv_zalrsc.
Alternative to the __riscv_a macro name, __riscv_atomic, is deprecated.

Use correct test macro __riscv_zaamo for the AMO variant of atomics.
It used to be __riscv_atomic that is both deprecated and incorrect
because it tests for the "a" extension; i.e. both "zaamo" and "zalrsc"
If ISA enables only zaamo but not zalrsc, code as it was would not compile.

Older toolchains may have neither __riscv_zaamo nor __riscv_zalrsc, so
query __riscv_atomic - it should be treated as both __riscv_zaamo and
__riscv_zalrsc, in all present cases __riscv_zaamo is more favorable
so take is as alternative for __riscv_zaamo

[1] https://github.com/riscv-non-isa/riscv-c-api-doc

Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251228073321.1533844-1-vladimir.kondratiev@mobileye.com
Signed-off-by: Anup Patel <anup@brainfault.org>

firmware/fw_base.S

@@ -59,10 +59,10 @@ _try_lottery:
 	/* Jump to relocation wait loop if we don't get relocation lottery */
 	lla	a6, _boot_lottery
 	li	a7, BOOT_LOTTERY_ACQUIRED
-#ifdef __riscv_atomic
+#if defined(__riscv_atomic) || defined(__riscv_zaamo)
 	amoswap.w a6, a7, (a6)
 	bnez	a6, _wait_for_boot_hart
-#elif __riscv_zalrsc
+#elif defined(__riscv_zalrsc)
 _sc_fail:
 	lr.w	t0, (a6)
 	sc.w	t1, a7, (a6)

firmware/payloads/test_head.S

@@ -30,9 +30,9 @@ _start:
 	/* Pick one hart to run the main boot sequence */
 	lla	a3, _hart_lottery
 	li	a2, 1
-#ifdef __riscv_atomic
+#if defined(__riscv_atomic) || defined(__riscv_zaamo)
 	amoadd.w a3, a2, (a3)
-#elif __riscv_zalrsc
+#elif defined(__riscv_zalrsc)
 _sc_fail:
 	lr.w	t0, (a3)
 	addw	t1, t0, a2

lib/sbi/riscv_atomic.c

@@ -12,8 +12,8 @@
 #include <sbi/riscv_atomic.h>
 #include <sbi/riscv_barrier.h>
 
-#if !defined(__riscv_atomic) && !defined(__riscv_zalrsc)
+#if !defined(__riscv_atomic) && !defined(__riscv_zaamo) && !defined(__riscv_zalrsc)
-#error "opensbi strongly relies on the A extension of RISC-V"
+#error "opensbi strongly relies on the Zaamo or Zalrsc extensions of RISC-V"
 #endif
 
 long atomic_read(atomic_t *atom)
@@ -31,7 +31,7 @@ void atomic_write(atomic_t *atom, long value)
 
 long atomic_add_return(atomic_t *atom, long value)
 {
-#ifdef __riscv_atomic
+#if defined(__riscv_atomic) || defined(__riscv_zaamo)
 	long ret;
 #if __SIZEOF_LONG__ == 4
 	__asm__ __volatile__("	amoadd.w.aqrl  %1, %2, %0"
@@ -44,7 +44,7 @@ long atomic_add_return(atomic_t *atom, long value)
 			     : "r"(value)
 			     : "memory");
 #endif
-#elif __riscv_zalrsc
+#elif defined(__riscv_zalrsc)
 	long ret, temp;
 #if __SIZEOF_LONG__ == 4
 	__asm__ __volatile__("1:lr.w.aqrl	%1,%0\n"
@@ -64,7 +64,7 @@ long atomic_add_return(atomic_t *atom, long value)
 			     : "memory");
 #endif
 #else
-#error "need a or zalrsc"
+#error "need A or Zaamo or Zalrsc"
 #endif
 
 	return ret + value;
@@ -75,7 +75,7 @@ long atomic_sub_return(atomic_t *atom, long value)
 	return atomic_add_return(atom, -value);
 }
 
-#ifdef __riscv_atomic
+#if defined(__riscv_atomic) || defined(__riscv_zaamo)
 #define __axchg(ptr, new, size)							\
 	({									\
 		__typeof__(ptr) __ptr = (ptr);					\
@@ -101,7 +101,7 @@ long atomic_sub_return(atomic_t *atom, long value)
 		}								\
 		__ret;								\
 	})
-#elif __riscv_zalrsc
+#elif defined(__riscv_zalrsc)
 #define __axchg(ptr, new, size)							\
 	({									\
 		__typeof__(ptr) __ptr = (ptr);					\
@@ -132,7 +132,7 @@ long atomic_sub_return(atomic_t *atom, long value)
 		__ret;								\
 	})
 #else
-#error "need a or zalrsc"
+#error "need A or Zaamo or Zalrsc"
 #endif
 
 #define axchg(ptr, x)								\

lib/sbi/riscv_locks.c

@@ -53,15 +53,15 @@ void spin_lock(spinlock_t *lock)
 
 	__asm__ __volatile__(
 		/* Atomically increment the next ticket. */
-#ifdef __riscv_atomic
+#if defined(__riscv_atomic) || defined(__riscv_zaamo)
 		"	amoadd.w.aqrl	%0, %4, %3\n"
-#elif __riscv_zalrsc
+#elif defined(__riscv_zalrsc)
 		"3:	lr.w.aqrl	%0, %3\n"
 		"	addw	%1, %0, %4\n"
 		"	sc.w.aqrl	%1, %1, %3\n"
 		"	bnez	%1, 3b\n"
 #else
-#error "need a or zalrsc"
+#error "need A or Zaamo or Zalrsc"
 #endif
 
 		/* Did we get the lock? */

lib/sbi/sbi_illegal_atomic.c

@@ -11,18 +11,18 @@
 #include <sbi/sbi_illegal_atomic.h>
 #include <sbi/sbi_illegal_insn.h>
 
-#if !defined(__riscv_atomic) && !defined(__riscv_zalrsc)
+#if !defined(__riscv_atomic) && !defined(__riscv_zaamo) && !defined(__riscv_zalrsc)
-#error "opensbi strongly relies on the A extension of RISC-V"
+#error "opensbi strongly relies on the Zaamo or Zalrsc extension of RISC-V"
 #endif
 
-#ifdef __riscv_atomic
+#if defined(__riscv_atomic) || defined(__riscv_zaamo)
 
 int sbi_illegal_atomic(ulong insn, struct sbi_trap_regs *regs)
 {
 	return truly_illegal_insn(insn, regs);
 }
 
-#elif __riscv_zalrsc
+#elif defined(__riscv_zalrsc)
 
 #define DEFINE_UNPRIVILEGED_LR_FUNCTION(type, aqrl, insn)			\
 	static type lr_##type##aqrl(const type *addr,				\