riscv: Add initial support for 32bit boards

* Adding separate targets for 32bit and 64bit qemu
* Using the riscv64 toolchain for 32bit builds requires setting -m elf32lriscv
* rv32/rv64 is currently configured with ARCH_RISCV_RV32/RV64 and not per stage.
  This should probably be changed later.

TEST=Boots to "Payload not loaded." on 32bit qemu using the following commands:

util/riscv/make-spike-elf.sh build/coreboot.rom build/coreboot.elf
qemu-system-riscv32 -M virt -m 1024M -nographic -kernel build/coreboot.elf

Change-Id: I35e59b459d1770df10b51fe9e77dcc474d7c75a0
Signed-off-by: Philipp Hug <philipp@hug.cx>
Reviewed-on: https://review.coreboot.org/c/31253
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: ron minnich <rminnich@gmail.com>

3 files changed, 23 insertions, 7 deletions

diff --git a/src/arch/riscv/include/arch/smp/spinlock.h b/src/arch/riscv/include/arch/smp/spinlock.h
index dc561d30a1..95e60bfefc 100644
--- a/src/arch/riscv/include/arch/smp/spinlock.h
+++ b/src/arch/riscv/include/arch/smp/spinlock.h
@@ -21,7 +21,7 @@
 #define barrier() { asm volatile ("fence" ::: "memory"); }
 
 typedef struct {
-	volatile atomic_t lock;
+	atomic_t lock;
 } spinlock_t;
 
 static inline void spinlock_lock(spinlock_t *lock)
diff --git a/src/arch/riscv/include/bits.h b/src/arch/riscv/include/bits.h
index f69c7ec0da..d824f3ec98 100644
--- a/src/arch/riscv/include/bits.h
+++ b/src/arch/riscv/include/bits.h
@@ -47,10 +47,19 @@
 #define STR(x) XSTR(x)
 #define XSTR(x) #x
 
-# define SLL32    sllw
-# define STORE    sd
-# define LOAD     ld
-# define LOG_REGBYTES 3
+#if __riscv_xlen == 64
+#define SLL32 sllw
+#define STORE sd
+#define LOAD ld
+#define LWU lwu
+#define LOG_REGBYTES 3
+#else
+#define SLL32 sll
+#define STORE sw
+#define LOAD lw
+#define LWU lw
+#define LOG_REGBYTES 2
+#endif
 
 #define REGBYTES (1 << LOG_REGBYTES)
 
diff --git a/src/arch/riscv/include/mcall.h b/src/arch/riscv/include/mcall.h
index cd1ed6dc18..192d2b4564 100644
--- a/src/arch/riscv/include/mcall.h
+++ b/src/arch/riscv/include/mcall.h
@@ -18,7 +18,13 @@
 
 // NOTE: this is the size of hls_t below. A static_assert would be
 // nice to have.
+#if __riscv_xlen == 64
 #define HLS_SIZE 88
+#endif
+
+#if __riscv_xlen == 32
+#define HLS_SIZE 52
+#endif
 
 /* We save 37 registers, currently. */
 #define MENTRY_FRAME_SIZE (HLS_SIZE + 37 * 8)
@@ -26,6 +32,7 @@
 #ifndef __ASSEMBLER__
 
 #include <arch/encoding.h>
+#include <arch/smp/atomic.h>
 #include <stdint.h>
 
 typedef struct {
@@ -38,8 +45,8 @@ typedef struct {
 struct blocker {
 	void *arg;
 	void (*fn)(void *arg);
-	uint32_t sync_a;
-	uint32_t sync_b;
+	atomic_t sync_a;
+	atomic_t sync_b;
 };
 
 typedef struct {