rockchip: back-to-bootrom: replace assembly-implementation with C-code
The back-to-bootrom implementation for Rockchip has always relied on
the stack-pointer being valid on entry, so there was little reason to
have this as an assembly implementation.
This provides a new C-only implementation of save_boot_params and
back_to_bootrom (relying on setjmp/longjmp) and removes the older
assembly-only implementation.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Andy Yan <andy.yan@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/bootrom.c b/arch/arm/mach-rockchip/bootrom.c
index 8380e4e..7b9b307 100644
--- a/arch/arm/mach-rockchip/bootrom.c
+++ b/arch/arm/mach-rockchip/bootrom.c
@@ -6,11 +6,61 @@
#include <common.h>
#include <asm/arch/bootrom.h>
+#include <asm/setjmp.h>
+#include <asm/system.h>
+
+/*
+ * Force the jmp_buf to the data-section, as .bss will not be valid
+ * when save_boot_params is invoked.
+ */
+static jmp_buf brom_ctx __section(".data");
void back_to_bootrom(void)
{
#if CONFIG_IS_ENABLED(LIBCOMMON_SUPPORT)
puts("Returning to boot ROM...\n");
#endif
- _back_to_bootrom_s();
+ longjmp(brom_ctx, BROM_BOOT_NEXTSTAGE);
+}
+
+/*
+ * All Rockchip BROM implementations enter with a valid stack-pointer,
+ * so this can safely be implemented in C (providing a single
+ * implementation both for ARMv7 and AArch64).
+ */
+int save_boot_params(void)
+{
+ int ret = setjmp(brom_ctx);
+
+ switch (ret) {
+ case 0:
+ /*
+ * This is the initial pass through this function
+ * (i.e. saving the context), setjmp just setup up the
+ * brom_ctx: transfer back into the startup-code at
+ * 'save_boot_params_ret' and let the compiler know
+ * that this will not return.
+ */
+ save_boot_params_ret();
+ while (true)
+ /* does not return */;
+ break;
+
+ case BROM_BOOT_NEXTSTAGE:
+ /*
+ * To instruct the BROM to boot the next stage, we
+ * need to return 0 to it: i.e. we need to rewrite
+ * the return code once more.
+ */
+ ret = 0;
+ break;
+
+ default:
+#if CONFIG_IS_ENABLED(LIBCOMMON_SUPPORT)
+ puts("FATAL: unexpected command to back_to_bootrom()\n");
+#endif
+ hang();
+ };
+
+ return ret;
}