riscv/efi_stub: Add 64bit boot-hartid support on RV64

The boot-hartid can be a 64bit value on RV64 platforms but
the "boot-hartid" in DT is assumed to be 32bit only.

Detect the size of the "boot-hartid" in DT and use 32bit or 64bit
read appropriately.
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Link: https://lore.kernel.org/r/20220527051743.2829940-6-sunilvl@ventanamicro.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

drivers/firmware/efi/libstub/riscv-stub.c

@@ -8,6 +8,7 @@
 
 #include <asm/efi.h>
 #include <asm/sections.h>
+#include <asm/unaligned.h>
 
 #include "efistub.h"
 
@@ -29,7 +30,7 @@ static int get_boot_hartid_from_fdt(void)
 {
 	const void *fdt;
 	int chosen_node, len;
-	const fdt32_t *prop;
+	const void *prop;
 
 	fdt = get_efi_config_table(DEVICE_TREE_GUID);
 	if (!fdt)
@@ -40,10 +41,16 @@ static int get_boot_hartid_from_fdt(void)
 		return -EINVAL;
 
 	prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
-	if (!prop || len != sizeof(u32))
+	if (!prop)
+		return -EINVAL;
+
+	if (len == sizeof(u32))
+		hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
+	else if (len == sizeof(u64))
+		hartid = (unsigned long) fdt64_to_cpu(__get_unaligned_t(fdt64_t, prop));
+	else
 		return -EINVAL;
 
-	hartid = fdt32_to_cpu(*prop);
 	return 0;
 }