riscv: Add a helper routine for finding firmware

This adds a helper routine for finding firmware. It is currently
used only for "-bios default" case.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

hw/riscv/boot.c

@@ -69,13 +69,7 @@ void riscv_find_and_load_firmware(MachineState *machine,
          * so then in the future we can make "-bios default" the default option
          * if no -bios option is set without breaking anything.
          */
-        firmware_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS,
-                                           default_machine_firmware);
-        if (firmware_filename == NULL) {
-            error_report("Unable to load the default RISC-V firmware \"%s\"",
-                         default_machine_firmware);
-            exit(1);
-        }
+        firmware_filename = riscv_find_firmware(default_machine_firmware);
     } else {
         firmware_filename = machine->firmware;
     }
@@ -90,6 +84,20 @@ void riscv_find_and_load_firmware(MachineState *machine,
     }
 }
 
+char *riscv_find_firmware(const char *firmware_filename)
+{
+    char *filename;
+
+    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, firmware_filename);
+    if (filename == NULL) {
+        error_report("Unable to load the RISC-V firmware \"%s\"",
+                     firmware_filename);
+        exit(1);
+    }
+
+    return filename;
+}
+
 target_ulong riscv_load_firmware(const char *firmware_filename,
                                  hwaddr firmware_load_addr)
 {

include/hw/riscv/boot.h

@@ -25,6 +25,7 @@
 void riscv_find_and_load_firmware(MachineState *machine,
                                   const char *default_machine_firmware,
                                   hwaddr firmware_load_addr);
+char *riscv_find_firmware(const char *firmware_filename);
 target_ulong riscv_load_firmware(const char *firmware_filename,
                                  hwaddr firmware_load_addr);
 target_ulong riscv_load_kernel(const char *kernel_filename);