hw/arm: Allwinner A10 enable SPL load from MMC

This patch enables copying of SPL from MMC if `-kernel` parameter is not
passed when starting QEMU. SPL is copied to SRAM_A.

The approach is reused from Allwinner H3 implementation.

Tested with Armbian and custom Yocto image.

Signed-off-by: Strahinja Jankovic <strahinja.p.jankovic@gmail.com>

Reviewed-by: Niek Linnenbank <nieklinnenbank@gmail.com>
Message-id: 20221226220303.14420-7-strahinja.p.jankovic@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

include/hw/arm/allwinner-a10.h

@@ -16,6 +16,7 @@
 #include "hw/misc/allwinner-a10-ccm.h"
 #include "hw/misc/allwinner-a10-dramc.h"
 #include "hw/i2c/allwinner-i2c.h"
+#include "sysemu/block-backend.h"
 
 #include "target/arm/cpu.h"
 #include "qom/object.h"
@@ -48,4 +49,24 @@ struct AwA10State {
     OHCISysBusState ohci[AW_A10_NUM_USB];
 };
 
+/**
+ * Emulate Boot ROM firmware setup functionality.
+ *
+ * A real Allwinner A10 SoC contains a Boot ROM
+ * which is the first code that runs right after
+ * the SoC is powered on. The Boot ROM is responsible
+ * for loading user code (e.g. a bootloader) from any
+ * of the supported external devices and writing the
+ * downloaded code to internal SRAM. After loading the SoC
+ * begins executing the code written to SRAM.
+ *
+ * This function emulates the Boot ROM by copying 32 KiB
+ * of data at offset 8 KiB from the given block device and writes it to
+ * the start of the first internal SRAM memory.
+ *
+ * @s: Allwinner A10 state object pointer
+ * @blk: Block backend device object pointer
+ */
+void allwinner_a10_bootrom_setup(AwA10State *s, BlockBackend *blk);
+
 #endif