[PATCH v5 10/18] hw/arm/allwinner-h3: add Boot ROM support

[Niek Linnenbank <nieklinnenbank@gmail.com>]

A real Allwinner H3 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 commits adds emulation of the Boot ROM firmware setup functionality
by loading user code from SD card in the A1 SRAM. While the A1 SRAM is
64KiB, we limit the size to 32KiB because the real H3 Boot ROM also rejects
sizes larger than 32KiB. For reference, this behaviour is documented
by the Linux Sunxi project wiki at:

  https://linux-sunxi.org/BROM#U-Boot_SPL_limitations

Signed-off-by: Niek Linnenbank <nieklinnenbank@gmail.com>
---
 include/hw/arm/allwinner-h3.h | 21 +++++++++++++++++++++
 hw/arm/allwinner-h3.c         | 18 ++++++++++++++++++
 hw/arm/orangepi.c             |  5 +++++
 3 files changed, 44 insertions(+)

diff --git a/include/hw/arm/allwinner-h3.h b/include/hw/arm/allwinner-h3.h
index f9b9a02373..d338003724 100644
--- a/include/hw/arm/allwinner-h3.h
+++ b/include/hw/arm/allwinner-h3.h
@@ -46,6 +46,7 @@
 #include "hw/sd/allwinner-sdhost.h"
 #include "hw/net/allwinner-sun8i-emac.h"
 #include "target/arm/cpu.h"
+#include "sysemu/block-backend.h"
 
 /**
  * Allwinner H3 device list
@@ -129,4 +130,24 @@ typedef struct AwH3State {
     MemoryRegion sram_c;
 } AwH3State;
 
+/**
+ * Emulate Boot ROM firmware setup functionality.
+ *
+ * A real Allwinner H3 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 from the given block device and writes it to
+ * the start of the first internal SRAM memory.
+ *
+ * @s: Allwinner H3 state object pointer
+ * @blk: Block backend device object pointer
+ */
+void allwinner_h3_bootrom_setup(AwH3State *s, BlockBackend *blk);
+
 #endif /* HW_ARM_ALLWINNER_H3_H */
diff --git a/hw/arm/allwinner-h3.c b/hw/arm/allwinner-h3.c
index d1245d2b01..56b5c563a8 100644
--- a/hw/arm/allwinner-h3.c
+++ b/hw/arm/allwinner-h3.c
@@ -29,6 +29,7 @@
 #include "hw/char/serial.h"
 #include "hw/misc/unimp.h"
 #include "hw/usb/hcd-ehci.h"
+#include "hw/loader.h"
 #include "sysemu/sysemu.h"
 #include "hw/arm/allwinner-h3.h"
 
@@ -170,6 +171,23 @@ enum {
     AW_H3_GIC_NUM_SPI       = 128
 };
 
+void allwinner_h3_bootrom_setup(AwH3State *s, BlockBackend *blk)
+{
+    const int64_t rom_size = 32 * KiB;
+    uint8_t *buffer = g_new0(uint8_t, rom_size);
+
+    if (blk_pread(blk, 8 * KiB, buffer, rom_size) < 0) {
+        error_setg(&error_fatal, "%s: failed to read BlockBackend data",
+                   __func__);
+        return;
+    }
+
+    rom_add_blob("allwinner-h3.bootrom", buffer, rom_size,
+                  rom_size, s->memmap[AW_H3_SRAM_A1],
+                  NULL, NULL, NULL, NULL, false);
+    g_free(buffer);
+}
+
 static void allwinner_h3_init(Object *obj)
 {
     AwH3State *s = AW_H3(obj);
diff --git a/hw/arm/orangepi.c b/hw/arm/orangepi.c
index 6bb49bf2a8..902fcfd11f 100644
--- a/hw/arm/orangepi.c
+++ b/hw/arm/orangepi.c
@@ -102,6 +102,11 @@ static void orangepi_init(MachineState *machine)
     memory_region_add_subregion(get_system_memory(), s->h3->memmap[AW_H3_SDRAM],
                                 &s->sdram);
 
+    /* Load target kernel or start using BootROM */
+    if (!machine->kernel_filename && blk_is_available(blk)) {
+        /* Use Boot ROM to copy data from SD card to SRAM */
+        allwinner_h3_bootrom_setup(s->h3, blk);
+    }
     orangepi_binfo.loader_start = s->h3->memmap[AW_H3_SDRAM];
     orangepi_binfo.ram_size = machine->ram_size;
     arm_load_kernel(ARM_CPU(first_cpu), machine, &orangepi_binfo);
-- 
2.17.1