aspeed: Add a boot_rom overlap region in the SoC spi_boot container

To avoid the SPI transactions fetching instructions from the FMC CE0
flash device and speed up boot, a ROM can be created if a drive is
available.

Reverse the logic to allow a machine to boot without a drive, using a
block device instead :

    -blockdev node-name=fmc0,driver=file,filename=/path/to/flash.img \
    -device mx66u51235f,bus=ssi.0,drive=fmc0

Signed-off-by: Cédric Le Goater <clg@kaod.org>

hw/arm/aspeed.c

@@ -241,12 +241,9 @@ static void aspeed_reset_secondary(ARMCPU *cpu,
     cpu_set_pc(cs, info->smp_loader_start);
 }
 
-#define FIRMWARE_ADDR 0x0
-
-static void write_boot_rom(DriveInfo *dinfo, hwaddr addr, size_t rom_size,
+static void write_boot_rom(BlockBackend *blk, hwaddr addr, size_t rom_size,
                            Error **errp)
 {
-    BlockBackend *blk = blk_by_legacy_dinfo(dinfo);
     g_autofree void *storage = NULL;
     int64_t size;
 
@@ -272,6 +269,22 @@ static void write_boot_rom(DriveInfo *dinfo, hwaddr addr, size_t rom_size,
     rom_add_blob_fixed("aspeed.boot_rom", storage, rom_size, addr);
 }
 
+/*
+ * Create a ROM and copy the flash contents at the expected address
+ * (0x0). Boots faster than execute-in-place.
+ */
+static void aspeed_install_boot_rom(AspeedSoCState *soc, BlockBackend *blk,
+                                    uint64_t rom_size)
+{
+    MemoryRegion *boot_rom = g_new(MemoryRegion, 1);
+
+    memory_region_init_rom(boot_rom, NULL, "aspeed.boot_rom", rom_size,
+                           &error_abort);
+    memory_region_add_subregion_overlap(&soc->spi_boot_container, 0,
+                                        boot_rom, 1);
+    write_boot_rom(blk, ASPEED_SOC_SPI_BOOT_ADDR, rom_size, &error_abort);
+}
+
 void aspeed_board_init_flashes(AspeedSMCState *s, const char *flashtype,
                                       unsigned int count, int unit0)
 {
@@ -332,7 +345,6 @@ static void aspeed_machine_init(MachineState *machine)
     AspeedMachineState *bmc = ASPEED_MACHINE(machine);
     AspeedMachineClass *amc = ASPEED_MACHINE_GET_CLASS(machine);
     AspeedSoCClass *sc;
-    DriveInfo *drive0 = drive_get(IF_MTD, 0, 0);
     int i;
     NICInfo *nd = &nd_table[0];
 
@@ -382,21 +394,6 @@ static void aspeed_machine_init(MachineState *machine)
                               bmc->spi_model ? bmc->spi_model : amc->spi_model,
                               1, amc->num_cs);
 
-    /* Install first FMC flash content as a boot rom. */
-    if (drive0) {
-        AspeedSMCFlash *fl = &bmc->soc.fmc.flashes[0];
-        MemoryRegion *boot_rom = g_new(MemoryRegion, 1);
-        uint64_t size = memory_region_size(&fl->mmio);
-
-        if (!ASPEED_MACHINE(machine)->mmio_exec) {
-            memory_region_init_rom(boot_rom, NULL, "aspeed.boot_rom",
-                                   size, &error_abort);
-            memory_region_add_subregion(get_system_memory(), FIRMWARE_ADDR,
-                                        boot_rom);
-            write_boot_rom(drive0, FIRMWARE_ADDR, size, &error_abort);
-        }
-    }
-
     if (machine->kernel_filename && sc->num_cpus > 1) {
         /* With no u-boot we must set up a boot stub for the secondary CPU */
         MemoryRegion *smpboot = g_new(MemoryRegion, 1);
@@ -427,6 +424,16 @@ static void aspeed_machine_init(MachineState *machine)
                            drive_get(IF_SD, 0, bmc->soc.sdhci.num_slots));
     }
 
+    if (!bmc->mmio_exec) {
+        DriveInfo *mtd0 = drive_get(IF_MTD, 0, 0);
+
+        if (mtd0) {
+            uint64_t rom_size = memory_region_size(&bmc->soc.spi_boot);
+            aspeed_install_boot_rom(&bmc->soc, blk_by_legacy_dinfo(mtd0),
+                                    rom_size);
+        }
+    }
+
     arm_load_kernel(ARM_CPU(first_cpu), machine, &aspeed_board_binfo);
 }