This commit adds RPi4B device tree modifications:
- disable pcie, rng200, thermal sensor and genet devices
  (they're going to be re-enabled in the following commits)
- create additional memory region in device tree
  if RAM amount exceeds VC base address.

Signed-off-by: Sergey Kambalin <sergey.kambalin@auriga.com>
---
 hw/arm/raspi.c                  |  5 +--
 hw/arm/raspi4b.c                | 60 +++++++++++++++++++++++++++++++++
 include/hw/arm/raspi_platform.h |  4 +++
 3 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/hw/arm/raspi.c b/hw/arm/raspi.c
index da1e9e7c13..895c305122 100644
--- a/hw/arm/raspi.c
+++ b/hw/arm/raspi.c
@@ -37,9 +37,6 @@ OBJECT_DECLARE_SIMPLE_TYPE(RaspiMachineState, RASPI_MACHINE)
 #define FIRMWARE_ADDR_3 0x80000 /* Pi 3 loads kernel.img here by default */
 #define SPINTABLE_ADDR  0xd8 /* Pi 3 bootloader spintable */
 
-/* Registered machine type (matches RPi Foundation bootloader and U-Boot) */
-#define MACH_TYPE_BCM2708   3138
-
 struct RaspiMachineState {
     /*< private >*/
     RaspiBaseMachineState parent_obj;
@@ -75,7 +72,7 @@ static const struct {
     [PROCESSOR_ID_BCM2838] = {TYPE_BCM2838, BCM283X_NCPUS},
 };
 
-static uint64_t board_ram_size(uint32_t board_rev)
+uint64_t board_ram_size(uint32_t board_rev)
 {
     assert(FIELD_EX32(board_rev, REV_CODE, STYLE)); /* Only new style */
     return 256 * MiB << FIELD_EX32(board_rev, REV_CODE, MEMORY_SIZE);
diff --git a/hw/arm/raspi4b.c b/hw/arm/raspi4b.c
index 2d33861c57..10376b62dc 100644
--- a/hw/arm/raspi4b.c
+++ b/hw/arm/raspi4b.c
@@ -21,6 +21,7 @@
 #include "hw/arm/boot.h"
 #include "qom/object.h"
 #include "hw/arm/bcm2838.h"
+#include <libfdt.h>
 
 #define TYPE_RASPI4B_MACHINE MACHINE_TYPE_NAME("raspi4b-2g")
 OBJECT_DECLARE_SIMPLE_TYPE(Raspi4bMachineState, RASPI4B_MACHINE)
@@ -32,6 +33,64 @@ struct Raspi4bMachineState {
     BCM2838State soc;
 };
 
+/* Add second memory region if board RAM amount exceeds VC base address
+ * (see https://datasheets.raspberrypi.com/bcm2711/bcm2711-peripherals.pdf
+ * 1.2 Address Map)
+ */
+static int raspi_add_memory_node(void *fdt, hwaddr mem_base, hwaddr mem_len)
+{
+    int ret;
+    uint32_t acells, scells;
+    char *nodename = g_strdup_printf("/memory@%" PRIx64, mem_base);
+
+    acells = qemu_fdt_getprop_cell(fdt, "/", "#address-cells",
+                                   NULL, &error_fatal);
+    scells = qemu_fdt_getprop_cell(fdt, "/", "#size-cells",
+                                   NULL, &error_fatal);
+    if (acells == 0 || scells == 0) {
+        fprintf(stderr, "dtb file invalid (#address-cells or #size-cells 0)\n");
+        ret = -1;
+    } else {
+        qemu_fdt_add_subnode(fdt, nodename);
+        qemu_fdt_setprop_string(fdt, nodename, "device_type", "memory");
+        ret = qemu_fdt_setprop_sized_cells(fdt, nodename, "reg",
+                                           acells, mem_base,
+                                           scells, mem_len);
+    }
+
+    g_free(nodename);
+    return ret;
+}
+
+static void raspi4_modify_dtb(const struct arm_boot_info *info, void *fdt)
+{
+
+    /* Temporarily disable following devices until they are implemented*/
+    const char *to_be_removed_from_dt_as_wa[] = {
+        "brcm,bcm2711-pcie",
+        "brcm,bcm2711-rng200",
+        "brcm,bcm2711-thermal",
+        "brcm,bcm2711-genet-v5",
+    };
+
+    for (int i = 0; i < ARRAY_SIZE(to_be_removed_from_dt_as_wa); i++) {
+        const char *dev_str = to_be_removed_from_dt_as_wa[i];
+
+        int offset = fdt_node_offset_by_compatible(fdt, -1, dev_str);
+        if (offset >= 0) {
+            if (!fdt_nop_node(fdt, offset)) {
+                warn_report("bcm2711 dtc: %s has been disabled!", dev_str);
+            }
+        }
+    }
+
+    uint64_t ram_size = board_ram_size(info->board_id);
+
+    if (info->ram_size > UPPER_RAM_BASE) {
+        raspi_add_memory_node(fdt, UPPER_RAM_BASE, ram_size - UPPER_RAM_BASE);
+    }
+}
+
 static void raspi4b_machine_init(MachineState *machine)
 {
     Raspi4bMachineState *s = RASPI4B_MACHINE(machine);
@@ -39,6 +98,7 @@ static void raspi4b_machine_init(MachineState *machine)
     RaspiBaseMachineClass *mc = RASPI_BASE_MACHINE_GET_CLASS(machine);
     BCM2838State *soc = &s->soc;
 
+    s_base->binfo.modify_dtb = raspi4_modify_dtb;
     s_base->binfo.board_id = mc->board_rev;
 
     object_initialize_child(OBJECT(machine), "soc", soc,
diff --git a/include/hw/arm/raspi_platform.h b/include/hw/arm/raspi_platform.h
index 45003e2425..0db146e592 100644
--- a/include/hw/arm/raspi_platform.h
+++ b/include/hw/arm/raspi_platform.h
@@ -31,6 +31,9 @@
 #include "hw/boards.h"
 #include "hw/arm/boot.h"
 
+/* Registered machine type (matches RPi Foundation bootloader and U-Boot) */
+#define MACH_TYPE_BCM2708   3138
+
 #define TYPE_RASPI_BASE_MACHINE MACHINE_TYPE_NAME("raspi-base")
 OBJECT_DECLARE_TYPE(RaspiBaseMachineState, RaspiBaseMachineClass,
                     RASPI_BASE_MACHINE)
@@ -59,6 +62,7 @@ void raspi_base_machine_init(MachineState *machine,
 
 void raspi_machine_class_common_init(MachineClass *mc,
                                      uint32_t board_rev);
+uint64_t board_ram_size(uint32_t board_rev);
 
 #define MSYNC_OFFSET            0x0000   /* Multicore Sync Block */
 #define CCPT_OFFSET             0x1000   /* Compact Camera Port 2 TX */
-- 
2.34.1