mips/mips_r4k: use memdev for RAM

memory_region_allocate_system_memory() API is going away, so
replace it with memdev allocated MemoryRegion. The later is
initialized by generic code, so board only needs to opt in
to memdev scheme by providing
  MachineClass::default_ram_id
and using MachineState::ram instead of manually initializing
RAM memory region.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200219160953.13771-58-imammedo@redhat.com>

hw/mips/mips_r4k.c

@@ -171,13 +171,11 @@ static const int sector_len = 32 * KiB;
 static
 void mips_r4k_init(MachineState *machine)
 {
-    ram_addr_t ram_size = machine->ram_size;
     const char *kernel_filename = machine->kernel_filename;
     const char *kernel_cmdline = machine->kernel_cmdline;
     const char *initrd_filename = machine->initrd_filename;
     char *filename;
     MemoryRegion *address_space_mem = get_system_memory();
-    MemoryRegion *ram = g_new(MemoryRegion, 1);
     MemoryRegion *bios;
     MemoryRegion *iomem = g_new(MemoryRegion, 1);
     MemoryRegion *isa_io = g_new(MemoryRegion, 1);
@@ -203,14 +201,12 @@ void mips_r4k_init(MachineState *machine)
     qemu_register_reset(main_cpu_reset, reset_info);
 
     /* allocate RAM */
-    if (ram_size > 256 * MiB) {
+    if (machine->ram_size > 256 * MiB) {
         error_report("Too much memory for this machine: %" PRId64 "MB,"
                      " maximum 256MB", ram_size / MiB);
         exit(1);
     }
-    memory_region_allocate_system_memory(ram, NULL, "mips_r4k.ram", ram_size);
-
-    memory_region_add_subregion(address_space_mem, 0, ram);
+    memory_region_add_subregion(address_space_mem, 0, machine->ram);
 
     memory_region_init_io(iomem, NULL, &mips_qemu_ops,
                           NULL, "mips-qemu", 0x10000);
@@ -261,7 +257,7 @@ void mips_r4k_init(MachineState *machine)
     g_free(filename);
 
     if (kernel_filename) {
-        loaderparams.ram_size = ram_size;
+        loaderparams.ram_size = machine->ram_size;
         loaderparams.kernel_filename = kernel_filename;
         loaderparams.kernel_cmdline = kernel_cmdline;
         loaderparams.initrd_filename = initrd_filename;
@@ -316,7 +312,7 @@ static void mips_machine_init(MachineClass *mc)
 #else
     mc->default_cpu_type = MIPS_CPU_TYPE_NAME("24Kf");
 #endif
-
+    mc->default_ram_id = "mips_r4k.ram";
 }
 
 DEFINE_MACHINE("mips", mips_machine_init)