MIPS: ingenic: Detect machtype from SoC compatible string

Previously, the mips_machtype variable was always initialized
to MACH_INGENIC_JZ4740 even if running on different SoCs.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Maarten ter Huurne <maarten@treewalker.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/18486/Signed-off-by: James Hogan <jhogan@kernel.org>

arch/mips/jz4740/prom.c

@@ -25,7 +25,6 @@
 
 void __init prom_init(void)
 {
-	mips_machtype = MACH_INGENIC_JZ4740;
 	fw_init_cmdline();
 }
 

arch/mips/jz4740/setup.c

@@ -53,6 +53,16 @@ static void __init jz4740_detect_mem(void)
 	add_memory_region(0, size, BOOT_MEM_RAM);
 }
 
+static unsigned long __init get_board_mach_type(const void *fdt)
+{
+	if (!fdt_node_check_compatible(fdt, 0, "ingenic,jz4780"))
+		return MACH_INGENIC_JZ4780;
+	if (!fdt_node_check_compatible(fdt, 0, "ingenic,jz4770"))
+		return MACH_INGENIC_JZ4770;
+
+	return MACH_INGENIC_JZ4740;
+}
+
 void __init plat_mem_setup(void)
 {
 	int offset;
@@ -63,6 +73,8 @@ void __init plat_mem_setup(void)
 	offset = fdt_path_offset(__dtb_start, "/memory");
 	if (offset < 0)
 		jz4740_detect_mem();
+
+	mips_machtype = get_board_mach_type(__dtb_start);
 }
 
 void __init device_tree_init(void)
@@ -75,10 +87,14 @@ void __init device_tree_init(void)
 
 const char *get_system_type(void)
 {
-	if (IS_ENABLED(CONFIG_MACH_JZ4780))
+	switch (mips_machtype) {
+	case MACH_INGENIC_JZ4780:
 		return "JZ4780";
-
+	case MACH_INGENIC_JZ4770:
+		return "JZ4770";
+	default:
 		return "JZ4740";
+	}
 }
 
 void __init arch_init_irq(void)