sh: add support for linking a builtin device tree blob in the kernel

Signed-off-by: Rich Felker <[e-mail]>

arch/sh/Kconfig

···
 
 menu "Boot options"
 
+config USE_BUILTIN_DTB
+	bool "Use builtin DTB"
+	default n
+	depends on SH_DEVICE_TREE
+	help
+	  Link a device tree blob for particular hardware into the kernel,
+	  suppressing use of the DTB pointer provided by the bootloader.
+	  This option should only be used with legacy bootloaders that are
+	  not capable of providing a DTB to the kernel, or for experimental
+	  hardware without stable device tree bindings.
+
+config BUILTIN_DTB_SOURCE
+	string "Source file for builtin DTB"
+	default ""
+	depends on USE_BUILTIN_DTB
+	help
+	  Base name (without suffix, relative to arch/sh/boot/dts) for the
+	  a DTS file that will be used to produce the DTB linked into the
+	  kernel.
+
 config ZERO_PAGE_OFFSET
 	hex
 	default "0x00010000" if PAGE_SIZE_64KB || SH_RTS7751R2D || \

arch/sh/Makefile

···
 core-y				+= arch/sh/kernel/ arch/sh/mm/ arch/sh/boards/
 core-$(CONFIG_SH_FPU_EMU)	+= arch/sh/math-emu/
 
+core-$(CONFIG_USE_BUILTIN_DTB)	+= arch/sh/boot/dts/
+
 # Mach groups
 machdir-$(CONFIG_SOLUTION_ENGINE)		+= mach-se
 machdir-$(CONFIG_SH_HP6XX)			+= mach-hp6xx

arch/sh/boards/of-generic.c

···
 
 static void __init sh_of_setup(char **cmdline_p)
 {
+	struct device_node *root;
+
+#ifdef CONFIG_USE_BUILTIN_DTB
+	unflatten_and_copy_device_tree();
+#else
 	unflatten_device_tree();
+#endif
 
 	board_time_init = sh_of_time_init;
 
-	sh_mv.mv_name = of_flat_dt_get_machine_name();
-	if (!sh_mv.mv_name)
-		sh_mv.mv_name = "Unknown SH model";
+	sh_mv.mv_name = "Unknown SH model";
+	root = of_find_node_by_path("/");
+	if (root) {
+		of_property_read_string(root, "model", &sh_mv.mv_name);
+		of_node_put(root);
+	}
 
 	sh_of_smp_probe();
 }

arch/sh/boot/dts/Makefile

···
+obj-$(CONFIG_USE_BUILTIN_DTB) += $(patsubst "%",%,$(CONFIG_BUILTIN_DTB_SOURCE)).dtb.o
+
+clean-files := *.dtb.S

arch/sh/kernel/setup.c

···
 	/* Avoid calling an __init function on secondary cpus. */
 	if (done) return;
 
+#ifdef CONFIG_USE_BUILTIN_DTB
+	dt_virt = __dtb_start;
+#else
 	dt_virt = phys_to_virt(dt_phys);
+#endif
 
 	if (!dt_virt || !early_init_dt_scan(dt_virt)) {
 		pr_crit("Error: invalid device tree blob"