CRISv32: add device tree support

Add support for booting CRISv32 with a built-in device tree.
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>

arch/cris/Kconfig

@@ -54,6 +54,8 @@ config CRIS
 	select OLD_SIGACTION
 	select ARCH_REQUIRE_GPIOLIB
 	select IRQ_DOMAIN if ETRAX_ARCH_V32
+	select OF if ETRAX_ARCH_V32
+	select OF_EARLY_FLATTREE if ETRAX_ARCH_V32
 
 config HZ
 	int
@@ -63,6 +65,10 @@ config NR_CPUS
 	int
 	default "1"
 
+config BUILTIN_DTB
+	string "DTB to build into the kernel image"
+	depends on OF
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"

arch/cris/Makefile

@@ -40,6 +40,10 @@ else
 MACH :=
 endif
 
+ifneq ($(CONFIG_BUILTIN_DTB),"")
+core-$(CONFIG_OF) += arch/cris/boot/dts/
+endif
+
 LD = $(CROSS_COMPILE)ld -mcrislinux
 
 OBJCOPYFLAGS := -O binary -R .note -R .comment -S

arch/cris/boot/dts/Makefile

+BUILTIN_DTB := $(patsubst "%",%,$(CONFIG_BUILTIN_DTB)).dtb.o
+ifneq ($(CONFIG_BUILTIN_DTB),"")
+obj-$(CONFIG_OF) += $(BUILTIN_DTB)
+endif
+
+clean-files := *.dtb.S

arch/cris/kernel/Makefile

@@ -7,6 +7,7 @@ CPPFLAGS_vmlinux.lds := -DDRAM_VIRTUAL_BASE=0x$(CONFIG_ETRAX_DRAM_VIRTUAL_BASE)
 extra-y	:= vmlinux.lds
 
 obj-y   := process.o traps.o irq.o ptrace.o setup.o time.o sys_cris.o
+obj-y += devicetree.o
 
 obj-$(CONFIG_MODULES)    += crisksyms.o
 obj-$(CONFIG_MODULES)	 += module.o

arch/cris/kernel/devicetree.c

+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/printk.h>
+
+void __init early_init_dt_add_memory_arch(u64 base, u64 size)
+{
+	pr_err("%s(%llx, %llx)\n",
+	       __func__, base, size);
+}
+
+void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
+{
+	return alloc_bootmem_align(size, align);
+}

arch/cris/kernel/setup.c

@@ -19,6 +19,9 @@
 #include <linux/utsname.h>
 #include <linux/pfn.h>
 #include <linux/cpu.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_platform.h>
 #include <asm/setup.h>
 #include <arch/system.h>
 
@@ -64,6 +67,10 @@ void __init setup_arch(char **cmdline_p)
 	unsigned long start_pfn, max_pfn;
 	unsigned long memory_start;
 
+#ifdef CONFIG_OF
+	early_init_dt_scan(__dtb_start);
+#endif
+
 	/* register an initial console printing routine for printk's */
 
 	init_etrax_debug();
@@ -141,6 +148,8 @@ void __init setup_arch(char **cmdline_p)
 
 	reserve_bootmem(PFN_PHYS(start_pfn), bootmap_size, BOOTMEM_DEFAULT);
 
+	unflatten_and_copy_device_tree();
+
 	/* paging_init() sets up the MMU and marks all pages as reserved */
 
 	paging_init();
@@ -204,3 +213,9 @@ static int __init topology_init(void)
 
 subsys_initcall(topology_init);
 
+static int __init cris_of_init(void)
+{
+	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
+	return 0;
+}
+core_initcall(cris_of_init);