[PATCH v3 32/71] ARC: [DeviceTree] Basic support

[PATCH v3 32/71] ARC: [DeviceTree] Basic support

[Vineet Gupta]

This is minimal infrastructure needed for devicetree work.
It uses an a sample "skeleton" devicetree - embedded in kernel image -
to print the board, manufacturer by parsing the top-level "compatible"
string.

As of now we don't need any additional "board" specific "machine_desc".

TODO: support interpreting the command line as boot-loader passed dtb

Signed-off-by: Vineet Gupta <vgupta-HKixBCOQz3hWk0Htik3J/w@public.gmane.org>
Cc: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Cc: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
---
 arch/arc/Kconfig                |    9 +++++
 arch/arc/Makefile               |    9 +++++
 arch/arc/boot/dts/Makefile      |   14 ++++++++
 arch/arc/boot/dts/skeleton.dts  |   10 ++++++
 arch/arc/boot/dts/skeleton.dtsi |   21 ++++++++++++
 arch/arc/include/asm/prom.h     |   15 ++++++++
 arch/arc/include/asm/sections.h |    1 +
 arch/arc/kernel/Makefile        |    2 +
 arch/arc/kernel/devtree.c       |   69 +++++++++++++++++++++++++++++++++++++++
 arch/arc/kernel/setup.c         |    9 +++++
 arch/arc/mm/init.c              |   13 +++++++
 11 files changed, 172 insertions(+), 0 deletions(-)
 create mode 100644 arch/arc/boot/dts/Makefile
 create mode 100644 arch/arc/boot/dts/skeleton.dts
 create mode 100644 arch/arc/boot/dts/skeleton.dtsi
 create mode 100644 arch/arc/include/asm/prom.h
 create mode 100644 arch/arc/kernel/devtree.c

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index a353849..7666857 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -24,8 +24,11 @@ config ARC
 	select GENERIC_SMP_IDLE_THREAD
 	select HAVE_GENERIC_HARDIRQS
 	select HAVE_MEMBLOCK
+	select IRQ_DOMAIN
 	select MODULES_USE_ELF_RELA
 	select NO_BOOTMEM
+	select OF
+	select OF_EARLY_FLATTREE
 
 config SCHED_OMIT_FRAME_POINTER
 	def_bool y
@@ -320,6 +323,12 @@ config CMDLINE_UBOOT
 	  to it. kernel startup code will copy the string into cmdline buffer
 	  and also append CONFIG_CMDLINE.
 
+config ARC_BUILTIN_DTB_NAME
+	string "Built in DTB"
+	help
+	  Set the name of the DTB to embed in the vmlinux binary
+	  Leaving it blank selects the minimal "skeleton" dtb
+
 source "kernel/Kconfig.preempt"
 
 endmenu	 # "ARC Architecture Configuration"
diff --git a/arch/arc/Makefile b/arch/arc/Makefile
index 4d52a3b..90570f9 100644
--- a/arch/arc/Makefile
+++ b/arch/arc/Makefile
@@ -83,6 +83,9 @@ head-y		:= arch/arc/kernel/head.o
 # See arch/arc/Kbuild for content of core part of the kernel
 core-y		+= arch/arc/
 
+# w/o this dtb won't embed into kernel binary
+core-y		+= arch/arc/boot/dts/
+
 # w/o this ifneq, make ARCH=arc clean was crapping out
 ifneq ($(platform-y),)
 core-y		+= arch/arc/plat-$(PLATFORM)/
@@ -101,6 +104,12 @@ bootpImage: vmlinux
 uImage: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
 
+%.dtb %.dtb.S %.dtb.o:
+	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
+
+dtbs:
+	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
+
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)
 
diff --git a/arch/arc/boot/dts/Makefile b/arch/arc/boot/dts/Makefile
new file mode 100644
index 0000000..4a972a3
--- /dev/null
+++ b/arch/arc/boot/dts/Makefile
@@ -0,0 +1,14 @@
+ifeq ($(CONFIG_OF),y)
+
+# Built-in dtb
+builtindtb-y		:= skeleton
+
+ifneq ($(CONFIG_ARC_BUILTIN_DTB_NAME),"")
+	builtindtb-y	:= $(CONFIG_ARC_BUILTIN_DTB_NAME)
+endif
+
+obj-y	+= $(patsubst "%",%,$(builtindtb-y)).dtb.o
+
+clean-files := *.dtb
+
+endif
diff --git a/arch/arc/boot/dts/skeleton.dts b/arch/arc/boot/dts/skeleton.dts
new file mode 100644
index 0000000..25a84fb
--- /dev/null
+++ b/arch/arc/boot/dts/skeleton.dts
@@ -0,0 +1,10 @@
+/*
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+/dts-v1/;
+
+/include/ "skeleton.dtsi"
diff --git a/arch/arc/boot/dts/skeleton.dtsi b/arch/arc/boot/dts/skeleton.dtsi
new file mode 100644
index 0000000..9b357d8
--- /dev/null
+++ b/arch/arc/boot/dts/skeleton.dtsi
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * Skeleton device tree; the bare minimum needed to boot; just include and
+ * add a compatible value.
+ */
+
+/ {
+	compatible = "snps,arc";
+	#address-cells = <1>;
+	#size-cells = <1>;
+	chosen { };
+	aliases { };
+	memory { device_type = "memory"; reg = <0 0>; };
+};
diff --git a/arch/arc/include/asm/prom.h b/arch/arc/include/asm/prom.h
new file mode 100644
index 0000000..f54489b
--- /dev/null
+++ b/arch/arc/include/asm/prom.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_ARC_PROM_H_
+#define _ASM_ARC_PROM_H_
+
+#define HAVE_ARCH_DEVTREE_FIXUPS
+extern int __init setup_machine_fdt(void *dt);
+
+#endif
diff --git a/arch/arc/include/asm/sections.h b/arch/arc/include/asm/sections.h
index fc15f2e..6fc1159 100644
--- a/arch/arc/include/asm/sections.h
+++ b/arch/arc/include/asm/sections.h
@@ -13,5 +13,6 @@
 
 extern char _int_vec_base_lds[];
 extern char __arc_dccm_base[];
+extern char __dtb_start[];
 
 #endif
diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
index 6d83431..8a55e99 100644
--- a/arch/arc/kernel/Makefile
+++ b/arch/arc/kernel/Makefile
@@ -8,6 +8,8 @@
 obj-y	:= arcksyms.o setup.o irq.o time.o reset.o ptrace.o entry.o process.o
 obj-y	+= signal.o traps.o sys.o troubleshoot.o stacktrace.o clk.o
 
+obj-$(CONFIG_OF)			+= devtree.o
+
 obj-$(CONFIG_ARC_FPU_SAVE_RESTORE)	+= fpu.o
 CFLAGS_fpu.o   += -mdpfp
 
diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
new file mode 100644
index 0000000..229f78e
--- /dev/null
+++ b/arch/arc/kernel/devtree.c
@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Based on highly stipped down version of METAG
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/reboot.h>
+#include <linux/memblock.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <asm/prom.h>
+
+/* called from unflatten_device_tree() to bootstrap devicetree itself */
+void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
+{
+	return __va(memblock_alloc(size, align));
+}
+
+/**
+ * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
+ * @dt:		virtual address pointer to dt blob
+ *
+ * If a dtb was passed to the kernel, then use it to choose the correct
+ * machine_desc and to setup the system.
+ */
+int __init setup_machine_fdt(void *dt)
+{
+	struct boot_param_header *devtree = dt;
+	unsigned long dt_root;
+	char *model, *compat;
+	char manufacturer[16];
+
+	/* check device tree validity */
+	if (be32_to_cpu(devtree->magic) != OF_DT_HEADER)
+		return 1;
+
+	/* Search the mdescs for the 'best' compatible value match */
+	initial_boot_params = devtree;
+	dt_root = of_get_flat_dt_root();
+
+	/* compat = "<manufacturer>,<model>" */
+	compat = of_get_flat_dt_prop(dt_root, "compatible", NULL);
+	if (!compat)
+		compat = "<unknown>";
+
+	model = strchr(compat, ',');
+	if (model)
+		model++;
+
+	strlcpy(manufacturer, compat, model ? model - compat : strlen(compat));
+
+	pr_info("Board \"%s\" from %s (Manufacturer)\n", model, manufacturer);
+
+	/* Retrieve various information from the /chosen node */
+	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+
+	return 0;
+}
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 82ac206..27aebd6 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -13,6 +13,8 @@
 #include <linux/console.h>
 #include <linux/module.h>
 #include <linux/cpu.h>
+#include <linux/of_fdt.h>
+#include <asm/sections.h>
 #include <asm/arcregs.h>
 #include <asm/tlb.h>
 #include <asm/cache.h>
@@ -20,6 +22,7 @@
 #include <asm/page.h>
 #include <asm/irq.h>
 #include <asm/arcregs.h>
+#include <asm/prom.h>
 
 #define FIX_PTR(x)  __asm__ __volatile__(";" : "+r"(x))
 
@@ -57,6 +60,8 @@ void __init __attribute__((weak)) arc_platform_early_init(void)
 
 void __init setup_arch(char **cmdline_p)
 {
+	int rc;
+
 #ifdef CONFIG_CMDLINE_UBOOT
 	/* Make sure that a whitespace is inserted before */
 	strlcat(command_line, " ", sizeof(command_line));
@@ -71,6 +76,8 @@ void __init setup_arch(char **cmdline_p)
 	strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = command_line;
 
+	rc = setup_machine_fdt(__dtb_start);
+
 	/* To force early parsing of things like mem=xxx */
 	parse_early_param();
 
@@ -81,6 +88,8 @@ void __init setup_arch(char **cmdline_p)
 
 	setup_arch_memory();
 
+	unflatten_device_tree();
+
 	/* Can be issue if someone passes cmd line arg "ro"
 	 * But that is unlikely so keeping it as it is
 	 */
diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index 63da347..682cf57 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -39,6 +39,11 @@ static int __init setup_mem_sz(char *str)
 }
 early_param("mem", setup_mem_sz);
 
+void __init early_init_dt_add_memory_arch(u64 base, u64 size)
+{
+	pr_err("%s(%llx, %llx)\n", __func__, base, size);
+}
+
 /*
  * First memory setup routine called from setup_arch()
  * 1. setup swapper's mm @init_mm
@@ -169,3 +174,11 @@ void __init free_initrd_mem(unsigned long start, unsigned long end)
 	free_init_pages("initrd memory", start, end);
 }
 #endif
+
+#ifdef CONFIG_OF_FLATTREE
+void __init early_init_dt_setup_initrd_arch(unsigned long start,
+					    unsigned long end)
+{
+	pr_err("%s(%lx, %lx)\n", __func__, start, end);
+}
+#endif /* CONFIG_OF_FLATTREE */
-- 
1.7.4.1

Re: [PATCH v3 32/71] ARC: [DeviceTree] Basic support

[James Hogan]

Hi Vineet,

On 24/01/13 10:50, Vineet Gupta wrote:
> diff --git a/arch/arc/Makefile b/arch/arc/Makefile
> index 4d52a3b..90570f9 100644
> --- a/arch/arc/Makefile
> +++ b/arch/arc/Makefile
> @@ -83,6 +83,9 @@ head-y		:= arch/arc/kernel/head.o
>  # See arch/arc/Kbuild for content of core part of the kernel
>  core-y		+= arch/arc/
>  
> +# w/o this dtb won't embed into kernel binary
> +core-y		+= arch/arc/boot/dts/
> +
>  # w/o this ifneq, make ARCH=arc clean was crapping out
>  ifneq ($(platform-y),)
>  core-y		+= arch/arc/plat-$(PLATFORM)/
> @@ -101,6 +104,12 @@ bootpImage: vmlinux
>  uImage: vmlinux
>  	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
>  
> +%.dtb %.dtb.S %.dtb.o:
> +	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@

arm64 also depends on scripts here, presumably for a reason. I've copied
this in metag too.

> +
> +dtbs:
> +	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@

arm64 does this like below which I think is slightly nicer than how
metag did it:

dtbs: scripts
	$(Q)$(MAKE) $(build)=$(boot)/dts dtbs

> +
>  archclean:
>  	$(Q)$(MAKE) $(clean)=$(boot)
>  
> diff --git a/arch/arc/boot/dts/Makefile b/arch/arc/boot/dts/Makefile
> new file mode 100644
> index 0000000..4a972a3
> --- /dev/null
> +++ b/arch/arc/boot/dts/Makefile
> @@ -0,0 +1,14 @@
> +ifeq ($(CONFIG_OF),y)
> +
> +# Built-in dtb
> +builtindtb-y		:= skeleton
> +
> +ifneq ($(CONFIG_ARC_BUILTIN_DTB_NAME),"")
> +	builtindtb-y	:= $(CONFIG_ARC_BUILTIN_DTB_NAME)
> +endif
> +
> +obj-y	+= $(patsubst "%",%,$(builtindtb-y)).dtb.o
> +
> +clean-files := *.dtb

You don't seem to have a rule for dtbs, but still redirect it in the
main Makefile. I suppose dtbs may want adding to your archhelp if you
use it.

arm64 also adds dtbs and $(dtb-y) to targets (at least in linux-next). I
think this makes sure that they don't get rebuilt unless they've
actually changed. I've also copied this for metag.


> --- a/arch/arc/kernel/Makefile
> +++ b/arch/arc/kernel/Makefile
> @@ -8,6 +8,8 @@
>  obj-y	:= arcksyms.o setup.o irq.o time.o reset.o ptrace.o entry.o process.o
>  obj-y	+= signal.o traps.o sys.o troubleshoot.o stacktrace.o clk.o
>  
> +obj-$(CONFIG_OF)			+= devtree.o
> +

You always select CONFIG_OF, so this could be obj-y. I'm not sure this
particularly matters though.

Cheers
James

Re: [PATCH v3 32/71] ARC: [DeviceTree] Basic support

[Vineet Gupta]

Hi James,

On Monday 28 January 2013 03:51 PM, James Hogan wrote:
> Hi Vineet,
> 
> On 24/01/13 10:50, Vineet Gupta wrote:
>> diff --git a/arch/arc/Makefile b/arch/arc/Makefile
>> index 4d52a3b..90570f9 100644
>> --- a/arch/arc/Makefile
>> +++ b/arch/arc/Makefile
>> @@ -83,6 +83,9 @@ head-y		:= arch/arc/kernel/head.o
>>  # See arch/arc/Kbuild for content of core part of the kernel
>>  core-y		+= arch/arc/
>>  
>> +# w/o this dtb won't embed into kernel binary
>> +core-y		+= arch/arc/boot/dts/
>> +
>>  # w/o this ifneq, make ARCH=arc clean was crapping out
>>  ifneq ($(platform-y),)
>>  core-y		+= arch/arc/plat-$(PLATFORM)/
>> @@ -101,6 +104,12 @@ bootpImage: vmlinux
>>  uImage: vmlinux
>>  	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
>>  
>> +%.dtb %.dtb.S %.dtb.o:
>> +	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
> 
> arm64 also depends on scripts here, presumably for a reason. I've copied
> this in metag too.

It probably has to do with forcing rebuild of DTs, in case scripts/dtc/dtc changes.

I'll add that as well.


>> +
>> +dtbs:
>> +	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
> 
> arm64 does this like below which I think is slightly nicer than how
> metag did it:
> 
> dtbs: scripts
> 	$(Q)$(MAKE) $(build)=$(boot)/dts dtbs

OK !

>> +
>>  archclean:
>>  	$(Q)$(MAKE) $(clean)=$(boot)
>>  
>> diff --git a/arch/arc/boot/dts/Makefile b/arch/arc/boot/dts/Makefile
>> new file mode 100644
>> index 0000000..4a972a3
>> --- /dev/null
>> +++ b/arch/arc/boot/dts/Makefile
>> @@ -0,0 +1,14 @@
>> +ifeq ($(CONFIG_OF),y)
>> +
>> +# Built-in dtb
>> +builtindtb-y		:= skeleton
>> +
>> +ifneq ($(CONFIG_ARC_BUILTIN_DTB_NAME),"")
>> +	builtindtb-y	:= $(CONFIG_ARC_BUILTIN_DTB_NAME)
>> +endif
>> +
>> +obj-y	+= $(patsubst "%",%,$(builtindtb-y)).dtb.o
>> +
>> +clean-files := *.dtb
> 
> You don't seem to have a rule for dtbs, but still redirect it in the
> main Makefile. I suppose dtbs may want adding to your archhelp if you
> use it.

The dtbs rule doesn't seem to be working for me here. I'll need to investigate a bit.

> 
> arm64 also adds dtbs and $(dtb-y) to targets (at least in linux-next). I
> think this makes sure that they don't get rebuilt unless they've
> actually changed. I've also copied this for metag.

Did you verify that it makes a difference - at least at my end it's not - the
default dtb is getting rebuilt everytime. I need to debug this some more.


>> --- a/arch/arc/kernel/Makefile
>> +++ b/arch/arc/kernel/Makefile
>> @@ -8,6 +8,8 @@
>>  obj-y	:= arcksyms.o setup.o irq.o time.o reset.o ptrace.o entry.o process.o
>>  obj-y	+= signal.o traps.o sys.o troubleshoot.o stacktrace.o clk.o
>>  
>> +obj-$(CONFIG_OF)			+= devtree.o
>> +
> 
> You always select CONFIG_OF, so this could be obj-y. I'm not sure this
> particularly matters though.

Right, for consistency we might add this unconditionally.

Thanks for your review
-Vineet

Re: [PATCH v3 32/71] ARC: [DeviceTree] Basic support

[James Hogan]

Hi Vineet,

>> arm64 also adds dtbs and $(dtb-y) to targets (at least in linux-next). I
>> think this makes sure that they don't get rebuilt unless they've
>> actually changed. I've also copied this for metag.
> 
> Did you verify that it makes a difference - at least at my end it's not - the
> default dtb is getting rebuilt everytime. I need to debug this some more.

Yeh, for me it prevents the following build lines appearing every time:
DTC     arch/metag/boot/dts/tz1090_01sp.dtb

but it still does these every time:
DTB    arch/metag/boot/dts/tz1090_01sp.dtb.S
AS      arch/metag/boot/dts/tz1090_01sp.dtb.o

Adding dtbs o targets actually didn't seem to be necessary with $(dtb-y)
added.

Cheers
James

Re: [PATCH v3 32/71] ARC: [DeviceTree] Basic support

[Rob Herring]

On 01/24/2013 04:50 AM, Vineet Gupta wrote:
> This is minimal infrastructure needed for devicetree work.
> It uses an a sample "skeleton" devicetree - embedded in kernel image -
> to print the board, manufacturer by parsing the top-level "compatible"
> string.
> 
> As of now we don't need any additional "board" specific "machine_desc".
> 
> TODO: support interpreting the command line as boot-loader passed dtb
> 
> Signed-off-by: Vineet Gupta <vgupta-HKixBCOQz3hWk0Htik3J/w@public.gmane.org>
> Cc: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
> Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
> Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> Cc: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>

One minor thing below, otherwise:

Reviewed-by: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>


> diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
> new file mode 100644
> index 0000000..229f78e
> --- /dev/null
> +++ b/arch/arc/kernel/devtree.c
> @@ -0,0 +1,69 @@
> +/*
> + * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
> + *
> + * Based on highly stipped down version of METAG
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +
> +#include <linux/init.h>
> +#include <linux/export.h>
> +#include <linux/errno.h>

Is this include needed?

> +#include <linux/types.h>
> +#include <linux/reboot.h>

And this?

> +#include <linux/memblock.h>
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
> +#include <linux/of_irq.h>

And this?

> +#include <linux/of_platform.h>

And this?

> +#include <asm/prom.h>
> +
> +/* called from unflatten_device_tree() to bootstrap devicetree itself */
> +void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
> +{
> +	return __va(memblock_alloc(size, align));
> +}
> +
> +/**
> + * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
> + * @dt:		virtual address pointer to dt blob
> + *
> + * If a dtb was passed to the kernel, then use it to choose the correct
> + * machine_desc and to setup the system.
> + */
> +int __init setup_machine_fdt(void *dt)
> +{
> +	struct boot_param_header *devtree = dt;
> +	unsigned long dt_root;
> +	char *model, *compat;
> +	char manufacturer[16];
> +
> +	/* check device tree validity */
> +	if (be32_to_cpu(devtree->magic) != OF_DT_HEADER)
> +		return 1;
> +
> +	/* Search the mdescs for the 'best' compatible value match */
> +	initial_boot_params = devtree;
> +	dt_root = of_get_flat_dt_root();
> +
> +	/* compat = "<manufacturer>,<model>" */
> +	compat = of_get_flat_dt_prop(dt_root, "compatible", NULL);
> +	if (!compat)
> +		compat = "<unknown>";
> +
> +	model = strchr(compat, ',');
> +	if (model)
> +		model++;
> +
> +	strlcpy(manufacturer, compat, model ? model - compat : strlen(compat));
> +
> +	pr_info("Board \"%s\" from %s (Manufacturer)\n", model, manufacturer);
> +
> +	/* Retrieve various information from the /chosen node */
> +	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
> +
> +	return 0;
> +}
> diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
> index 82ac206..27aebd6 100644
> --- a/arch/arc/kernel/setup.c
> +++ b/arch/arc/kernel/setup.c
> @@ -13,6 +13,8 @@
>  #include <linux/console.h>
>  #include <linux/module.h>
>  #include <linux/cpu.h>
> +#include <linux/of_fdt.h>
> +#include <asm/sections.h>
>  #include <asm/arcregs.h>
>  #include <asm/tlb.h>
>  #include <asm/cache.h>
> @@ -20,6 +22,7 @@
>  #include <asm/page.h>
>  #include <asm/irq.h>
>  #include <asm/arcregs.h>
> +#include <asm/prom.h>
>  
>  #define FIX_PTR(x)  __asm__ __volatile__(";" : "+r"(x))
>  
> @@ -57,6 +60,8 @@ void __init __attribute__((weak)) arc_platform_early_init(void)
>  
>  void __init setup_arch(char **cmdline_p)
>  {
> +	int rc;
> +
>  #ifdef CONFIG_CMDLINE_UBOOT
>  	/* Make sure that a whitespace is inserted before */
>  	strlcat(command_line, " ", sizeof(command_line));
> @@ -71,6 +76,8 @@ void __init setup_arch(char **cmdline_p)
>  	strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
>  	*cmdline_p = command_line;
>  
> +	rc = setup_machine_fdt(__dtb_start);
> +
>  	/* To force early parsing of things like mem=xxx */
>  	parse_early_param();
>  
> @@ -81,6 +88,8 @@ void __init setup_arch(char **cmdline_p)
>  
>  	setup_arch_memory();
>  
> +	unflatten_device_tree();
> +
>  	/* Can be issue if someone passes cmd line arg "ro"
>  	 * But that is unlikely so keeping it as it is
>  	 */
> diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
> index 63da347..682cf57 100644
> --- a/arch/arc/mm/init.c
> +++ b/arch/arc/mm/init.c
> @@ -39,6 +39,11 @@ static int __init setup_mem_sz(char *str)
>  }
>  early_param("mem", setup_mem_sz);
>  
> +void __init early_init_dt_add_memory_arch(u64 base, u64 size)
> +{
> +	pr_err("%s(%llx, %llx)\n", __func__, base, size);
> +}
> +
>  /*
>   * First memory setup routine called from setup_arch()
>   * 1. setup swapper's mm @init_mm
> @@ -169,3 +174,11 @@ void __init free_initrd_mem(unsigned long start, unsigned long end)
>  	free_init_pages("initrd memory", start, end);
>  }
>  #endif
> +
> +#ifdef CONFIG_OF_FLATTREE
> +void __init early_init_dt_setup_initrd_arch(unsigned long start,
> +					    unsigned long end)
> +{
> +	pr_err("%s(%lx, %lx)\n", __func__, start, end);
> +}
> +#endif /* CONFIG_OF_FLATTREE */
> 

Re: [PATCH v3 32/71] ARC: [DeviceTree] Basic support

[Vineet Gupta]

On Tuesday 29 January 2013 06:55 PM, Rob Herring wrote:
> On 01/24/2013 04:50 AM, Vineet Gupta wrote:
>> This is minimal infrastructure needed for devicetree work.
>> It uses an a sample "skeleton" devicetree - embedded in kernel image -
>> to print the board, manufacturer by parsing the top-level "compatible"
>> string.
>>
>> As of now we don't need any additional "board" specific "machine_desc".
>>
>> TODO: support interpreting the command line as boot-loader passed dtb
>>
>> Signed-off-by: Vineet Gupta <vgupta-HKixBCOQz3hWk0Htik3J/w@public.gmane.org>
>> Cc: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
>> Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
>> Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
>> Cc: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
> One minor thing below, otherwise:
>
> Reviewed-by: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
>
>
>> diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
>> new file mode 100644
>> index 0000000..229f78e
>> --- /dev/null
>> +++ b/arch/arc/kernel/devtree.c
>> @@ -0,0 +1,69 @@
>> +/*
>> + * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
>> + *
>> + * Based on highly stipped down version of METAG
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +
>> +#include <linux/init.h>
>> +#include <linux/export.h>
>> +#include <linux/errno.h>
> Is this include needed?

Nope - removed.

>
>> +#include <linux/types.h>
>> +#include <linux/reboot.h>
> And this?

reboot.h is needed for the machine_halt() prototype.

>
>> +#include <linux/memblock.h>
>> +#include <linux/of.h>
>> +#include <linux/of_fdt.h>
>> +#include <linux/of_irq.h>
> And this?
>
>> +#include <linux/of_platform.h>
> And this?

Both of the above removed.

I'll send a revised patch which also addresses James' review comments as well -
(namely broken dtbs rule, adding dependency on scripts ...)
See https://lkml.org/lkml/2013/1/28/138 for reference.

[PATCH v4 32/71] ARC: [DeviceTree] Basic support

[Vineet Gupta]

This is minimal infrastructure needed for devicetree work.
It uses an a sample "skeleton" devicetree - embedded in kernel image -
to print the board, manufacturer by parsing the top-level "compatible"
string.

As of now we don't need any additional "board" specific "machine_desc".

TODO: support interpreting the command line as boot-loader passed dtb

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: James Hogan <james.hogan@imgtec.com>
---
 arch/arc/Kconfig                |    9 +++++
 arch/arc/Makefile               |    9 +++++
 arch/arc/boot/dts/Makefile      |   17 ++++++++++
 arch/arc/boot/dts/skeleton.dts  |   10 ++++++
 arch/arc/boot/dts/skeleton.dtsi |   21 +++++++++++++
 arch/arc/include/asm/prom.h     |   15 +++++++++
 arch/arc/include/asm/sections.h |    1 +
 arch/arc/kernel/Makefile        |    1 +
 arch/arc/kernel/devtree.c       |   64 +++++++++++++++++++++++++++++++++++++++
 arch/arc/kernel/setup.c         |    9 +++++
 arch/arc/mm/init.c              |   13 ++++++++
 11 files changed, 169 insertions(+), 0 deletions(-)
 create mode 100644 arch/arc/boot/dts/Makefile
 create mode 100644 arch/arc/boot/dts/skeleton.dts
 create mode 100644 arch/arc/boot/dts/skeleton.dtsi
 create mode 100644 arch/arc/include/asm/prom.h
 create mode 100644 arch/arc/kernel/devtree.c

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index a353849..7666857 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -24,8 +24,11 @@ config ARC
 	select GENERIC_SMP_IDLE_THREAD
 	select HAVE_GENERIC_HARDIRQS
 	select HAVE_MEMBLOCK
+	select IRQ_DOMAIN
 	select MODULES_USE_ELF_RELA
 	select NO_BOOTMEM
+	select OF
+	select OF_EARLY_FLATTREE
 
 config SCHED_OMIT_FRAME_POINTER
 	def_bool y
@@ -320,6 +323,12 @@ config CMDLINE_UBOOT
 	  to it. kernel startup code will copy the string into cmdline buffer
 	  and also append CONFIG_CMDLINE.
 
+config ARC_BUILTIN_DTB_NAME
+	string "Built in DTB"
+	help
+	  Set the name of the DTB to embed in the vmlinux binary
+	  Leaving it blank selects the minimal "skeleton" dtb
+
 source "kernel/Kconfig.preempt"
 
 endmenu	 # "ARC Architecture Configuration"
diff --git a/arch/arc/Makefile b/arch/arc/Makefile
index 4d52a3b..29b5fcd 100644
--- a/arch/arc/Makefile
+++ b/arch/arc/Makefile
@@ -83,6 +83,9 @@ head-y		:= arch/arc/kernel/head.o
 # See arch/arc/Kbuild for content of core part of the kernel
 core-y		+= arch/arc/
 
+# w/o this dtb won't embed into kernel binary
+core-y		+= arch/arc/boot/dts/
+
 # w/o this ifneq, make ARCH=arc clean was crapping out
 ifneq ($(platform-y),)
 core-y		+= arch/arc/plat-$(PLATFORM)/
@@ -101,6 +104,12 @@ bootpImage: vmlinux
 uImage: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
 
+%.dtb %.dtb.S %.dtb.o: scripts
+	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
+
+dtbs: scripts
+	$(Q)$(MAKE) $(build)=$(boot)/dts dtbs
+
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)
 
diff --git a/arch/arc/boot/dts/Makefile b/arch/arc/boot/dts/Makefile
new file mode 100644
index 0000000..ea3114c
--- /dev/null
+++ b/arch/arc/boot/dts/Makefile
@@ -0,0 +1,17 @@
+ifeq ($(CONFIG_OF),y)
+
+# Built-in dtb
+builtindtb-y		:= skeleton
+
+ifneq ($(CONFIG_ARC_BUILTIN_DTB_NAME),"")
+	builtindtb-y	:= $(patsubst "%",%,$(CONFIG_ARC_BUILTIN_DTB_NAME))
+endif
+
+obj-y   += $(builtindtb-y).dtb.o
+targets += $(builtindtb-y).dtb
+
+dtbs:  $(addprefix  $(obj)/, $(builtindtb-y).dtb)
+
+clean-files := *.dtb
+
+endif
diff --git a/arch/arc/boot/dts/skeleton.dts b/arch/arc/boot/dts/skeleton.dts
new file mode 100644
index 0000000..25a84fb
--- /dev/null
+++ b/arch/arc/boot/dts/skeleton.dts
@@ -0,0 +1,10 @@
+/*
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+/dts-v1/;
+
+/include/ "skeleton.dtsi"
diff --git a/arch/arc/boot/dts/skeleton.dtsi b/arch/arc/boot/dts/skeleton.dtsi
new file mode 100644
index 0000000..9b357d8
--- /dev/null
+++ b/arch/arc/boot/dts/skeleton.dtsi
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * Skeleton device tree; the bare minimum needed to boot; just include and
+ * add a compatible value.
+ */
+
+/ {
+	compatible = "snps,arc";
+	#address-cells = <1>;
+	#size-cells = <1>;
+	chosen { };
+	aliases { };
+	memory { device_type = "memory"; reg = <0 0>; };
+};
diff --git a/arch/arc/include/asm/prom.h b/arch/arc/include/asm/prom.h
new file mode 100644
index 0000000..f54489b
--- /dev/null
+++ b/arch/arc/include/asm/prom.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_ARC_PROM_H_
+#define _ASM_ARC_PROM_H_
+
+#define HAVE_ARCH_DEVTREE_FIXUPS
+extern int __init setup_machine_fdt(void *dt);
+
+#endif
diff --git a/arch/arc/include/asm/sections.h b/arch/arc/include/asm/sections.h
index fc15f2e..6fc1159 100644
--- a/arch/arc/include/asm/sections.h
+++ b/arch/arc/include/asm/sections.h
@@ -13,5 +13,6 @@
 
 extern char _int_vec_base_lds[];
 extern char __arc_dccm_base[];
+extern char __dtb_start[];
 
 #endif
diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
index 6d83431..eeab7c79 100644
--- a/arch/arc/kernel/Makefile
+++ b/arch/arc/kernel/Makefile
@@ -7,6 +7,7 @@
 
 obj-y	:= arcksyms.o setup.o irq.o time.o reset.o ptrace.o entry.o process.o
 obj-y	+= signal.o traps.o sys.o troubleshoot.o stacktrace.o clk.o
+obj-y   += devtree.o
 
 obj-$(CONFIG_ARC_FPU_SAVE_RESTORE)	+= fpu.o
 CFLAGS_fpu.o   += -mdpfp
diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
new file mode 100644
index 0000000..48e157e
--- /dev/null
+++ b/arch/arc/kernel/devtree.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Based on reduced version of METAG
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+
+#include <linux/init.h>
+#include <linux/reboot.h>
+#include <linux/memblock.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <asm/prom.h>
+
+/* called from unflatten_device_tree() to bootstrap devicetree itself */
+void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
+{
+	return __va(memblock_alloc(size, align));
+}
+
+/**
+ * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
+ * @dt:		virtual address pointer to dt blob
+ *
+ * If a dtb was passed to the kernel, then use it to choose the correct
+ * machine_desc and to setup the system.
+ */
+int __init setup_machine_fdt(void *dt)
+{
+	struct boot_param_header *devtree = dt;
+	unsigned long dt_root;
+	char *model, *compat;
+	char manufacturer[16];
+
+	/* check device tree validity */
+	if (be32_to_cpu(devtree->magic) != OF_DT_HEADER)
+		return 1;
+
+	/* Search the mdescs for the 'best' compatible value match */
+	initial_boot_params = devtree;
+	dt_root = of_get_flat_dt_root();
+
+	/* compat = "<manufacturer>,<model>" */
+	compat = of_get_flat_dt_prop(dt_root, "compatible", NULL);
+	if (!compat)
+		compat = "<unknown>";
+
+	model = strchr(compat, ',');
+	if (model)
+		model++;
+
+	strlcpy(manufacturer, compat, model ? model - compat : strlen(compat));
+
+	pr_info("Board \"%s\" from %s (Manufacturer)\n", model, manufacturer);
+
+	/* Retrieve various information from the /chosen node */
+	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+
+	return 0;
+}
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 82ac206..27aebd6 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -13,6 +13,8 @@
 #include <linux/console.h>
 #include <linux/module.h>
 #include <linux/cpu.h>
+#include <linux/of_fdt.h>
+#include <asm/sections.h>
 #include <asm/arcregs.h>
 #include <asm/tlb.h>
 #include <asm/cache.h>
@@ -20,6 +22,7 @@
 #include <asm/page.h>
 #include <asm/irq.h>
 #include <asm/arcregs.h>
+#include <asm/prom.h>
 
 #define FIX_PTR(x)  __asm__ __volatile__(";" : "+r"(x))
 
@@ -57,6 +60,8 @@ void __init __attribute__((weak)) arc_platform_early_init(void)
 
 void __init setup_arch(char **cmdline_p)
 {
+	int rc;
+
 #ifdef CONFIG_CMDLINE_UBOOT
 	/* Make sure that a whitespace is inserted before */
 	strlcat(command_line, " ", sizeof(command_line));
@@ -71,6 +76,8 @@ void __init setup_arch(char **cmdline_p)
 	strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = command_line;
 
+	rc = setup_machine_fdt(__dtb_start);
+
 	/* To force early parsing of things like mem=xxx */
 	parse_early_param();
 
@@ -81,6 +88,8 @@ void __init setup_arch(char **cmdline_p)
 
 	setup_arch_memory();
 
+	unflatten_device_tree();
+
 	/* Can be issue if someone passes cmd line arg "ro"
 	 * But that is unlikely so keeping it as it is
 	 */
diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index 63da347..682cf57 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -39,6 +39,11 @@ static int __init setup_mem_sz(char *str)
 }
 early_param("mem", setup_mem_sz);
 
+void __init early_init_dt_add_memory_arch(u64 base, u64 size)
+{
+	pr_err("%s(%llx, %llx)\n", __func__, base, size);
+}
+
 /*
  * First memory setup routine called from setup_arch()
  * 1. setup swapper's mm @init_mm
@@ -169,3 +174,11 @@ void __init free_initrd_mem(unsigned long start, unsigned long end)
 	free_init_pages("initrd memory", start, end);
 }
 #endif
+
+#ifdef CONFIG_OF_FLATTREE
+void __init early_init_dt_setup_initrd_arch(unsigned long start,
+					    unsigned long end)
+{
+	pr_err("%s(%lx, %lx)\n", __func__, start, end);
+}
+#endif /* CONFIG_OF_FLATTREE */
-- 
1.7.4.1

Re: [PATCH v4 32/71] ARC: [DeviceTree] Basic support

[James Hogan]

Hi Vineet

On 29/01/13 13:55, Vineet Gupta wrote:
> diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
> index a353849..7666857 100644
> --- a/arch/arc/Kconfig
> +++ b/arch/arc/Kconfig
> @@ -24,8 +24,11 @@ config ARC

> +	select OF

> diff --git a/arch/arc/Makefile b/arch/arc/Makefile
> index 4d52a3b..29b5fcd 100644
> --- a/arch/arc/Makefile
> +++ b/arch/arc/Makefile
> @@ -83,6 +83,9 @@ head-y		:= arch/arc/kernel/head.o

> +# w/o this dtb won't embed into kernel binary
> +core-y		+= arch/arc/boot/dts/

> diff --git a/arch/arc/boot/dts/Makefile b/arch/arc/boot/dts/Makefile
> new file mode 100644
> index 0000000..ea3114c
> --- /dev/null
> +++ b/arch/arc/boot/dts/Makefile
> @@ -0,0 +1,17 @@
> +ifeq ($(CONFIG_OF),y)

This doesn't seem necessary since you select OF (and if you didn't you
could put core-$(CONFIG_OF) in the main Makefile.

> diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
> index 6d83431..eeab7c79 100644
> --- a/arch/arc/kernel/Makefile
> +++ b/arch/arc/kernel/Makefile
> @@ -7,6 +7,7 @@
>  
>  obj-y	:= arcksyms.o setup.o irq.o time.o reset.o ptrace.o entry.o process.o
>  obj-y	+= signal.o traps.o sys.o troubleshoot.o stacktrace.o clk.o
> +obj-y   += devtree.o

nit: whitespace is inconsistent here.

> diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
> index 82ac206..27aebd6 100644
> --- a/arch/arc/kernel/setup.c
> +++ b/arch/arc/kernel/setup.c

> @@ -71,6 +76,8 @@ void __init setup_arch(char **cmdline_p)
>  	strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
>  	*cmdline_p = command_line;
>  
> +	rc = setup_machine_fdt(__dtb_start);

Should this panic or something if it fails? Actually I see it does in
your -next branch, so I guess it's fixed in a later patch.

So other than the stuff above:
Reviewed-by: James Hogan <james.hogan@imgtec.com>

Re: [PATCH v4 32/71] ARC: [DeviceTree] Basic support

[Vineet Gupta]

On Wednesday 30 January 2013 04:38 PM, James Hogan wrote:
> Hi Vineet
>
> On 29/01/13 13:55, Vineet Gupta wrote:
>> diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
>> index a353849..7666857 100644
>> --- a/arch/arc/Kconfig
>> +++ b/arch/arc/Kconfig
>> @@ -24,8 +24,11 @@ config ARC
>> +	select OF
>> diff --git a/arch/arc/Makefile b/arch/arc/Makefile
>> index 4d52a3b..29b5fcd 100644
>> --- a/arch/arc/Makefile
>> +++ b/arch/arc/Makefile
>> @@ -83,6 +83,9 @@ head-y		:= arch/arc/kernel/head.o
>> +# w/o this dtb won't embed into kernel binary
>> +core-y		+= arch/arc/boot/dts/
>> diff --git a/arch/arc/boot/dts/Makefile b/arch/arc/boot/dts/Makefile
>> new file mode 100644
>> index 0000000..ea3114c
>> --- /dev/null
>> +++ b/arch/arc/boot/dts/Makefile
>> @@ -0,0 +1,17 @@
>> +ifeq ($(CONFIG_OF),y)
> This doesn't seem necessary since you select OF (and if you didn't you
> could put core-$(CONFIG_OF) in the main Makefile.

Right - taken care of.

>
>> diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
>> index 6d83431..eeab7c79 100644
>> --- a/arch/arc/kernel/Makefile
>> +++ b/arch/arc/kernel/Makefile
>> @@ -7,6 +7,7 @@
>>  
>>  obj-y	:= arcksyms.o setup.o irq.o time.o reset.o ptrace.o entry.o process.o
>>  obj-y	+= signal.o traps.o sys.o troubleshoot.o stacktrace.o clk.o
>> +obj-y   += devtree.o
> nit: whitespace is inconsistent here.

OK !

>> diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
>> index 82ac206..27aebd6 100644
>> --- a/arch/arc/kernel/setup.c
>> +++ b/arch/arc/kernel/setup.c
>> @@ -71,6 +76,8 @@ void __init setup_arch(char **cmdline_p)
>>  	strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
>>  	*cmdline_p = command_line;
>>  
>> +	rc = setup_machine_fdt(__dtb_start);
> Should this panic or something if it fails? Actually I see it does in
> your -next branch, so I guess it's fixed in a later patch.

Yes, it does in [62/71] when the return value is a machine description which is
NULL. Since my DT support was incrementally added - this patch only enables
printing the board name from the "early" flattened DT and does no more - and
doesn't care if that succeeds or not.

> So other than the stuff above:
> Reviewed-by: James Hogan <james.hogan@imgtec.com>

Thx,
-Vineet