Re: [PATCH v2 32/76] ARC: [DeviceTree] Basic support

[Rob Herring <robherring2@gmail.com>]

On 01/18/2013 06:24 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@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>
> ---
>  arch/arc/Kconfig                |    9 +++++
>  arch/arc/Makefile               |    9 +++++
>  arch/arc/boot/dtb/Makefile      |   22 ++++++++++++

This is .../boot/dts/Makefile on other arches. We should be consistent.

>  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, 180 insertions(+), 0 deletions(-)
>  create mode 100644 arch/arc/boot/dtb/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 d457a83..5175cf7 100644
> --- a/arch/arc/Kconfig
> +++ b/arch/arc/Kconfig
> @@ -21,7 +21,10 @@ config ARC
>  	select GENERIC_SMP_IDLE_THREAD
>  	select HAVE_GENERIC_HARDIRQS
>  	select HOTPLUG if !INITRAMFS_SOURCE=""
> +	select IRQ_DOMAIN
>  	select MODULES_USE_ELF_RELA
> +	select OF
> +	select OF_EARLY_FLATTREE
>  
>  config SCHED_OMIT_FRAME_POINTER
>  	def_bool y
> @@ -316,6 +319,12 @@ 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..d697e9c 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/dtb/
> +
>  # 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)/dtb $(boot)/dtb/$@
> +
> +dtbs:
> +	$(Q)$(MAKE) $(build)=$(boot)/dtb $(boot)/dtb/$@
> +
>  archclean:
>  	$(Q)$(MAKE) $(clean)=$(boot)
>  
> diff --git a/arch/arc/boot/dtb/Makefile b/arch/arc/boot/dtb/Makefile
> new file mode 100644
> index 0000000..825af84
> --- /dev/null
> +++ b/arch/arc/boot/dtb/Makefile
> @@ -0,0 +1,22 @@
> +ifeq ($(CONFIG_OF),y)
> +
> +dtb-y	+= skeleton.dtb
> +
> +# Built-in dtb
> +builtindtb-y				:= skeleton
> +
> +ifneq ($(CONFIG_ARC_BUILTIN_DTB_NAME),"")
> +	builtindtb-y			:= $(CONFIG_ARC_BUILTIN_DTB_NAME)
> +endif
> +
> +obj-y	+= $(patsubst "%",%,$(builtindtb-y)).dtb.o
> +
> +clean-files += $(obj)/$(dtb-y) $(obj)/*.dtb.S $(obj)/*.dtb.o
> +
> +# Rule to build device tree blobs
> +$(obj)/%.dtb: $(src)/../dts/%.dts FORCE
> +	$(call if_changed_dep,dtc)

There are common rules that went into 3.8. Please use them.

> +
> +$(obj)/dtbs: $(addprefix $(obj)/, $(dtb-y))
> +
> +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..f6a457a
> --- /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-angel4", "snps,arc-ml509";

Normally, you wouldn't have this as part of skeleton. If you need
something generic, then perhaps generic.dts would be better.

> +	#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 ae140e5..5fefb7d 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 \
>  	   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..021293d
> --- /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/bootmem.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 alloc_bootmem_align(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 9897847..1087a97 100644
> --- a/arch/arc/mm/init.c
> +++ b/arch/arc/mm/init.c
> @@ -38,6 +38,11 @@ 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);

? Is this todo?

> +}
> +
>  /*
>   * First memory setup routine called from setup_arch()
>   * 1. setup swapper's mm @init_mm
> @@ -181,3 +186,11 @@ 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);

And this?

> +}
> +#endif /* CONFIG_OF_FLATTREE */
>