[PATCH v6 1/5] arm/dt: Make __vet_atags also accept a dtb image

[PATCH v6 1/5] arm/dt: Make __vet_atags also accept a dtb image

[Grant Likely]

The dtb is passed to the kernel via register r2, which is the same
method that is used to pass an atags pointer.  This patch modifies
__vet_atags to not clear r2 when it encounters a dtb image.

v2: fixed bugs pointed out by Nicolas Pitre

Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 arch/arm/kernel/head-common.S |   24 ++++++++++++++++++------
 arch/arm/kernel/head.S        |    8 ++++----
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index c84b57d..854bd22 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -15,6 +15,12 @@
 #define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
 #define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)
 
+#ifdef CONFIG_CPU_BIG_ENDIAN
+#define OF_DT_MAGIC 0xd00dfeed
+#else
+#define OF_DT_MAGIC 0xedfe0dd0 /* 0xd00dfeed in big-endian */
+#endif
+
 /*
  * Exception handling.  Something went wrong and we can't proceed.  We
  * ought to tell the user, but since we don't have any guarantee that
@@ -28,20 +34,26 @@
 
 /* Determine validity of the r2 atags pointer.  The heuristic requires
  * that the pointer be aligned, in the first 16k of physical RAM and
- * that the ATAG_CORE marker is first and present.  Future revisions
+ * that the ATAG_CORE marker is first and present.  If CONFIG_OF_FLATTREE
+ * is selected, then it will also accept a dtb pointer.  Future revisions
  * of this function may be more lenient with the physical address and
  * may also be able to move the ATAGS block if necessary.
  *
  * Returns:
- *  r2 either valid atags pointer, or zero
+ *  r2 either valid atags pointer, valid dtb pointer, or zero
  *  r5, r6 corrupted
  */
 __vet_atags:
 	tst	r2, #0x3			@ aligned?
 	bne	1f
 
-	ldr	r5, [r2, #0]			@ is first tag ATAG_CORE?
-	cmp	r5, #ATAG_CORE_SIZE
+	ldr	r5, [r2, #0]
+#ifdef CONFIG_OF_FLATTREE
+	ldr	r6, =OF_DT_MAGIC		@ is it a DTB?
+	cmp	r5, r6
+	beq	2f
+#endif
+	cmp	r5, #ATAG_CORE_SIZE		@ is first tag ATAG_CORE?
 	cmpne	r5, #ATAG_CORE_SIZE_EMPTY
 	bne	1f
 	ldr	r5, [r2, #4]
@@ -49,7 +61,7 @@ __vet_atags:
 	cmp	r5, r6
 	bne	1f
 
-	mov	pc, lr				@ atag pointer is ok
+2:	mov	pc, lr				@ atag/dtb pointer is ok
 
 1:	mov	r2, #0
 	mov	pc, lr
@@ -61,7 +73,7 @@ ENDPROC(__vet_atags)
  *
  *  r0  = cp#15 control register
  *  r1  = machine ID
- *  r2  = atags pointer
+ *  r2  = atags/dtb pointer
  *  r9  = processor ID
  */
 	__INIT
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index c9173cf..a5e5c5b 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -59,7 +59,7 @@
  *
  * This is normally called from the decompressor code.  The requirements
  * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
- * r1 = machine nr, r2 = atags pointer.
+ * r1 = machine nr, r2 = atags or dtb pointer.
  *
  * This code is mostly position independent, so if you link the kernel at
  * 0xc0008000, you call this at __pa(0xc0008000).
@@ -91,7 +91,7 @@ ENTRY(stext)
 #endif
 
 	/*
-	 * r1 = machine no, r2 = atags,
+	 * r1 = machine no, r2 = atags or dtb,
 	 * r8 = phys_offset, r9 = cpuid, r10 = procinfo
 	 */
 	bl	__vet_atags
@@ -339,7 +339,7 @@ __secondary_data:
  *
  *  r0  = cp#15 control register
  *  r1  = machine ID
- *  r2  = atags pointer
+ *  r2  = atags or dtb pointer
  *  r4  = page table pointer
  *  r9  = processor ID
  *  r13 = *virtual* address to jump to upon completion
@@ -376,7 +376,7 @@ ENDPROC(__enable_mmu)
  *
  *  r0  = cp#15 control register
  *  r1  = machine ID
- *  r2  = atags pointer
+ *  r2  = atags or dtb pointer
  *  r9  = processor ID
  *  r13 = *virtual* address to jump to upon completion
  *

[PATCH v6 2/5] arm/dt: Allow CONFIG_OF on ARM

[Grant Likely]

Add some basic empty infrastructure for DT support on ARM.

v5: - Fix off-by-one error in size calculation of initrd
    - Stop mucking with cmd_line, and load command line from dt into
      boot_command_line instead which matches the behaviour of ATAGS booting
v3: - moved cmd_line export and initrd setup to this patch to make the
      series bisectable.
    - switched to alloc_bootmem_align() for allocation when
      unflattening the device tree.  memblock_alloc() was not the
      right interface.

Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 arch/arm/Kconfig             |    7 ++++++
 arch/arm/include/asm/prom.h  |   25 ++++++++++++++++++++++
 arch/arm/include/asm/setup.h |    2 ++
 arch/arm/kernel/Makefile     |    1 +
 arch/arm/kernel/devtree.c    |   47 ++++++++++++++++++++++++++++++++++++++++++
 arch/arm/kernel/setup.c      |    2 +-
 arch/arm/mm/init.c           |    9 ++++++++
 7 files changed, 92 insertions(+), 1 deletions(-)
 create mode 100644 arch/arm/include/asm/prom.h
 create mode 100644 arch/arm/kernel/devtree.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 377a7a5..efc7f3c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1687,6 +1687,13 @@ endmenu
 
 menu "Boot options"
 
+config USE_OF
+	bool "Flattened Device Tree support"
+	select OF
+	select OF_EARLY_FLATTREE
+	help
+	  Include support for flattened device tree machine descriptions.
+
 # Compressed boot loader in ROM.  Yes, we really want to ask about
 # TEXT and BSS so we preserve their values in the config files.
 config ZBOOT_ROM_TEXT
diff --git a/arch/arm/include/asm/prom.h b/arch/arm/include/asm/prom.h
new file mode 100644
index 0000000..8f1037f
--- /dev/null
+++ b/arch/arm/include/asm/prom.h
@@ -0,0 +1,25 @@
+/*
+ *  arch/arm/include/asm/prom.h
+ *
+ *  Copyright (C) 2009 Canonical Ltd. <jeremy.kerr@canonical.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 __ASMARM_PROM_H
+#define __ASMARM_PROM_H
+
+#ifdef CONFIG_OF
+
+#include <asm/setup.h>
+#include <asm/irq.h>
+
+static inline void irq_dispose_mapping(unsigned int virq)
+{
+	return;
+}
+
+#endif /* CONFIG_OF */
+#endif /* ASMARM_PROM_H */
diff --git a/arch/arm/include/asm/setup.h b/arch/arm/include/asm/setup.h
index 95176af..93b4702 100644
--- a/arch/arm/include/asm/setup.h
+++ b/arch/arm/include/asm/setup.h
@@ -217,6 +217,8 @@ extern struct meminfo meminfo;
 #define bank_phys_end(bank)	((bank)->start + (bank)->size)
 #define bank_phys_size(bank)	(bank)->size
 
+extern int arm_add_memory(phys_addr_t start, unsigned long size);
+
 #endif  /*  __KERNEL__  */
 
 #endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 8d95446..908c78c 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_ARM_THUMBEE)	+= thumbee.o
 obj-$(CONFIG_KGDB)		+= kgdb.o
 obj-$(CONFIG_ARM_UNWIND)	+= unwind.o
 obj-$(CONFIG_HAVE_TCM)		+= tcm.o
+obj-$(CONFIG_OF)		+= devtree.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_SWP_EMULATE)	+= swp_emulate.o
 CFLAGS_swp_emulate.o		:= -Wa,-march=armv7-a
diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
new file mode 100644
index 0000000..75e3df8
--- /dev/null
+++ b/arch/arm/kernel/devtree.c
@@ -0,0 +1,47 @@
+/*
+ *  linux/arch/arm/kernel/devtree.c
+ *
+ *  Copyright (C) 2009 Canonical Ltd. <jeremy.kerr@canonical.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.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/bootmem.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/setup.h>
+#include <asm/page.h>
+
+void __init early_init_dt_add_memory_arch(u64 base, u64 size)
+{
+	arm_add_memory(base, size);
+}
+
+void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
+{
+	return alloc_bootmem_align(size, align);
+}
+
+/**
+ * irq_create_of_mapping - Hook to resolve OF irq specifier into a Linux irq#
+ *
+ * Currently the mapping mechanism is trivial; simple flat hwirq numbers are
+ * mapped 1:1 onto Linux irq numbers.  Cascaded irq controllers are not
+ * supported.
+ */
+unsigned int irq_create_of_mapping(struct device_node *controller,
+				   const u32 *intspec, unsigned int intsize)
+{
+	return intspec[0];
+}
+EXPORT_SYMBOL_GPL(irq_create_of_mapping);
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 006c1e8..109997e 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -466,7 +466,7 @@ static struct machine_desc * __init setup_machine(unsigned int nr)
 		/* can't use cpu_relax() here as it may require MMU setup */;
 }
 
-static int __init arm_add_memory(phys_addr_t start, unsigned long size)
+int __init arm_add_memory(phys_addr_t start, unsigned long size)
 {
 	struct membank *bank = &meminfo.bank[meminfo.nr_banks];
 
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index e5f6fc4..26c4054 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -15,6 +15,7 @@
 #include <linux/mman.h>
 #include <linux/nodemask.h>
 #include <linux/initrd.h>
+#include <linux/of_fdt.h>
 #include <linux/highmem.h>
 #include <linux/gfp.h>
 #include <linux/memblock.h>
@@ -71,6 +72,14 @@ static int __init parse_tag_initrd2(const struct tag *tag)
 
 __tagtable(ATAG_INITRD2, parse_tag_initrd2);
 
+#ifdef CONFIG_OF_FLATTREE
+void __init early_init_dt_setup_initrd_arch(unsigned long start, unsigned long end)
+{
+	phys_initrd_start = start;
+	phys_initrd_size = end - start;
+}
+#endif /* CONFIG_OF_FLATTREE */
+
 /*
  * This keeps memory configuration data used by a couple memory
  * initialization functions, as well as show_mem() for the skipping

[PATCH v6 3/5] arm/dt: consolidate atags setup into setup_machine_atags

[Grant Likely]

In preparation for adding device tree support, this patch consolidates
all of the atag-specific setup into a single function.

v5: - drop double printk("Machine; %s\n", ...); call.
    - leave copying boot_command_line in setup_arch() since it isn't
      atags specific.
v4: - adapt to the removal of lookup_machine_type()
    - break out dump of machine_desc table into dump_machine_table()
      because the device tree probe code will use it.
    - Add for_each_machine_desc() macro

Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 arch/arm/include/asm/mach/arch.h |    7 ++++
 arch/arm/kernel/setup.c          |   69 ++++++++++++++++++++++----------------
 2 files changed, 47 insertions(+), 29 deletions(-)

diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
index bf13b81..4764e67 100644
--- a/arch/arm/include/asm/mach/arch.h
+++ b/arch/arm/include/asm/mach/arch.h
@@ -48,6 +48,13 @@ struct machine_desc {
 extern struct machine_desc *machine_desc;
 
 /*
+ * Machine type table - also only accessible during boot
+ */
+extern struct machine_desc __arch_info_begin[], __arch_info_end[];
+#define for_each_machine_desc(p)			\
+	for (p = __arch_info_begin; p < __arch_info_end; p++)
+
+/*
  * Set of macros to define architecture features.  This is built into
  * a table by the linker.
  */
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 109997e..42c2f0c 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -439,25 +439,12 @@ void cpu_init(void)
 	    : "r14");
 }
 
-static struct machine_desc * __init setup_machine(unsigned int nr)
+static void __init dump_machine_table(void)
 {
-	extern struct machine_desc __arch_info_begin[], __arch_info_end[];
 	struct machine_desc *p;
 
-	/*
-	 * locate machine in the list of supported machines.
-	 */
-	for (p = __arch_info_begin; p < __arch_info_end; p++)
-		if (nr == p->nr) {
-			printk("Machine: %s\n", p->name);
-			return p;
-		}
-
-	early_print("\n"
-		"Error: unrecognized/unsupported machine ID (r1 = 0x%08x).\n\n"
-		"Available machine support:\n\nID (hex)\tNAME\n", nr);
-
-	for (p = __arch_info_begin; p < __arch_info_end; p++)
+	early_print("Available machine support:\n\nID (hex)\tNAME\n");
+	for_each_machine_desc(p)
 		early_print("%08x\t%s\n", p->nr, p->name);
 
 	early_print("\nPlease check your kernel config and/or bootloader.\n");
@@ -796,23 +783,29 @@ static void __init squash_mem_tags(struct tag *tag)
 			tag->hdr.tag = ATAG_NONE;
 }
 
-void __init setup_arch(char **cmdline_p)
+static struct machine_desc * __init setup_machine_tags(unsigned int nr)
 {
 	struct tag *tags = (struct tag *)&init_tags;
-	struct machine_desc *mdesc;
+	struct machine_desc *mdesc = NULL, *p;
 	char *from = default_command_line;
 
 	init_tags.mem.start = PHYS_OFFSET;
 
-	unwind_init();
-
-	setup_processor();
-	mdesc = setup_machine(machine_arch_type);
-	machine_desc = mdesc;
-	machine_name = mdesc->name;
+	/*
+	 * locate machine in the list of supported machines.
+	 */
+	for_each_machine_desc(p)
+		if (nr == p->nr) {
+			printk("Machine: %s\n", p->name);
+			mdesc = p;
+			break;
+		}
 
-	if (mdesc->soft_reboot)
-		reboot_setup("s");
+	if (!mdesc) {
+		early_print("\nError: unrecognized/unsupported machine ID"
+			" (r1 = 0x%08x).\n\n", nr);
+		dump_machine_table(); /* does not return */
+	}
 
 	if (__atags_pointer)
 		tags = phys_to_virt(__atags_pointer);
@@ -857,14 +850,32 @@ void __init setup_arch(char **cmdline_p)
 		parse_tags(tags);
 	}
 
+	/* parse_early_param needs a boot_command_line */
+	strlcpy(boot_command_line, from, COMMAND_LINE_SIZE);
+
+	return mdesc;
+}
+
+
+void __init setup_arch(char **cmdline_p)
+{
+	struct machine_desc *mdesc;
+
+	unwind_init();
+
+	setup_processor();
+	mdesc = setup_machine_tags(machine_arch_type);
+	machine_desc = mdesc;
+	machine_name = mdesc->name;
+
+	if (mdesc->soft_reboot)
+		reboot_setup("s");
+
 	init_mm.start_code = (unsigned long) _text;
 	init_mm.end_code   = (unsigned long) _etext;
 	init_mm.end_data   = (unsigned long) _edata;
 	init_mm.brk	   = (unsigned long) _end;
 
-	/* parse_early_param needs a boot_command_line */
-	strlcpy(boot_command_line, from, COMMAND_LINE_SIZE);
-
 	/* populate cmd_line too for later use, preserving boot_command_line */
 	strlcpy(cmd_line, boot_command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = cmd_line;

[PATCH v6 4/5] arm/dt: probe for platforms via the device tree

[Grant Likely]

If a dtb is passed to the kernel then the kernel needs to iterate
through compiled-in mdescs looking for one that matches and move the
dtb data to a safe location before it gets accidentally overwritten by
the kernel.

This patch creates a new function, setup_machine_fdt() which is
analogous to the setup_machine_atags() created in the previous patch.
It does all the early setup needed to use a device tree machine
description.

v5: - Print warning with neither dtb nor atags are passed to the kernel
    - Fix bug in setting of __machine_arch_type to the selected machine,
      not just the last machine in the list.
      Reported-by: Tixy <tixy@yxit.co.uk>
    - Copy command line directly into boot_command_line instead of cmd_line
v4: - Dump some output when a matching machine_desc cannot be found
v3: - Added processing of reserved list.
    - Backed out the v2 change that copied instead of reserved the
      dtb.  dtb is reserved again and the real problem was fixed by
      using alloc_bootmem_align() for early allocation of RAM for
      unflattening the tree.
    - Moved cmd_line and initrd changes to earlier patch to make series
      bisectable.
v2: Changed to save the dtb by copying into an allocated buffer.
    - Since the dtb will very likely be passed in the first 16k of ram
      where the interrupt vectors live, memblock_reserve() is
      insufficient to protect the dtb data.

[based on work originally written by Jeremy Kerr <jeremy.kerr@canonical.com>]
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 arch/arm/include/asm/mach/arch.h |    2 +
 arch/arm/include/asm/prom.h      |   12 +++++
 arch/arm/include/asm/setup.h     |    2 +
 arch/arm/kernel/devtree.c        |   98 ++++++++++++++++++++++++++++++++++++++
 arch/arm/kernel/setup.c          |   23 +++++++--
 arch/arm/mm/init.c               |    2 +
 6 files changed, 135 insertions(+), 4 deletions(-)

diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
index 4764e67..946f4d7 100644
--- a/arch/arm/include/asm/mach/arch.h
+++ b/arch/arm/include/asm/mach/arch.h
@@ -18,6 +18,8 @@ struct machine_desc {
 	unsigned int		nr;		/* architecture number	*/
 	const char		*name;		/* architecture name	*/
 	unsigned long		boot_params;	/* tagged list		*/
+	const char		**dt_compat;	/* array of device tree
+						 * 'compatible' strings	*/
 
 	unsigned int		nr_irqs;	/* number of IRQs */
 
diff --git a/arch/arm/include/asm/prom.h b/arch/arm/include/asm/prom.h
index 8f1037f..11b8708 100644
--- a/arch/arm/include/asm/prom.h
+++ b/arch/arm/include/asm/prom.h
@@ -21,5 +21,17 @@ static inline void irq_dispose_mapping(unsigned int virq)
 	return;
 }
 
+extern struct machine_desc *setup_machine_fdt(unsigned int dt_phys);
+extern void arm_dt_memblock_reserve(void);
+
+#else /* CONFIG_OF */
+
+static inline struct machine_desc *setup_machine_fdt(unsigned int dt_phys)
+{
+	return NULL;
+}
+
+static inline void arm_dt_memblock_reserve(void) { }
+
 #endif /* CONFIG_OF */
 #endif /* ASMARM_PROM_H */
diff --git a/arch/arm/include/asm/setup.h b/arch/arm/include/asm/setup.h
index 93b4702..ee2ad8a 100644
--- a/arch/arm/include/asm/setup.h
+++ b/arch/arm/include/asm/setup.h
@@ -218,6 +218,8 @@ extern struct meminfo meminfo;
 #define bank_phys_size(bank)	(bank)->size
 
 extern int arm_add_memory(phys_addr_t start, unsigned long size);
+extern void early_print(const char *str, ...);
+extern void dump_machine_table(void);
 
 #endif  /*  __KERNEL__  */
 
diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index 75e3df8..a701e42 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c
@@ -21,6 +21,8 @@
 
 #include <asm/setup.h>
 #include <asm/page.h>
+#include <asm/mach/arch.h>
+#include <asm/mach-types.h>
 
 void __init early_init_dt_add_memory_arch(u64 base, u64 size)
 {
@@ -32,6 +34,102 @@ void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
 	return alloc_bootmem_align(size, align);
 }
 
+void __init arm_dt_memblock_reserve(void)
+{
+	u64 *reserve_map, base, size;
+
+	if (!initial_boot_params)
+		return;
+
+	/* Reserve the dtb region */
+	memblock_reserve(virt_to_phys(initial_boot_params),
+			 be32_to_cpu(initial_boot_params->totalsize));
+
+	/*
+	 * Process the reserve map.  This will probably overlap the initrd
+	 * and dtb locations which are already reserved, but overlaping
+	 * doesn't hurt anything
+	 */
+	reserve_map = ((void*)initial_boot_params) +
+			be32_to_cpu(initial_boot_params->off_mem_rsvmap);
+	while (1) {
+		base = be64_to_cpup(reserve_map++);
+		size = be64_to_cpup(reserve_map++);
+		if (!size)
+			break;
+		memblock_reserve(base, size);
+	}
+}
+
+/**
+ * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
+ * @dt_phys: physical address of dt blob
+ *
+ * If a dtb was passed to the kernel in r2, then use it to choose the
+ * correct machine_desc and to setup the system.
+ */
+struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
+{
+	struct boot_param_header *devtree;
+	struct machine_desc *mdesc, *mdesc_best = NULL;
+	unsigned int score, mdesc_score = ~1;
+	unsigned long dt_root;
+	const char *model;
+
+	devtree = phys_to_virt(dt_phys);
+
+	/* check device tree validity */
+	if (be32_to_cpu(devtree->magic) != OF_DT_HEADER)
+		return NULL;
+
+	/* Search the mdescs for the 'best' compatible value match */
+	initial_boot_params = devtree;
+	dt_root = of_get_flat_dt_root();
+	for_each_machine_desc(mdesc) {
+		score = of_flat_dt_match(dt_root, mdesc->dt_compat);
+		if (score > 0 && score < mdesc_score) {
+			mdesc_best = mdesc;
+			mdesc_score = score;
+		}
+	}
+	if (!mdesc_best) {
+		const char *prop;
+		long size;
+
+		early_print("\nError: unrecognized/unsupported "
+			    "device tree compatible list:\n[ ");
+
+		prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
+		while (size > 0) {
+			early_print("'%s' ", prop);
+			size -= strlen(prop) + 1;
+			prop += strlen(prop) + 1;
+		}
+		early_print("]\n\n");
+
+		dump_machine_table(); /* does not return */
+	}
+
+	model = of_get_flat_dt_prop(dt_root, "model", NULL);
+	if (!model)
+		model = of_get_flat_dt_prop(dt_root, "compatible", NULL);
+	if (!model)
+		model = "<unknown>";
+	pr_info("Machine: %s, model: %s\n", mdesc_best->name, model);
+
+	/* Retrieve various information from the /chosen node */
+	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+	/* Initialize {size,address}-cells info */
+	of_scan_flat_dt(early_init_dt_scan_root, NULL);
+	/* Setup memory, calling early_init_dt_add_memory_arch */
+	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
+
+	/* Change machine number to match the mdesc we're using */
+	__machine_arch_type = mdesc_best->nr;
+
+	return mdesc_best;
+}
+
 /**
  * irq_create_of_mapping - Hook to resolve OF irq specifier into a Linux irq#
  *
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 42c2f0c..05db25e 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -20,6 +20,7 @@
 #include <linux/screen_info.h>
 #include <linux/init.h>
 #include <linux/kexec.h>
+#include <linux/of_fdt.h>
 #include <linux/crash_dump.h>
 #include <linux/root_dev.h>
 #include <linux/cpu.h>
@@ -42,6 +43,7 @@
 #include <asm/cachetype.h>
 #include <asm/tlbflush.h>
 
+#include <asm/prom.h>
 #include <asm/mach/arch.h>
 #include <asm/mach/irq.h>
 #include <asm/mach/time.h>
@@ -309,7 +311,7 @@ static void __init cacheid_init(void)
  */
 extern struct proc_info_list *lookup_processor_type(unsigned int);
 
-static void __init early_print(const char *str, ...)
+void __init early_print(const char *str, ...)
 {
 	extern void printascii(const char *);
 	char buf[256];
@@ -439,7 +441,7 @@ void cpu_init(void)
 	    : "r14");
 }
 
-static void __init dump_machine_table(void)
+void __init dump_machine_table(void)
 {
 	struct machine_desc *p;
 
@@ -837,8 +839,17 @@ static struct machine_desc * __init setup_machine_tags(unsigned int nr)
 	if (tags->hdr.tag != ATAG_CORE)
 		convert_to_tag_list(tags);
 #endif
-	if (tags->hdr.tag != ATAG_CORE)
+
+	if (tags->hdr.tag != ATAG_CORE) {
+#if defined(CONFIG_OF)
+		/*
+		 * If CONFIG_OF is set, then assume this is a reasonably
+		 * modern system that should pass boot parameters
+		 */
+		early_print("Warning: Neither atags nor dtb found\n");
+#endif
 		tags = (struct tag *)&init_tags;
+	}
 
 	if (mdesc->fixup)
 		mdesc->fixup(mdesc, tags, &from, &meminfo);
@@ -864,7 +875,9 @@ void __init setup_arch(char **cmdline_p)
 	unwind_init();
 
 	setup_processor();
-	mdesc = setup_machine_tags(machine_arch_type);
+	mdesc = setup_machine_fdt(__atags_pointer);
+	if (!mdesc)
+		mdesc = setup_machine_tags(machine_arch_type);
 	machine_desc = mdesc;
 	machine_name = mdesc->name;
 
@@ -887,6 +900,8 @@ void __init setup_arch(char **cmdline_p)
 	paging_init(mdesc);
 	request_standard_resources(mdesc);
 
+	unflatten_device_tree();
+
 #ifdef CONFIG_SMP
 	if (is_smp())
 		smp_init_cpus();
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 26c4054..b265975 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -22,6 +22,7 @@
 #include <linux/sort.h>
 
 #include <asm/mach-types.h>
+#include <asm/prom.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/sizes.h>
@@ -322,6 +323,7 @@ void __init arm_memblock_init(struct meminfo *mi, struct machine_desc *mdesc)
 #endif
 
 	arm_mm_memblock_reserve();
+	arm_dt_memblock_reserve();
 
 	/* reserve any platform specific memblock areas */
 	if (mdesc->reserve)

[PATCH v6 5/5] dt: add documentation of ARM dt boot interface

[Grant Likely]

v6: typo fixes
v5: clarified that dtb should be aligned on a 64 bit boundary in RAM.
v3: added details to Documentation/arm/Booting

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 Documentation/arm/Booting                       |   33 ++++++++++++++--
 Documentation/devicetree/booting-without-of.txt |   48 +++++++++++++++++++++--
 2 files changed, 73 insertions(+), 8 deletions(-)

diff --git a/Documentation/arm/Booting b/Documentation/arm/Booting
index 7685029..4e686a2 100644
--- a/Documentation/arm/Booting
+++ b/Documentation/arm/Booting
@@ -65,13 +65,19 @@ looks at the connected hardware is beyond the scope of this document.
 The boot loader must ultimately be able to provide a MACH_TYPE_xxx
 value to the kernel. (see linux/arch/arm/tools/mach-types).
 
-
-4. Setup the kernel tagged list
--------------------------------
+4. Setup boot data
+------------------
 
 Existing boot loaders:		OPTIONAL, HIGHLY RECOMMENDED
 New boot loaders:		MANDATORY
 
+The boot loader must provide either a tagged list or a dtb image for
+passing configuration data to the kernel.  The physical address of the
+boot data is passed to the kernel in register r2.
+
+4a. Setup the kernel tagged list
+--------------------------------
+
 The boot loader must create and initialise the kernel tagged list.
 A valid tagged list starts with ATAG_CORE and ends with ATAG_NONE.
 The ATAG_CORE tag may or may not be empty.  An empty ATAG_CORE tag
@@ -101,6 +107,24 @@ The tagged list must be placed in a region of memory where neither
 the kernel decompressor nor initrd 'bootp' program will overwrite
 it.  The recommended placement is in the first 16KiB of RAM.
 
+4b. Setup the device tree
+-------------------------
+
+The boot loader must load a device tree image (dtb) into system ram
+at a 64bit aligned address and initialize it with the boot data.  The
+dtb format is documented in Documentation/devicetree/booting-without-of.txt.
+The kernel will look for the dtb magic value of 0xd00dfeed at the dtb
+physical address to determine if a dtb has been passed instead of a
+tagged list.
+
+The boot loader must pass at a minimum the size and location of the
+system memory, and the root filesystem location.  The dtb must be
+placed in a region of memory where the kernel decompressor will not
+overwrite it.  The recommended placement is in the first 16KiB of RAM
+with the caveat that it may not be located at physical address 0 since
+the kernel interprets a value of 0 in r2 to mean neither a tagged list
+nor a dtb were passed.
+
 5. Calling the kernel image
 ---------------------------
 
@@ -125,7 +149,8 @@ In either case, the following conditions must be met:
 - CPU register settings
   r0 = 0,
   r1 = machine type number discovered in (3) above.
-  r2 = physical address of tagged list in system RAM.
+  r2 = physical address of tagged list in system RAM, or
+       physical address of device tree block (dtb) in system RAM
 
 - CPU mode
   All forms of interrupts must be disabled (IRQs and FIQs)
diff --git a/Documentation/devicetree/booting-without-of.txt b/Documentation/devicetree/booting-without-of.txt
index 50619a0..7c1329d 100644
--- a/Documentation/devicetree/booting-without-of.txt
+++ b/Documentation/devicetree/booting-without-of.txt
@@ -12,8 +12,9 @@ Table of Contents
 =================
 
   I - Introduction
-    1) Entry point for arch/powerpc
-    2) Entry point for arch/x86
+    1) Entry point for arch/arm
+    2) Entry point for arch/powerpc
+    3) Entry point for arch/x86
 
   II - The DT block format
     1) Header
@@ -148,7 +149,46 @@ upgrades without significantly impacting the kernel code or cluttering
 it with special cases.
 
 
-1) Entry point for arch/powerpc
+1) Entry point for arch/arm
+---------------------------
+
+   There is one single entry point to the kernel, at the start
+   of the kernel image. That entry point supports two calling
+   conventions.  A summary of the interface is described here.  A full
+   description of the boot requirements is documented in
+   Documentation/arm/Booting
+
+        a) ATAGS interface.  Minimal information is passed from firmware
+        to the kernel with a tagged list of predefined parameters.
+
+                r0 : 0
+
+                r1 : Machine type number
+
+                r2 : Physical address of tagged list in system RAM
+
+        b) Entry with a flattened device-tree block.  Firmware loads the
+        physical address of the flattened device tree block (dtb) into r2,
+        r1 is not used, but it is considered good practise to use a valid
+        machine number as described in Documentation/arm/Booting.
+
+                r0 : 0
+
+                r1 : Valid machine type number.  When using a device tree,
+                a single machine type number will often be assigned to
+                represent a class or family of SoCs.
+
+                r2 : physical pointer to the device-tree block
+                (defined in chapter II) in RAM.  Device tree can be located
+                anywhere in system RAM, but it should be aligned on a 64 bit
+                boundary.
+
+   The kernel will differentiate between ATAGS and device tree booting by
+   reading the memory pointed to by r2 and looking for either the flattened
+   device tree block magic value (0xd00dfeed) or the ATAG_CORE value at
+   offset 0x4 from r2 (0x54410001).
+
+2) Entry point for arch/powerpc
 -------------------------------
 
    There is one single entry point to the kernel, at the start
@@ -226,7 +266,7 @@ it with special cases.
   cannot support both configurations with Book E and configurations
   with classic Powerpc architectures.
 
-2) Entry point for arch/x86
+3) Entry point for arch/x86
 -------------------------------
 
   There is one single 32bit entry point to the kernel at code32_start,