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
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
---------------------------
- 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)
=================
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
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
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,
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
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 */
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.
*/
--- /dev/null
+/*
+ * 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;
+}
+
+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 */
#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);
+extern void early_print(const char *str, ...);
+extern void dump_machine_table(void);
+
#endif /* __KERNEL__ */
#endif
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
--- /dev/null
+/*
+ * 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>
+#include <asm/mach/arch.h>
+#include <asm/mach-types.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);
+}
+
+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#
+ *
+ * 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);
#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
/* 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]
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
*
* r0 = cp#15 control register
* r1 = machine ID
- * r2 = atags pointer
+ * r2 = atags/dtb pointer
* r9 = processor ID
*/
__INIT
*
* 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).
#endif
/*
- * r1 = machine no, r2 = atags,
+ * r1 = machine no, r2 = atags or dtb,
* r8 = phys_offset, r9 = cpuid, r10 = procinfo
*/
bl __vet_atags
*
* 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
*
* 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
*
#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>
#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>
*/
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];
: "r14");
}
-static struct machine_desc * __init setup_machine(unsigned int nr)
+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");
/* 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];
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);
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);
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_fdt(__atags_pointer);
+ if (!mdesc)
+ 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;
paging_init(mdesc);
request_standard_resources(mdesc);
+ unflatten_device_tree();
+
#ifdef CONFIG_SMP
if (is_smp())
smp_init_cpus();
#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>
#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>
__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
#endif
arm_mm_memblock_reserve();
+ arm_dt_memblock_reserve();
/* reserve any platform specific memblock areas */
if (mdesc->reserve)
* device-tree, including the platform type, initrd location and
* size, TCE reserve, and more ...
*/
- of_scan_flat_dt(early_init_dt_scan_chosen, NULL);
+ of_scan_flat_dt(early_init_dt_scan_chosen, cmd_line);
/* Scan memory nodes and rebuild MEMBLOCKs */
memblock_init();
#ifdef CONFIG_OF
#include <asm/bootinfo.h>
-/* which is compatible with the flattened device tree (FDT) */
-#define cmd_line arcs_cmdline
-
extern int early_init_dt_scan_memory_arch(unsigned long node,
const char *uname, int depth, void *data);
* device-tree, including the platform type, initrd location and
* size, and more ...
*/
- of_scan_flat_dt(early_init_dt_scan_chosen, NULL);
+ of_scan_flat_dt(early_init_dt_scan_chosen, arcs_cmdline);
+
/* Scan memory nodes */
of_scan_flat_dt(early_init_dt_scan_root, NULL);
* device-tree, including the platform type, initrd location and
* size, TCE reserve, and more ...
*/
- of_scan_flat_dt(early_init_dt_scan_chosen_ppc, NULL);
+ of_scan_flat_dt(early_init_dt_scan_chosen_ppc, cmd_line);
/* Scan memory nodes and rebuild MEMBLOCKs */
memblock_init();
pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
- if (depth != 1 ||
+ if (depth != 1 || !data ||
(strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
return 0;
/* Retrieve command line */
p = of_get_flat_dt_prop(node, "bootargs", &l);
if (p != NULL && l > 0)
- strlcpy(cmd_line, p, min((int)l, COMMAND_LINE_SIZE));
+ strlcpy(data, p, min((int)l, COMMAND_LINE_SIZE));
#ifdef CONFIG_CMDLINE
#ifndef CONFIG_CMDLINE_FORCE
if (p == NULL || l == 0 || (l == 1 && (*p) == 0))
#endif
- strlcpy(cmd_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+ strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
#endif /* CONFIG_CMDLINE */
- pr_debug("Command line is: %s\n", cmd_line);
+ pr_debug("Command line is: %s\n", (char*)data);
/* break now */
return 1;
OSDN Git Service
