基于Linux kernel 3.10.87分析
一、什么是device tree？
二、为什么使用device tree？
三、怎么使用device tree？
1、初始化流程。也就是扫描dtb并将其转换成Device Tree Structure。
2、传递运行时参数传递以及platform的识别流程分析
3、如何将Device Tree Structure并入linux kernel的设备驱动模型。
//linux kernel 第一链接脚本文件Vmlinux.lds.in (h:\work\kernel\linux-3.10.87\linux-3.10.87\arch\arm\boot\compressed) 1639 2015/8/17
OUTPUT_ARCH(arm)
ENTRY(_start)
SECTIONS
{
/DISCARD/ : {
*(.ARM.exidx*)
*(.ARM.extab*)
/*
* Discard any r/w data - this produces a link error if we have any,
* which is required for PIC decompression. Local data generates
* GOTOFF relocations, which prevents it being relocated independently
* of the text/got segments.
*/
*(.data)
}
. = TEXT_START;
_text = .;
.text : {
_start = .;
*(.start)
*(.text)
*(.text.*)
*(.fixup)
*(.gnu.warning)
*(.glue_7t)
*(.glue_7)
}
.rodata : {
*(.rodata)
*(.rodata.*)
}
.piggydata : {
*(.piggydata)
}
. = ALIGN(4);
_etext = .;
.got.plt : { *(.got.plt) }
_got_start = .;
.got : { *(.got) }
_got_end = .;
/* ensure the zImage file size is always a multiple of 64 bits */
/* (without a dummy byte, ld just ignores the empty section) */
.pad : { BYTE(0); . = ALIGN(8); }
_edata = .;
. = BSS_START;
__bss_start = .;
.bss : { *(.bss) }
_end = .;
. = ALIGN(8); /* the stack must be 64-bit aligned */
.stack : { *(.stack) }
.stab 0 : { *(.stab) }
.stabstr 0 : { *(.stabstr) }
.stab.excl 0 : { *(.stab.excl) }
.stab.exclstr 0 : { *(.stab.exclstr) }
.stab.index 0 : { *(.stab.index) }
.stab.indexstr 0 : { *(.stab.indexstr) }
.comment 0 : { *(.comment) }
}
linux kernel 进入的第一执行文件
//head.S (h:\work\kernel\linux-3.10.87\linux-3.10.87\arch\arm\boot\compressed) 31868 2015/8/17
.section ".start", #alloc, #execinstr
/*
* sort out different calling conventions
*/
.align
.arm @ Always enter in ARM state
start:
.type start,#function
.rept 7
mov r0, r0
.endr
ARM( mov r0, r0 )
ARM( b 1f )
THUMB( adr r12, BSYM(1f) )
THUMB( bx r12 )
.word 0x016f2818 @ Magic numbers to help the loader
.word start @ absolute load/run zImage address
.word _edata @ zImage end address
THUMB( .thumb )
1:
mrs r9, cpsr
#ifdef CONFIG_ARM_VIRT_EXT
bl __hyp_stub_install @ get into SVC mode, reversibly
#endif
mov r7, r1 @ save architecture ID
mov r8, r2 @ save atags pointer
#ifndef __ARM_ARCH_2__
/*
* Booting from Angel - need to enter SVC mode and disable
* FIQs/IRQs (numeric definitions from angel arm.h source).
* We only do this if we were in user mode on entry.
*/
mrs r2, cpsr @ get current mode
tst r2, #3 @ not user?
bne not_angel
mov r0, #0x17 @ angel_SWIreason_EnterSVC
ARM( swi 0x123456 ) @ angel_SWI_ARM
THUMB( svc 0xab ) @ angel_SWI_THUMB
not_angel:
safe_svcmode_maskall r0
msr spsr_cxsf, r9 @ Save the CPU boot mode in
@ SPSR
#else
teqp pc, #0x0c000003 @ turn off interrupts
#endif
/*
* Note that some cache flushing and other stuff may
* be needed here - is there an Angel SWI call for this?
*/
/*
* some architecture specific code can be inserted
* by the linker here, but it should preserve r7, r8, and r9.
*/
.text
#ifdef CONFIG_AUTO_ZRELADDR
@ determine final kernel image address
mov r4, pc
and r4, r4, #0xf8000000
add r4, r4, #TEXT_OFFSET
#else
ldr r4, =zreladdr
#endif
bl cache_on
restart: adr r0, LC0
ldmia r0, {r1, r2, r3, r6, r10, r11, r12}
ldr sp, [r0, #28]
/*
* We might be running at a different address. We need
* to fix up various pointers.
*/
sub r0, r0, r1 @ calculate the delta offset
add r6, r6, r0 @ _edata
add r10, r10, r0 @ inflated kernel size location
/*
* The kernel build system appends the size of the
* decompressed kernel at the end of the compressed data
* in little-endian form.
*/
ldrb r9, [r10, #0]
ldrb lr, [r10, #1]
orr r9, r9, lr, lsl #8
ldrb lr, [r10, #2]
ldrb r10, [r10, #3]
orr r9, r9, lr, lsl #16
orr r9, r9, r10, lsl #24
#ifndef CONFIG_ZBOOT_ROM
/* malloc space is above the relocated stack (64k max) */
add sp, sp, r0
add r10, sp, #0x10000
#else
/*
* With ZBOOT_ROM the bss/stack is non relocatable,
* but someone could still run this code from RAM,
* in which case our reference is _edata.
*/
mov r10, r6
#endif
mov r5, #0 @ init dtb size to 0
#ifdef CONFIG_ARM_APPENDED_DTB
/*
* r0 = delta
* r2 = BSS start
* r3 = BSS end
* r4 = final kernel address
* r5 = appended dtb size (still unknown)
* r6 = _edata
* r7 = architecture ID
* r8 = atags/device tree pointer
* r9 = size of decompressed image
* r10 = end of this image, including bss/stack/malloc space if non XIP
* r11 = GOT start
* r12 = GOT end
* sp = stack pointer
*
* if there are device trees (dtb) appended to zImage, advance r10 so that the
* dtb data will get relocated along with the kernel if necessary.
*/
ldr lr, [r6, #0]
#ifndef __ARMEB__
ldr r1, =0xedfe0dd0 @ sig is 0xd00dfeed big endian
#else
ldr r1, =0xd00dfeed
#endif
cmp lr, r1
bne dtb_check_done @ not found
#ifdef CONFIG_ARM_ATAG_DTB_COMPAT
/*
* OK... Let's do some funky business here.
* If we do have a DTB appended to zImage, and we do have
* an ATAG list around, we want the later to be translated
* and folded into the former here. To be on the safe side,
* let's temporarily move the stack away into the malloc
* area. No GOT fixup has occurred yet, but none of the
* code we're about to call uses any global variable.
*/
add sp, sp, #0x10000
stmfd sp!, {r0-r3, ip, lr}
mov r0, r8
mov r1, r6
sub r2, sp, r6
bl atags_to_fdt
/*
* If returned value is 1, there is no ATAG at the location
* pointed by r8. Try the typical 0x100 offset from start
* of RAM and hope for the best.
*/
cmp r0, #1
sub r0, r4, #TEXT_OFFSET
add r0, r0, #0x100
mov r1, r6
sub r2, sp, r6
bleq atags_to_fdt
ldmfd sp!, {r0-r3, ip, lr}
sub sp, sp, #0x10000
#endif
mov r8, r6 @ use the appended device tree
/*
* Make sure that the DTB doesn't end up in the final
* kernel's .bss area. To do so, we adjust the decompressed
* kernel size to compensate if that .bss size is larger
* than the relocated code.
*/
ldr r5, =_kernel_bss_size
adr r1, wont_overwrite
sub r1, r6, r1
subs r1, r5, r1
addhi r9, r9, r1
/* Get the dtb's size */
ldr r5, [r6, #4]
#ifndef __ARMEB__
/* convert r5 (dtb size) to little endian */
eor r1, r5, r5, ror #16
bic r1, r1, #0x00ff0000
mov r5, r5, ror #8
eor r5, r5, r1, lsr #8
#endif
/* preserve 64-bit alignment */
add r5, r5, #7
bic r5, r5, #7
/* relocate some pointers past the appended dtb */
add r6, r6, r5
add r10, r10, r5
add sp, sp, r5
dtb_check_done:
#endif
/*
* Check to see if we will overwrite ourselves.
* r4 = final kernel address
* r9 = size of decompressed image
* r10 = end of this image, including bss/stack/malloc space if non XIP
* We basically want:
* r4 - 16k page directory >= r10 -> OK
* r4 + image length <= address of wont_overwrite -> OK
*/
add r10, r10, #16384
cmp r4, r10
bhs wont_overwrite
add r10, r4, r9
adr r9, wont_overwrite
cmp r10, r9
bls wont_overwrite
/*
* Relocate ourselves past the end of the decompressed kernel.
* r6 = _edata
* r10 = end of the decompressed kernel
* Because we always copy ahead, we need to do it from the end and go
* backward in case the source and destination overlap.
*/
/*
* Bump to the next 256-byte boundary with the size of
* the relocation code added. This avoids overwriting
* ourself when the offset is small.
*/
add r10, r10, #((reloc_code_end - restart + 256) & ~255)
bic r10, r10, #255
/* Get start of code we want to copy and align it down. */
adr r5, restart
bic r5, r5, #31
/* Relocate the hyp vector base if necessary */
#ifdef CONFIG_ARM_VIRT_EXT
mrs r0, spsr
and r0, r0, #MODE_MASK
cmp r0, #HYP_MODE
bne 1f
bl __hyp_get_vectors
sub r0, r0, r5
add r0, r0, r10
bl __hyp_set_vectors
1:
#endif
sub r9, r6, r5 @ size to copy
add r9, r9, #31 @ rounded up to a multiple
bic r9, r9, #31 @ ... of 32 bytes
add r6, r9, r5
add r9, r9, r10
1: ldmdb r6!, {r0 - r3, r10 - r12, lr}
cmp r6, r5
stmdb r9!, {r0 - r3, r10 - r12, lr}
bhi 1b
/* Preserve offset to relocated code. */
sub r6, r9, r6
#ifndef CONFIG_ZBOOT_ROM
/* cache_clean_flush may use the stack, so relocate it */
add sp, sp, r6
#endif
bl cache_clean_flush
adr r0, BSYM(restart)
add r0, r0, r6
mov pc, r0
wont_overwrite:
/*
* If delta is zero, we are running at the address we were linked at.
* r0 = delta
* r2 = BSS start
* r3 = BSS end
* r4 = kernel execution address
* r5 = appended dtb size (0 if not present)
* r7 = architecture ID
* r8 = atags pointer
* r11 = GOT start
* r12 = GOT end
* sp = stack pointer
*/
orrs r1, r0, r5
beq not_relocated
add r11, r11, r0
add r12, r12, r0
#ifndef CONFIG_ZBOOT_ROM
/*
* If we're running fully PIC === CONFIG_ZBOOT_ROM = n,
* we need to fix up pointers into the BSS region.
* Note that the stack pointer has already been fixed up.
*/
add r2, r2, r0
add r3, r3, r0
/*
* Relocate all entries in the GOT table.
* Bump bss entries to _edata + dtb size
*/
1: ldr r1, [r11, #0] @ relocate entries in the GOT
add r1, r1, r0 @ This fixes up C references
cmp r1, r2 @ if entry >= bss_start &&
cmphs r3, r1 @ bss_end > entry
addhi r1, r1, r5 @ entry += dtb size
str r1, [r11], #4 @ next entry
cmp r11, r12
blo 1b
/* bump our bss pointers too */
add r2, r2, r5
add r3, r3, r5
#else
/*
* Relocate entries in the GOT table. We only relocate
* the entries that are outside the (relocated) BSS region.
*/
1: ldr r1, [r11, #0] @ relocate entries in the GOT
cmp r1, r2 @ entry < bss_start ||
cmphs r3, r1 @ _end < entry
addlo r1, r1, r0 @ table. This fixes up the
str r1, [r11], #4 @ C references.
cmp r11, r12
blo 1b
#endif
not_relocated: mov r0, #0
1: str r0, [r2], #4 @ clear bss
str r0, [r2], #4
str r0, [r2], #4
str r0, [r2], #4
cmp r2, r3
blo 1b
/*
* The C runtime environment should now be setup sufficiently.
* Set up some pointers, and start decompressing.
* r4 = kernel execution address
* r7 = architecture ID
* r8 = atags pointer
*/
mov r0, r4
mov r1, sp @ malloc space above stack
add r2, sp, #0x10000 @ 64k max
mov r3, r7
bl decompress_kernel
bl cache_clean_flush
bl cache_off
mov r1, r7 @ restore architecture number
mov r2, r8 @ restore atags pointer
#ifdef CONFIG_ARM_VIRT_EXT
mrs r0, spsr @ Get saved CPU boot mode
and r0, r0, #MODE_MASK
cmp r0, #HYP_MODE @ if not booted in HYP mode...
bne __enter_kernel @ boot kernel directly
adr r12, .L__hyp_reentry_vectors_offset
ldr r0, [r12]
add r0, r0, r12
bl __hyp_set_vectors
__HVC(0) @ otherwise bounce to hyp mode
b . @ should never be reached
.align 2
.L__hyp_reentry_vectors_offset: .long __hyp_reentry_vectors - .
#else
b __enter_kernel
#endif
// head.S (h:\work\kernel\linux-3.10.87\linux-3.10.87\arch\arm\kernel) 16335 2015/8/17
/*
* Kernel startup entry point.
* ---------------------------
*
* 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 or dtb pointer.
*
* This code is mostly position independent, so if you link the kernel at
* 0xc0008000, you call this at __pa(0xc0008000).
*
* See linux/arch/arm/tools/mach-types for the complete list of machine
* numbers for r1.
*
* We're trying to keep crap to a minimum; DO NOT add any machine specific
* crap here - that's what the boot loader (or in extreme, well justified
* circumstances, zImage) is for.
*/
.arm
__HEAD
ENTRY(stext)
THUMB( adr r9, BSYM(1f) ) @ Kernel is always entered in ARM.
THUMB( bx r9 ) @ If this is a Thumb-2 kernel,
THUMB( .thumb ) @ switch to Thumb now.
THUMB(1: )
#ifdef CONFIG_ARM_VIRT_EXT
bl __hyp_stub_install
#endif
@ ensure svc mode and all interrupts masked
safe_svcmode_maskall r9
mrc p15, 0, r9, c0, c0 @ get processor id
bl __lookup_processor_type @ r5=procinfo r9=cpuid
movs r10, r5 @ invalid processor (r5=0)?
THUMB( it eq ) @ force fixup-able long branch encoding
beq __error_p @ yes, error 'p'
#ifdef CONFIG_ARM_LPAE
mrc p15, 0, r3, c0, c1, 4 @ read ID_MMFR0
and r3, r3, #0xf @ extract VMSA support
cmp r3, #5 @ long-descriptor translation table format?
THUMB( it lo ) @ force fixup-able long branch encoding
blo __error_p @ only classic page table format
#endif
#ifndef CONFIG_XIP_KERNEL
adr r3, 2f
ldmia r3, {r4, r8}
sub r4, r3, r4 @ (PHYS_OFFSET - PAGE_OFFSET)
add r8, r8, r4 @ PHYS_OFFSET
#else
ldr r8, =PLAT_PHYS_OFFSET @ always constant in this case
#endif
/*
* r1 = machine no, r2 = atags or dtb,
* r8 = phys_offset, r9 = cpuid, r10 = procinfo
*/
bl __vet_atags
#ifdef CONFIG_SMP_ON_UP
bl __fixup_smp
#endif
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
bl __fixup_pv_table
#endif
bl __create_page_tables
/*
* The following calls CPU specific code in a position independent
* manner. See arch/arm/mm/proc-*.S for details. r10 = base of
* xxx_proc_info structure selected by __lookup_processor_type
* above. On return, the CPU will be ready for the MMU to be
* turned on, and r0 will hold the CPU control register value.
*/
ldr r13, =__mmap_switched @ address to jump to after //goto head-common.S
@ mmu has been enabled
adr lr, BSYM(1f) @ return (PIC) address
mov r8, r4 @ set TTBR1 to swapper_pg_dir
ARM( add pc, r10, #PROCINFO_INITFUNC )
THUMB( add r12, r10, #PROCINFO_INITFUNC )
THUMB( mov pc, r12 )
1: b __enable_mmu
ENDPROC(stext)
//head-common.S (h:\work\kernel\linux-3.10.87\linux-3.10.87\arch\arm\kernel) 5280 2015/8/17
__mmap_switched:
adr r3, __mmap_switched_data
ldmia r3!, {r4, r5, r6, r7}
cmp r4, r5 @ Copy data segment if needed
1: cmpne r5, r6
ldrne fp, [r4], #4
strne fp, [r5], #4
bne 1b
mov fp, #0 @ Clear BSS (and zero fp)
1: cmp r6, r7
strcc fp, [r6],#4
bcc 1b
ARM( ldmia r3, {r4, r5, r6, r7, sp})
THUMB( ldmia r3, {r4, r5, r6, r7} )
THUMB( ldr sp, [r3, #16] )
str r9, [r4] @ Save processor ID
str r1, [r5] @ Save machine type
str r2, [r6] @ Save atags pointer
cmp r7, #0
bicne r4, r0, #CR_A @ Clear 'A' bit
stmneia r7, {r0, r4} @ Save control register values
b start_kernel //goto main.c
ENDPROC(__mmap_switched)
//Main.c (h:\work\kernel\linux-3.10.87\linux-3.10.87\init) 22533 2015/8/17
asmlinkage void __init start_kernel(void)
{
char * command_line;
extern const struct kernel_param __start___param[], __stop___param[];
/*
* Need to run as early as possible, to initialize the
* lockdep hash:
*/
lockdep_init();
smp_setup_processor_id();
debug_objects_early_init();
/*
* Set up the the initial canary ASAP:
*/
boot_init_stack_canary();
cgroup_init_early();
local_irq_disable();
early_boot_irqs_disabled = true;
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
*/
boot_cpu_init();
page_address_init();
pr_notice("%s", linux_banner);
setup_arch(&command_line); //set ==>arch/arm/
mm_init_owner(&init_mm, &init_task);
mm_init_cpumask(&init_mm);
setup_command_line(command_line);
setup_nr_cpu_ids();
setup_per_cpu_areas();
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
build_all_zonelists(NULL, NULL);
page_alloc_init();
pr_notice("Kernel command line: %s\n", boot_command_line);
parse_early_param();
parse_args("Booting kernel", static_command_line, __start___param,
__stop___param - __start___param,
-1, -1, &unknown_bootoption);
jump_label_init();
/*
* These use large bootmem allocations and must precede
* kmem_cache_init()
*/
setup_log_buf(0);
pidhash_init();
vfs_caches_init_early();
sort_main_extable();
trap_init();
mm_init();
/*
* Set up the scheduler prior starting any interrupts (such as the
* timer interrupt). Full topology setup happens at smp_init()
* time - but meanwhile we still have a functioning scheduler.
*/
sched_init();
/*
* Disable preemption - early bootup scheduling is extremely
* fragile until we cpu_idle() for the first time.
*/
preempt_disable();
if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
local_irq_disable();
idr_init_cache();
perf_event_init();
rcu_init();
tick_nohz_init();
radix_tree_init();
/* init some links before init_ISA_irqs() */
early_irq_init();
init_IRQ();
tick_init();
init_timers();
hrtimers_init();
softirq_init();
timekeeping_init();
time_init();
profile_init();
call_function_init();
WARN(!irqs_disabled(), "Interrupts were enabled early\n");
early_boot_irqs_disabled = false;
local_irq_enable();
kmem_cache_init_late();
/*
* HACK ALERT! This is early. We're enabling the console before
* we've done PCI setups etc, and console_init() must be aware of
* this. But we do want output early, in case something goes wrong.
*/
console_init();
if (panic_later)
panic(panic_later, panic_param);
lockdep_info();
/*
* Need to run this when irqs are enabled, because it wants
* to self-test [hard/soft]-irqs on/off lock inversion bugs
* too:
*/
locking_selftest();
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start && !initrd_below_start_ok &&
page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
page_to_pfn(virt_to_page((void *)initrd_start)),
min_low_pfn);
initrd_start = 0;
}
#endif
page_cgroup_init();
debug_objects_mem_init();
kmemleak_init();
setup_per_cpu_pageset();
numa_policy_init();
if (late_time_init)
late_time_init();
sched_clock_init();
calibrate_delay();
pidmap_init();
anon_vma_init();
#ifdef CONFIG_X86
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_enter_virtual_mode();
#endif
#ifdef CONFIG_X86_ESPFIX64
/* Should be run before the first non-init thread is created */
init_espfix_bsp();
#endif
thread_info_cache_init();
cred_init();
fork_init(totalram_pages);
proc_caches_init();
buffer_init();
key_init();
security_init();
dbg_late_init();
vfs_caches_init(totalram_pages);
signals_init();
/* rootfs populating might need page-writeback */
page_writeback_init();
#ifdef CONFIG_PROC_FS
proc_root_init();
#endif
cgroup_init();
cpuset_init();
taskstats_init_early();
delayacct_init();
check_bugs();
acpi_early_init(); /* before LAPIC and SMP init */
sfi_init_late();
if (efi_enabled(EFI_RUNTIME_SERVICES)) {
efi_late_init();
efi_free_boot_services();
}
ftrace_init();
/* Do the rest non-__init'ed, we're now alive */
rest_init();
}
void __init setup_arch(char **cmdline_p)
{
const struct machine_desc *mdesc;
setup_processor();
mdesc = setup_machine_fdt(__atags_pointer); //set machine
if (!mdesc)
mdesc = setup_machine_tags(__atags_pointer, __machine_arch_type);
machine_desc = mdesc;
machine_name = mdesc->name;
dump_stack_set_arch_desc("%s", mdesc->name);
if (mdesc->reboot_mode != REBOOT_HARD)
reboot_mode = mdesc->reboot_mode;
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;
/* populate cmd_line too for later use, preserving boot_command_line */
strlcpy(cmd_line, boot_command_line, COMMAND_LINE_SIZE);
*cmdline_p = cmd_line;
parse_early_param();
early_paging_init(mdesc, lookup_processor_type(read_cpuid_id()));
setup_dma_zone(mdesc);
sanity_check_meminfo();
arm_memblock_init(mdesc);
paging_init(mdesc);
request_standard_resources(mdesc);
if (mdesc->restart)
arm_pm_restart = mdesc->restart;
unflatten_device_tree(); // malloc platform_device struct and join in bus
arm_dt_init_cpu_maps();
psci_init();
#ifdef CONFIG_SMP
if (is_smp()) {
if (!mdesc->smp_init || !mdesc->smp_init()) {
if (psci_smp_available())
smp_set_ops(&psci_smp_ops);
else if (mdesc->smp)
smp_set_ops(mdesc->smp);
}
smp_init_cpus();
smp_build_mpidr_hash();
}
#endif
if (!is_smp())
hyp_mode_check();
reserve_crashkernel();
#ifdef CONFIG_MULTI_IRQ_HANDLER
handle_arch_irq = mdesc->handle_irq;
#endif
#ifdef CONFIG_VT
#if defined(CONFIG_VGA_CONSOLE)
conswitchp = &vga_con;
#elif defined(CONFIG_DUMMY_CONSOLE)
conswitchp = &dummy_con;
#endif
#endif
if (mdesc->init_early)
mdesc->init_early();
}
device tree 相关的结构体
struct machine_desc {
unsigned int nr; /* architecture number */
const char *name; /* architecture name */
unsigned long atag_offset; /* tagged list (relative) */
const char *const *dt_compat; /* array of device tree
* 'compatible' strings */
unsigned int nr_irqs; /* number of IRQs */
#ifdef CONFIG_ZONE_DMA
unsigned long dma_zone_size; /* size of DMA-able area */
#endif
unsigned int video_start; /* start of video RAM */
unsigned int video_end; /* end of video RAM */
unsigned char reserve_lp0 :1; /* never has lp0 */
unsigned char reserve_lp1 :1; /* never has lp1 */
unsigned char reserve_lp2 :1; /* never has lp2 */
char restart_mode; /* default restart mode */
struct smp_operations *smp; /* SMP operations */
void (*fixup)(struct tag *, char **,
struct meminfo *);
void (*reserve)(void);/* reserve mem blocks */
void (*map_io)(void);/* IO mapping function */
void (*init_early)(void);
void (*init_irq)(void);
void (*init_time)(void);
void (*init_machine)(void);
void (*init_late)(void);
#ifdef CONFIG_MULTI_IRQ_HANDLER
void (*handle_irq)(struct pt_regs *);
#endif
void (*restart)(char, const char *);
}
/*
* This is what gets passed to the kernel by prom_init or kexec
*
* The dt struct contains the device tree structure, full pathes and
* property contents. The dt strings contain a separate block with just
* the strings for the property names, and is fully page aligned and
* self contained in a page, so that it can be kept around by the kernel,
* each property name appears only once in this page (cheap compression)
*
* the mem_rsvmap contains a map of reserved ranges of physical memory,
* passing it here instead of in the device-tree itself greatly simplifies
* the job of everybody. It's just a list of u64 pairs (base/size) that
* ends when size is 0
*/
struct boot_param_header {
__be32 magic; /* magic word OF_DT_HEADER */
__be32 totalsize; /* total size of DT block */
__be32 off_dt_struct; /* offset to structure */
__be32 off_dt_strings; /* offset to strings */
__be32 off_mem_rsvmap; /* offset to memory reserve map */
__be32 version; /* format version */
__be32 last_comp_version; /* last compatible version */
/* version 2 fields below */
__be32 boot_cpuid_phys; /* Physical CPU id we're booting on */
/* version 3 fields below */
__be32 dt_strings_size; /* size of the DT strings block */
/* version 17 fields below */
__be32 dt_struct_size; /* size of the DT structure block */
}
struct device_node {
const char *name;
const char *type;
phandle phandle;
const char *full_name;
struct property *properties;
struct property *deadprops; /* removed properties */
struct device_node *parent;
struct device_node *child;
struct device_node *sibling;
struct device_node *next; /* next device of same type */
struct device_node *allnext; /* next in list of all nodes */
struct proc_dir_entry *pde; /* this node's proc directory */
struct kref kref;
unsigned long _flags;
void *data;
#if defined(CONFIG_SPARC)
const char *path_component_name;
unsigned int unique_id;
struct of_irq_controller *irq_trans;
#endif
}
未完待续....