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本帖最后由 kenson 于 2017-3-22 09:26 编辑
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http://blog.chinaunix.NET/uid-28458801-id-3486399.html 2 r/ o* H5 H/ H
" `+ `6 D# g9 c1 N, D# V参考文件: 1,AM335x ARM Cortex-A8 Microprocessors (MPUs) Technical Reference Manual.pdf; 2,am3359.pdf; % w. R$ x1 r0 Z
1,am335x的cpu上电后,会跳到哪个地址去执行? 答: " Y2 o% d3 U7 K3 o
芯片到uboot启动流程 :ROM → MLO(SPL)→ uboot.img AM335x 中bootloader被分成了 3 个部分: 第一级 bootloader:引导加载程序,板子上电后会自动执行这些代码,如选择哪种方式启动(NAND,SDcard,UART。。。),然后跳转转到第二级 bootloader。这些代码应该是存放在 176KB 的 ROM 中。 " m4 @+ D( p& q- z1 i- Q
第二级 bootloader:MLO(SPL),用以硬件初始化:关闭看门狗,关闭中断,设置 CPU 时钟频率、速度等操作。然后会跳转到第三级bootloader。MLO文件应该会被映射到 64 KB的 Internal SRAM 中。
" f. q$ x: c- ?+ J: h3 N* N- r第三级 bootloader:uboot.img,C代码的入口。
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其中第一级 bootloader 是板子固化的,第二级和第三级是通过编译 uboot 所得的。 / @7 y) K' Z5 i* v: _, u3 Q& U
2 S5 i4 |9 a# T2,第二级 bootloader:MLO(SPL)做了哪些事情? MLO(SPL)内存分布如下: SPL内存重映射:
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| < PATH : /arch/arm/cpu/armv7/omap-common/u-boot-spl.lds >
* I+ R# F" m5 _6 _MEMORY { .sram : ORIGIN = CONFIG_SPL_TEXT_BASE,% i! j7 ^/ \; d' g% m
LENGTH = CONFIG_SPL_MAX_SIZE }
( j+ }+ I9 r" e. l8 C {3 ^% QMEMORY { .sdram : ORIGIN = CONFIG_SPL_BSS_START_ADDR, # x# O2 u, g) U+ u1 B! p
LENGTH = CONFIG_SPL_BSS_MAX_SIZE }
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OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
$ J, W. i: n8 H6 oOUTPUT_ARCH(arm)% j: b. [1 W& t: D
ENTRY(_start)
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.text :; l& ]0 O. W- _
{
0 S6 d7 ]3 l% `! V& Y __start = .;2 E! o( U5 L" o$ p7 i4 e7 a5 ~
arch/arm/cpu/armv7/start.o (.text)9 d" P1 P% s% F1 a8 x+ F$ f. E1 }
*(.text*)
; k* L# ]& P4 ~# E& ]( `# x4 D8 l } >.sram
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. = ALIGN(4);
9 K: o( v" \2 t: |- \5 [ .rodata : { *(SORT_BY_ALIGNMENT(.rodata*)) } >.sram
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4 l0 w- E6 w/ I5 z: r3 ~ . = ALIGN(4);
3 ~4 @$ [7 h3 k ~ .data : { *(SORT_BY_ALIGNMENT(.data*)) } >.sram) E4 q' }6 z+ p: ?2 b) S
. = ALIGN(4);
' ? w4 G" w9 o4 S, x. x __image_copy_end = .;( H9 t1 s C) u) Q% C4 b
_end = .; L# |3 E/ {6 T x, u4 Q5 q
& H0 e1 |# {8 l% j9 M .bss :
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. = ALIGN(4);
$ U* j: m: |3 l' z& Q __bss_start = .;9 G+ g I1 ]$ x: y0 N' B3 u3 g
*(.bss*)9 G: x( }- t3 k' ~
. = ALIGN(4);
5 N" R9 L N* O5 ^, v L __bss_end__ = .;. ]2 E7 F3 j, F1 G) F4 w
} >.sdram! B% B' g$ ^9 s+ w* `
}
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#define CONFIG_SPL_TEXT_BASE 0x402F0400
$ I% a X, ]8 b, p, O) E#define CONFIG_SPL_MAX_SIZE (46 * 1024)( D+ p' a# l$ E6 `
#define CONFIG_SPL_STACK LOW_LEVEL_SRAM_STACK& _( F% k& s# o2 p1 R' N7 a* H/ |
/ o1 V, s) I, F# i6 S#define CONFIG_SPL_BSS_START_ADDR 0x80000000- |0 L5 X8 e1 |6 n
#define CONFIG_SPL_BSS_MAX_SIZE 0x80000 /* 512 KB */
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@1@ 保存启动参数 bl save_boot_params & _# H8 V, [% A& E9 ?
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/*
2 T7 z6 D+ |4 \1 } * the actual reset code
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reset:
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.global save_boot_params
' n( a4 `7 w# k4 C' o% A isave_boot_params:* x2 k6 i+ a- K; e" Z0 [
/*
1 I+ ]% z' w" \1 ?( D * See if the rom code passed pointer is valid: |1 y$ @8 }1 o: R+ R, C
* It is not valid if it is not in non-secure SRAM
& U& y @5 T# b5 n, l- [5 S) \9 k * This may happen if you are booting with the help of
1 A# ^ ^% e3 }. h2 e * debugger
' @1 k% i/ B; }$ p, Q+ R+ } */- S( O) L; f# F, X
ldr r2, =NON_SECURE_SRAM_START
& t) R2 w$ ]5 M" b' P cmp r2, r0
1 E k1 W+ ?- b5 A bgt 1f
5 d8 p' Y0 C, [2 z. @5 j ldr r2, =NON_SECURE_SRAM_END' c0 w( @, o5 e
cmp r2, r0
5 o$ ]- z+ x; y; g8 D! o blt 1f
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' F; \3 E% [2 y' Z /*
# _8 r; Z1 b- r' [2 Y# g! p9 J * store the boot params passed from rom code or saved- @+ S" E6 Z& L' Y9 A1 |( f1 q
* and passed by SPL( G, i1 \7 D% W! l
*/
& @; b' b4 a) X. I# y9 o# ^' m cmp r0, #0, T, b- B, k; Y$ M
beq 1f; l% [# U; K8 Y$ t5 E
ldr r1, =boot_params
: i) m( F! h( c$ y str r0, [r1]; Y" X2 d( Q- N2 y6 u, g. C
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| /*《PATH: /arch/arm/include/asm/arch-ti81xx/omap.h》
6 G1 I% O" m8 [" O3 M* O$ a: B# I * Non-secure SRAM Addresses5 ]9 C0 Z s1 s. d- Z3 n9 ~# l5 |
* Non-secure RAM starts at 0x40300000 for GP devices. But we keep SRAM_BASE
; C6 ~; p; h; P: {: k/ l) c * at 0x40304000(EMU base) so that our code works for both EMU and GP
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#define NON_SECURE_SRAM_START 0x40304000( F' Y6 }( q% G' Y: C3 j q" ^8 g
#define NON_SECURE_SRAM_END 0x4030E000( G$ _) U* p' p, \- F* r d0 ^
#define LOW_LEVEL_SRAM_STACK 0x4030B7FC
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问题:这些参数是保存在哪里的?大概有哪些参数? 答: 这些参数保存的内存地址为 64 KB 的 OCM RAM 中: 注:Dowloaded Image 区域:是用来保存 MLO(SPL) 文件的,其最大可达到 109 KB
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@a2@ 设置 CPU 为 SVC32 模式 1
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5 g4 A& R5 V3 g /*
. u; F9 N' L3 v3 _9 b, I) E+ J5 K+ u * set the cpu to SVC32 mode+ C& w/ {9 K; K" L2 K, N
*/7 j$ J8 n/ p; P9 U
mrs r0, cpsr
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orr r0, r0, #0xd38 k) I2 w* E2 e
msr cpsr,r0+ F+ {! C* x% _0 y7 i
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8 Y: i9 S; w* {& @- v9 Z8 n CPSR:程序状态寄存器(current program status register)(当前程序状态寄存器),在任何处理器模式下被访问。它包含了条件标志位、中断禁止位、当前处理器模式标志以及其他的一些控制和状态位。/ Q. b) H$ Q) P! `+ R; i+ |8 M& |
CPSR在用户级编程时用于存储条件码。 SPSR:程序状态保存寄存器(saved program statusregister),每一种处理器模式下都有一个状态寄存器SPSR,SPSR用于保存CPSR的状态,以便异常返回后恢复异常发生时的工作状态。当特定的异常中断发生时,这个寄存器用于存放当前程序状态寄存器的内容。在异常中断退出时,可以用SPSR来恢复CPSR。由于用户模式和系统模式不是异常中断模式,所以他没有SPSR。当用户在用户模式或系统模式访问SPSR,将产生不可预知的后果。 CPSR格式如下所示。SPSR和CPSR格式相同。. K" y7 U( ?/ p1 |
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@a3@ CPU的初始化 1
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. w2 k6 F% z4 {8 g | 《PATH : /arch/arm/cpu/armv7/start.S》4 K& g8 B6 A4 {$ j) T
/* the mask ROM code should have PLL and others stable */4 k$ |+ g1 S& U, A1 n2 E9 }
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
+ m4 W: e4 r2 ]2 ~' V, j$ W bl cpu_init_crit
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.globl lowlevel_init
: k% c4 ?# v0 u3 elowlevel_init:, \/ G! A3 ~0 a" g: c9 t2 |
/*4 w9 \; m: [0 @4 w) ~: q
* Setup a temporary stack
) v" V% O& o1 R3 }8 I */
" G! o5 W3 R5 h3 q, S) D ldr sp, =LOW_LEVEL_SRAM_STACK2 G+ E7 c2 J- M! O/ r- n, v+ I
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/*
d6 _2 Y0 C) V7 ^9 {: E$ ]1 p * Save the old lr(passed in ip) and the current lr to stack @6 v3 a% o& u/ D! f5 Z; h, }
*/
% U' \9 X+ O; t3 g5 ~3 s! I push {ip, lr}" G6 ]( s& S3 }! Q$ u/ \2 {
* B; h. m( K4 I$ U
/*
% p3 w- F9 S, Z9 p * go setup pll, mux, memory) ~- e* f' T6 s
*/
* X; {7 T+ n, g) d1 {- h bl s_init2 ]6 S& B$ B, B, S5 {
pop {ip, pc}
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6 z/ I) o9 R! I( e问题:CPU的初始化有哪些内容? 答: @b1@ 首先要设置堆栈区,因为将会调用 C函数来实现CPU的初始化
1 t4 ~) h) E l- Z+ k 问题:这个堆栈在什么位置,其内存大小是多少? 答 12 A9 C$ x+ c1 o1 b) k
2
- o. Y- O6 T+ ?, a( K | 《PATH :/arch/arm/include/asm/arch-ti81xx/omap.h》
$ o- J3 c/ x1 V#define LOW_LEVEL_SRAM_STACK 0x4030B7FC
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9 U: Z$ q% j/ y2 u) Q @b2@ 执行 s_init() 函数,实现 CPU 的初始化
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52% b3 b3 h% C7 D1 p; ~& f
53
; f$ D% h+ t0 V6 A; ~& B546 U- J8 l( G( L+ j
55- n3 Q O9 ^ N
56
6 n; d+ Y; b+ v$ A/ {' j$ i S! r0 B57
: `0 _, J6 {" Q% |58. O0 I$ z) [9 g ?& ]
59& i/ y& u/ ?1 }) ~. O' b
60, O& A5 ~ l4 Y4 z
|
9 i/ ?# `& P1 P+ m, f; ^- r; Q/*
# o+ ~, t0 [& n; k+ t; J * early system init of muxing and clocks.
+ j2 t' l8 F" i */
; g( G( b. r1 h R/ S0 O: [7 {void s_init(void)5 n2 c8 Z- i7 ~2 r, a3 @/ z
{6 Z x, g0 D% k4 X8 W2 F. q
/* Can be removed as A8 comes up with L2 enabled */
& h, g8 V6 S! d, i7 K l2_cache_enable();+ y5 M6 O, e+ f" D0 F
; t7 ^. m3 i# u1 F1 u% c
/* WDT1 is already running when the bootloader gets control
0 d1 `2 v* ?# S% B5 W * Disable it to avoid "random" resets
' g& [2 T0 f! l# @/ g */, J4 E( m5 Z( O3 _
__raw_writel(0xAAAA, WDT_WSPR);
+ c: t9 b" `- O( t) t4 M7 q. L3 P while(__raw_readl(WDT_WWPS) != 0x0);
9 q6 I. N, T1 z& f$ ]* H- M' ^2 W __raw_writel(0x5555, WDT_WSPR);
- o4 h" t6 e! Q4 Y3 P) ?' A. ~* ^ while(__raw_readl(WDT_WWPS) != 0x0);
' O% p" u$ x+ y) n
. _+ H1 j' z' j* s' G/ |, @#ifdef CONFIG_SPL_BUILD
: o# g- f! \: D: B# f+ ~5 T( | /* Setup the PLLs and the clocks for the peripherals */
" H5 W/ y7 A( t# a0 Q pll_init();
- u) ~6 M3 x, F, x+ A2 F2 J. K \* M+ q$ C$ l$ s% L! ~% f
/* Enable RTC32K clock */- q H# p R2 V
rtc32k_enable();
) J4 v. B0 `: u% G) D, e, o5 P- `! {2 ?/ v4 h4 u! K, O
/* UART softreset */# o6 u- h2 O0 P! f/ X' @/ n/ j
u32 regVal;
1 ^. z$ t1 ^" G4 e7 l! V u32 uart_base = DEFAULT_UART_BASE;% D+ H9 [0 y" z2 S. l+ e. Z" Q
: ]$ l M- Q+ j8 y7 [4 G enable_uart0_pin_mux();
4 \* U4 ?9 h' Q0 D1 ^ /* IA Motor Control Board has default console on UART3*/5 I6 j6 H% D% o6 A% u! z% `* A
/* XXX: This is before we've probed / set board_id */( T U7 {, m, G, @
if (board_id == IA_BOARD) {3 N& q0 j8 E# F! n3 R5 X* a
uart_base = UART3_BASE;7 p$ [) Y- P* {- G
}% `. ^, K* ]& s3 `9 Q _
7 M. }& g$ e z6 b" T" W/ Z
regVal = __raw_readl(uart_base + UART_SYSCFG_OFFSET);0 i! U, }1 O% g. T; l
regVal |= UART_RESET;
$ o" w: X3 k; A, J6 r __raw_writel(regVal, (uart_base + UART_SYSCFG_OFFSET) );
4 n6 Q% D7 K- k, R2 z$ I5 x while ((__raw_readl(uart_base + UART_SYSSTS_OFFSET) &
) I. e; F1 k7 C0 r/ r0 ] [" G" b UART_CLK_RUNNING_MASK) != UART_CLK_RUNNING_MASK);
$ c; d2 E, e k
; I; p6 }6 {/ P# L( ]2 a /* Disable smart idle */
/ m3 w8 \ N) W; b7 B2 [1 m regVal = __raw_readl((uart_base + UART_SYSCFG_OFFSET));4 z: N' h4 ^& t) J. \
regVal |= UART_SMART_IDLE_EN;
. s) T# w/ I+ d' l __raw_writel(regVal, (uart_base + UART_SYSCFG_OFFSET));) p4 R1 k# V' h+ I5 F3 N
- T8 G( ]0 B3 ~9 S& {1 Y/ O
/* Initialize the Timer */
+ B& g$ d0 u6 }5 M( o init_timer();$ @! ?7 z9 S- o u3 t q
/ Q6 q& i8 ~8 a( c/ @$ J# y7 W
preloader_console_init();8 |( ^" w3 ` p% [! `/ ]1 s: X
7 L2 j2 a( z7 w' P r s
printf("location /board/ti/am335x"); //@@! J0 G0 B* r W+ x
/*@@*/
/ c! p4 L) g s* ^# M// led();1 z# p. t8 R H( A9 X3 q
/*@@*/
2 o4 a3 m$ w: E& c) }1 w3 S
3 a. O! a) a+ [: w: H6 A2 t7 k; a config_am335x_ddr();* k P+ Y' L+ Q) z) c; H5 {
, Y0 |* ?. N8 P2 l
#endif
1 \( J. y% F. Q i4 H. z2 \}
6 _3 l+ b9 \. o# J
9 a3 E3 y) K* q. C | ) ?; ^& ]4 c V V4 [. q
: Y3 _8 c. _) _/ L/ ?5 S+ l@c1@ 使能第二级缓冲区 5 g% b" ]) J0 _7 L
15 g( \0 G: k- m$ @' S- A5 k
2
/ Y+ n; k+ q6 Y* m' x: m37 a* c6 r: @- V( ?6 j/ h* E7 ^
4
: q8 a) @% B% g% a: J: z4 b# C55 X4 A$ T* Y; q7 h
6- f1 }: H, D" _* P
7
: G+ ?5 E* E$ V! n8
! k. ]+ j2 X% m y9
3 _' V: [$ {* c: D' ?. T9 N10
5 g6 D, D' |8 ] h+ } | /* Can be removed as A8 comes up with L2 enabled */
5 \* {/ f! S% S% c0 G l2_cache_enable();
- f9 {5 t" ]3 |# n% F/ P
; L2 W ]# ?8 n; J# A8 e5 E. R% p; c, ?0 i6 e3 Z% E! V
l2_cache_enable:% Y; r7 b8 N* y$ G# X# U5 V
push {r0, r1, r2, lr}' ?; x6 m: z ~- c6 U
mrc 15, 0, r3, cr1, cr0, 1
1 p: \! m4 w0 M9 b3 Y, |5 f$ ] orr r3, r3, #2, G1 p4 \6 o& e% f: A# n
mcr 15, 0, r3, cr1, cr0, 1$ h8 s% K2 j3 t
pop {r1, r2, r3, pc}
% o0 t# t. l, V5 \
6 G6 N* Z8 V& e+ ]0 K6 k |
) M0 j1 {0 a" C- m( c0 L. X p
+ a6 P( |3 y' k8 |& r
; H: F: G" J& p( j; t@c2@ 关闭看门狗(WDT)
; I6 X( i6 [& o1 ]: n: `+ D
* K6 h Z' p! S1
7 \+ M/ m, `3 ~" x) w1 [4 X2
7 w( l7 S! p8 ]1 [) \& Z4 S1 E# y3
. J) {# Y6 T1 E6 h) ~! g! ]4
, g% {; O* n f; I5/ d) l$ O- w3 w( v$ s
6
# h# c( L. \4 ?2 T5 m7
6 b" a- N: @, ?7 y$ O | /* WDT1 is already running when the bootloader gets control& B: @( ~' e0 J
* Disable it to avoid "random" resets! ]& d+ `; W6 ?' K) U: a$ W
*/
# A2 r f O: A__raw_writel(0xAAAA, WDT_WSPR);) D Q) [* H" a. |( a: U* c
while(__raw_readl(WDT_WWPS) != 0x0);
i9 y! I! t& |: Q$ O; d; Z__raw_writel(0x5555, WDT_WSPR);% e4 ]" \) j+ I! q
while(__raw_readl(WDT_WWPS) != 0x0);
1 U/ Q, X* y! n4 F' l5 n# a
+ g- ~4 M* s0 x5 A" Z2 I( i$ y | , O ~2 i; O9 O1 P; n7 F- \
' ?" J0 [8 U# k4 E6 E4 u- x3 j
& h! w; h' t" u. b0 Q# N9 ?# c8 x; r7 h
1
. ]8 ^5 u& U* |9 J/ l2
, q+ e2 O+ p8 B3
% k' g2 ]8 M7 r, w8 p' S: _& H4' i7 x# ?0 t; z6 l1 V5 Z4 x7 N
5
% G, k6 i- `6 W3 l$ m* x6/ z2 V/ B, e/ m* t
7
2 s6 `( m. ]* Z8
5 a4 V2 x8 ^ U4 N) s/ d9" ]$ ~% |6 i+ c$ T2 A! H
10
6 k# _6 y6 q! e% D# k# u, Q5 B11
0 B$ ] @& j0 o2 v |
, j% z: u, i6 Y#define WDT_WSPR (WDT_BASE + 0x048)8 M \& }' Y1 D+ W. W6 G! Y; c" `
- {+ w% p. c d* ~- r2 V/ C0 o1 x. S- h! H0 M+ e/ J! g
) U0 v3 l) E7 c& @
/* Watchdog Timer */
4 L" R( g. C+ l& N* e$ e#ifdef CONFIG_AM335X5 h( Q& N, c7 {( I L9 K
#define WDT_BASE 0x44E35000" } R( ~' f9 B. k3 V" w
#else4 H! ^4 r, x6 T) @* _( W' k. V
#define WDT_BASE 0x480C2000
0 x7 G0 U" s2 ^- Q#endif( @$ S' p8 e+ K( Z$ Q0 D
! g& f' c) D; s5 J9 \ J+ Z2 y |
( C4 a& ]+ x5 z8 N/ y+ k! g: H' D# b
, S+ n7 |1 J- L* ]& I
$ H- d3 n8 B1 O- D" q
K# X, M9 |" \
@c3@ 给外设设置好 PLL 和 时钟频率等 $ ]0 Z) d7 G. l
1% U7 o5 Y6 t6 ?2 A' F) A6 C
2
% S4 A4 ~& A" A( l2 P4 ]3! d1 T% T( T0 {; C. r0 ?& b
4) I& E* X6 X! p, C) k$ |, H
5" L+ J0 E% B$ J
6# \; M9 D" [* M0 y
7
2 y+ c, J8 d, C85 L+ z" t/ Y. j6 ]! g
9
" |9 p2 `- Q5 A102 W" B8 w; P! E* ?1 h7 g
11
& T/ m. p0 P' T A/ Z* `+ o9 [12
! B$ m6 p2 j( u: z/ R6 ~) }& {13" z; _9 a, _* p+ R
14
3 o# s" @$ @* k" [6 P3 g' H15
+ l/ g% I/ w3 t7 f$ ]. _8 X5 S16/ X. O/ }0 a h( |# X7 Q
17& g) j7 w: T# H& h
183 L: w8 [7 Y8 y
193 K$ f0 b' V8 B9 z+ P
20% T6 F6 V4 S b r. h
21
2 B7 C6 Z9 k! d* G6 b | /* Setup the PLLs and the clocks for the peripherals */
, _* p/ U" ~) b2 P pll_init();
) O) P# F2 h6 p; N- \7 k$ W1 @5 Q) L5 H, c0 ?5 [2 H3 s. z/ Q7 b6 ^
# z8 o) m" i2 [+ v6 c
6 V* x3 h3 V/ }' ~" G9 O/*
% Q3 |! G" g c) ^, C& b * Configure the PLL/PRCM for necessary peripherals
. }* m7 [' c! {$ [ */
/ Y7 R) U/ E$ H1 vvoid pll_init()
8 }6 X: c; c5 y1 J$ h$ F" a( L! W{) S/ y/ z% ?+ y
mpu_pll_config(MPUPLL_M_500);1 I( I- T8 O: Q, a: U8 R& @* M
core_pll_config();
3 K+ v: X8 W9 y# B4 g per_pll_config();
1 g/ v; A% z& _+ ~/ q ddr_pll_config();
$ S) Z5 F' P6 K, Z4 J8 R- R2 M /* Enable the required interconnect clocks */
+ b$ z8 K7 [" c interface_clocks_enable();
. P: [! |1 Q& t' e; u7 y3 _ /* Enable power domain transition */
6 P, k) r3 L; ?5 ~+ U" A1 q power_domain_transition_enable();0 T, s- ]& d0 H8 B
/* Enable the required peripherals */
# E: K7 j5 t0 U- l per_clocks_enable();) X; H/ I5 [" O# s8 x3 X
}
' I, {6 f+ i* ]) A5 E: @# f" f+ h4 Y; g; }' V
|
2 ~2 s$ `& V. ?7 }; c+ ^
, d) @( }9 g9 @8 D) o6 R* E+ p0 c
) h' I* A0 a; x9 F. L' A
6 q" q+ y$ e" R9 I5 y- T! N2 R9 U @c4@ 使能 32-KHz 频率的实时时钟 / k1 H1 H7 r0 [" T) e( @7 n
1
5 v6 H7 z% {9 e0 D: G$ O$ N2* y+ L9 s+ x3 Z- P* a9 O
3
, v" o$ M0 e( O0 z- U! _& O4
- J5 L4 W$ g% ^ G1 G5
% ]6 M4 M' {. G9 i66 N3 \+ K; Z0 ~* g0 d; t
7. r1 J2 d4 n3 a$ D9 }
8* H. q$ @, _$ |
9; s# Q; a- @4 R) `" b
10+ M* |. T, W9 D% w: O6 X3 _/ T) m
11
0 Z, U2 c. _* t12" J& L2 N- \8 R( H
13
. R' W) ^, a! D5 N7 {! Z14) V* l4 T: j) z8 z; G
15 @ B3 K( a5 h- N: P6 y
16
8 g) g; M4 B% w3 B/ w2 O1 M4 c+ c17
$ U; [" A' k5 a* h8 U- t* z1 U18
* T( Z' x M8 j. l3 N19
4 d$ \+ K5 X8 ~2 b203 y6 C" @) |5 N5 n. K& s8 c# y
21% D( O6 p8 ~! n. r( B* [
22! A$ J" F1 O' ^8 q: T
23
/ T5 B, l2 W* z" G | /* Enable RTC32K clock */
+ t1 V: D, r: ?- g2 ?0 ^8 h) y9 f* ` rtc32k_enable();
/ J" o0 ]" R' E- n
Y7 d) {! u3 j' }+ U# R
R: B/ @1 }# B. c- |《PATH : /board/ti/am335x/evm.c》8 y+ K! r) w1 m) n) t
static void rtc32k_enable(void)' v! ~( A, }: q( A
{6 d# |/ K, r7 v/ R
/* Unlock the rtc's registers */
3 y0 c O+ S' l6 D __raw_writel(0x83e70b13, (AM335X_RTC_BASE + RTC_KICK0_REG));
/ D7 _ _' ^- a& I! e __raw_writel(0x95a4f1e0, (AM335X_RTC_BASE + RTC_KICK1_REG));
) ?% o6 l6 _! k! `; \: k3 F
% h' e7 S! {9 D" `/ W. ~3 L /* Enable the RTC 32K OSC */ _* W$ X) h6 x( b: r: {5 M: M
__raw_writel(0x48, (AM335X_RTC_BASE + RTC_OSC_REG));8 S7 ` m# s4 O2 r2 ^
}4 B- h; v* y8 v0 R
, G5 Y/ f' M; E0 K
( z' W7 F0 i" l% ]/* RTC base address */
. ~ o2 [/ F1 g% y#define AM335X_RTC_BASE 0x44E3E000
3 y' }6 r1 L! { z+ ]# t* R9 t* N1 n: B. e; t9 F/ p0 c- {' |- ?
! ?) {" \2 q3 i# {% [5 K
#define RTC_KICK0_REG 0x6c
3 O% S# z- K3 Z" t; b; i4 P1 C4 D#define RTC_KICK1_REG 0x70
8 Z8 E* `5 I' z" E4 y#define RTC_OSC_REG 0x54
5 p- B$ n; r [: v6 c7 [: u+ z- m/ p4 G) R/ r0 M
|
4 Q5 {! F) ~+ e2 U) r# x! x; j, |8 Q1 \$ p0 ]& V ?
: g& _ V" _+ E% ~
@c5@ 使能UART0 , {1 b5 |" m$ }" V0 a
1
. K2 L+ K5 Q# ^$ g9 @9 I27 X3 k4 y% r' c1 N
3) `. H4 L/ f9 Z9 z% x7 m# s# w2 |, J
4
3 J! ?9 z3 j, o# k, R E% ?5
3 Q5 h1 g6 H( d# K4 N( N6 w64 J3 }3 m) D* N* L" t9 K( D$ @8 N
7
# y; a6 x" Q& n# E" F8; i! |; d* K5 l- p: W
9" f6 a9 v% {. f4 {) }, N
10
" g7 z' Z7 q2 ~# o11% \- ~) ~% w0 M
12
* Z0 G; W% L- n j13* L- Q4 _" j* Y" a5 [6 Q. d
14
7 z& O* K+ R' v8 p7 W8 Q15
. U" d' q/ m/ k0 f0 d1 d8 u3 |5 j0 R3 N& w164 _0 N2 h* g% ]. q3 u$ v" q
17 G2 Q7 n9 E3 H O
18
2 ?: {) a* e+ B! _# B8 c: p+ [' ]19
' k% T1 L8 r% s: q' ?0 x6 R20/ n. z5 ^, u0 m+ l. N# S
21
3 ]% ], q5 A+ ?/ N3 l7 U) Y* y227 g# Z! S! o0 f+ \/ M. S6 b
23
# ~ y( I6 ~/ @6 ~5 N+ Q* F249 ~7 A/ _* d- b4 Z% M C9 N2 I
25$ r' O% k% \! k7 x2 V: A
26) R6 Z* B6 j9 g0 H
27
) z2 g# w, _/ ~( A" [5 r" m280 Z+ r" U4 o% ]/ T9 p% I( o
29* X5 \/ v, C8 o( y; N! H
30
$ b* B+ ]+ Q% S6 H' W31
0 g. u. [+ J+ L) D. Q+ ?5 l: k32; c& ?2 p) u# n5 \8 r, g4 |
33, z$ S: l$ r. \; b
34
- m! c8 A3 A7 B! v N0 [- P | /* UART softreset */. v3 q& s0 W! ?3 @& R: i/ R }
u32 regVal;* Q4 D2 ~4 b8 g% l( l, U8 [
u32 uart_base = DEFAULT_UART_BASE;) {$ I) J, U/ a
1 n2 Q" n7 K. O: Z6 z; y
enable_uart0_pin_mux();
6 C* E; u1 d3 r" ] /* IA Motor Control Board has default console on UART3*/& d2 f) g% r0 a' l5 z$ J( `
/* XXX: This is before we've probed / set board_id */
+ P. r- L9 M+ Y- k$ R1 i if (board_id == IA_BOARD) {$ S+ s# J7 H2 c* `7 x+ k
uart_base = UART3_BASE;
3 f6 u' I' Z* P4 h0 V' z% o. e }/ |1 R( ^' `/ S
( r z& n* ?" n2 z* w regVal = __raw_readl(uart_base + UART_SYSCFG_OFFSET);8 |- B1 M! L! }
regVal |= UART_RESET;, J, }( ^1 Z+ X, I- L
__raw_writel(regVal, (uart_base + UART_SYSCFG_OFFSET) );, C, z5 [3 o' K& l
while ((__raw_readl(uart_base + UART_SYSSTS_OFFSET) &8 {0 c. a" a; O
UART_CLK_RUNNING_MASK) != UART_CLK_RUNNING_MASK);$ A2 G0 P5 u8 N# {+ }- e5 c( S+ q
& V8 |6 j; E" v' ? /* Disable smart idle */
5 z$ j# g+ j# i/ Q# }0 p regVal = __raw_readl((uart_base + UART_SYSCFG_OFFSET));
2 Y$ O. C; \# Y+ a4 {: P+ {# a regVal |= UART_SMART_IDLE_EN;* F. {) g9 ~/ V2 [4 Y6 Z
__raw_writel(regVal, (uart_base + UART_SYSCFG_OFFSET));
. {5 X( v8 f. r. u8 Y: ~4 `! z7 V! P! d: f' E" `
9 L! Y* M+ T3 f b I
6 r+ M6 Y% a+ [* Z4 j6 v#ifdef CONFIG_AM335X
5 z; a8 a2 L. g, u#define DEFAULT_UART_BASE UART0_BASE
+ |6 J0 `1 j* d/ n4 H8 G#endif5 ^7 Z& Q" _1 _
& u& M- p3 F! K( Z
- i# ~% o# `6 @: C
#ifdef CONFIG_AM335X, D! M) B. v- G+ Q& ~5 C( b
#define UART0_BASE 0x44E09000
0 l2 L; [6 l1 G' P7 R- D#else
$ {+ R- |2 X- F#define UART0_BASE 0x48020000; l R$ P9 c5 N
#endif
' e3 f; h C% x6 S
6 U r( m' p7 y; z" v3 u |
9 u" N4 M/ _4 ~9 Z% Q7 e: a! A7 W) B/ y
5 V6 e3 T, K) I: F! |. D$ |$ V. |/ [& L& ]
@c6@ 初始化 定时器 # d5 Z- D" y" S6 J0 L; ^! l
1
6 J9 Q g9 v5 [% W1 \22 h" Y8 i, l l8 e* S
30 q2 s2 k" t8 e3 I; p
48 v" h6 p" C' S' J7 g) o6 g
5
; a$ |5 K: r2 a6 u6, Y, X5 m; R* H
7& ?) B: s* d8 e& o( @7 d
8
6 a) ?8 ]1 d- i; N1 F; z" m93 k5 t( z7 O1 E/ M, K
10+ H: O+ c n& K7 u$ k7 y
11
3 ^1 h# T- |5 V. z12& p' }( A) g e7 r
13
# j! O) T. D. C2 V- w* p- @1 B14% I6 |: u2 ^3 \3 |
15
1 l& k% Z# p. [' Y16
. `& H/ K( e% P$ p. B, i17
: f3 `. i' Q, X, Z# k18
8 E: s5 d- Z/ g( o3 o* ?19
) o9 b% s3 u4 O+ r! c* _20
1 d7 A% g, P% t& Z8 `2 }( V, k217 a: X2 m# |" k0 h
227 m1 t- Z; O# l1 \& l* \1 q5 r `2 e
23
) p1 \ B0 @, @1 Z9 U1 q24# U. K) J& n+ H/ a; f
25
/ o: [) ?, r! v* C; C+ P7 U0 `26
. }) b3 t! ?/ m274 S0 m+ z. O; `0 i; @* c6 Y
| /* Initialize the Timer */3 {5 e- e, O9 J9 N6 U* Z# T8 v
init_timer();+ O) X* [7 S* n% x
8 V9 O Z+ c$ D9 @/ K
8 s: L2 s5 Z/ {: B9 k! W9 {
) e' V; \' Q+ nstatic void init_timer(void)
p' K) ~; |( f{
! J" M M8 F/ S6 w% [+ b4 @ /* Reset the Timer */6 e( H2 W V u/ P) X- b- z
__raw_writel(0x2, (DM_TIMER2_BASE + TSICR_REG));6 [. t% P2 U4 @( x1 w! H& [$ b/ u: a e
& w& e' S, N# _8 ^ /* Wait until the reset is done */3 X& _* }- B: d
while (__raw_readl(DM_TIMER2_BASE + TIOCP_CFG_REG) & 1);6 f) g2 C) S7 x* l! I0 b5 q% ?
! }: N0 p6 f6 c7 E/ Q /* Start the Timer */+ U5 x: O5 s$ ]/ g) X7 `
__raw_writel(0x1, (DM_TIMER2_BASE + TCLR_REG));
/ d# j$ x+ h3 Q. M, ~& ~}# X% H1 w3 b& |( d( v
! p9 g+ H" l& ~' }: m* B
# v) g2 X$ T; s! m* u/* DM Timer base addresses */9 e6 V: S5 {8 {( p4 v
#define DM_TIMER0_BASE 0x4802C0003 r8 X% M i# ^5 p% Z. d
#define DM_TIMER1_BASE 0x4802E000+ N2 P7 @" [, g2 _4 y# @1 F. S1 {
#define DM_TIMER2_BASE 0x48040000
& r( N! l; T8 s2 F+ J3 l#define DM_TIMER3_BASE 0x480420001 P% u/ d# s! m* v1 [2 @2 Q" m
#define DM_TIMER4_BASE 0x48044000# O" |8 v1 n& a* p }- S* \
#define DM_TIMER5_BASE 0x48046000$ R8 Z6 u# W4 B! e7 S* O
#define DM_TIMER6_BASE 0x48048000
7 r' X; w i# Z& K' X9 l: A9 C2 B2 R#define DM_TIMER7_BASE 0x4804A000
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8 s+ O/ H2 N2 f- e: t1 D@c7@ 初始化控制台,通过UART可以查看相关信息 3 e$ N# l5 B# H$ W
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| preloader_console_init();
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《PATH : /arch/arm/cpu/armv7/omap-common/spl.c》
9 J* A U3 S& E6 R+ Z8 f1 g" v! q/ X/* This requires UART clocks to be enabled */0 ]6 C. L- k1 q6 ], d
void preloader_console_init(void)
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const char *u_boot_rev = U_BOOT_VERSION;/ Z( y1 L1 w6 E- O
char rev_string_buffer[50];
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2 Q' l, U5 G7 q gd = &gdata;3 ]( R; |' v: }( G2 ~
gd->bd = &bdata;
" K* _3 f J% o6 H; _& ?4 ] gd->flags |= GD_FLG_RELOC;4 ]. u3 v* W3 [& A7 c
gd->baudrate = CONFIG_BAUDRATE;# \: ~8 B/ G y( A5 A0 y
, M( i7 z; z& T( L9 _7 P serial_init(); /* serial communications setup */
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/* Avoid a second "U-Boot" coming from this string */
" L" k6 [% b3 t: J: o5 Z0 D u_boot_rev = &u_boot_rev[7];2 R7 J, M% c# r. x9 V' g
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printf("U-Boot SPL %s (%s - %s)", u_boot_rev, U_BOOT_DATE,
7 a) ]& V. I( D; I4 c$ D% R. i U_BOOT_TIME);6 M$ `) L! y. X! t# r" x- E. i2 R
omap_rev_string(rev_string_buffer);
$ O4 e# U5 X* w printf("Texas Instruments %s", rev_string_buffer);
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@c8@ 配置 DDR
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| config_am335x_ddr();# L5 {% ?6 Y1 o0 `) y; R) a
- a3 O7 J6 I! [/ L$ B2 W2 k5 U《PATH :》# U3 @, z6 E7 W( q# v
/* void DDR2_EMIF_Config(void); */& c9 \; T( F3 Q+ W" B# L
static void config_am335x_ddr(void)0 {3 i+ M9 w" S+ K1 {
{1 ~' W, a# H+ ]' ?% I
int data_macro_0 = 0;
4 ]/ v: G8 j( e7 M int data_macro_1 = 1;
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' m. U: D" R' b enable_ddr_clocks();/ L& S$ M! c v, r
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config_vtp();7 O+ l s2 p* H3 r, h7 `
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Cmd_Macro_Config();
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" l6 k7 C; I- p3 e: _, N Data_Macro_Config(data_macro_0);
2 A+ y- o5 S+ `, R Data_Macro_Config(data_macro_1);1 [/ q# y- {' n7 K) L9 t
4 F- d% `3 S8 d __raw_writel(PHY_RANK0_DELAY, DATA0_RANK0_DELAYS_0);" }0 ~% x7 t' K% ^( H$ `6 I9 G( r
__raw_writel(PHY_RANK0_DELAY, DATA1_RANK0_DELAYS_0);( t3 G/ p- p' I: M: l x
* ~8 J$ Z5 q7 u# ^* P( \) _/ { __raw_writel(DDR_IOCTRL_VALUE, DDR_CMD0_IOCTRL);- A D) i8 T" s/ t9 y
__raw_writel(DDR_IOCTRL_VALUE, DDR_CMD1_IOCTRL);) Z, `# y) r. E7 {4 D% r
__raw_writel(DDR_IOCTRL_VALUE, DDR_CMD2_IOCTRL);/ j5 [7 [: {% f
__raw_writel(DDR_IOCTRL_VALUE, DDR_DATA0_IOCTRL);9 V, L8 o% t1 F8 W/ b
__raw_writel(DDR_IOCTRL_VALUE, DDR_DATA1_IOCTRL);4 c; ]! n( Q4 A& B" W
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__raw_writel(__raw_readl(DDR_IO_CTRL) & 0xefffffff, DDR_IO_CTRL);
3 ]! I( T3 k; |6 m5 Z8 ^ __raw_writel(__raw_readl(DDR_CKE_CTRL) | 0x00000001, DDR_CKE_CTRL);2 g; _ y; e. Y6 G1 c
2 n/ J1 U0 [6 \, e. o6 [ config_emif_ddr2();3 \9 s# j; N( X& s6 {1 g
}
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3 ]% J& b& g0 C# Y6 I* u* g" v《PATH : /arm/include/asm/arch-ti81xx/cpu.h》
4 o; ?- r9 D; ]; O#define DATA0_RANK0_DELAYS_0 (DDR_PHY_BASE_ADDR + 0x134)
/ Q+ C5 j* j* Y; [9 \#define DATA1_RANK0_DELAYS_0 (DDR_PHY_BASE_ADDR + 0x1D8)
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/* DDR offsets */: J C8 d8 V. s, I6 N
#define DDR_PHY_BASE_ADDR 0x44E12000+ r7 U3 r, y0 c0 ]0 ?' ^
#define DDR_IO_CTRL 0x44E10E04
& U" ]' u9 B9 l5 j2 R#define DDR_CKE_CTRL 0x44E1131C
- o- b5 J6 Z' z; a#define CONTROL_BASE_ADDR 0x44E10000 m- e; n6 U/ M; G3 h7 }
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9 y3 e( X" V, q( A R@c DONE@ @b DONE@ @a4@ 设置 internal RAM 内存空间的栈指针,调用 board_init_f()函数 + \! e, y9 \1 ?8 O+ C/ A; V# H0 l
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8 P: p) }8 K. k+ w, w4 Q: r- b9 c | /* Set stackpointer in internal RAM to call board_init_f */- i$ W g# r c, f; t, J
call_board_init_f:' G& H; C# D6 _7 F# _/ h I% k
ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)
( t; A9 W8 ~9 c$ L8 ?1 N3 @ bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
, }. s7 d8 q: n$ W7 l u. L' \ ldr r0,=0x00000000
: i- P9 n& h2 B# ?, K3 P& @ bl board_init_f+ u0 R6 g, Q- G' e) V
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. F1 g* G9 h/ f' `% D% j#define CONFIG_SYS_INIT_SP_ADDR (CONFIG_SYS_INIT_RAM_ADDR +
6 j6 U" u. b" ?8 I CONFIG_SYS_INIT_RAM_SIZE -
+ h- N4 j- U5 ^/ R+ O/ a, U# M7 [ GENERATED_GBL_DATA_SIZE)
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0 o w8 G+ m& _! X7 n9 O# A) U9 K, @( ]#define CONFIG_SYS_INIT_RAM_ADDR SRAM0_START9 x( s( Z6 |0 f- c
#define CONFIG_SYS_INIT_RAM_SIZE SRAM0_SIZE$ z' z# I- [- N+ \- V5 @1 s0 W s
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#ifdef CONFIG_AM335X$ v( d, G4 ?' J
#define SRAM0_START 0x402F04001 V) W6 L8 I3 U. ^4 C
#else* c& I3 j0 `) t( `) t3 l
#define SRAM0_START 0x40300000) y7 f! j/ X% z
#endif
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* s8 a0 z/ B# X8 W6 }4 u& d3 {( w#if defined(CONFIG_AM335X) || defined(CONFIG_TI814X)8 }+ C. `4 n* b0 F- v# w
#define SRAM0_SIZE (0x1B400) /* 109 KB */. N8 o) {9 [2 v, D- c; `& o6 _' L% t
#define SRAM_GPMC_STACK_SIZE (0x40)/ f" D1 b/ v3 f) z
#endif
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#define GENERATED_GBL_DATA_SIZE (128) /* (sizeof(struct global_data) + 15) & ~15 */
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void board_init_f(ulong dummy)
0 r5 Z! ?+ l; D: a+ ]1 k8 `4 \3 `{
7 p% D, f' Z! y9 L/ v( q /*) a3 P* y! ], x( E% Z/ [: R/ D
* We call relocate_code() with relocation target same as the) R5 [' L7 U0 M* P3 _) f
* CONFIG_SYS_SPL_TEXT_BASE. This will result in relocation getting8 c' G/ D h9 v) m$ ]
* skipped. Instead, only .bss initialization will happen. That's4 f/ ]7 L3 G9 h7 R8 ^) n' [
* all we need' g0 Z" ] X( \9 n V
*/% C% ^8 O& @( v7 k; f
debug(">>board_init_f()");: @' k% H# K8 _9 j" d( ~) P
relocate_code(CONFIG_SPL_STACK, &gdata, CONFIG_SPL_TEXT_BASE);
+ x4 p2 P% u% s( i& y}
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#define CONFIG_SPL_TEXT_BASE 0x402F04006 g. c1 u5 a+ f7 c) ^
#define CONFIG_SPL_MAX_SIZE (46 * 1024)
/ {, o. w. h+ o" J$ T) D6 m#define CONFIG_SPL_STACK LOW_LEVEL_SRAM_STACK9 K, u# g9 z1 |1 y$ q' T) K3 D
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1 }3 ^6 S* \* N6 f0 L# \" }# j" j0 H' ~* I( W
#define LOW_LEVEL_SRAM_STACK 0x4030B7FC
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( {3 a2 n- Y% V* M/*8 ]0 J5 I# Z9 Z* H. q7 q* g" ~: ^
* void relocate_code (addr_sp, gd, addr_moni)4 o0 N/ }0 X5 ^, X5 [2 _
*7 ^7 H1 C; b" h, v; F; G
* This "function" does not return, instead it continues in RAM
( m3 |' U# I* P. r/ @& {' O7 a * after relocating the monitor code.* e( k% V. i1 l5 U+ E0 y9 G) }
*! j; g" |5 h$ u. P3 C
*/
: y! w5 R" Z& v. O# e0 t .globl relocate_code
8 B. D$ w/ G: j, J7 g/ P# k3 _relocate_code:
, t5 I# A8 k6 K3 R. t mov r4, r0 /* save addr_sp */$ n7 ~( K3 F& m8 _
mov r5, r1 /* save addr of gd */' Q$ ~) h/ w. i1 C' w" R- [
mov r6, r2 /* save addr of destination 0x402F0400*/7 \7 s8 E$ x$ t) h- M( R4 ^7 v
$ ~8 T9 I0 J9 q! R9 Z |
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2 |" m5 }, y x, v3 [@a5@ 代码重定位 代码重定向,它首先检测自己(MLO)是否已经在内存中: 如果是直接跳到下面的堆栈初始化代码 clear_bss。 如果不是就将自己从Nor Flash中拷贝到内存中。) {5 m' ^+ q0 z. i; d! v
Nor Flash 和Nand Flash 本质区别就在于是否进行代码拷贝,也就是下面代码所表述:无论
5 n, }, p' O6 ?8 Z$ I6 P" F是Nor Flash 还是Nand Flash,核心思想就是将 uboot 代码搬运到内存中去运行,但是没有拷
1 s) s( R v+ Z% D6 V贝bss 后面这段代码,只拷贝bss 前面的代码,bss 代码是放置全局变量的。Bss 段代码是为
) I; G2 X! b# z& M$ c& _2 V了清零,拷贝过去再清零重复操作。
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1
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6 O G) a0 Y+ N% D0 g0 a8 {( n2 y1 P: k | /* Set up the stack */( Z: u: ]1 g' T3 m" p
stack_setup:
' k( }8 ?& N4 q; Y. a mov sp, r4
& z' b7 d6 S5 b E' P e/ z& z8 i( S2 {) S: B" l
adr r0, _start
' T s% p8 D& r$ \/ b0 f, { cmp r0, r6: I8 h' l. g, n
moveq r9, #0 /* no relocation. relocation offset(r9) = 0 */* b, v7 o- J* i& x1 x8 J: E
beq clear_bss /* skip relocation */
0 o. m$ @8 `6 k mov r1, r6 /* r1 <- scratch for copy_loop */' Z$ y, M) F" N( I8 S* D
ldr r3, _image_copy_end_ofs6 ?4 e& H6 |/ L) T2 B
add r2, r0, r3 /* r2 <- source end address */
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copy_loop: /* 自拷贝 */' m, ~* y8 Z- l1 M! l! h/ e. g
ldmia r0!, {r9-r10} /* copy from source address [r0] */$ i% t6 C3 S) S5 E5 I6 y
stmia r1!, {r9-r10} /* copy to target address [r1] */
- T, `0 J3 X4 O! w' h3 k, w cmp r0, r2 /* until source end address [r2] */
( t9 x2 W, h( |% x) g; x2 r2 K blo copy_loop0 Q3 o3 G; T `, x! W
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| . t; G: Z& X8 ?1 [
1 ~4 k: W2 G+ n, ?: S@a6@ 清空 bss 段 0 [" ^2 X5 J( D2 }( X
1
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12
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15
6 z% D3 A$ Y3 T8 S. ?/ S16! M1 R: H6 j! }( u
17
/ T( t: W1 H7 i" I18' x N$ j, |/ u, _% v1 v6 H, {
19
+ x; Q' R% T# b7 _& Z20
8 [" W& N7 X3 ^! X" U" G1 e% z; |215 E% z* F8 G" ]$ [( l/ c
| clear_bss:1 `' e; Y: c% \. J, w
) Z* a6 a6 o5 O1 H ldr r0, _bss_start_ofs4 P/ L/ c- T; u. K
ldr r1, _bss_end_ofs w. Y1 c7 r( q; E
mov r4, r6 /* reloc addr */0 h1 B# q* W6 X+ h# ]
add r0, r0, r4
% L i6 ~) {) A, J" l. o' s add r1, r1, r4
* r: K3 C1 u+ N! x4 o& C6 b* d5 f1 c, o3 o( r
mov r2, #0x00000000 /* clear */& L5 A% `6 i- Q. T$ w
8 |$ {0 ~9 B: @# _
clbss_l:str r2, [r0] /* clear loop... */2 q5 B! K; d% H4 W: x7 Y7 I
add r0, r0, #4
& e7 b( ^7 ?# U7 X% V/ U cmp r0, r1* Q0 T% w7 G" N0 @1 r: G
bne clbss_l
' K# W9 r" |$ J8 E& f7 Z( N9 x2 l" U5 o6 F+ q; |- i5 r- H1 m
/*7 P1 ]& y. K( E1 ?9 t0 H$ }% B
* These are defined in the board-specific linker script.
; `2 Y/ d) Y7 [: Y */- w+ n; r5 E/ A/ z
.globl _bss_start_ofs. U. x: E" G* W/ f6 i M! @5 C5 ?
_bss_start_ofs:
' R& N* y4 W9 _. a6 s- [) t+ a .word __bss_start - _start /* __bss_start = 0x80000000 */
9 t- V9 z: j; ?% p. L
4 l2 e7 L( V7 s4 b/ N3 n |
; z1 u9 t* r: b+ U$ n: B5 }$ K) N2 }9 @ S# G2 T
! d' r1 U; l/ U% o: {! @* R@a7@ 调用函数 board_init_r,用以完成 MLO(SPI)阶段的所有初始化,并跳转到 uboot.img 阶段 % l$ U8 c" r# O6 x9 W1 H
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2
9 K) l9 y" V# j" d7 {6 `& `5 O3
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6, |. D6 s4 ^: h
7
9 {: Z8 t# y% B2 V0 {6 d1 m0 |8" A% | ~" V# `' G9 j7 X( Z
9
7 ]3 b% F) P3 _ i! Y9 p10
& ]. j- k' r1 v, d4 Q11
4 r `* |+ g5 L# W7 X6 k12
$ v7 u- z9 Z+ R3 G+ L135 H' S# g S+ |( B' i8 \
14
+ ?5 c6 ?- z& B* J: s! k6 Z% {1 y15
0 _6 p! n5 M9 ?$ {16
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/ V( y/ \% `! Z+ e187 D; x) n$ {( R
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20
- e8 M L# n/ [3 G: D21
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8 H3 y/ g- l M" E D0 i& n+ L24( h6 H( t! h1 `7 U3 u: R5 f
25
0 l$ T7 ?, t/ e% X4 e! I, ~ | /*
* l( Y& c. d3 {: P9 d( e! U * We are done. Do not return, instead branch to second part of board
( r9 D" @# [! `) t- o# x* M. \( c * initialization, now running from RAM.
' k# t; g% v8 W& D# W3 v */
5 p& R! t# ]% o$ s" ujump_2_ram:1 [ C' E( L# v; K( w
/*
; Q( ^7 n F4 b( |2 G * If I-cache is enabled invalidate it9 b( A5 v6 _! |/ v/ h- d8 p+ Q; K
*/
# |. i! w, k! ?8 o4 B! Y" j& ?8 M; i#ifndef CONFIG_SYS_ICACHE_OFF7 Y0 v5 J/ w3 H! ?
mcr p15, 0, r0, c7, c5, 0 @ invalidate icache2 f$ O5 Y( X1 j# q# A3 X
mcr p15, 0, r0, c7, c10, 4 @ DSB4 [( U% \) L4 t# m* s
mcr p15, 0, r0, c7, c5, 4 @ ISB
$ T; u) b5 U! c" `7 \#endif
" e! f- i* u) {7 `& B, H3 j6 r& V ldr r0, _board_init_r_ofs
8 m3 t1 w/ f Y" f e* f4 ~( B# W; c% h adr r1, _start0 f3 y* T" D# ?( J j X+ q
add lr, r0, r1
) m7 m' ]0 B p! J9 _ add lr, lr, r91 H+ G: G! K6 m4 ?
/* setup parameters for board_init_r */
/ j( B: k5 `. A4 d& X) ~0 W+ p4 Z mov r0, r5 /* gd_t */
/ T) d: y! l& Q mov r1, r6 /* dest_addr */% E1 \+ B6 V8 N0 [3 h. C
/* jump to it ... */
% A1 ?8 n6 w" n; S) S- S' X mov pc, lr
2 L, q: Y0 ?1 x" j) F% w) k0 U# U6 d9 W- n
_board_init_r_ofs:$ E8 T" q3 q4 R* V+ D: _4 f1 C
.word board_init_r - _start9 z ~5 e) a( L5 X7 }" F
' z A& s& r$ N$ c( l
| 7 }& x# |" r- {& m/ X5 S* E
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3 U; p0 r p9 [2 ]
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26 z& o4 D( U! _
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46 Z0 }$ h$ T4 I1 n/ e
5
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9
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15
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196 P1 A; O' h+ ~9 C( ?
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4 l" `! k/ @* z: n* _256 E6 i/ H* X1 }' X; k0 J
269 Y Y, @0 U: ~
27
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40
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4 e6 b7 H( o' G4 C l, A1 {; T" ]" [42* ~, I- X5 x: s ^; t/ y0 a
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44
& E( n: g+ T- ~( t451 P! M2 z) r% x! N, H b7 k
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48
( N" d7 y" f! c' q! O/ } | 《PATH : /arch/arm/cpu/armv7/omap-common/spl.c 》5 V5 f6 T* h$ k5 B8 `% }
void board_init_r(gd_t *id, ulong dummy)
) U! H( H [$ t0 p- p{
0 D) g& D) G' ~$ U7 b( f u32 boot_device;( q, m+ o3 m' q- _ A
debug(">>spl:board_init_r()");
' n& S, c9 v9 s
7 s" {, B. e. U timer_init();
! \( ?3 H+ a& O, P2 }8 W1 _' k r i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
/ m7 p8 B. H8 Q: ?) c9 I4 C' c/ V! W& {4 P$ P; x7 f! [- {5 U' g. N$ @9 c
#ifdef CONFIG_SPL_BOARD_INIT. M0 O; b0 J; S7 B# Z9 I
spl_board_init();
( M5 `0 _4 z: h$ y: v: I#endif
+ e- G2 c) B4 [/ }' O6 ? v$ q
$ n- x2 K( k x5 s4 b boot_device = omap_boot_device();
+ D' f. j2 C( ^! | debug("boot device - %d", boot_device);% c v% j$ z% L8 z1 D2 ]
switch (boot_device) {
; [& c, Q+ J+ p& L/ e' `#ifdef CONFIG_SPL_MMC_SUPPORT
& ?+ p+ m" w4 j) J case BOOT_DEVICE_MMC1:
3 ~5 U/ ^5 t5 R: }/ x$ Y case BOOT_DEVICE_MMC2:
9 Z& F0 G i0 x4 q/ q) b spl_mmc_load_image();: J$ a0 s+ l; }6 W1 Z% G' P7 T8 w
break;
) v- Z- o/ f- S' X$ u, t- |- \#endif. m" K/ Q9 A/ D) p; M
#ifdef CONFIG_SPL_NAND_SUPPORT
, D( S* F- U3 P. ^5 K( J case BOOT_DEVICE_NAND:6 p, _* }: i9 [7 [. y& K8 r
spl_nand_load_image();' K& s5 V: w; N1 }9 [# |" g
break;3 F+ B/ N# a& T5 f% W
#endif
& _+ V. M# k4 s#ifdef CONFIG_SPL_YMODEM_SUPPORT
0 B( g E9 n% X; Y9 Z+ V, M( R case BOOT_DEVICE_UART:# j( k. U, r9 }/ [$ Q
spl_ymodem_load_image();
$ o; R0 `: ~4 m! e1 }3 G( b9 q break;0 f7 y7 @8 k- r
#endif! Q3 r+ t, J3 j1 W$ i3 x
default:
5 _7 k2 H7 q4 y& c printf("SPL: Un-supported Boot Device - %d!!!", boot_device);' }# Y" c: F) {
hang();4 O# B. f; @; |7 {6 b" M. m; w
break;
4 U6 r+ r' g* P ?* y6 Y& f }
. Z* q: }4 U9 M4 R
% w$ a D6 m5 m2 j- a switch (spl_image.os) {$ p- Z. l* S7 v5 a% q3 ]3 Y; Q
case IH_OS_U_BOOT:
+ `. Z; a0 G! @5 z0 W/ O debug("Jumping to U-Boot");
( u( R- ^% K0 v% T" N/ E8 O jump_to_image_no_args();( s0 e8 A% ^, k
break;
Z6 I$ _* e- p default:+ o9 k2 M; v5 r7 A% Z0 l4 i! E
puts("Unsupported OS image.. Jumping nevertheless..");
. m* C+ w0 ~5 G- L$ Q! o: e. F: a jump_to_image_no_args();
& C. w3 i4 m7 \* y7 t }
) M8 s4 X( J9 _: A9 ]: A( V5 L$ Z}
; Z, d# E A8 I( i7 u
: W1 A' l) k2 A R0 I |
6 H: _- K4 ]/ @# d0 X) K
7 M3 ]7 ]& `* A. v# v/ F+ U
2 {3 v# K& u" }' I- }; j@a DONE@
8 ~% e1 P& R' Z3,第三级 bootloader:uboot.img 做了哪些事情? uboot.img 内存分布如下: 访问 /arch/arm/lib/board.c 中 的 board_init_f() 函数: 3 Q- c- v* b3 F2 r
在 uboot.img 运行过程中,有两个非常重要的结构体:gd_t 和 bd_t 。 其中 gd_t :global_data 数据结构的定义,位于:/arch/arm/include/asm/global_data.h 中。 其成员主要是一些全局的系统初始化参数。 其中 bd_t :bd_info 数据结构的定义,位于:/arch/arm/include/asm/u-boot.h 中。 其成员是开发板的相关参数。
' [6 x$ s0 n8 Q& H. g8 y4 l' E) [/ C: Q1 c
1
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4
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9
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11
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23
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29
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311 g* K9 C$ p' T# [9 H8 l7 c' t( }! F
32) j) `' ^% } r) G G
338 |- M- {' ^' C# R" c6 W5 e: u, j
34
+ t' P$ G( b! z) ~+ p35/ }$ e# Y6 x* J, d; R5 \+ A
36
7 M T* c0 X, S37
) N' v+ c( j4 |9 [38" R6 n1 I- d+ ^" M* T
39
# E7 B. h2 }3 `) j8 {40# |/ X% M4 M9 t4 g2 o9 R
416 Z( @8 f' s$ m9 T7 |. I
42' O# s3 U# S8 u+ S
43) c3 Y" g" T9 s' z: ] B! v* W
44 U2 X+ S9 C. N5 p7 h v; U3 j, L k
451 m. l6 a z; ^4 {
469 b3 C4 e5 Z z* C9 \ ]" W
47( N( d9 }4 t/ L
48
7 j8 n" z+ r7 W; b* V; R7 w49
- u1 f; I5 D9 S1 K! B0 X9 t( G509 T4 V$ v5 f8 W' Z- y% X5 p$ u
51
% z( l8 C3 I8 E8 |8 h+ ^523 j/ f4 b' t9 ?$ O
53
, P' n. t: _9 A" T& ]- P& |54
2 K$ R2 r8 n) i3 C! I552 @7 h) _" I( @- p, u( N' \
567 o& M! ~0 k# S1 E: Y
57" o' w+ S0 X1 \
58) y1 ]0 O, u1 \! e1 I
59
8 }, R6 c' R3 m: I60. M& A* w0 a2 ~0 H+ ~
610 r W1 j( j' b. d/ [2 I( y( Y
62
2 Z7 S8 m9 I* e3 m, S63. U, s% e5 r; p, g9 g) N
64
8 d z) j# V$ A# u# ?654 e/ R4 r7 [7 u
66$ v* Z5 ^7 s" o% _* A
67
8 R; \9 t4 |, G7 A, X+ ^! n68
6 ~' F9 z, L8 ]' l698 K; }' c& N% T' o) Q7 i k! f
70
" L) i2 i& x7 d! b2 n | ' y. i; B; q8 h; F4 u2 H% O& W& Y4 B
/*9 |: n4 m4 c) v. _# [6 y
* The following data structure is placed in some memory which is
9 f4 V) i* N5 o3 b * available very early after boot (like DPRAM on MPC8xx/MPC82xx, or. F; C! S }) y+ E$ E
* some locked parts of the data cache) to allow for a minimum set of
! O/ h, R6 [8 w7 G% h2 H * global variables during system initialization (until we have set
) a( S* d' z8 ~2 _3 g * up the memory controller so that we can use RAM).% g& i% ]- B/ B, ]3 W3 q
*
& ~% [* \$ J1 k b * Keep it *SMALL* and remember to set GENERATED_GBL_DATA_SIZE > sizeof(gd_t)
! W0 f |; @! V* M0 S */6 i; k. K- q0 L5 j
. b; B( o2 Z7 p- t7 [) C2 I+ mtypedef struct global_data {% q8 @: H1 @/ K3 [) L$ `/ p
bd_t *bd;- n8 Y6 m7 c" D# E/ L& Y( W" O
unsigned long flags;9 n* P# I4 S t! ^8 x/ o/ u
unsigned long baudrate;
: \2 y' A7 `' E3 W$ h+ t unsigned long have_console; /* serial_init() was called */$ G* ~' H- I+ o
unsigned long env_addr; /* Address of Environment struct */
# |/ C( }1 a& B7 P7 } unsigned long env_valid; /* Checksum of Environment valid? */* q& l1 l5 I( X$ K" q2 @- {
unsigned long fb_base; /* base address of frame buffer */
. R2 d2 ^4 @8 J+ p% h" o#ifdef CONFIG_FSL_ESDHC
( b4 ?1 {# V0 ?+ H$ m$ ^% ? unsigned long sdhc_clk;
4 M2 o, J) A2 N2 z, ~#endif
1 a6 @7 f+ y( r- w; k4 k: y7 Z5 e2 ]#ifdef CONFIG_AT91FAMILY- m$ M& V4 E' w8 J W. I
/* "static data" needed by at91's clock.c */7 B: t5 d- u0 V; z: @+ h" q- _
unsigned long cpu_clk_rate_hz;
6 N6 C W% l' r! l/ U unsigned long main_clk_rate_hz;
- J7 H1 m( k: i0 z unsigned long mck_rate_hz;
& f; P% @6 |: q) F/ X unsigned long plla_rate_hz;
3 v# y. q9 ^. \$ M; T* c unsigned long pllb_rate_hz;
; D9 H9 y/ P" d3 i/ J4 r& }, p1 p unsigned long at91_pllb_usb_init;3 y& P- `# L% \, L, c
#endif' y! J2 I# x: h6 }0 R
#ifdef CONFIG_ARM8 Z( f) Y* j/ {/ K( Q' |
/* "static data" needed by most of timer.c on ARM platforms */% R& W2 c* f' {9 Z: O* P# W
unsigned long timer_rate_hz;
2 n% F8 S5 r7 X/ i% r0 r unsigned long tbl;
+ E! p* N5 S7 V unsigned long tbu;9 c2 D* I% Z) k' s
unsigned long long timer_reset_value;7 H9 Q2 u0 R @/ `! Q$ Q
unsigned long lastinc;
7 Z9 ^2 a5 v. _! {#endif
: |2 Q, W' g3 a1 ] Q#ifdef CONFIG_IXP425- P* Y; V- k/ M0 x' ^2 Q
unsigned long timestamp;
; U8 {+ S8 ^5 [! y#endif
a% B5 f0 d; R, {: }+ ?+ k8 r- f unsigned long relocaddr; /* Start address of U-Boot in RAM */
0 _ Q/ P; K; ]3 m8 Z9 G phys_size_t ram_size; /* RAM size */( S- H1 A3 N, g+ W* P
unsigned long mon_len; /* monitor len */
# G+ |$ k# z6 M unsigned long irq_sp; /* irq stack pointer */
& s4 I' b% F( L unsigned long start_addr_sp; /* start_addr_stackpointer */
- X& m$ P; t3 D7 _2 L# n unsigned long reloc_off;
: O8 z$ U7 A9 D* ^$ }* [+ V4 T! s; D#if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF)): }7 X% ]% e6 D6 t
unsigned long tlb_addr;
( m$ q4 N% ]+ A+ @. t#endif
% m3 g5 x/ z; i void **jt; /* jump table */
( N% N) d3 L4 G0 D char env_buf[32]; /* buffer for getenv() before reloc. */6 v/ Y, H; u: p
} gd_t;$ R) q" r- C/ M/ M" a* C
$ r3 Y. \: E) l#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("r8")
5 P) b9 I9 E. o" G# W% _0 Y8 S& r- I0 t4 c" m
. ]" m- V O7 U6 T2 ]/ V" b% Q# Z5 y2 ^. u. N& s* f9 U
typedef struct bd_info {3 [$ J+ i2 p8 Z* O2 V
int bi_baudrate; /* serial console baudrate */
" W K2 x( P: d6 ]; q5 ~! } unsigned long bi_ip_addr; /* IP Address */# l; M, k" T& [4 ^% ~& S: ?
ulong bi_arch_number; /* unique id for this board */
7 t5 V) I% A) o) P' D' m7 T0 ~: ` ulong bi_boot_params; /* where this board expects params */
. J/ H7 `1 l6 @# e struct /* RAM configuration */
' D j- O2 I0 k8 w* E {- x) \: A- @8 y7 o- O
ulong start;% a% C+ O9 J4 a% {" C
ulong size;0 z8 z: G& i o/ X3 w
} bi_dram[CONFIG_NR_DRAM_BANKS];
% r5 {; C* M! K- F4 t5 `* w} bd_t;
3 Y' W- B" w. @' \% T3 I( f; v8 G
|
6 T6 K v+ ]5 z
5 t2 q' h+ t1 H: D( n4 \5 d! c9 |1 ?其中 DECLARE_GLOBAL_DATA_PTR 宏定义在系统初始化过程中会被频繁调用,% ^. s$ J/ {; h" B' N
其的作用是,声明gd这么一个全局的指针,这个指针指向gd_t结构体类型,并且这个gd指针是保存在ARM的r8这个寄存器里面的。 uboot.img 第一个运行的文件还是 start.o,其在运行访问的 board_init_f() 函数定义在 /arch/arm/lib/board.c 中: 2 ?& l, [6 T7 K
1
/ o. `- g: u: A3 u2: ?9 j2 f$ e; }; q- e( S$ g
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4
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7" J) ~7 M$ B+ |- C
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9
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|
) g# {8 Q; U/ h& _* X, Zvoid board_init_f(ulong bootflag)( ], v) W/ ?4 |3 q \' ]0 l7 |
{4 ` J* G& S0 o/ {
bd_t *bd;
4 r- x& E% h8 ~' }4 V init_fnc_t **init_fnc_ptr;
; c6 L9 p+ s. u& Y4 Y gd_t *id;* a3 q: {" U- C. l! e% }, R6 n2 B6 H
ulong addr, addr_sp;
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. {3 j$ Z3 L2 E1 g" s0 @* d7 h' \ /* Pointer is writable since we allocated a register for it */
+ k( ~7 j3 c! { gd = (gd_t *) ((CONFIG_SYS_INIT_SP_ADDR) & ~0x07);
p8 U- y0 Z" c+ { /* compiler optimization barrier needed for GCC >= 3.4 */! X4 i) t8 b \ b, Z) D+ ]7 t
__asm__ __volatile__("": : :"memory");, h) O; |9 f- T# c5 [$ ~& N+ j# b ?8 Z
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memset((void *)gd, 0, sizeof(gd_t));- M& e2 R2 q! q5 q
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#define CONFIG_SYS_INIT_RAM_ADDR SRAM0_START! m$ l* B) u! D; B; D
#define CONFIG_SYS_INIT_RAM_SIZE SRAM0_SIZE. Z/ c' W' I8 I* f& L
#define CONFIG_SYS_INIT_SP_ADDR (CONFIG_SYS_INIT_RAM_ADDR +
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GENERATED_GBL_DATA_SIZE)
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% K- a! m! X, ^/ H. m. \" N#define SRAM0_START 0x402F04000 q5 s9 }: Z# \, J/ d
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1 w* ]. W' B t+ A( B' |#define SRAM0_SIZE (0x1B400) /* 109 KB */4 l8 d4 _+ @7 [" m% j" F2 i
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4 f) V0 Q" F" a5 i& b#define GENERATED_GBL_DATA_SIZE (128) /* (sizeof(struct global_data) + 15) & ~15 */
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7 g8 R1 J5 j! z3 D+ N因此,系统初始化参数将会被保存在 (保存 MLO(SPL)文件的内存空间的)末尾 2 KB 处。 通过计算的 gb 指针指向的内存空间地址为 gb = 0x4030B000 gb_t 结构体中某些元素的值是来自于 uboot.img's header,这个header的数据保存在内存的0x807FFFCO,大小为 64字节 - t. q1 ? _+ T4 ~2 n! k: E& Q B
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& f- h. M" h' U3 k4 U6 s/*3 A, K5 L; V3 y. Z' d& U
* Legacy format image header,
6 z+ D% d- r/ A& T1 I1 X$ j * all data in network byte order (aka natural aka bigendian).$ x; f; H1 t9 t* h
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typedef struct image_header {
5 p4 \ U4 f6 c/ [$ S6 q9 @ uint32_t ih_magic; /* Image Header Magic Number */
- ]+ P" {5 s. y) | uint32_t ih_hcrc; /* Image Header CRC Checksum */
, b1 [+ T" U/ o7 n* P. W uint32_t ih_time; /* Image Creation Timestamp */
- I- _( k( x7 W# q( Z( i/ H8 s# z uint32_t ih_size; /* Image Data Size */1 ]* g+ N" ~& v
uint32_t ih_load; /* Data Load Address *// T) J: {: j0 x# r. K! L$ M
uint32_t ih_ep; /* Entry Point Address */0 m) V) E! ~3 p. ~
uint32_t ih_dcrc; /* Image Data CRC Checksum */6 G y `7 P+ O" }# |) T
uint8_t ih_os; /* Operating System */
% U8 ?2 ~/ I* D& f4 U5 o uint8_t ih_arch; /* CPU architecture */ y; s; E5 D l% U/ Y
uint8_t ih_type; /* Image Type */3 M$ [: c6 Y! M* ]5 x
uint8_t ih_comp; /* Compression Type */5 d H C8 w3 y. y
uint8_t ih_name[IH_NMLEN]; /* Image Name */5 d' U, {; h+ @$ C
} image_header_t;
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* 8MB into the SDRAM to allow for SPL's bss at the beginning of SDRAM.( g9 u! D w# Z' ^. `8 D
* 64 bytes before this address should be set aside for u-boot.img's5 E5 i8 B V% v. k0 s
* header. That is 0x807FFFC0--0x80800000 should not be used for any
. ~5 t& Z9 s5 r: f( g * other needs.' s* j: H3 s* w0 n' j8 T( B/ q
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#define CONFIG_SYS_TEXT_BASE 0x808000008 N, A) Y- z+ P, z% S% s
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