移植U-Boot-2008.10到友善之臂mini2440（二）

1.2 修改U－Boot中的文件，以同时匹配2440和2410

1.2.1 修改/cpu/arm920t/start.S

?

??? (1)删除AT91RM9200使用的LED代码

#include <config.h>
#include <version.h>
//#include <status_led.h> /*这是针对AT91RM9200DK开发板的LED代码，注释掉。*/
......
start_code:
????/*
?????* set the cpu to SVC32 mode
?????*/
????mrs r0,cpsr
????bic r0,r0,#0x1f
????orr r0,#0xd3
????msr cpsr,r0
????//bl coloured_LED_init
????//bl red_LED_on

??? (2)修改编译条件支持2440，修改寄存器地址定义

#if defined(CONFIG_S3C2400) || defined(CONFIG_S3C2410)|| defined(CONFIG_S3C2440)
????/* turn off the watchdog */

#if defined(CONFIG_S3C2400)
#define pWTCON 0x15300000
#define INTMSK 0x14400008 /* Interupt-Controller base addresses */
#define CLKDIVN 0x14800014 /* clock divisor register */
#else
#define pWTCON 0x53000000
#define INTMSK 0x4A000008 /* Interupt-Controller base addresses */
#define INTSUBMSK 0x4A00001C
#define CLKDIVN 0x4C000014 /* clock divisor register */
#endif
#define CLK_CTL_BASE 0x4C000000
#define MDIV_405 0x7f << 12
#define PSDIV_405 0x21
#define UPLL_MDIV_48 0x38 << 12
#define UPLL_PSDIV_48 0x22
#define MDIV_200 0xa1 << 12
#define PSDIV_200 0x31

??? (3)修改中断禁止部分

#if defined(CONFIG_S3C2410)
????ldr r1,=0x7ff /*根据2410芯片手册，INTSUBMSK有11位可用*/
????ldr r0,=INTSUBMSK
????str r1,[r0]
#endif
#if defined(CONFIG_S3C2440)
????ldr r1,=0x7fff /*根据2440芯片手册，INTSUBMSK有15位可用*/
????ldr r0,[r0]
#endif

??? (4)修改时钟设置（2440的主频为405MHz。）

?注释掉原来的代码：

??????? /* FCLK:HCLK:PCLK = 1:2:4 */

??????? /* default FCLK is 120 MHz ! */

??????? //ldr?? r0,=CLKDIVN

??????? //mov?? r1,#3

??????? //str?? r1,[r0]

//#endif?????? /* CONFIG_S3C2400 || CONFIG_S3C2410 */

?

改为：

# if defined(CONFIG_S3C2440)

??? /* FCLK:HCLK:PCLK = 1:4:8 */

??? ldr r0,=CLKDIVN

??? mov r1,#5

??? str r1,[r0]

???

??? mrc p15,r1,c1,c0,0 /*read ctrl register? */

??? orr r1,#0xc0000000 /*Asynchronous? */

??? mcr p15,0 /*write ctrl register? */

?

?

??? /*now,CPU clock is 405.00 Mhz? */

??? mov r1,#CLK_CTL_BASE

?

??? mov r2,#UPLL_MDIV_48??? /*UPLL */

??? add r2,r2,#UPLL_PSDIV_48

??? str r2,[r1,#0x08]? /*write UPLL first,48MHz */

?

??? mov r2,#MDIV_405 /* mpll_405mhz? */

??? add r2,#PSDIV_405 /* mpll_405mhz? */

??? str r2,#0x04] /* MPLLCON?? */

?

#else

??? /* FCLK:HCLK:PCLK = 1:2:4 */

??? /* default FCLK is 12 MHz ! 在这里U－Boot有一个错误：以为默认时钟为120MHz。其实如果没有添加以下设置FCLK的语句，芯片内部的PLL是无效的，即FCLK为12MHz。S3C24x0的芯片手册说得很明白。*/

??? ldr??? r0,=CLKDIVN

??? mov??? r1,#3

??? str??? r1,[r0]

?

??? mrc p15,0 /*write ctrl register? */

?

??? /*now,CPU clock is 202.8 Mhz? */

mov r1,#CLK_CTL_BASE

mov r2,#MDIV_200 /* mpll_200mhz? */

??? add r2,#PSDIV_200 /* mpll_200mhz? */

??? str r2,#0x04]

?

?# endif

#endif????????? /*CONFIG_S3C2400 || CONFIG_S3C2410 || CONFIG_S3C2440*/

?

?? (5)将从Flash启动改成从NAND Flash启动

在以下U－Boot的设置堆栈语句段(作用是将u-boot的源代码从nor flash到sdram中)：

??????? /* Set up the stack */

?stack_setup:

??? ldr r0,_TEXT_BASE?????? /* upper 128 KiB: relocated uboot?

??? 的前面添加上以下的nand boot代码：

#ifdef CONFIG_S3C2440_NAND_BOOT

??????? @ reset NAND

??????? mov???? r1,#NAND_CTL_BASE

??????? ldr???? r2,=( (7<<12)|(7<<8)|(7<<4)|(0<<0) )

??????? str???? r2,#oNFCONF]

??????? ldr???? r2,#oNFCONF]

???????

??????? ldr???? r2,=( (1<<4)|(0<<1)|(1<<0) )? @ Active low CE Control

??????? str???? r2,#oNFCONT]

??????? ldr???? r2,#oNFCONT]

???????

??????? ldr???? r2,=(0x6)???? @ RnB Clear

??????? str???? r2,#oNFSTAT]

??????? ldr???? r2,#oNFSTAT]

???????

??????? mov???? r2,#0xff????? @ RESET command

??????? strb??? r2,#oNFCMD]

???????

??????? mov???? r3,#0? @ wait

nand1:

??????? add???? r3,r3,#0x1

??????? cmp???? r3,#0xa

??????? blt???? nand1

?

nand2:

??????? ldr???? r2,#oNFSTAT]???? @ wait ready

??????? tst???? r2,#0x4

??????? beq???? nand2

???????

???????

??????? ldr???? r2,#oNFCONT]

??????? orr???? r2,#0x2?? @ Flash Memory Chip Disable

??????? str???? r2,#oNFCONT]

???????

??????? @ get read to call C functions (for nand_read())

??????? ldr???? sp,DW_STACK_START???? @ setup stack pointer

??????? mov???? fp,#0? @ no previous frame,so fp=0

?

??????? @ copy U-Boot to RAM

??????? ldr???? r0,=TEXT_BASE

??????? mov???? r1,#0x0

??????? mov???? r2,#0x30000

?

??????? bl????? nand_read_ll

?

??????? tst???? r0,#0x0

??????? beq???? ok_nand_read

?

bad_nand_read:

loop2:

??????? b?????? loop2?? @ infinite loop

?

ok_nand_read:

??????? @ verify

??????? mov???? r0,#0

??????? ldr???? r1,=TEXT_BASE

??????? mov???? r2,#0x400???? @ 4 bytes * 1024 = 4K-bytes

go_next:

??????? ldr???? r3,[r0],#4

??????? ldr???? r4,[r1],#4

??????? teq???? r3,r4

??????? bne???? notmatch

??????? subs??? r2,#4

??????? beq???? stack_setup

??????? bne???? go_next

?

notmatch:

loop3:

??????? b?????? loop3?? @ infinite loop

?

#endif

?

#ifdef? CONFIG_S3C2410_NAND_BOOT

??????? @ reset NAND

??????? mov???? r1,=0xf830??? @ initial value

??????? str???? r2,#oNFCONF]

??????? bic???? r2,#0x800 @ enable chip

??????? str???? r2,#oNFCONF]

??????? mov???? r2,#0xff????????????? @ RESET command

??????? strb??? r2,#0? @ wait

nand1:

??????? add???? r3,#0x1

??????? beq???? nand2

???????

??????? ldr???? r2,#oNFCONF]

??????? orr???? r2,#0x800 @ disable chip

??????? str???? r2,#oNFCONF]

???????

??????? @ get read to call C functions (for nand_read())

??????? ldr???? sp,so fp=0

???????

??????? @ copy U-Boot to RAM

??????? ldr???? r0,#0x0????? @start address

??????? mov???? r2,#0x30000? @code size

??????? bl????? nand_read_ll

??????? tst???? r0,#4

??????? beq???? stack_setup

??????? bne???? go_next

?

notmatch:

loop3:

??????? b?????? loop3?? @ infinite loop

?

#endif

在“ldr??? pc,_start_armboot”之前加入：

#if? defined(CONFIG_mini2440_LED)

?????????????? @? LED1 on u-boot stage 1 is ok!

?? mov? r1,#GPIO_CTL_BASE

?? add? r1,#oGPIO_B

?? ldr? r2,=0x155aa

?? str? r2,#oGPIO_CON]

?? mov? r2,#0xff

?? str? r2,#oGPIO_UP]

?? mov? r2,#0x1c0

?? str? r2,#oGPIO_DAT]

#endif?

修改目的：如果看到只有LED1亮了，并响起蜂鸣器，说明U－Boot的第一阶段已完成！(针对mini2440，若不是这块开发板的，必须修改或不添加)。

在 “? _start_armboot:??? .word start_armboot? ” 后加入：

??????? .align? 2

DW_STACK_START: .word?? STACK_BASE+STACK_SIZE-4