00. 目錄

文章目錄

• • 00. 目錄
  • 01. 開發環境
  • 02. Tiny4412內存布局
  • 03. 配置MMU
  • 04. 程序示例一
  • 05. 程序示例二
  • 06. 附錄

01. 開發環境

• 開發板：Tiny4412SDK標準版 「Tiny4412 SDK 1506」
• 工具：「arm-linux-gcc-4.5.1」 「minicom」 「dnw」
• 平臺：Ubuntu 20.04

02. Tiny4412內存布局

咱們的內存是1G，范圍是0x40000000~0x8000000

在0x40000000~0x80000000, 程序示例

#include <string.h> #include <adc.h> #include <gpio.h>void (*udelay)(unsigned int) = (void*)0x43e26480; int (*print)(const char *format, ...) = (void*)0x43e11a2c;extern unsigned int __bss_start; extern unsigned int __bss_end;int main(void) {//0x40000000 ~ 0x80000000 1Gmemset((void*)&__bss_start, 0, (int)&__bss_end -(int)&__bss_start);print("main start\n");U32 *p = (void*)0x72345678;*p = 0x11223344;print("*p = %#x\n", *p);p = (void*)0x82345678;*p = 0x11112222;print("*p = %#x\n", *p);print("main end\n");return 0; }

執行結果

## Starting application at 0x50000000 ... main start *p = 0x11223344

03. 配置MMU

3.1 使能MMU

B3.2.4 Enabling MMUs

.section .text.align 2.global mmu_enable mmu_enable:mrc p15, 0, r0, c1, c0, 0orr r0, r0, #1 @將M為設置為1mcr p15, 0, r0, c1, c0, 0mov pc, lr

3.2 禁用MMU

.section .text.align 2.global disable_mmu disable_mmu:mrc p15, 0, r0, c1, c0, 0bic r0, r0, #1 @將M為設置為0mcr p15, 0, r0, c1, c0, 0mov pc, lr

3.3 設置頁表基地址

B4.1.154 TTBR0, Translation Table Base Register 0, VMSA

訪問TTBR0的方法

MRC p15, 0, <Rt>, c2, c0, 0 ; Read 32-bit TTBR0 into Rt MCR p15, 0, <Rt>, c2, c0, 0 ; Write Rt to 32-bit TTBR0

設置TTB的基地址

.section .text.align 2.global set_ttb set_ttb:mcr p15, 0, r0, c2, c0, 0mov pc, lr

3.4 設置Domain訪問權限

B4.1.43 DACR, Domain Access Control Register, VMSA

To access the DACR, software reads or writes the CP15 registers with <opc1> set to 0, <CRn> set to c3, <CRm> set to c0, and <opc2> set to 0. For example: MRC p15, 0, <Rt>, c3, c0, 0 ; Read DACR into Rt MCR p15, 0, <Rt>, c3, c0, 0 ; Write Rt to DACR

設置域訪問權限

.section .text.align 2.global set_domain set_domain:mcr p15, 0, r0, c3, c0, 0mov pc, lr

04. 程序示例一

sp15.S文件內容如下

.section .text.align 2.global get_midr get_midr:MRC p15, 0, r0, c0, c0, 0 mov pc, lr.section .text.align 2.global get_ccsidr get_ccsidr:MRC p15, 1, r0, c0, c0, 0mov pc, lr.section .text.align 2.global get_sctlr get_sctlr:MRC p15, 0, r0, c1, c0, 0mov pc, lr.section .text.align 2.global get_id_mmfr3 get_id_mmfr3:MRC p15, 0, r0, c0, c1, 7mov pc, lr.section .text.align 2.global enable_mmu enable_mmu:mrc p15, 0, r0, c1, c0, 0orr r0, r0, #1mcr p15, 0, r0, c1, c0, 0mov pc, lr.section .text.align 2.global disable_mmu disable_mmu:mrc p15, 0, r0, c1, c0, 0bic r0, r0, #1mcr p15, 0, r0, c1, c0, 0mov pc, lr.section .text.align 2.global set_ttb set_ttb:mcr p15, 0, r0, c2, c0, 0mov pc, lr.section .text.align 2.global set_domain set_domain:mcr p15, 0, r0, c3, c0, 0mov pc, lr

test.c文件內容如下

#include <string.h> #include <stdlib.h> #include <adc.h> #include <gpio.h>void (*udelay)(unsigned int) = (void*)0x43e26480; int (*print)(const char *format, ...) = (void*)0x43e11a2c;extern unsigned int __bss_start; extern unsigned int __bss_end;//TTB的基地址 U32 *ttb = (void*)0x60000000;int main(void) {int i = 0;//0x40000000 ~ 0x80000000 1Gmemset((void*)&__bss_start, 0, (int)&__bss_end -(int)&__bss_start);print("main start\n");U32 *p = (void*)0x72345678;*p = 0x11223344;print("*p = %#x\n", *p);//清零 4K * 4Bytememset((void*)ttb, 0, 4096 * 4);//將0xC2345678地址映射到0x52345678ttb[0xc23] = (0x523 << 20) | (0 << 18) | 2;//test.binttb[0x500] = (0x500 << 20) | (0 << 18) | 2;//U-Boot.bin stackfor (i = 0x42000000; i < 0x44000000; i += 100000) {ttb[i >> 20] = i | (0 << 18) | 2;}//所有寄存器的地址for (i = 0x10000000; i < 0x14000000; i += 100000) {ttb[i >> 20] = i | (0 << 18) | 2;}//設置TTB基地址set_ttb(ttb);//設置域訪問權限set_domain(0xffffffff);//使能MMUenable_mmu();p = (void*)0xC2345678;*p = 0x11112222;print("*p = %#x\n", *p);print("main end\n");//禁用MMUdisable_mmu();return 0; }

執行結果

## Starting application at 0x50000000 ... main start *p = 0x11223344 *p = 0x11112222 main end ## Application terminated, rc = 0x0

05. 程序示例二

將0x00005648地址映射到0x70005648

test.c文件

#include <string.h> #include <stdlib.h> #include <adc.h> #include <gpio.h>void (*udelay)(unsigned int) = (void*)0x43e26480; int (*print)(const char *format, ...) = (void*)0x43e11a2c;extern unsigned int __bss_start; extern unsigned int __bss_end;//TTB的基地址 U32 *ttb = (void*)0x60000000;int main(void) {int i = 0;//0x40000000 ~ 0x80000000 1Gmemset((void*)&__bss_start, 0, (int)&__bss_end -(int)&__bss_start);print("main start\n");U32 *p = (void*)0x70005648;*p = 0x11223344;print("*p = %#x\n", *p);//清零 4K * 4Bytememset((void*)ttb, 0, 4096 * 4);//0x00005648 --> 0x70005648ttb[0x0] = (0x700 << 20) | (0 << 18) | 2;//test.binttb[0x500] = (0x500 << 20) | (0 << 18) | 2;//U-Boot.bin stackfor (i = 0x42000000; i < 0x44000000; i += 100000) {ttb[i >> 20] = i | (0 << 18) | 2;}//所有寄存器的地址for (i = 0x10000000; i < 0x14000000; i += 100000) {ttb[i >> 20] = i | (0 << 18) | 2;}//設置TTB基地址set_ttb(ttb);//設置域訪問權限set_domain(0xffffffff);//使能MMUenable_mmu();p = (void*)0x5648;print("*p = %#x\n", *p);print("main end\n");//禁用MMUdisable_mmu();return 0; }

執行結果

## Starting application at 0x50000000 ... main start *p = 0x11223344 *p = 0x11223344 main end ## Application terminated, rc = 0x0

06. 附錄

Exynos 4412 SCP_Users Manual_Ver.0.10.00_Preliminary0.pdf

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