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【ARM】Tiny4412裸板编程之MMU(页 4K)

發布時間：2024/4/24 编程问答 34 豆豆

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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

一級頁表描述符格式

二級頁表描述符格式

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; U32 *ttb_c = (void*)0x61000000;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*)0x72345648;for (i = 0; i < 100; i++){p[i] = i; }print("*p = %#x\n", *p);//清零 4K * 4Bytememset((void*)ttb, 0, 4096 * 4);memset((void*)ttb_c, 0, 256* 4);//0xC2345648 --> 0x72345648ttb[0xC23] = (int)ttb_c | 0x1;ttb_c[0x45] = (0x72345 << 12) | 0x2;//test.bin//ttb[0x500] = (0x50 << 24) | (1 << 18) | 2;ttb[0x500] = (int)ttb_c | 0x1;ttb_c[0x0] = (0x50000 << 12) | 0x2;//U-Boot.bin stackU32 pa;for (i = 0x42000000; i < 0x44000000; i += 1000000) {pa = i >> 24;ttb[i >> 20] = (pa << 24) | (1 << 18) | 2;}//所有寄存器的地址for (i = 0x10000000; i < 0x14000000; i += 1000000) {pa = i >> 24;ttb[i >> 20] = (pa << 24) | (1 << 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*)0xC2345648;for (i = 0; i < 100; i++){print("p[%d] = %d\n", i, p[i]); }print("main end\n");//禁用MMUdisable_mmu();return 0; }

執行結果

## Starting application at 0x50000000 ... main start *p = 0x0 p[0] = 0 p[1] = 1 p[2] = 2 p[3] = 3 p[4] = 4 p[5] = 5 p[6] = 6 p[7] = 7 p[8] = 8 p[9] = 9 p[10] = 10 p[11] = 11 p[12] = 12 p[13] = 13 p[14] = 14 p[15] = 15 p[16] = 16 p[17] = 17 p[18] = 18 p[19] = 19 p[20] = 20 p[21] = 21 p[22] = 22 p[23] = 23 p[24] = 24 p[25] = 25 p[26] = 26 p[27] = 27 p[28] = 28 p[29] = 29 p[30] = 30 p[31] = 31 p[32] = 32 p[33] = 33 p[34] = 34 p[35] = 35 p[36] = 36 p[37] = 37 p[38] = 38 p[39] = 39 p[40] = 40 p[41] = 41 p[42] = 42 p[43] = 43 p[44] = 44 p[45] = 45 p[46] = 46 p[47] = 47 p[48] = 48 p[49] = 49 p[50] = 50 p[51] = 51 p[52] = 52 p[53] = 53 p[54] = 54 p[55] = 55 p[56] = 56 p[57] = 57 p[58] = 58 p[59] = 59 p[60] = 60 p[61] = 61 p[62] = 62 p[63] = 63 p[64] = 64 p[65] = 65 p[66] = 66 p[67] = 67 p[68] = 68 p[69] = 69 p[70] = 70 p[71] = 71 p[72] = 72 p[73] = 73 p[74] = 74 p[75] = 75 p[76] = 76 p[77] = 77 p[78] = 78 p[79] = 79 p[80] = 80 p[81] = 81 p[82] = 82 p[83] = 83 p[84] = 84 p[85] = 85 p[86] = 86 p[87] = 87 p[88] = 88 p[89] = 89 p[90] = 90 p[91] = 91 p[92] = 92 p[93] = 93 p[94] = 94 p[95] = 95 p[96] = 96 p[97] = 97 p[98] = 98 p[99] = 99 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; U32 *ttb_c = (void*)0x61000000;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*)0x72345648;for (i = 0; i < 100; i++){p[i] = i; }print("*p = %#x\n", *p);//清零 4K * 4Bytememset((void*)ttb, 0, 4096 * 4);memset((void*)ttb_c, 0, 256* 4);//0x5648 --> 0x72345648ttb[0x0] = (int)ttb_c | 0x1;ttb_c[0x5] = (0x72345 << 12) | 0x2;//test.bin//ttb[0x500] = (0x50 << 24) | (1 << 18) | 2;ttb[0x500] = (int)ttb_c | 0x1;ttb_c[0x0] = (0x50000 << 12) | 0x2;//U-Boot.bin stackU32 pa;for (i = 0x42000000; i < 0x44000000; i += 1000000) {pa = i >> 24;ttb[i >> 20] = (pa << 24) | (1 << 18) | 2;}//所有寄存器的地址for (i = 0x10000000; i < 0x14000000; i += 1000000) {pa = i >> 24;ttb[i >> 20] = (pa << 24) | (1 << 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;for (i = 0; i < 100; i++){print("p[%d] = %d\n", i, p[i]); }print("main end\n");//禁用MMUdisable_mmu();return 0; }

執行結果

06. 附錄

Exynos 4412 SCP_Users Manual_Ver.0.10.00_Preliminary0.pdf

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