00. 目錄

文章目錄

• • 00. 目錄
  • 01. 開發(fā)環(huán)境
  • 02. Tiny4412內(nèi)存布局
  • 03. 配置MMU
  • 04. 程序示例
  • 05. 附錄

01. 開發(fā)環(huán)境

• 開發(fā)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(nèi)存布局

咱們的內(nèi)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(zhí)行結(jié)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(shè)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(shè)置為0mcr p15, 0, r0, c1, c0, 0mov pc, lr

3.3 設(shè)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(shè)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(shè)置Domain訪問權(quán)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(shè)置域訪問權(quán)限

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

04. 程序示例

一級頁表描述符格式

二級頁表描述符格式

sp15.S文件內(nèi)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

ttb.c文件內(nèi)容如下

#include <string.h> #include <gpio.h>//一級頁表初始化 void ttb_l1_init(U32 *ttb) {U32 va;U32 pa;//test.binfor (va = 0x50000000; va < 0x50100000; va += 0x100000){pa = va; ttb[va >> 20] = pa | 0x2;}//uboot.bin Uboot需要多一點空間for (va = 0x43000000; va < 0x44000000; va += 0x100000){pa = va; ttb[va >> 20] = pa | 0x2;}//GPIOfor (va = 0x10000000; va < 0x14000000; va += 0x100000){pa = va; ttb[va >> 20] = pa | 0x2;} }//一級頁表映射 void ttb_l1_mmap(U32 *ttb, U32 va, U32 pa) {ttb[va >> 20] = (pa & 0xfff00000) | 0x2; }//二級頁表初始化 void ttb_l2_init(U32 *ttb, U32 **ttb_c) {U32 va;U32 pa;U32 tmp;//test.binfor (va = 0x50000000; va < 0x58000000; (*ttb_c) += 0x100) {ttb[va >> 20] = (int)(*ttb_c) | 0x1; memset((void*)*ttb_c, 0, 256 * 4);//4Kfor (tmp = va + 0x100000; va < tmp; va += 0x1000){pa = va; (*ttb_c)[(va >> 12) & 0xff] = (pa & 0xfffff000) | 0x2;}}//uboot.binfor (va = 0x43000000; va < 0x44000000; (*ttb_c) += 0x100) {ttb[va >> 20] = (int)(*ttb_c) | 0x1; memset((void*)*ttb_c, 0, 256 * 4);//4Kfor (tmp = va + 0x100000; va < tmp; va += 0x1000){pa = va; (*ttb_c)[(va >> 12) & 0xff] = (pa & 0xfffff000) | 0x2;}}//gpiofor (va = 0x10000000; va < 0x14000000; (*ttb_c) += 0x100) {ttb[va >> 20] = (int)(*ttb_c) | 0x1; memset((void*)*ttb_c, 0, 256 * 4);//4Kfor (tmp = va + 0x100000; va < tmp; va += 0x1000){pa = va; (*ttb_c)[(va >> 12) & 0xff] = (pa & 0xfffff000) | 0x2;}} }//二級頁表映射 void ttb_l2_mmap(U32 *ttb, U32 **ttb_c, U32 va, U32 pa) {ttb[va >> 20] = (int)(*ttb_c) | 0x1;memset((void*)*ttb_c, 0, 256 * 4);(*ttb_c)[(va >> 12) & 0xff] = (pa & 0xfffff000) | 0x2;(*ttb_c) += 0x100; }

test.c文件內(nèi)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);#if 0ttb_l1_init(ttb);ttb_l1_mmap(ttb, 0xC2345648, 0x72345648);#elsettb_l2_init(ttb, &ttb_c);ttb_l2_mmap(ttb, &ttb_c, 0xC2345648, 0x72345648); #endif//設(shè)置TTB基地址set_ttb(ttb);//設(shè)置域訪問權(quán)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(zhí)行結(jié)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. 附錄

ARM ? Architecture Reference Manual ARMv7-A and ARMv7-R edition

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