【ARM】Tiny4412裸板编程之MMU封装

00. 目录

文章目录

00. 目录
01. 开发环境
02. Tiny4412内存布局
03. 配置MMU
04. 程序示例
05. 附录

01. 开发环境

开发板：Tiny4412SDK标准版「Tiny4412 SDK 1506」
工具：「arm-linux-gcc-4.5.1」「minicom」「dnw」
平台：Ubuntu 20.04

02. Tiny4412内存布局

咱们的内存是1G，范围是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;
}

执行结果

## 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 @将M为设置为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 @将M为设置为0mcr p15, 0, r0, c1, c0, 0mov pc, lr

3.3 设置页表基地址

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

访问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

设置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 设置Domain访问权限

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

设置域访问权限

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

04. 程序示例

一级页表描述符格式

二级页表描述符格式

sp15.S文件内容如下

    .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文件内容如下

#include <string.h>
#include <gpio.h>//一级页表初始化
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需要多一点空间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;}
}//一级页表映射
void ttb_l1_mmap(U32 *ttb, U32 va, U32 pa)
{ttb[va >> 20] = (pa & 0xfff00000) | 0x2;
}//二级页表初始化
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;}}
}//二级页表映射
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文件内容如下

#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//设置TTB基地址set_ttb(ttb);//设置域访问权限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;
}

执行结果

## 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. 附录

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

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