ARM用MIG调用DDR3的c程序解析

淡淡的烟草味﹌ 2022-05-20 04:16 1011阅读 0赞

**背景：**用ARM（PS：zynq7 processing system）控制Mig调用了DDR3，我们希望用IPcore控制Mig调用DDR3

**目录**

1 platform.h与platform.h

1.1 d-cache与i-cache

2 . memory\_config.h与memory\_config\_g.c

3 主程序

4.  DDR3的调用

--------------------

[FPGA实践教程（五）调用DDR][FPGA_DDR]

**目的：**看懂xilinx用PS调用DDR3的测试代码，找到用Mig调用DDR的代码行。

结果非常简单，系统搭建正确的话，PS直接用指针调用DDR，指针地址为DDR对应的地址。同时，我们需要注意到，相应的c程序是SDK根据前一步vivado实际搭建的系统来生成的。所以我们在以后的工程中，除了保证看懂能用相应的c程序之外还需要保证前一步vivado搭建的系统是正确的。

搭建的系统：PS通过MIG模块与DDR3相连。

![70][]

程序运行结果

![70 1][]

# 1 platform.h与platform.h #

## 1.1 d-cache与i-cache ##

两者为两种不同的cache，不同类型的缓冲区

[https://blog.csdn.net/bytxl/article/details/50275377][https_blog.csdn.net_bytxl_article_details_50275377]

// platform.c
    #include "xparameters.h"
    #include "xil_cache.h"
    
    #include "platform_config.h"
    
    #ifdef STDOUT_IS_16550
    #include "xuartns550_l.h"
    #endif
    
    void
    enable_caches()
    {
    #ifdef __PPC__
        Xil_ICacheEnableRegion(XPAR_CACHEABLE_REGION_MASK);
        // Do not enable caches for memory tests, this has pros and cons
        // Pros - If caches are enabled, under certain configurations, there will be very few 
        //        transactions to external memory
        // Con  - This might not generate a burst cacheline request
        // Xil_DCacheEnableRegion(CACHEABLE_REGION_MASK);
    #elif __MICROBLAZE__
    #ifdef XPAR_MICROBLAZE_USE_ICACHE 
        Xil_ICacheEnable();
    #endif
    #ifdef XPAR_MICROBLAZE_USE_DCACHE 
        // See reason above for not enabling D Cache
        // Xil_DCacheEnable();
    #endif
    #elif __arm__
        // For ARM, BSP enables caches by default.
    #endif
    }
    
    void
    disable_caches()
    {
        Xil_DCacheDisable();
        Xil_ICacheDisable();
    }
    
    void
    init_platform()
    {
        enable_caches();
    
    #ifdef __arm__
        // For ARM, BSP enables caches by default. Disable them here.
        // See reason above for disabling D Cache
        Xil_DCacheDisable();
    #endif
    
        /* if we have a uart 16550, then that needs to be initialized */
    #ifdef STDOUT_IS_16550
        XUartNs550_SetBaud(STDOUT_BASEADDR, XPAR_XUARTNS550_CLOCK_HZ, 9600);
        XUartNs550_SetLineControlReg(STDOUT_BASEADDR, XUN_LCR_8_DATA_BITS);
    #endif
    }
    
    void
    cleanup_platform()
    {
        disable_caches();
    }

1.2 platform这两个函数是针对arm单片机的，对于IPcore调用DDR3意义不大。platform\_config.h为空的。

platform.h使能了两个函数，一个是init\_platform，一个是cleanup\_platform。

platform.c中定义了具体的对中cache的enable和disable的操作

推测单片机具体的cache驱动与使能等等存在于\#include "xparameters.h"和\#include "xil\_cache.h"这两个头文件中。

1.3 enable\_caches 函数使能了I-cache，

disable\_caches与cleanup\_platform函数中disable了D-cache与I-cache

init\_platform函数，首先使能I-cache,然后disable D-cache，然后运行了：

#ifdef STDOUT_IS_16550
        XUartNs550_SetBaud(STDOUT_BASEADDR, XPAR_XUARTNS550_CLOCK_HZ, 9600);
        XUartNs550_SetLineControlReg(STDOUT_BASEADDR, XUN_LCR_8_DATA_BITS);
    #endif

这段函数意义不明，大致与UART有关。

# 2 . memory\_config.h与memory\_config\_g.c #

//memory_config.h
    struct memory_range_s {
        char *name;
        char *ip;
        unsigned long base;
        unsigned long size;
    };
    
    /* generated memory ranges defined in memory_ranges_g.c */
    extern struct memory_range_s memory_ranges[];
    extern int n_memory_ranges;

// memory_config_g.c
    /* This file is automatically generated based on your hardware design. */
    #include "memory_config.h"
    
    struct memory_range_s memory_ranges[] = { { "mig_7series_0_memaddr",
    		"mig_7series_0", 0x40000000, 1073741824, }, { "ps7_ddr_0", "ps7_ddr_0",
    		0x00100000, 1072693248, },
    /* ps7_ram_0 memory will not be tested since application resides in the same memory */
    { "ps7_ram_1", "ps7_ram_1", 0xFFFF0000, 65024, }, };
    
    int n_memory_ranges = 3;

2.1 memory\_config.h中定义了memory\_range\_s的结构体，一个name字符串，一个IP字符串，base与size，分别表示：Testing memory region, Memory controller, Base address,  Size

memory\_ranges为结构体串，也是一个结构体指针。extern表明为全局变量，所有程序都能用。n\_memory\_ranges=3表示有三个这样的字符串。

2.2 memory\_config\_g.c 定义了三个具体的结构体，后两个分别表示PS的DDR与RAM，第一个是用mig控制的DDR3，这个是最重要的。我们需要将此结构体记下来。

运用Mig控制的DDR3的参数：Testing memory region, memory controller, Base address,  size分别为

{ "mig_7series_0_memaddr",
    "mig_7series_0", 
    0x40000000, 
    1073741824, }

2.3 程序前说这个程序是基于hardware design自动生成的。（我们是否需要保证用IPcore调用DDR3时重新生成？）相应的mig的IPcore的名称为mig\_7series\_0，size为1072693248个字节则刚好为1GB。表明FPGA的片上DDR3的大小为1GB

PS的DDR将近1GB，PS的RAM约63.5KB

# 3 主程序 #

//主函数
    int main()
    {
        int i;
    
        init_platform();
    
        print("--Starting Memory Test Application--\n\r");
        print("NOTE: This application runs with D-Cache disabled.");
        print("As a result, cacheline requests will not be generated\n\r");
    
        for (i = 0; i < n_memory_ranges; i++) {
            test_memory_range(&memory_ranges[i]);
        }
    
        print("--Memory Test Application Complete--\n\r");
    
        cleanup_platform();
        return 0;
    }

3.1 根据前面memory\_config定义的表示内存空间的结构体，结构体串memory\_ranges表示三个需要测试的内存空间的定义。

首先使能ARM的I-cache，不使能D-cache，然后分别测试三个内存空间，分别为Mig控制的DDR3，PS的DDR，PS的RAM，然后取消使能整个Cache

void test_memory_range(struct memory_range_s *range) {
        XStatus status;
    
        print("Testing memory region: "); print(range->name);  print("\n\r");
        print("    Memory Controller: "); print(range->ip);  print("\n\r");
        #ifdef __MICROBLAZE__
            print("         Base Address: 0x"); putnum(range->base); print("\n\r");
            print("                 Size: 0x"); putnum(range->size); print (" bytes \n\r");
        #else
            xil_printf("         Base Address: 0x%lx \n\r",range->base);
            xil_printf("                 Size: 0x%lx bytes \n\r",range->size);
        #endif
    
        status = Xil_TestMem32((u32*)range->base, 1024, 0xAAAA5555, XIL_TESTMEM_ALLMEMTESTS);
        print("          32-bit test: "); print(status == XST_SUCCESS? "PASSED!":"FAILED!"); print("\n\r");
        status = Xil_TestMem16((u16*)range->base, 2048, 0xAA55, XIL_TESTMEM_ALLMEMTESTS);
        print("          16-bit test: "); print(status == XST_SUCCESS? "PASSED!":"FAILED!"); print("\n\r");
        status = Xil_TestMem8((u8*)range->base, 4096, 0xA5, XIL_TESTMEM_ALLMEMTESTS);
        print("           8-bit test: "); print(status == XST_SUCCESS? "PASSED!":"FAILED!"); print("\n\r");
    }

3.2 test\_memory\_range

这个函数为输入的三个区域的Testing memory region, Memory controller, Base address,  Size

然后用Xil\_TestMem32，Xil\_TestMem16，Xil\_TestMem8对每一个内存空间进行检查，分别为32位测试，16位测试和8位测试。

3.3 我们发现真正对于DDR的调用还在更细的子函数中，我们需要找到xil\_testmem.h这个头文件进而找到相应的函数来调用DDR。最终发现这个函数在xil\_testmem.c中，通过SDK软件可以打开相应的函数，可以拷出来到notepad中

s32 Xil_TestMem32(u32 *Addr, u32 Words, u32 Pattern, u8 Subtest)
    {
    	u32 I;
    	u32 j;
    	u32 Val;
    	u32 FirtVal;
    	u32 WordMem32;
    	s32 Status = 0;
    
    	Xil_AssertNonvoid(Words != (u32)0);
    	Xil_AssertNonvoid(Subtest <= (u8)XIL_TESTMEM_MAXTEST);
    	Xil_AssertNonvoid(Addr != NULL);
    
    	Val = XIL_TESTMEM_INIT_VALUE;
    	FirtVal = XIL_TESTMEM_INIT_VALUE;
    
    	if((Subtest == XIL_TESTMEM_ALLMEMTESTS) || (Subtest == XIL_TESTMEM_INCREMENT)) {
    		/ * Fill the memory with incrementing
    		 * values starting from 'FirtVal'    */ 
    		for (I = 0U; I < Words; I++) {
    			*(Addr+I) = Val;
    			Val++;
    		}
    
    		/*
    		 * Restore the reference 'Val' to the
    		 * initial value
    		 */
    		Val = FirtVal;
    
    		/*
    		 * Check every word within the words
    		 * of tested memory and compare it
    		 * with the incrementing reference
    		 * Val
    		 */
    
    		for (I = 0U; I < Words; I++) {
    			WordMem32 = *(Addr+I);
    
    			if (WordMem32 != Val) {
    				Status = -1;
    				goto End_Label;
    			}
    			Val++;
    		}
    	}
    
    	if((Subtest == XIL_TESTMEM_ALLMEMTESTS) || (Subtest == XIL_TESTMEM_WALKONES)) {
    		/*
    		 * set up to cycle through all possible initial
    		 * test Patterns for walking ones test
    		 */
    
    		for (j = 0U; j < (u32)32; j++) {
    			/*
    			 * Generate an initial value for walking ones test
    			 * to test for bad data bits
    			 */
    
    			Val = (1U << j);
    
    			/*
    			 * START walking ones test
    			 * Write a one to each data bit indifferent locations
    			 */
    
    			for (I = 0U; I < (u32)32; I++) {
    				/* write memory location */
    				*(Addr+I) = Val;
    				Val = (u32) RotateLeft(Val, 32U);
    			}
    
    			/*
    			 * Restore the reference 'val' to the
    			 * initial value
    			 */
    			Val = 1U << j;
    
    			/* Read the values from each location that was
    			 * written */
    			for (I = 0U; I < (u32)32; I++) {
    				/* read memory location */
    
    				WordMem32 = *(Addr+I);
    
    				if (WordMem32 != Val) {
    					Status = -1;
    					goto End_Label;
    				}
    
    				Val = (u32)RotateLeft(Val, 32U);
    			}
    		}
    	}
    
    
    End_Label:
    	return Status;
    }

# 4.  DDR3的调用 #

xil\_memtest 函数就是用不同的方式填充内存，如果之后对填充后的内存进行对比，我们不关心这个函数是怎么工作的，我们只关心内存比如DDR3是如何被调用的。

//核心的调用语句用指针Addr实现DDR的调用
    for (I = 0U; I < Words; I++) {
        *(Addr+I) = Val;
        Val++;
    }
    
    //函数的声明语句
    extern s32 Xil_TestMem32(u32 *Addr, u32 Words, u32 Pattern, u8 Subtest);
    
    //主函数中给此函数传递参数的语句
    status = Xil_TestMem32((u32*)range->base, 1024, 0xAAAA5555, XIL_TESTMEM_ALLMEMTESTS);
    
    //相应的参数
    struct memory_range_s memory_ranges[] = { { "mig_7series_0_memaddr",
            "mig_7series_0", 0x40000000, 1073741824, }, { "ps7_ddr_0", "ps7_ddr_0",
            0x00100000, 1072693248, },
    /* ps7_ram_0 memory will not be tested since application resides in the same memory */
    { "ps7_ram_1", "ps7_ram_1", 0xFFFF0000, 65024, }, };

找到调用内存的核心是指针，根据Addr指针一个一个向前回溯，内存是DDR3的rage->base，例如这里Addr指针就是0x40000000，也是对应DDR分配的地址。

我们在vivado集成系统时设置的参数也是这样，地址0x40000000，内存大小1G。

![70 2][]

结果就是PS用MIG调用DDR3的过程中，直接运用了MIG的offset address的地址指针位置。

到此我们弄清楚了MIG调用DDR3的原理，系统搭建与相应的程序。后面，我们就要研究如何用IPcore对DDR3进行相应的调用。

[FPGA_DDR]: https://blog.csdn.net/weixin_36474809/article/details/80997945
[70]: /images/20220520/1d2122805b394c0091f1a8715838480c.png
[70 1]: /images/20220520/acea2ebf64624cf88f33989c9a8da8be.png
[https_blog.csdn.net_bytxl_article_details_50275377]: https://blog.csdn.net/bytxl/article/details/50275377
[70 2]: /images/20220520/f6fb1440829644c3b7231b751f63bf52.png