bram example阅读：xbram_example.c

Posted 2021-01-22 iwanna

/**
 * 这个example比较简单，主要是用config初始化真设备，然后用虚址写bram
* @file xbram_example.c
* 用XBram测
* This file contains a self test example using the BRAM driver (XBram).
*
*
* <pre>
* MODIFICATION HISTORY:
*
* Ver   Who  Date     Changes
* ----- ---- -------- -------------------------------------------------------
* 1.00a sa   05/11/10 Initial release.
* 3.01a sa   13/01/12 Changed XBram_SelfTest(InstancePtr) to
*              XBram_SelfTest(InstancePtr,0) as per
*             new API (CR 639274)
* 4.1   ms   01/23/17 Modified xil_printf statement in main function to
*                     ensure that "Successfully ran" and "Failed" strings are
*                     available in all examples. This is a fix for CR-965028.
*</pre>
*
******************************************************************************/

/***************************** Include Files *********************************/

#include "xparameters.h"
#include "xbram.h"
#include <stdio.h>

/************************** Constant Definitions *****************************/

/*xpar是xparameters.h（这个文件是特异的吗？怎么找自己的硬件地址？）里的
 *用来定义bram的id
 * The following constants map to the XPAR parameters created in the
 * xparameters.h file. They are defined here such that a user can easily
 * change all the needed parameters in one place.
 */
#define BRAM_DEVICE_ID        XPAR_BRAM_0_DEVICE_ID//这个是ctr的地址


/************************** Function Prototypes ******************************/

int BramExample(u16 DeviceId);
static void InitializeECC(XBram_Config *ConfigPtr, u32 EffectiveAddr);


/************************** Variable Definitions *****************************/

/*
 * The following are declared globally so they are zeroed and so they are
 * easily accessible from a debugger
 */
//BRAM驱动实例，之后赋值
XBram Bram;    /* The Instance of the BRAM Driver */


/****************************************************************************/
/**
*
* This function is the main function of the BRAM example.
*
* @param    None.
*
* @return
*        - XST_SUCCESS to indicate success.
*        - XST_FAILURE to indicate failure.
*
* @note        None.
*
*****************************************************************************/
#ifndef TESTAPP_GEN
int main(void)
{
    int Status;

    Status = BramExample(BRAM_DEVICE_ID);//BRAM_DEVICE_ID就是之前那个宏定义，
    //应该传自己的ctr的设备号，去哪里找？？
    if (Status != XST_SUCCESS ) {
        xil_printf("Bram Example Failed
");
        return XST_FAILURE;
    }

    xil_printf("Successfully ran Bram Example
");
    return XST_SUCCESS;
}
#endif

/*****************************************************************************/
/**
*入口点
* This is the entry point for the BRAM example.
*
* @param    DeviceId is the XPAR_<BRAM_instance>_DEVICE_ID value from
*        xparameters.h
*
* @return
*        - XST_SUCCESS to indicate success.
*        - XST_FAILURE to indicate failure.
*
* @note        None.
*
******************************************************************************/
int BramExample(u16 DeviceId)
{
    int Status;
    XBram_Config *ConfigPtr;//bram设置

    /*初始化BRAM驱动
     * Initialize the BRAM driver. If an error occurs then exit
     */

    /*给设备设置数据（pl设的一堆参数什么的）赋值（基本操作，直接抄就行
     * Lookup configuration data in the device configuration table.
     * Use this configuration info down below when initializing this
     * driver.
     */
    //先找出来，把指针给过去（相当于结构，给个首地址后面的数据就都知道了
    ConfigPtr = XBram_LookupConfig(DeviceId);
    if (ConfigPtr == (XBram_Config *) NULL) {
        return XST_FAILURE;
    }
    //把cfg连上？用cfg数据，给Bram驱动实例赋值，初始化？
    Status = XBram_CfgInitialize(&Bram, ConfigPtr,
                     ConfigPtr->CtrlBaseAddress);
    if (Status != XST_SUCCESS) {
        return XST_FAILURE;
    }

        //这个是自定义函数，ecc是加密方式（错误检查和纠正
        InitializeECC(ConfigPtr, ConfigPtr->CtrlBaseAddress);


    /*用自带的seltest，干什么的？查ecc
     * Execute the BRAM driver selftest.
     */
    Status = XBram_SelfTest(&Bram, 0);
    if (Status != XST_SUCCESS) {
        return XST_FAILURE;
    }

    return XST_SUCCESS;
}


/****************************************************************************/
/**
*
* This function ensures that ECC in the BRAM is initialized if no hardware
* initialization is available. The ECC bits are initialized by reading and
* writing data in the memory. This code is not optimized to only read data
* in initialized sections of the BRAM.
*
* 这里讲函数的两个参数：
*证实了猜测，configPtr就是数据结构体，就用来从pl传过来数据，用来初始化设备
* @param    ConfigPtr is a reference to a structure containing information
*        about a specific BRAM device.
*
*实际的虚拟地址，注意是虚存的地址，
*base和ctl的id号不是一回事，ctl的地址是方便给参数的，不是真正的存东西的地址
*需要复习一下OS
* @param     EffectiveAddr is the device base address in the virtual memory
*        address space.
*
* @return
*        None
*
* @note        None.
*
*****************************************************************************/
void InitializeECC(XBram_Config *ConfigPtr, u32 EffectiveAddr)
{
    u32 Addr;
    volatile u32 Data;

    if (ConfigPtr->EccPresent &&
        ConfigPtr->EccOnOffRegister &&
        ConfigPtr->EccOnOffResetValue == 0 &&
        ConfigPtr->WriteAccess != 0) {
        for (Addr = ConfigPtr->MemBaseAddress;
             Addr < ConfigPtr->MemHighAddress; Addr+=4) {
            Data = XBram_In32(Addr);
            XBram_Out32(Addr, Data);
        }
        //写bram函数，基地址（虚址，偏移，数据
        XBram_WriteReg(EffectiveAddr, XBRAM_ECC_ON_OFF_OFFSET, 1);
    }
}