ARM扩展问题

Question

我想用ARM的外部总线RDATA[15:0]和RADDR[25:0]扩展FPGA，在有操作系统的情况下，应该如何操作呢？是否还要写一个针对FPGA的驱动？我看了芯片手册，ARM共有6个SROM扩展区域，片选为nRCS[5:0]，这些区域正处于WinCE的低2GB的用户区，若用这些区域中的一个扩展FPGA，在有操作系统情况下，这个区域是否会与操作系统的进程空间相冲突？应如何处理？
望各位大哥指教。

Answer 1

呵呵，这个问题好“硬”。

您在处理器手册上看到的低2GB其实是物理内存，跟WinCE的低2GB没关系。Win CE的低2GB是虚拟内存。

具体这2GB映射到哪里去了，要看oemaddresstable中内存的虚实映射关系。

Answer 2

我用的是S3C2440,写成流式驱动程序,把物理内存0X10000000映射虚拟内存为0XA4000080,编译后下载驱动到平台，读数据不准确,没法写数据,但我用裸机测试过(ADS1.2软件),FPGA的接口是OK的,只是没有用映射虚拟内存的方法,相关的程序如下,请各位老师帮帮忙忙除一下错,

#define PC104bus2  (*(volatile unsigned *)0x10000082)
#define PC104bus4  (*(volatile unsigned *)0x10000084)
#define PC104bus6  (*(volatile unsigned *)0x10000086)
#define PC104bus8  (*(volatile unsigned *)0x10000088)
#define PC104_BASE      0xA4000080 

typedef struct {
    unsigned int PC104bus2;
    unsigned int PC104bus4;
    unsigned int PC104bus6;
    unsigned int PC104bus8;
}PC104reg;

volatile PC104reg   *s2440PC104 = (PC104reg *)PC104_BASE;

 // PC104bus Virtual alloc    
s2440PC104 = (volatile PC104reg *) VirtualAlloc(0,sizeof(PC104reg),MEM_RESERVE, PAGE_NOACCESS);
 if(s2440PC104 == NULL)
 {
     RETAILMSG(1,(TEXT("For s2440PC104: VirtualAlloc faiLED!\r\n")));
  }
  if(!VirtualCopy((PVOID)s2440PC104,(PVOID)(PC104_BASE),sizeof(PC104reg),PAGE_READWRITE | PAGE_NOCACHE ))
 {
   RETAILMSG(1,(TEXT("For s2440PC104: VirtualCopy faiLED!\r\n")));
 }
 
 s2440MEM->rBWSCON = (s2440MEM->rBWSCON & ~(0xf<<8))|(0x1<<8);
 s2440MEM->rBANKCON2 = 0x54a0;

DWORD LED_Write(DWORD hOpenContext,LPVOID pSourceBytes,DWORD NumberOfBytes)
{ unsigned int *pReadBuffer;
    pReadBuffer = (unsigned int *)MapPtrToProcess((LPVOID)pSourceBytes,GetCallerProcess());
 if(NumberOfBytes == 2)
    {
      s2440PC104->PC104bus2 = *pReadBuffer;
    }
}

DWORD LED_Read(DWORD hOpenContext,LPVOID pBuffer, DWORD Count)
{ unsigned int *pReadBuffer;
    unsigned int adcvalue;
    pReadBuffer = (unsigned int *)MapPtrToProcess(pBuffer,GetCallerProcess());
    *pReadBuffer = s2440PC104->PC104bus8;
}

谢谢了!