Reading and writing from/to VME device
Didier Kryn
kryn at in2p3.fr
Tue Mar 27 22:38:56 EST 2007
Sorry, I was wrong about my second point, mmap: MAP_SHARED works
fine and anyway seems more reasonable than MAP_PRIVATE. I just made
A24/D16 transfers, with a sequence similar to yours.
Good luck.
Didier
Didier Kryn a écrit :
> Hi Konstantin,
> I am new to this board, and, by chance I am just starting this week
> my first test wit the VME on this board (I have however more than 20
> years of VME experience). Your whole logic is mainly OK. My driver uses
> slightly different device names but it seems very similar and the API
> uses the same structures. I just noticed three things which bother me:
> 1) You declare outWinCfg and use later in the code outWinCfgADC. I
> guess the compiler will complain, unless I missed something. I guess
> this is not the file you actually compiled.
> 2) Why do you specify MAP_SHARED in the mmap() call ? I sort of
> understood that the philosophy of this driver was all against sharing.
> Maybe it works, but I wouldn't try it the first time.
> 3) I think it is an error to declare your data pointer as a u_char
> *. If you configure your interface for D16, you must perform D16 access.
> For example, you might do the following:
>
> unsigned short *rdPtr;
> ...
> rdPtr = (unsigned short *)mmap(...);
> for(i=0;i<0x50;i++){
> printf("# Read at VME address %x = %x\n", i*sizeof(*rdPtr),
> rdPtr[i] );
> }
>
> I like using sizeof() instead of 2 because it remains valid if you
> convert your code for D32.
> If you want to perform D8 access, you should configure your window
> accordingly. Beware that there are 2 kinds of D8 transfers, which make
> them more complicated and, for that reason mostly abandonned. IIRC, the
> VITA standard for CR/CSR defines 1byte data words at even addresses so
> as to transfer them as D16. Therefore you should transfer them as short
> and then mask the high order byte. I don't know what the high order byte
> will be in case of successfull transfer. If it is 0, then it is fine,
> because, since a bus error would set all bits to 1, you can check
> immediately the sucess of the transfer.
>
> Hope this helps.
> Didier
>
> Konstantin Boyanov a écrit :
>
>> Hi list,
>>
>> I'm using the MVME6100 board with the Motorola driver for linux v3.5
>> (kernel 2.6.15). I try to access the CSR registers of an ADC board, in
>> order to configure it as to be able to access its memory, on the VME
>> bus using one of the outbound windows defined by the driver. As I am
>> new to the whole VME stuff, I'm getting into trouble to find out when
>> I'm actually reading something on the VME, i.e. which addresses respond.
>> I'm trying the following schema (source code @ EOM):
>>
>> 1. open() and ioctl() one of the /dev/vme_m* devices, which I assume
>> is corresponding to an outbound window (at least I try to configure it
>> as one),
>> 2. then mmap() a memory area to hold the contents of the /dev/vme_m*
>> device file
>> 3. and finally doing incrementation of the pointer returned by mmap()
>> and dereferencing it in the hope that I'll read something, which in
>> most cases is 0xFF
>>
>> In fact my code is very similar to test code that comes with the
>> driver and also with a sample code I found in this thread
>> ->http://ozlabs.org/pipermail/linuxppc-dev/1999-May/001906.html
>> <http://ozlabs.org/pipermail/linuxppc-dev/1999-May/001906.html>
>> I've tried to do a read() on the opened /dev/vme_m* device but I only
>> succeed in reading 0 bytes, and when I try to read in chunks from the
>> VME bus i get errno 22 on reads like read(fd, buffer, 1024) for example.
>>
>> I don't know if my strategy is correct in the first place but that's
>> what I came up with.
>> When I try to run one of the test applications that came with the
>> driver (the "testout" one) I get an errno = 29 (Illegal seek?! ) on
>> the read() operations.
>> So my question is whether I make the right steps in reading an address
>> on the VME bus. I know I'm missing something, so I'll be glad to get
>> some directions as to how to be sure whether I'm reading something
>> from the VME bus and where I'm able to write.
>>
>> Best regards,
>> Konstantin
>> ________________________________
>>
>> #include <stdio.h>
>> #include <string.h>
>> #include <errno.h>
>> #include <sys/ioctl.h>
>> #include <unistd.h>
>> #include "vmedrv.h"
>>
>> int main(int argc, char* argv[])
>> {
>> vmeOutWindowCfg_t outWinCfg;
>> vmeOutWindowCfg_t outWinGet;
>>
>> int fdOut, status, i, j;
>> unsigned int n;
>> u_char *rdPtr, *getPtr;
>>
>> if(getMyVmeInfo()){
>> printf("getMyVmeInfo failed.\n");
>> exit (1);
>> }
>>
>> fdOut = open("/dev/vme_m0", O_RDWR);
>> perror("open");
>> if(fdOut < 0){
>> printf("Opening /dev/vme_m0 failed. Errno = %d\n", errno);
>> }
>>
>> memset(&outWinCfgADC, 0, sizeof(vmeOutWindowCfg_t));
>> perror("memset");
>>
>> outWinCfgADC.windowNbr = 0;
>> outWinCfgADC.windowEnable = 1;
>> outWinCfgADC.wrPostEnable = 0;
>> outWinCfgADC.userAccessType = VME_SUPER;
>> outWinCfgADC.dataAccessType = VME_DATA;
>> outWinCfgADC.windowSizeL = 0x200000;
>> outWinCfgADC.xferProtocol = VME_SCT;
>> outWinCfgADC.addrSpace = VME_A24;
>> outWinCfgADC.maxDataWidth = VME_D16;
>>
>> status = ioctl(fdOut, VME_IOCTL_SET_OUTBOUND, &outWinCfgADC);
>> perror("ioctl");
>> if(status < 0){
>> printf("*** ioctl set on outWinCfgADC failed. Errno = %d\n",
>> errno);
>> exit (1);
>> }
>> memset(&outWinGetADC, 0, sizeof(vmeOutWindowCfg_t));
>> outWinGetADC.windowNbr = 0;
>>
>> status = ioctl(fdOut, VME_IOCTL_GET_OUTBOUND, &outWinGetADC);
>> perror("ioctl");
>> if(status < 0){
>> printf("*** ioctl get on outWinGetADC failed. Errno = %d\n",
>> errno);
>> exit (1);
>> }
>>
>> /*
>> * Check wheather the get and set configurations are the same
>> */
>>
>> getPtr = (u_char *) mmap(0, outWinCfgADC.windowSizeL,
>> PROT_READ|PROT_WRITE, MAP_SHARED, fdOut, 0);
>> perror("mmap");
>> printf("# Start of outbound win in virtual address space of the
>> process: %p\n", getPtr);
>>
>> rdPtr = getPtr;
>>
>> for(i=0;i<0x100;i++){
>> printf("# Read at address %x = %x\n", rdPtr, *rdPtr);
>> rdPtr++;
>> }
>>
>> status = close(fdOut);
>> if(status != 0){
>> printf("*** close() failed. Errno = %d\n", errno);
>> exit (1);
>> }
>>
>> return 0;
>> }
>>
>> __________________________________
>> Part of the output:
>>
>> mmap: Illegal seek
>> # Start of outbound win in virtual address space of the process:
>> 0x30029000
>> # Read at address 30029000 = ff
>> # Read at address 30029001 = ff
>> # Read at address 30029002 = ff
>> # Read at address 30029003 = ff
>> # Read at address 30029004 = ff
>> # Read at address 30029005 = ff
>> # Read at address 30029006 = ff
>> # Read at address 30029007 = ff
>> # Read at address 30029008 = ff
>> # Read at address 30029009 = ff
>> # Read at address 3002900a = ff
>> # Read at address 3002900b = ff
>>
>> and etc.
>> ------------------------------------------------------------------------
>>
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>> Linuxppc-embedded at ozlabs.org
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>>
>
>
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