Re: [ts-7000] Re: Accessing Latched Outputs TS7390

[Jim Jackson <>]

On Wed, 1 Oct 2008, PeterElliot wrote:

> Hi,
>
> When you use mmap you should always use a page aligned base address
> and then add an offset to the returned pointer.
>
> Thus:
>
> spi_ioptr = (unsigned long)mmap(0, getpagesize(),
> PROT_READ|PROT_WRITE, MAP_SHARED, spi_fd, 0x600FF084);
>
> should be:
>
> volatile unsigned long *spi_ioptr
>
> spi_ioptr = (unsigned long)mmap(0, getpagesize(),
               (unsigned long *).....



> PROT_READ|PROT_WRITE, MAP_SHARED, spi_fd, 0x600FF000);
>
> <check it's assigned correctly here>
>
> spi_ioptr += spi_ioptr (0x84/sizeof(unsigned long));
>
> You then access the data via spi_ioptr[offset];
>
> Hope this helps.
>
> PJE
>
> --- In  "jtckendrick" <> wrote:
>>
>> I am having an issue with getting access to the memory area
> specified.
>> When I try to write to that area of memory I get SIGSEGV faults.  I
> am
>> referencing the TS7350 preliminary manual. Here is a sample of the
> code.
>> spi_fd is integer type and spi_ioptr it unsigned long.  SPI_IOBASE
> is
>> defined as 0x600FF084.
>>
>> spi_fd = open("/dev/mem", O_RDWR|O_SYNC);
>>
>> spi_ioptr = (unsigned long)mmap(0, getpagesize(),
> PROT_READ|PROT_WRITE,spi_fd, SPI_IOBASE);
>>
>>
>> assert(&spi_ioptr != MAP_FAILED);
>>
>> PEEK32(spi_ioptr,1);
>>
>> SIGSEGV is thrown on PEEK32
>>
>
>
>
>

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