[ts-7000] Re: Accessing Latched Outputs TS7390

["PeterElliot" <>]

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(), 
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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