Re: MRST SPI

[Feng Tang <feng.tang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

Hi Tom,

On Thu, 10 Feb 2011 18:48:00 +0800
Tom <tom.spi.devel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> Hi All,
> 
> I have a SPI device problem on MRST CDK.
> 
> I use a GPIO as SS because my slave device expects the SS to be low
> between byte transfers.

The DW spi controller has a slave select register for that purpose, and
myself don't have experience of using an external GPIO lines for SS, so
no comment here.

> My probe function does a read as:
> 
> int read_val;
> -------
> ---
> read_val = spi_w8r8(&spi_dev,0x20);
>  if ( read_val < 0 )
> printk ( "spi_read err\n");
> else
>  printk ( "spi_read %d\n",read_val );
> ----
> --
> 
> The MRST SFI interface passes the device board info. Because, my
> device is not listed in the IA32 f/w I modified the MRST.c code
> sfi_handle_spi_dev function as:
> 
> while(dev->name[0])
> {
>                 if (dev->type == SFI_DEV_TYPE_SPI &&
>                                 !strncmp(dev->name,
> spi_info->modalias, 16)) {
>                         if (!strncmp("spi_old_device",
> spi_info->modalias, 16)){
>                                 strncpy (spi_info->modalias,
> "spi_my_dev",16);
>                                 pdata =
> dev->get_platform_data(spi_info); pr_info ( "spi_old_device modalias
> to spi_my_dev ");
>                         }
>                        else
>                        {
>                              pdata = dev->get_platform_data(spi_info);
>                        }
>                       break;
>                 }
>           dev++;
> }
> 
> i also modified the devs_id array to change the platform_data
> 
>  {"spi_old_dev", SFI_DEV_TYPE_SPI, 0, &no_platform_data}
> 
> The issue is  that for the spi_w8r8 call, i get multiple read
> (multiple * (8 clock cycles/SS toggle))on the SPI bus.
> 
> Also regarding the spi->irq, is it the responsibility of the protocol
> driver to register for this irq and handle it or does the spi
> framework or master driver take care of this ?
> 
> Any pointers would be really helpful. ( attached is the test code)

Suggest you refer the arch/platform/mrst/mrst.c about setting up
the max3110 spi device's platform and controller data, you can 
find it in Alan Cox's MID reference tree:

git://git.kernel.org/pub/scm/linux/kernel/git/alan/linux-2.6-mid-ref.git 

Thanks,
Feng

> 
> Regards,
> Tom

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