Re: [PATCH] drivers/char/mem.c: Add /dev/ioports, supporting 16-bit and 32-bit ports

Santosh Shukla
2015-12-23T11:34:40Z

On 23 December 2015 at 03:26, Arnd Bergmann <arnd@arndb.de> wrote:
> On Tuesday 22 December 2015, Santosh Shukla wrote:
>> }
>>
>> So I care for /dev/ioport types interface who could do more than byte
>> data copy to/from user-space. I tested this patch with little
>> modification and could able to run pmd driver for arm/arm64 case.
>>
>> Like to know how to address pci_io region mapping problem for
>> arm/arm64, in-case /dev/ioports approach is not acceptable or else I
>> can spent time on restructuring the patch?
>>
>
> For the use case you describe, can't you use the vfio framework to
> access the PCI BARs?
>

I looked at file: drivers/vfio/pci/vfio_pci.c, func vfio_pci_map() and
it look to me that it only maps ioresource_mem pci region, pasting
code snap:

if (!(pci_resource_flags(pdev, index) & IORESOURCE_MEM))
return -EINVAL;
....

and I want to map ioresource_io pci region for arm platform in my
use-case. Not sure vfio maps pci_iobar region?

> After all, you are talking about regular PCI devices, not access to
> random unknown I/O port numbers.
>
Yes, pci_iobar region.

> Arnd
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/