Re: [PATCH 1/4] PCI: Add #defines for accessing PCIE DVSEC fields

[Bjorn Helgaas]

[+cc Dan, Jonathan]

On Thu, Jun 17, 2021 at 02:54:05PM -0700, David E. Box wrote:
> Add #defines for accessing Vendor ID, Revision, Length, and ID offsets
> in the Designated Vendor Specific Extended Capability (DVSEC). Defined
> in PCIe r5.0, sec 7.9.6.
> 
> Signed-off-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx>

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

I don't have time right now to really look at the
intel_extended_caps.c patch [1], but I wonder if there's anything
there that could be abstracted and shared with CXL, etc?  If not, no
worries.

[1] https://lore.kernel.org/r/20210617215408.1412409-5-david.e.box@xxxxxxxxxxxxxxx

> ---
>  include/uapi/linux/pci_regs.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index e709ae8235e7..57ee51f19283 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -1080,7 +1080,11 @@
>  
>  /* Designated Vendor-Specific (DVSEC, PCI_EXT_CAP_ID_DVSEC) */
>  #define PCI_DVSEC_HEADER1		0x4 /* Designated Vendor-Specific Header1 */
> +#define  PCI_DVSEC_HEADER1_VID(x)	((x) & 0xffff)
> +#define  PCI_DVSEC_HEADER1_REV(x)	(((x) >> 16) & 0xf)
> +#define  PCI_DVSEC_HEADER1_LEN(x)	(((x) >> 20) & 0xfff)
>  #define PCI_DVSEC_HEADER2		0x8 /* Designated Vendor-Specific Header2 */
> +#define  PCI_DVSEC_HEADER2_ID(x)		((x) & 0xffff)
>  
>  /* Data Link Feature */
>  #define PCI_DLF_CAP		0x04	/* Capabilities Register */
> -- 
> 2.25.1
>