Re: [PATCH 01/14] cxl/mem: Introduce a driver for CXL-2.0-Type-3 endpoints

Christoph Hellwig
2021-02-02T18:03:36Z

> +static int cxl_mem_dvsec(struct pci_dev *pdev, int dvsec)
> +{
> + int pos;
> +
> + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DVSEC);
> + if (!pos)
> + return 0;
> +
> + while (pos) {
> + u16 vendor, id;
> +
> + pci_read_config_word(pdev, pos + PCI_DVSEC_VENDOR_ID_OFFSET,
> + &vendor);
> + pci_read_config_word(pdev, pos + PCI_DVSEC_ID_OFFSET, &id);
> + if (vendor == PCI_DVSEC_VENDOR_ID_CXL && dvsec == id)
> + return pos;
> +
> + pos = pci_find_next_ext_capability(pdev, pos,
> + PCI_EXT_CAP_ID_DVSEC);
> + }
> +
> + return 0;
> +}

There should be a patch with a generic version of this find a vendor
specific capability helper on linux-pci.

> +#define PCI_CLASS_MEMORY_CXL 0x050210

I think this should go into linux/pci_ids.h.