Re: [PATCH v4 1/2] PCI: dwc: Add support for vendor specific capability search

Bjorn Helgaas
2024-12-06T16:13:15Z

On Fri, Dec 06, 2024 at 01:14:55PM +0530, Shradha Todi wrote:
> Add vendor specific extended configuration space capability search API
> using struct dw_pcie pointer for DW controllers.
>
> Signed-off-by: Shradha Todi <shradha.t@samsung.com>
> ---
> drivers/pci/controller/dwc/pcie-designware.c | 16 ++++++++++++++++
> drivers/pci/controller/dwc/pcie-designware.h | 1 +
> 2 files changed, 17 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 6d6cbc8b5b2c..41230c5e4a53 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -277,6 +277,22 @@ static u16 dw_pcie_find_next_ext_capability(struct dw_pcie *pci, u16 start,
> return 0;
> }
>
> +u16 dw_pcie_find_vsec_capability(struct dw_pcie *pci, u8 vsec_cap)

To make sure that we find a VSEC ID that corresponds to the expected
vendor, I think this interface needs to be the same as
pci_find_vsec_capability(). In particular, it needs to take a "u16
vendor" and a "u16 vsec_cap".

(pci_find_vsec_capability() takes an "int cap", but I don't think
that's quite right).

> +{
> + u16 vsec = 0;
> + u32 header;
> +
> + while (vsec = dw_pcie_find_next_ext_capability(pci, vsec,
> + PCI_EXT_CAP_ID_VNDR)) {
> + header = dw_pcie_readl_dbi(pci, vsec + PCI_VNDR_HEADER);
> + if (PCI_VNDR_HEADER_ID(header) == vsec_cap)
> + return vsec;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(dw_pcie_find_vsec_capability);
> +
> u16 dw_pcie_find_ext_capability(struct dw_pcie *pci, u8 cap)
> {
> return dw_pcie_find_next_ext_capability(pci, 0, cap);
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 347ab74ac35a..98a057820bc7 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -476,6 +476,7 @@ void dw_pcie_version_detect(struct dw_pcie *pci);
>
> u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap);
> u16 dw_pcie_find_ext_capability(struct dw_pcie *pci, u8 cap);
> +u16 dw_pcie_find_vsec_capability(struct dw_pcie *pci, u8 vsec_cap);
>
> int dw_pcie_read(void __iomem *addr, int size, u32 *val);
> int dw_pcie_write(void __iomem *addr, int size, u32 val);
> --
> 2.17.1
>