Re: [PATCH V4 06/16] PCI: dwc: Add ext config space capability search API

Bjorn Helgaas
2019-04-23T20:35:15Z

On Tue, Apr 23, 2019 at 01:57:20PM +0530, Vidya Sagar wrote:
> Add extended configuration space capability search API using struct dw_pcie *
> pointer
>
> Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
> Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
> ---
> Changes from [v3]:
> * None
>
> Changes from [v2]:
> * None
>
> Changes from [v1]:
> * This is a new patch in v2 series
>
> drivers/pci/controller/dwc/pcie-designware.c | 41 ++++++++++++++++++++
> drivers/pci/controller/dwc/pcie-designware.h | 1 +
> 2 files changed, 42 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 6a98135244d6..ecf5fe8842f6 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -53,6 +53,47 @@ u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap)
> return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap);
> }
>

Please make sure there's a comment here about why
pci_find_ext_capability() can't be used (a comment covering both this
and pci_find_capability() is fine, if the reason is the same).

> +static int dw_pcie_find_next_ext_capability(struct dw_pcie *pci, int start,
> + int cap)
> +{
> + u32 header;
> + int ttl;
> + int pos = PCI_CFG_SPACE_SIZE;
> +
> + /* minimum 8 bytes per capability */
> + ttl = (PCI_CFG_SPACE_EXP_SIZE - PCI_CFG_SPACE_SIZE) / 8;
> +
> + if (start)
> + pos = start;
> +
> + header = dw_pcie_readl_dbi(pci, pos);
> + /*
> + * If we have no capabilities, this is indicated by cap ID,
> + * cap version and next pointer all being 0.
> + */
> + if (header == 0)
> + return 0;
> +
> + while (ttl-- > 0) {
> + if (PCI_EXT_CAP_ID(header) == cap && pos != start)
> + return pos;
> +
> + pos = PCI_EXT_CAP_NEXT(header);
> + if (pos < PCI_CFG_SPACE_SIZE)
> + break;
> +
> + header = dw_pcie_readl_dbi(pci, pos);
> + }
> +
> + return 0;
> +}
> +
> +int dw_pcie_find_ext_capability(struct dw_pcie *pci, int cap)
> +{
> + return dw_pcie_find_next_ext_capability(pci, 0, cap);
> +}
> +EXPORT_SYMBOL_GPL(dw_pcie_find_ext_capability);
> +
> int dw_pcie_read(void __iomem *addr, int size, u32 *val)
> {
> if (!IS_ALIGNED((uintptr_t)addr, size)) {
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 35160b4ce929..67307842e003 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -249,6 +249,7 @@ struct dw_pcie {
> container_of((endpoint), struct dw_pcie, ep)
>
> u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap);
> +int dw_pcie_find_ext_capability(struct dw_pcie *pci, int 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
>