[ add Ben ]
On Mon, Feb 1, 2021 at 2:39 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>
> [+cc Vinod, Dan, dmaengine]
>
> On Tue, Dec 15, 2020 at 06:30:13PM +0100, Gustavo Pimentel wrote:
> > Add pci_find_vsec_capability() that crawls through the device config
> > space searching in all Vendor-Specific Extended Capabilities for a
> > particular capability ID.
> >
> > Vendor-Specific Extended Capability (VSEC) is a PCIe capability (acts
> > like a wrapper) specified by PCI-SIG that allows the vendor to create
> > their own and specific capability in the device config space.
> >
> > Signed-off-by: Gustavo Pimentel <gustavo.pimentel@xxxxxxxxxxxx>
>
> If you fix the below, feel free to add my
>
> Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>
> Otherwise, I can take it myself. But that will be an ordering issue
> in the merge window if you merge the rest of the series via another
> tree.
I wonder if this warrants and if you'd be willing to stand up a stable
branch for just this commit for concerned parties to integrate,
because CXL development should adopt it as well.
>
> > ---
> > drivers/pci/pci.c | 29 +++++++++++++++++++++++++++++
> > include/linux/pci.h | 1 +
> > include/uapi/linux/pci_regs.h | 5 +++++
> > 3 files changed, 35 insertions(+)
> >
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 6d4d5a2..235d0b2 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -623,6 +623,35 @@ u64 pci_get_dsn(struct pci_dev *dev)
> > }
> > EXPORT_SYMBOL_GPL(pci_get_dsn);
> >
> > +/**
> > + * pci_find_vsec_capability - Find a vendor-specific extended capability
> > + * @dev: PCI device to query
> > + * @cap: vendor-specific capability id code
>
> s/id/ID/
>
> > + *
> > + * Returns the address of the vendor-specific structure that matches the
> > + * requested capability id code within the device's PCI configuration space
>
> s/id/ID/
>
> > + * or 0 if it does not find a match.
> > + */
> > +int pci_find_vsec_capability(struct pci_dev *dev, int vsec_cap_id)
> > +{
> > + u32 header;
> > + int vsec;
>
> int vsec;
> u32 header;
>
> since that's the order they're used.
>
> > +
> > + vsec = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_VNDR);
> > + while (vsec) {
> > + if (pci_read_config_dword(dev, vsec + 0x4,
>
> s/0x4/PCI_VSEC_HDR/
>
> > + &header) == PCIBIOS_SUCCESSFUL &&
> > + PCI_VSEC_CAP_ID(header) == vsec_cap_id)
> > + break;
>
> return vsec;
>
> > +
> > + vsec = pci_find_next_ext_capability(dev, vsec,
> > + PCI_EXT_CAP_ID_VNDR);
> > + }
> > +
> > + return vsec;
>
> return 0;
>
> > +}
> > +EXPORT_SYMBOL_GPL(pci_find_vsec_capability);
> > +
> > static int __pci_find_next_ht_cap(struct pci_dev *dev, int pos, int ht_cap)
> > {
> > int rc, ttl = PCI_FIND_CAP_TTL;
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 22207a7..effecb0 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -1067,6 +1067,7 @@ int pci_find_capability(struct pci_dev *dev, int cap);
> > int pci_find_next_capability(struct pci_dev *dev, u8 pos, int cap);
> > int pci_find_ext_capability(struct pci_dev *dev, int cap);
> > int pci_find_next_ext_capability(struct pci_dev *dev, int pos, int cap);
> > +int pci_find_vsec_capability(struct pci_dev *dev, int vsec_cap_id);
> > int pci_find_ht_capability(struct pci_dev *dev, int ht_cap);
> > int pci_find_next_ht_capability(struct pci_dev *dev, int pos, int ht_cap);
> > struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
> > diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> > index a95d55f..f5d17be 100644
> > --- a/include/uapi/linux/pci_regs.h
> > +++ b/include/uapi/linux/pci_regs.h
> > @@ -730,6 +730,11 @@
> > #define PCI_EXT_CAP_DSN_SIZEOF 12
> > #define PCI_EXT_CAP_MCAST_ENDPOINT_SIZEOF 40
> >
> > +/* Vendor-Specific Extended Capabilities */
> > +#define PCI_VSEC_CAP_ID(header) (header & 0x0000ffff)
> > +#define PCI_VSEC_CAP_REV(header) ((header >> 16) & 0xf)
> > +#define PCI_VSEC_CAP_LEN(header) ((header >> 20) & 0xffc)
>
> Please put these next to the existing PCI_VSEC_HDR.
>
> Why does PCI_VSEC_CAP_LEN mask with 0xffc instead of 0xfff? I don't
> see anything in the spec about VSEC Length having to be a multiple of
> 4 (PCIe r5.0, sec 7.9.5.2).
>
> But you don't use this anyway, so I'd just drop it (and
> PCI_VSEC_CAP_REV) altogether.
>
> > /* Advanced Error Reporting */
> > #define PCI_ERR_UNCOR_STATUS 4 /* Uncorrectable Error Status */
> > #define PCI_ERR_UNC_UND 0x00000001 /* Undefined */
> > --
> > 2.7.4
> >
