Re: [v3 PATCH 1/2] PCI: read fixed bus numbers in EA for type 1 functions

[sundeep subbaraya]

Hi Bjorn,

Any comments?

Thanks,
Sundeep

On Wed, Jan 23, 2019 at 6:48 PM <sundeep.lkml@xxxxxxxxx> wrote:
>
> From: Subbaraya Sundeep <sbhatta@xxxxxxxxxxx>
>
> As per the spec - ECN_Enhanced_Allocation_23_Oct_2014_Final
> and section 6.9.1.2, EA capability contains fixed secondary
> and subordinate bus numbers for type 1 functions.
> This patch adds support to read the fixed bus numbers
> from EA capability for bridge.
>
> Signed-off-by: Subbaraya Sundeep <sbhatta@xxxxxxxxxxx>
> ---
> v3:
>   As per Bjorn's suggestion placed EA stuff in pci_ea_init and
>   captured bus numbers in pci_dev
> v2:
>   None just added Sean
>
>  drivers/pci/pci.c             | 10 ++++++++--
>  include/linux/pci.h           |  4 ++++
>  include/uapi/linux/pci_regs.h |  4 ++++
>  3 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index c25acac..484b63e 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2909,6 +2909,7 @@ void pci_ea_init(struct pci_dev *dev)
>         u8 num_ent;
>         int offset;
>         int i;
> +       u32 dw;
>
>         /* find PCI EA capability in list */
>         ea = pci_find_capability(dev, PCI_CAP_ID_EA);
> @@ -2922,9 +2923,14 @@ void pci_ea_init(struct pci_dev *dev)
>
>         offset = ea + PCI_EA_FIRST_ENT;
>
> -       /* Skip DWORD 2 for type 1 functions */
> -       if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
> +       /* Note fixed bus numbers for type 1 functions */
> +       if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> +               pci_read_config_dword(dev, offset, &dw);
> +               dev->fixed_sec_busnr = dw & PCI_EA_FIXED_SEC_BUS;
> +               dev->fixed_sub_busnr = (dw & PCI_EA_FIXED_SUB_BUS) >>
> +                                       PCI_EA_FIXED_SUB_SHIFT;
>                 offset += 4;
> +       }
>
>         /* parse each EA entry */
>         for (i = 0; i < num_ent; ++i)
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 65f1d8c..3e9a3ae 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -459,6 +459,10 @@ struct pci_dev {
>         char            *driver_override; /* Driver name to force a match */
>
>         unsigned long   priv_flags;     /* Private flags for the PCI driver */
> +
> +       /* bus numbers from EA capability if this device is a bridge */
> +       u8 fixed_sec_busnr; /* Fixed Secondary Bus number */
> +       u8 fixed_sub_busnr; /* Fixed Subordinate Bus number */
>  };
>
>  static inline struct pci_dev *pci_physfn(struct pci_dev *dev)
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index e1e9888..51e9ac0 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -372,6 +372,10 @@
>  #define PCI_EA_FIRST_ENT_BRIDGE        8       /* First EA Entry for Bridges */
>  #define  PCI_EA_ES             0x00000007 /* Entry Size */
>  #define  PCI_EA_BEI            0x000000f0 /* BAR Equivalent Indicator */
> +/* Fixed Secondary and Subordinate bus numbers in EA for Bridge */
> +#define   PCI_EA_FIXED_SEC_BUS         0xff
> +#define   PCI_EA_FIXED_SUB_BUS         0xff00
> +#define   PCI_EA_FIXED_SUB_SHIFT       8
>  /* 0-5 map to BARs 0-5 respectively */
>  #define   PCI_EA_BEI_BAR0              0
>  #define   PCI_EA_BEI_BAR5              5
> --
> 1.8.3.1
>