On Mon, Mar 02, 2020 at 06:25:00PM -0800, Jacob Keller wrote:
> Several device drivers read their Device Serial Number from the PCIe
> extended config space.
>
> Introduce a new helper function, pci_get_dsn(). This function reads the
> eight bytes of the DSN and returns them as a u64. If the capability does not
> exist for the device, the function returns 0.
>
> Signed-off-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
> Cc: Michael Chan <michael.chan@xxxxxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Looks good, thanks! Feel free to merge this via the net tree.
> ---
> drivers/pci/pci.c | 34 ++++++++++++++++++++++++++++++++++
> include/linux/pci.h | 5 +++++
> 2 files changed, 39 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index d828ca835a98..03f50e706c0d 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -557,6 +557,40 @@ int pci_find_ext_capability(struct pci_dev *dev, int cap)
> }
> EXPORT_SYMBOL_GPL(pci_find_ext_capability);
>
> +/**
> + * pci_get_dsn - Read and return the 8-byte Device Serial Number
> + * @dev: PCI device to query
> + *
> + * Looks up the PCI_EXT_CAP_ID_DSN and reads the 8 bytes of the Device Serial
> + * Number.
> + *
> + * Returns the DSN, or zero if the capability does not exist.
> + */
> +u64 pci_get_dsn(struct pci_dev *dev)
> +{
> + u32 dword;
> + u64 dsn;
> + int pos;
> +
> + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DSN);
> + if (!pos)
> + return 0;
> +
> + /*
> + * The Device Serial Number is two dwords offset 4 bytes from the
> + * capability position. The specification says that the first dword is
> + * the lower half, and the second dword is the upper half.
> + */
> + pos += 4;
> + pci_read_config_dword(dev, pos, &dword);
> + dsn = (u64)dword;
> + pci_read_config_dword(dev, pos + 4, &dword);
> + dsn |= ((u64)dword) << 32;
> +
> + return dsn;
> +}
> +EXPORT_SYMBOL_GPL(pci_get_dsn);
> +
> 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 3840a541a9de..d92cf2da1ae1 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1045,6 +1045,8 @@ 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);
>
> +u64 pci_get_dsn(struct pci_dev *dev);
> +
> struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device,
> struct pci_dev *from);
> struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
> @@ -1699,6 +1701,9 @@ static inline int pci_find_next_capability(struct pci_dev *dev, u8 post,
> static inline int pci_find_ext_capability(struct pci_dev *dev, int cap)
> { return 0; }
>
> +static inline u64 pci_get_dsn(struct pci_dev *dev)
> +{ return 0; }
> +
> /* Power management related routines */
> static inline int pci_save_state(struct pci_dev *dev) { return 0; }
> static inline void pci_restore_state(struct pci_dev *dev) { }
> --
> 2.25.0.368.g28a2d05eebfb
>
