| Message ID | 20200303022506.1792776-2-jacob.e.keller@intel.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | PCI: Implement function to read Device Serial Number | expand |
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@intel.com> > Cc: Bjorn Helgaas <bhelgaas@google.com> > Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> > Cc: Michael Chan <michael.chan@broadcom.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> 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 >
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) { }
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@intel.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Cc: Michael Chan <michael.chan@broadcom.com> --- drivers/pci/pci.c | 34 ++++++++++++++++++++++++++++++++++ include/linux/pci.h | 5 +++++ 2 files changed, 39 insertions(+)