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PCI: Introduce pci_get_dsn 

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jacob Keller 2020-03-02 18:25:00 -08:00 committed by David S. Miller
parent 367ab29e3d
commit 70c0923b0e
2 changed files with 39 additions and 0 deletions
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34
drivers/pci/pci.c
View File

@ -580,6 +580,40 @@ 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;

5
include/linux/pci.h
View File

@ -1052,6 +1052,8 @@ 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,
@ -1707,6 +1709,9 @@ 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) { }