Commit 70c0923b authored by Jacob Keller's avatar Jacob Keller Committed by David S. Miller
Browse files

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: default avatarJacob 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: default avatarBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 367ab29e

drivers/pci/pci.c

+34 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/pci.h

+5 −0
Original line number Diff line number Diff line
@@ -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) { }

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