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authorJacob Keller <jacob.e.keller@intel.com>2020-03-03 05:25:00 +0300
committerDavid S. Miller <davem@davemloft.net>2020-03-06 04:36:24 +0300
commit70c0923b0ef10b1c8d8f78fb50fcaef8eaae619d (patch)
tree13fa85fb4022d726761d0e49f3c01ffc014d8d03 /drivers/pci/pci.c
parent367ab29e3d88be42504aca0af13f8ebb9451a1ed (diff)
downloadlinux-70c0923b0ef10b1c8d8f78fb50fcaef8eaae619d.tar.xz
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>
Diffstat (limited to 'drivers/pci/pci.c')
-rw-r--r--drivers/pci/pci.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index c16b0ba2a895..86821313c007 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -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;