Several device drivers read their Device Serial Number from the PCIe
extended config space.
Introduce a new helper function, pci_get_dsn, which will read the
eight bytes of the DSN into the provided buffer.
Signed-off-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
Cc: QLogic-Storage-Upstream@xxxxxxxxxx
Cc: Michael Chan <michael.chan@xxxxxxxxxxxx>
---
drivers/pci/pci.c | 33 +++++++++++++++++++++++++++++++++
include/linux/pci.h | 5 +++++
2 files changed, 38 insertions(+)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index d828ca835a98..12d8101724d7 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -33,6 +33,7 @@
#include <linux/pci-ats.h>
#include <asm/setup.h>
#include <asm/dma.h>
+#include <asm/unaligned.h>
#include <linux/aer.h>
#include "pci.h"
@@ -557,6 +558,38 @@ int pci_find_ext_capability(struct pci_dev *dev, int cap)
}
EXPORT_SYMBOL_GPL(pci_find_ext_capability);
+/**
+ * pci_get_dsn - Read the 8-byte Device Serial Number
+ * @dev: PCI device to query
+ * @dsn: storage for the DSN. Must be at least 8 bytes
+ *
+ * Looks up the PCI_EXT_CAP_ID_DSN and reads the 8 bytes into the dsn storage.
+ * Returns -EOPNOTSUPP if the device does not have the capability.
+ */
+int pci_get_dsn(struct pci_dev *dev, u8 dsn[])
+{
+ u32 dword;
+ int pos;
+
+
+ pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DSN);
+ if (!pos)
+ return -EOPNOTSUPP;
+
+ /*
+ * The Device Serial Number is two dwords offset 4 bytes from the
+ * capability position.
+ */
+ pos += 4;
+ pci_read_config_dword(dev, pos, &dword);
+ put_unaligned_le32(dword, &dsn[0]);
+ pci_read_config_dword(dev, pos + 4, &dword);
+ put_unaligned_le32(dword, &dsn[4]);
+
+ return 0;
+}
+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..883562323df3 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);
+int pci_get_dsn(struct pci_dev *dev, u8 dsn[]);
+
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 int pci_get_dsn(struct pci_dev *dev, u8 dsn[])
+{ return -EOPNOTSUPP; }
+
/* 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
