PCI: Add accessors for PCI Express Capability
The PCI Express Capability (PCIe spec r3.0, sec 7.8) comes in two
versions, v1 and v2. In v1 Capability structures (PCIe spec r1.0 and
r1.1), some fields are optional, so the structure size depends on the
device type.
This patch adds functions to access this capability so drivers don't
have to be aware of the differences between v1 and v2. Note that these
new functions apply only to the "PCI Express Capability," not to any of
the other "PCI Express Extended Capabilities" (AER, VC, ACS, MFVC, etc.)
Function pcie_capability_read_word/dword() reads the PCIe Capabilities
register and returns the value in the reference parameter "val". If
the PCIe Capabilities register is not implemented on the PCIe device,
"val" is set to 0.
Function pcie_capability_write_word/dword() writes the value to the
specified PCIe Capability register.
Function pcie_capability_clear_and_set_word/dword() sets and/or clears bits
of a PCIe Capability register.
[bhelgaas: changelog, drop "pci_" prefixes, don't export
pcie_capability_reg_implemented()]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/include/linux/pci_regs.h b/include/linux/pci_regs.h
index 7fb75b1..3958f70 100644
--- a/include/linux/pci_regs.h
+++ b/include/linux/pci_regs.h
@@ -549,6 +549,7 @@
#define PCI_EXP_LNKCAP2_SLS_8_0GB 0x04 /* Current Link Speed 8.0GT/s */
#define PCI_EXP_LNKCAP2_CROSSLINK 0x100 /* Crosslink supported */
#define PCI_EXP_LNKCTL2 48 /* Link Control 2 */
+#define PCI_EXP_LNKSTA2 50 /* Link Status 2 */
#define PCI_EXP_SLTCTL2 56 /* Slot Control 2 */
/* Extended Capabilities (PCI-X 2.0 and Express) */