PCI: Add pcie_flags_reg to cache PCIe capabilities register

Since PCI Express Capabilities Register is read only, cache its value
into struct pci_dev to avoid repeatedly calling pci_read_config_*().

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 5faa8310eec9..95662b2f0c3d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -258,6 +258,7 @@ struct pci_dev {
         u8              pcie_mpss:3;    /* PCI-E Max Payload Size Supported */
         u8              rom_base_reg;   /* which config register controls the ROM */
         u8              pin;            /* which interrupt pin this device uses */
+        u16             pcie_flags_reg; /* cached PCI-E Capabilities Register */
 
         struct pci_driver *driver;      /* which driver has allocated this device */
         u64             dma_mask;       /* Mask of the bits of bus address this
@@ -1650,6 +1651,15 @@ static inline bool pci_is_pcie(struct pci_dev *dev)
         return !!pci_pcie_cap(dev);
 }
 
+/**
+ * pci_pcie_type - get the PCIe device/port type
+ * @dev: PCI device
+ */
+static inline int pci_pcie_type(const struct pci_dev *dev)
+{
+        return (dev->pcie_flags_reg & PCI_EXP_FLAGS_TYPE) >> 4;
+}
+
 void pci_request_acs(void);
 bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags);
 bool pci_acs_path_enabled(struct pci_dev *start,