功能(capability)集

功能(capability)APIs 

int pcie_capability_read_word(struct pci_dev *dev, int pos, u16 *val);
int pcie_capability_read_dword(struct pci_dev *dev, int pos, u32 *val);
int pcie_capability_write_word(struct pci_dev *dev, int pos, u16 val);
int pcie_capability_write_dword(struct pci_dev *dev, int pos, u32 val);
int pcie_capability_clear_and_set_word(struct pci_dev *dev, int pos, u16 clear, u16 set);
int pcie_capability_clear_and_set_dword(struct pci_dev *dev, int pos, u32 clear, u32 set);

读PCIe读请求大小代码 

/**
 * pcie_get_readrq - get PCI Express read request size
 * @dev: PCI device to query
 *
 * Returns maximum memory read request in bytes or appropriate error value.
 */
int pcie_get_readrq(struct pci_dev *dev)
{
        u16 ctl;
        pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &ctl);
        return 128 << ((ctl & PCI_EXP_DEVCTL_READRQ) >> 12);
}

通过pci_bus_read_config完成功能存取 


int pci_read_config_word(const struct pci_dev *dev, int where, u16 *val)
{
        if (pci_dev_is_disconnected(dev)) {
                PCI_SET_ERROR_RESPONSE(val);
                return PCIBIOS_DEVICE_NOT_FOUND;
        }
        return pci_