相关知识：《linux中pci设备》
很多网络接口卡都是PCI设备，必须与Linux PCI子系统协同工作。新的PCI设备是PCI Express设备．PCI设备都有只读的配置空间，可以通过lspci命令来读取。
#lspci -xxx可以查看PCI配置空间内容的十六进制表示
#lspci -xxxx可以查看扩展PCI配置空间内容的十六进制表示
当然linux PCI API提供了３个读取配置空间的方法,位于文件
drivers/pci/access.c中：
pci_read_config_byte, pci_read_config_word, pci_read_config_dword
还有写配置的方法
pci_write_config_byte, pci_write _config_word, pci_write _config_dword
在Linux PCI子系统中，PCI设备用pci_device_id对象表示，位于文件
include/linux/mod_devicetable.h:
struct pci_device_id {
__u32 vendor, device; /* Vendor and device ID or PCI_ANY_ID*/
__u32 subvendor, subdevice; /* Subsystem ID's or PCI_ANY_ID */
__u32 class, class_mask; /* (class,subclass,prog-if) triplet */
kernel_ulong_t driver_data; /* Data private to the driver */
};
每个pci设备驱动程序都声明了一个pci_drier对象，位于文件include/linux/pci.h
struct pci_driver {
struct list_head node;
const char *name;
const struct pci_device_id *id_table; /* must be non-NULL for probe to be called */
int (*probe) (struct pci_dev *dev, const struct pci_device_id *id); /* New device inserted */
void (*remove) (struct pci_dev *dev); /* Device removed (NULL if not a hot-plug capable driver) */
int (*suspend) (struct pci_dev *dev, pm_message_t state); /* Device suspended */
int (*suspend_late) (struct pci_dev *dev, pm_message_t state);
int (*resume_early) (struct pci_dev *dev);
int (*resume) (struct pci_dev *dev); /* Device woken up */
void (*shutdown) (struct pci_dev *dev);
int (*sriov_configure) (struct pci_dev *dev, int num_vfs); /* PF pdev */
const struct pci_error_handlers *err_handler;
const struct attribute_group **groups;
struct device_driver driver;
struct pci_dynids dynids;
};
其中name是PCI设备的名称。
id_table：支持的pci_device_id对象组
probe一个对设备进行初始化的方法
remove释放设备的方法
suspend:电源管理回调函数，支持电源管理的设备切换到低耗电状态。
resume:电源管理回调函数，支持电源管理的设备从低耗电状态唤醒。
PCI设备用结构pci_dev表示，该结构定义在文件
struct pci_dev {
struct list_head bus_list; /* node in per-bus list */
struct pci_bus *bus; /* bus this device is on */
struct pci_bus *subordinate; /* bus this device bridges to */
void *sysdata; /* hook for sys-specific extension */
struct proc_dir_entry *procent; /* device entry in /proc/bus/pci */
struct pci_slot *slot; /* Physical slot this device is in */
unsigned int devfn; /* encoded device & function index */
unsigned short vendor;
unsigned short device;
unsigned short subsystem_vendor;
unsigned short subsystem_device;
unsigned int class; /* 3 bytes: (base,sub,prog-if) */
u8 revision; /* PCI revision, low byte of class word */
u8 hdr_type; /* PCI header type (`multi' flag masked out) */
#ifdef CONFIG_PCIEAER
u16 aer_cap; /* AER capability offset */
#endif
u8 pcie_cap; /* PCIe capability offset */
u8 msi_cap; /* MSI capability offset */
u8 msix_cap; /* MSI-X capability offset */
u8 pcie_mpss:3; /* PCIe 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 PCIe Capabilities Register */
unsigned long *dma_alias_mask;/* mask of enabled devfn aliases */
struct pci_driver *driver; /* which driver has allocated this device */
u64 dma_mask; /* Mask of the bits of bus address this
device implements. Normally this is
0xffffffff. You only need to change
this if your device has broken DMA
or supports 64-bit transfers. */
struct device_dma_parameters dma_parms;
pci_power_t current_state; /* Current operating state. In ACPI-speak,
this is D0-D3, D0 being fully functional,
and D3 being off. */
u8 pm_cap; /* PM capability offset */
unsigned int pme_support:5; /* Bitmask of states from which PME#
can be generated */
unsigned int pme_poll:1; /* Poll device's PME status bit */
unsigned int d1_support:1; /* Low power state D1 is supported */
unsigned int d2_support:1; /* Low power state D2 is supported */
unsigned int no_d1d2:1; /* D1 and D2 are forbidden */
unsigned int no_d3cold:1; /* D3cold is forbidden */
unsigned int bridge_d3:1; /* Allow D3 for bridge */
unsigned int d3cold_allowed:1; /* D3cold is allowed by user */
unsigned int mmio_always_on:1; /* disallow turning off io/mem
decoding during bar sizing */
unsigned int wakeup_prepared:1;
unsigned int runtime_d3cold:1; /* whether go through runtime
D3cold, not set for devices
powered on/off by the
corresponding bridge */
unsigned int ignore_hotplug:1; /* Ignore hotplug events */
unsigned int hotplug_user_indicators:1; /* SlotCtl indicators
controlled exclusively by
user sysfs */
unsigned int d3_delay; /* D3->D0 transition time in ms */
unsigned int d3cold_delay; /* D3cold->D0 transition time in ms */
#ifdef CONFIG_PCIEASPM
struct pcie_link_state *link_state; /* ASPM link state */
#endif
pci_channel_state_t error_state; /* current connectivity state */
struct device dev; /* Generic device interface */
int cfg_size; /* Size of configuration space */
/*
* Instead of touching interrupt line and base address registers
* directly, use the values stored here. They might be different!
*/
unsigned int irq;
struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */
bool match_driver; /* Skip attaching driver */
/* These fields are used by common fixups */
unsigned int transparent:1; /* Subtractive decode PCI bridge */
unsigned int multifunction:1;/* Part of multi-function device */
/* keep track of device state */
unsigned int is_added:1;
unsigned int is_busmaster:1; /* device is busmaster */
unsigned int no_msi:1; /* device may not use msi */
unsigned int no_64bit_msi:1; /* device may only use 32-bit MSIs */
unsigned int block_cfg_access:1; /* config space access is blocked */
unsigned int broken_parity_status:1; /* Device generates false positive parity */
unsigned int irq_reroute_variant:2; /* device needs IRQ rerouting variant */
unsigned int msi_enabled:1;
unsigned int msix_enabled:1;
unsigned int ari_enabled:1; /* ARI forwarding */
unsigned int ats_enabled:1; /* Address Translation Service */
unsigned int pasid_enabled:1; /* Process Address Space ID */
unsigned int pri_enabled:1; /* Page Request Interface */
unsigned int is_managed:1;
unsigned int needs_freset:1; /* Dev requires fundamental reset */
unsigned int state_saved:1;
unsigned int is_physfn:1;
unsigned int is_virtfn:1;
unsigned int reset_fn:1;
unsigned int is_hotplug_bridge:1;
unsigned int is_thunderbolt:1; /* Thunderbolt controller */
unsigned int __aer_firmware_first_valid:1;
unsigned int __aer_firmware_first:1;
unsigned int broken_intx_masking:1; /* INTx masking can't be used */
unsigned int io_window_1k:1; /* Intel P2P bridge 1K I/O windows */
unsigned int irq_managed:1;
unsigned int has_secondary_link:1;
unsigned int non_compliant_bars:1; /* broken BARs; ignore them */
unsigned int is_probed:1; /* device probing in progress */
pci_dev_flags_t dev_flags;
atomic_t enable_cnt; /* pci_enable_device has been called */
u32 saved_config_space[16]; /* config space saved at suspend time */
struct hlist_head saved_cap_space;
struct bin_attribute *rom_attr; /* attribute descriptor for sysfs ROM entry */
int rom_attr_enabled; /* has display of the rom attribute been enabled? */
struct bin_attribute *res_attr[DEVICE_COUNT_RESOURCE]; /* sysfs file for resources */
struct bin_attribute *res_attr_wc[DEVICE_COUNT_RESOURCE]; /* sysfs file for WC mapping of resources */
#ifdef CONFIG_PCIE_PTM
unsigned int ptm_root:1;
unsigned int ptm_enabled:1;
u8 ptm_granularity;
#endif
#ifdef CONFIG_PCI_MSI
const struct attribute_group **msi_irq_groups;
#endif
struct pci_vpd *vpd;
#ifdef CONFIG_PCI_ATS
union {
struct pci_sriov *sriov; /* SR-IOV capability related */
struct pci_dev *physfn; /* the PF this VF is associated with */
};
u16 ats_cap; /* ATS Capability offset */
u8 ats_stu; /* ATS Smallest Translation Unit */
atomic_t ats_ref_cnt; /* number of VFs with ATS enabled */
#endif
#ifdef CONFIG_PCI_PRI
u32 pri_reqs_alloc; /* Number of PRI requests allocated */
#endif
#ifdef CONFIG_PCI_PASID
u16 pasid_features;
#endif
phys_addr_t rom; /* Physical address of ROM if it's not from the BAR */
size_t romlen; /* Length of ROM if it's not from the BAR */
char *driver_override; /* Driver name to force a match */
unsigned long priv_flags; /* Private flags for the pci driver */
};
其中driver是分配该设备的驱动程序。
current_state表示当前运行状态。
cfg_size是配置空间的大小。
1. 注册设备
如果要向PCI子系统注册PCI网络设备，需要如下操作：
定义一个pci_driver对象，并调用pci_register_driver宏。
在PCI设备使用前要进行初始化，这个工作由驱动程序调用pci_enable_device()来操作，会分配必要的I/O资源和内存资源。同时还要通过request_irq来指定IRQ处理程序（在设备关闭时要调用free_irq来释放）。
2. 设备特性
为支持局域网唤醒(Wake-On-LAN)功能，设备驱动程序必须在操作函数集中定义一个set_wol()函数。
查看设备是否支持局域网唤醒功能，可以通过ethtool命令来进行查看，