注册设备驱动程序
注册设备驱动程序：在进行一些检查和初始化工作之后，driver_register调用bus_add_driver将一个新驱动程序添加到一个总线来。驱动程序要有名字，然后注册到通用数据结构框架。
bus_add_driver
//注册设备驱动程序 int bus_add_driver(struct device_driver *drv) { struct bus_type *bus; struct driver_private *priv; int error = 0; bus = bus_get(drv->bus); if (!bus) return -EINVAL; pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name); priv = kzalloc(sizeof(*priv), GFP_KERNEL); if (!priv) { error = -ENOMEM; goto out_put_bus; } klist_init(&priv->klist_devices, NULL, NULL); priv->driver = drv; drv->p = priv; priv->kobj.kset = bus->p->drivers_kset; error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL, "%s", drv->name); if (error) goto out_unregister; klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers); if (drv->bus->p->drivers_autoprobe) { error = driver_attach(drv); if (error) goto out_unregister; } module_add_driver(drv->owner, drv); error = driver_create_file(drv, &driver_attr_uevent); if (error) { printk(KERN_ERR "%s: uevent attr (%s) failed\n", __func__, drv->name); } error = driver_add_groups(drv, bus->drv_groups); if (error) { /* How the hell do we get out of this pickle? Give up */ printk(KERN_ERR "%s: driver_create_groups(%s) failed\n", __func__, drv->name); } if (!drv->suppress_bind_attrs) { error = add_bind_files(drv); if (error) { /* Ditto */ printk(KERN_ERR "%s: add_bind_files(%s) failed\n", __func__, drv->name); } } return 0; out_unregister: kobject_put(&priv->kobj); kfree(drv->p); drv->p = NULL; out_put_bus: bus_put(bus); return error; }
如果总线支持自动探测，调用driver_attach，该函数迭代总线上所有设备，使用驱动程序的match函数进行检测，确定是否有某些设备可使用该驱动程序管理。最后将该驱动程序添加到总线上注册的所有驱动程序的链表中(klist_add_tail)。
PCI总线
PCI是peripheral component interconnect的缩写，是英持尔公司开发的一种标准总线，它迅速在系统组件和体系结构厂商中间确立了自身的地位，成为一种非常流行的总线。其原因不在于市场策略方面的技巧，而是因为其技术水平。
PCl总线设计目标：
- 支持高传输带宽，以适合具有大数据流的多媒体应用；
- 简单且易于自动化配置外设；
- 平台独立性，即不绑定到特定的处理器类型或系统平台。
PCI系统布局
- 设备标识：系统某个PCI总线上的每个设备，都由一组3个编号标识；
- 总线编号：设备所有总线的编号，编号从0开始，PCI规范准许每个系统最多255个总线；
- 插槽编号：总线内核的一个唯一标识编号，一个总线最多能够附接32个设备
- 功能编号：用于在一个扩展卡上，实现包括多个扩展设备的设备。
PCI地址空间
有3个地址空间支持与PCI设备的通信。
- I/O空间通过32个比特描述。对用于与设备通信端口地址，提供了最大4GB空间。
- 取决于处理器类型，数据空间由32或64个比特位描述。
- 配置空间包含各个设备的类型和特征的详细信息。
内核提供几个数据结构类型来管理系统的PCI结构：
总线的表示
在内存中，每个PCI总线都通过pci_bus數据结构的一个实例表示，该结构定义如下：
pci_bus
struct pci_bus { struct list_head node; //总线链表中的节点 /* node in list of buses */ struct pci_bus *parent;//桥接器所在的父总线 /* parent bus this bridge is on */ struct list_head children; //子总线链表 /* list of child buses */ struct list_head devices;//总线上设备的链表 /* list of devices on this bus */ struct pci_dev *self; //父总线所看到的桥接器设备 /* bridge device as seen by parent */ struct list_head slots; /* list of slots on this bus */ struct resource *resource[PCI_BRIDGE_RESOURCE_NUM];//导向到该总线的地址空间 struct list_head resources; /* address space routed to this bus */ struct resource busn_res; /* bus numbers routed to this bus */ struct pci_ops *ops; //访问配置信息的各函数 /* configuration access functions */ struct msi_controller *msi; /* MSI controller */ void *sysdata; //挂钩，用于特定硬件的拓展 /* hook for sys-specific extension */ struct proc_dir_entry *procdir; /* directory entry in /proc/bus/pci */ unsigned char number; //总线号 /* bus number */ unsigned char primary;//主桥接器编号 /* number of primary bridge */ unsigned char max_bus_speed; //次桥接器编号 /* enum pci_bus_speed */ unsigned char cur_bus_speed; /* enum pci_bus_speed */ #ifdef CONFIG_PCI_DOMAINS_GENERIC int domain_nr; #endif char name[48]; unsigned short bridge_ctl; /* manage NO_ISA/FBB/et al behaviors */ pci_bus_flags_t bus_flags; /* inherited by child buses */ struct device *bridge; struct device dev; struct bin_attribute *legacy_io; /* legacy I/O for this bus */ struct bin_attribute *legacy_mem; /* legacy mem */ unsigned int is_added:1; };
设备管理
struct pci_dev是一个关键的数据结构，用于表示系统中的各个PCI设备。
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) */ 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 */ u8 dma_alias_devfn;/* devfn of DMA alias, if any */ 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_interrupt:1; 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 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 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 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 __aer_firmware_first_valid:1; unsigned int __aer_firmware_first:1; unsigned int broken_intx_masking:1; unsigned int io_window_1k:1; /* Intel P2P bridge 1K I/O windows */ unsigned int irq_managed:1; 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_PCI_MSI struct list_head msi_list; 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 */ }; struct pci_ats *ats; /* Address Translation Service */ #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 */ };
设备驱动程序
struct module; 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; struct device_driver driver; struct pci_dynids dynids; };
PCI驱动程序通过pci_register_driver注册：
#define pci_register_driver(driver) \ __pci_register_driver(driver, THIS_MODULE, KBUILD_MODNAME)
int __pci_register_driver(struct pci_driver *drv, struct module *owner, const char *mod_name) { /* initialize common driver fields */ drv->driver.name = drv->name; drv->driver.bus = &pci_bus_type; drv->driver.owner = owner; drv->driver.mod_name = mod_name; spin_lock_init(&drv->dynids.lock); INIT_LIST_HEAD(&drv->dynids.list); /* register with core */ return driver_register(&drv->driver); }
USB
USB（Universal Serial Bus,通用串行总线）开发于上世纪90年代末。它是一种外部总线，用于满足不断发展的PC的需求，并用于建立针对新类型计机的解决方案，如手持设备、PDA等。作为一种通用的外部总线，在用于连接中低数据传输速率的设备时（如鼠标、网络摄像头、键盘），USB很有优势。但带宽要求更高的设备如外部硬盘、光驱、CD刻录机也可以通过USB总线运行。USB1．1的最大传输速率限于12兆比特/秒，该标准的2．0版本最高速率提升到480兆比特/杪。
所有USB设备都划分到不同类型当中，在内核源代码中，我们可以看到这样划分，各个驱动程序源代码按照所属类型归纳到不同的目录。
USB标准定义4种不同传输模式：控制传输、块传输、中断传输及同步传输。
USB子系统有4种主要任务：
- 注册和管理现存的设备驱动程序；
- 为USB设备查找适当的驱动程序，以及初始化和配置；
- 在内核内存中表示设备树；
- 与设备通信（交换数据）
USB设备
struct usb_device { int devnum; char devpath[16]; u32 route; enum usb_device_state state; enum usb_device_speed speed; struct usb_tt *tt; int ttport; unsigned int toggle[2]; struct usb_device *parent; struct usb_bus *bus; struct usb_host_endpoint ep0; struct device dev; struct usb_device_descriptor descriptor; struct usb_host_bos *bos; struct usb_host_config *config; struct usb_host_config *actconfig; struct usb_host_endpoint *ep_in[16]; struct usb_host_endpoint *ep_out[16]; char **rawdescriptors; unsigned short bus_mA; u8 portnum; u8 level; unsigned can_submit:1; unsigned persist_enabled:1; unsigned have_langid:1; unsigned authorized:1; unsigned authenticated:1; unsigned wusb:1; unsigned lpm_capable:1; unsigned usb2_hw_lpm_capable:1; unsigned usb2_hw_lpm_besl_capable:1; unsigned usb2_hw_lpm_enabled:1; unsigned usb2_hw_lpm_allowed:1; unsigned usb3_lpm_enabled:1; int string_langid; /* static strings from the device */ char *product; char *manufacturer; char *serial; struct list_head filelist; int maxchild; u32 quirks; atomic_t urbnum; unsigned long active_duration; #ifdef CONFIG_PM unsigned long connect_time; unsigned do_remote_wakeup:1; unsigned reset_resume:1; unsigned port_is_suspended:1; #endif struct wusb_dev *wusb_dev; int slot_id; enum usb_device_removable removable; struct usb2_lpm_parameters l1_params; struct usb3_lpm_parameters u1_params; struct usb3_lpm_parameters u2_params; unsigned lpm_disable_count; };
USB驱动
struct usb_driver { const char *name; int (*probe) (struct usb_interface *intf, const struct usb_device_id *id); void (*disconnect) (struct usb_interface *intf); int (*unlocked_ioctl) (struct usb_interface *intf, unsigned int code, void *buf); int (*suspend) (struct usb_interface *intf, pm_message_t message); int (*resume) (struct usb_interface *intf); int (*reset_resume)(struct usb_interface *intf); int (*pre_reset)(struct usb_interface *intf); int (*post_reset)(struct usb_interface *intf); const struct usb_device_id *id_table; struct usb_dynids dynids; struct usbdrv_wrap drvwrap; unsigned int no_dynamic_id:1; unsigned int supports_autosuspend:1; unsigned int disable_hub_initiated_lpm:1; unsigned int soft_unbind:1; };
USB设备驱动
struct usb_device_driver { const char *name; int (*probe) (struct usb_device *udev); void (*disconnect) (struct usb_device *udev); int (*suspend) (struct usb_device *udev, pm_message_t message); int (*resume) (struct usb_device *udev, pm_message_t message); struct usbdrv_wrap drvwrap; unsigned int supports_autosuspend:1; };
