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• <巨人的肩膀> ehci知识分享

数据结构

qemu中结构体大致上和 kernel中的结构体是有一个对应的
PCIDevice == ehci_hcd
EHCIState::caps == ehci_hcd::ehci_caps
EHCIState::mem_caps 响应 guest对ehci_hcd::ehci_caps的读写处理
EHCIState::opreg == ehci_hcd::ehci_regs
EHCIState::mem_opreg响应 guest对ehci_hcd::ehci_regs的读写处理

classDiagram
    class PCIDevice{
        pci_irq_handler()/*处理PCI设备的中断*/;
    }
    class PCIBus{
        set_irq()*
    }
    Object --|> EHCIPCIState
    Object --|> DeviceState
    EHCIPCIState *-- EHCIState
    EHCIPCIState *-- PCIDevice

classDiagram
    class EHCIState{
        qemu_irq irq
        uint16_t capsbase
        uint16_t opregbase
        uint16_t portscbase
        uint8_t caps[CAPA_SIZE]
        uint32_t opreg[44]
        usb_ehci_pci_init()/*修改opregbase*/
    }
    EHCIState : USBPacket ipacket
    EHCIState : asynclistaddr
    EHCIState : usb_ehci_init()
    EHCIState : usb_ehci_finalize()
    EHCIState : usb_ehci_realize()
    EHCIState : usb_ehci_unrealize()
    EHCIState : ehci_advance_periodic_state()
    EHCIState : ehci_advance_async_state()
    EHCIState : ehci_advance_state()
    EHCIState : get_dwords()
    EHCIState : ehci_state_fetchentry() 
    EHCIState <|-- DeviceState
    EHCIState *-- mem_caps
    EHCIState *-- mem_opreg
    EHCIState *-- mem_ports
    EHCIState *-- mem
    EHCIState *-- caps
    EHCIState *-- opreg
    EHCIState *-- ports

    class MemoryRegion {
        write()*
        read()*
        memory_region_init_io()
    }
    MemoryRegion --|> mem_caps
    MemoryRegion --|> mem_opreg
    MemoryRegion --|> mem_ports
    MemoryRegion --|> mem

    class mem_caps{
        read()=ehci_caps_read()
        write()=ehci_caps_write()  
    }
    mem_caps -- caps

    class mem_opreg{
        read()=ehci_opreg_read()
        write()=ehci_opreg_write()
    }
    mem_opreg -- opreg

    class mem_ports{
        read()=ehci_ports_read()
        write()=ehci_ports_write()
    }
    mem_ports -- ports

classDiagram
    vmstateehci <|.. VMStateDescription
    VMStateDescription *-- fields
    fields <|.. VMStateField

    class SysBusEHCIClass
    SysBusEHCIClass : +uint64 capsbase
    SysBusEHCIClass : +uint64 opregbase
    SysBusEHCIClass : +uint64 portscbase

状态跳转

stateDiagram
    EST_INACTIVE --> EST_ACTIVE: if USBCMD_RUNSTOP
    EST_ACTIVE --> EST_WAITLISTHEAD
    EST_WAITLISTHEAD --> EST_FETCHENTRY
    EST_FETCHENTRY --> EST_FETCHQH: if NLPTR_TYPE_QH
    EST_FETCHENTRY --> EST_FETCHITD: if NLPTR_TYPE_ITD
    EST_FETCHENTRY --> EST_FETCHSITD: if NLPTR_TYPE_STITD

寄存器命令

EHCIState::opreg::usbcmd

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// file hw/usb/ehci-regs.h
#define USBCMD           0x0000
#define USBCMD_RUNSTOP   (1 << 0)      //0x1 run / Stop
#define USBCMD_HCRESET   (1 << 1)      //0x2 HC Reset
#define USBCMD_FLS       (3 << 2)      //0xc Frame List Size
#define USBCMD_FLS_SH    2             // Frame List Size Shift
#define USBCMD_PSE       (1 << 4)      //0x10 Periodic Schedule Enable
#define USBCMD_ASE       (1 << 5)      //0x20 Asynch Schedule Enable
#define USBCMD_IAAD      (1 << 6)      //0x40 Int Asynch Advance Doorbell
#define USBCMD_LHCR      (1 << 7)      //0x80 Light Host Controller Reset
#define USBCMD_ASPMC     (3 << 8)      //0x300 Async Sched Park Mode Count
#define USBCMD_ASPME     (1 << 11)     //0x800 Async Sched Park Mode Enable
#define USBCMD_ITC       (0x7f << 16)  //0x7f0000 Int Threshold Control
#define USBCMD_ITC_SH    16            // Int Threshold Control Shift

• 寄存器 对应kernel中 ehci_hcd::regs::command字段
• 在 EHCIState::mem_caps::read(即ehci_opreg_write) 函数中被处理

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static const MemoryRegionOps ehci_mmio_caps_ops = {
    .read = ehci_caps_read,
    .write = ehci_caps_write,
    .valid.min_access_size = 1,
    .valid.max_access_size = 4,
    .impl.min_access_size = 1,
    .impl.max_access_size = 1,
    .endianness = DEVICE_LITTLE_ENDIAN,
};