用于CentOS /RedHat7.8的Pericom串口驱动程序(适当的baud_base)

Question

我需要将CentOS 8.2附带的串行驱动程序移植到CentOS 7.8，并且，如果可能的话，对它进行一些改进(除非这不是唯一的解决方案)。

硬件是一台CompactPCIe计算机，它包括：

• CPU卡+侧卡SCZ-NVM (2 x RS-232，串行控制器: Pericom半导体器件7954，子系统: Pericom半导体器件SU2 2- card ) (4 x RS-232，串行控制器: Pericom半导体器件7954，子系统: EKF Elektronik GmbH Device e224)

在CentOS 7.8中，6个串行端口中没有一个能工作；在CentOS 8.2中，所有串行端口都能正常工作*，所以我认为CentOS 7.8附带的驱动程序是不正确的。造成此问题的原因是"baud_base“参数(115200)不正确，临时解决方案是将其设置为921600 (使用set串行)。

* CentOS 7.8/8.2提供的串行口驱动程序有一个共同的缺点，不是很大的缺点：

• 检测到的串行端口是现有端口的两倍(4代替2，8代替4)。

如果有一个驱动程序来设置正确的"baud_base“并检测出正确的串口数量，那就太好了。

在内核源代码中，我可以找到负责为上面提到的硬件设置"baud_base“的部分吗？(以及负责检测串口数字的部分，但这并不重要)它最终会编译内核模块还是编译整个内核？

lspci -vvv

08:00.0 Serial controller: Pericom Semiconductor Device 7954 (prog-if 02 [16550])
    Subsystem: EKF Elektronik GmbH Device e224
    Control: I/O+ Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
    Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
    Interrupt: pin A routed to IRQ 19
    Region 0: I/O ports at a000 [size=64]
    Region 1: Memory at d1100000 (32-bit, non-prefetchable) [size=4K]
    Capabilities: [80] Power Management version 3
        Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=375mA PME(D0-,D1-,D2-,D3hot+,D3cold-)
        Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
    Capabilities: [8c] MSI: Enable- Count=1/1 Maskable- 64bit+
        Address: 0000000000000000  Data: 0000
    Capabilities: [9c] Vital Product Data
        Not readable
    Capabilities: [a4] Vendor Specific Information: Len=28 <?>
    Capabilities: [e0] Express (v1) Legacy Endpoint, MSI 00
        DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
            ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
        DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
            RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
            MaxPayload 128 bytes, MaxReadReq 128 bytes
        DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq+ AuxPwr+ TransPend-
        LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <512ns, L1 <1us
            ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp-
        LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
            ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
        LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk- DLActive- BWMgmt- ABWMgmt-
    Capabilities: [100 v1] Advanced Error Reporting
        UESta:  DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
        UEMsk:  DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
        UESvrt: DLP+ SDES- TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
        CESta:  RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr-
        CEMsk:  RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
        AERCap: First Error Pointer: 00, GenCap- CGenEn- ChkCap- ChkEn-
    Kernel driver in use: serial

09:00.0 Serial controller: Pericom Semiconductor Device 7954 (prog-if 02 [16550])
    Subsystem: Pericom Semiconductor Device 7954
    Control: I/O+ Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
    Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
    Interrupt: pin A routed to IRQ 18
    Region 0: I/O ports at 9000 [size=64]
    Region 1: Memory at d1000000 (32-bit, non-prefetchable) [size=4K]
    Capabilities: [80] Power Management version 3
        Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=375mA PME(D0-,D1-,D2-,D3hot+,D3cold-)
        Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
    Capabilities: [8c] MSI: Enable- Count=1/1 Maskable- 64bit+
        Address: 0000000000000000  Data: 0000
    Capabilities: [9c] Vital Product Data
        Not readable
    Capabilities: [a4] Vendor Specific Information: Len=28 <?>
    Capabilities: [e0] Express (v1) Legacy Endpoint, MSI 00
        DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
            ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
        DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
            RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
            MaxPayload 128 bytes, MaxReadReq 128 bytes
        DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq+ AuxPwr+ TransPend-
        LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <512ns, L1 <1us
            ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp-
        LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
            ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
        LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
    Capabilities: [100 v1] Advanced Error Reporting
        UESta:  DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
        UEMsk:  DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
        UESvrt: DLP+ SDES- TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
        CESta:  RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr-
        CEMsk:  RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
        AERCap: First Error Pointer: 00, GenCap- CGenEn- ChkCap- ChkEn-
    Kernel driver in use: serial

Answer 1

在3.10内核中，baud_table位于驱动程序/tty/tty_ioctl.c中。你会注意到它支持921600赫兹。https://elixir.bootlin.com/linux/v3.10/source/drivers/tty/tty_ioctl.c#L263

在后面的4.12内核中，添加了一个新文件tty_baudrate.c。该文件似乎是备份到CentOS 7的。