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GPIO controller driver with PMIO registers

Marshall_CaiMarshall_Cai Member Posts: 234

Hi All,

I am developing a WDF GPIO controller driver for our own ACPI GPIO. However, the ACPI document about the GPIO pins are all marked as PMIO instead of MMIO.

Our Linux team uses inb/outb to read/write the registers. I am wondering how the WDF GPIO controller driver read/write such registers.

From the sample code, the GPIO controller driver would read/write GPIO registers in the way CmResourceTypeMemory and CmResourceTypeCollection. In my case, I think CmResourceTypeCollection would be returned by calling WdfCmResourceListGetDescriptor. Do I need to call READ_PORT_*** API to read the registers?



  • Shane_CorbinShane_Corbin Member Posts: 307

    You should be able to do something like this:

       // Walk through the resource list and store each GPIO in `pDevExt->ConnectionIds`.
       resource_count = WdfCmResourceListGetCount(ResourcesTranslated);
       for (index = 0; index < resource_count; ++index)
          descriptor = WdfCmResourceListGetDescriptor(ResourcesTranslated, index);
          switch (descriptor->Type) 
             // This memory resource supplies the base of the device registers.
             case CmResourceTypeConnection:
                //  Check against expected connection type
                if ((descriptor->u.Connection.Class ==
                   (descriptor->u.Connection.Type ==
                   pDevExt->ConnectionIds[io_resource_index].LowPart =
                   pDevExt->ConnectionIds[io_resource_index].HighPart =

    Then when you want to read/write from one you'll need to find the RESOURCE_HUB request string for the GPIO by doing something like:

       // Find the RESOURCE_HUB request string for this GPIO pin

    Once you have the request string you'll have to open the IoTarget by name with WDF_IO_TARGET_OPEN_PARAMS_INIT_OPEN_BY_NAME.
    From there you can use WdfIoTargetFormatRequestForIoctl with the IOCTL_GPIO_READ_PINS/IOCTL_GPIO_WRITE_PINS ioctls do the equivalent of your Linux teams inb/outb IO.
    Once you've formated the request you can use WdfRequestSend to send it.

  • Tim_RobertsTim_Roberts Member - All Emails Posts: 14,718

    It is difficult for me to believe that any modern product is still using the x86 I/O ports. How do you even handle that on an ARM system that doesn't have the special instructions?

    Tim Roberts, [email protected]
    Providenza & Boekelheide, Inc.

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