Re: sysbus usb xhci

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 1/2/20 10:45 AM, kraxel@redhat.com wrote:
> On Thu, Jan 02, 2020 at 07:13:25AM +0000, Sai Pavan Boddu wrote:
>> Hi Gred,
>>
>> We are seeing of options to reuse the hcd-xhci model and use it over system bus interface rather than pci. (for Xilinx ZynqMP SOC, usb emulation)
>> Are there any plans of implementing a sysbus device ? if none it would be good if provided few pointers to start.
> 
> There have been some discussions about this for a (IIRC) sbsa machine,
> but I'm not sure whenever that where just ideas or some code exists.
> 
>> Im looking at hcd-ehci/ochi as a reference, let me know if there are any know limitations for this usecase.
> 
> Yep, the path for xhci would be quite simliar:  Create a new
> XHCIPciState struct, move over all pci-specific bits from XHCIState,
> leaving the generic stuff in XHCIState for sharing with sysbus.
> Possibly move all pci-specific code bits into a new source file (for
> cleanup, will also allow to build qemu with CONFIG_PCI=n and still have
> XHCI enabled).
> 
> Once this separation is done you should be able to create a sysbus
> device, reusing the generic xhci code and adding sysbus plumbing
> (mmio, irq, ...)

The SDHCI commits b635d98cf32..8b7455c75e seem similar to what you want 
to achieve (see also commit ce8646034).