Re: [PATCH v4 2/3] misc: tc9564: introduce base PCI driver

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc Andrea, Herve, Lizhi for of_pci_make_dev_node() quirks]

On Fri, Sep 18, 2026 at 10:26:57AM -0500, Alex Elder wrote:
> The Toshiba TC9564 is small and highly-specialized SoC that implements
> a PCIe switch as well as an Ethernet AVB/TSN bridge.  In addition to
> these, the SoC implements other functions, including a reset and clock
> controller, an address translation unit, and a few other devices.  PCIe
> BARs provide access to registers that manage these IP blocks, and the
> SoC is modeled using a PCI endpoint bus in devicetree.  This allows the
> IP blocks to be bound to platform drivers that do MMIO via the PCI BARs.
> 
> Create a new PCI driver under drivers/misc that binds with the embedded
> PCI endpoint functions within the TC9564 SoC.  Because these functions
> will use devicetree pci-ep-bus to provide access to other IP blocks
> within the TC9564 chip, the main purpose of this driver is to do basic
> PCI initialization, then call of_platform_default_populate() to scan for
> the any endpoint bus children, and probe all devices defined therein.
> 
> Because we're using pci-ep-bus, we need to use the PCI quirks mechanism
> to have of_pci_make_dev_node() be called for each endpoint device in
> pci_bus_add_device() (via pci_fixup_device(pci_fixup_final, dev)).
> 
> Co-developed-by: Daniel Thompson <daniel@riscstar.com>
> Signed-off-by: Daniel Thompson <daniel@riscstar.com>
> Signed-off-by: Alex Elder <elder@riscstar.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>	# quirks.c

Not an issue for this patch, but I'm not sure the quirk mechanism is
the best mechanism for doing this.  It's not working around a device
defect like most quirks do.

I wonder if pci_bus_add_device() should unconditionally call a wrapper 
that calls of_pci_make_dev_node() for bridges and any device that
appears in an allow-list.  I guess it sort of amounts to the same
thing in the end, but it might be a little more explicit and not
subject to CONFIG_PCI_QUIRKS.

> +++ b/drivers/pci/quirks.c
> @@ -6391,6 +6391,7 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_XILINX, 0x5020, of_pci_make_dev_node);
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_XILINX, 0x5021, of_pci_make_dev_node);
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_REDHAT, 0x0005, of_pci_make_dev_node);
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_EFAR, 0x9660, of_pci_make_dev_node);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_TOSHIBA, 0x0220, of_pci_make_dev_node);
>  
>  /*
>   * Devices known to require a longer delay before first config space access
> -- 
> 2.53.0
>