Messages in this thread Patch in this message |  | | Date | Thu, 7 May 2026 06:42:56 +0900 | | Subject | Re: [PATCH v2 1/2] usb: xhci-pci: add generic auxiliary device interface | | From | Jihong Min <> |
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Thank you.
I've changed the code by removing the preprocessor macros and protecting the two entry points with `if (IS_ENABLED(CONFIG_USB_XHCI_PCI_AUXDEV))`, for v3.
Jihong Min
On 5/7/26 06:15, Michal Pecio wrote: > On Thu, 7 May 2026 05:40:33 +0900, Jihong Min wrote: >> Some xHCI PCI controllers expose controller-specific functionality that is >> not part of generic xHCI operation and is better handled by optional child >> drivers in other subsystems. Add a small auxiliary device registration path >> for selected xHCI PCI controllers. >> >> The initial table creates an xhci_pci.hwmon auxiliary device for AMD >> 1022:43fd controllers. Store the created auxiliary device in devres so the >> xhci-pci remove path destroys it before HCD teardown. Use a >> PCI-domain-qualified id so auxiliary device names remain unique across PCI >> domains. >> >> This keeps xhci-pci responsible only for publishing selected controller >> functions while allowing subsystem-specific drivers to bind through the >> auxiliary bus. >> >> Assisted-by: Codex:gpt-5.5 >> Signed-off-by: Jihong Min <hurryman2212@gmail.com> >> --- >> drivers/usb/host/Kconfig | 10 ++++ >> drivers/usb/host/xhci-pci.c | 114 ++++++++++++++++++++++++++++++++++++ >> 2 files changed, 124 insertions(+) >> >> diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig >> index 0a277a07cf70..e0c2c7ac5c97 100644 >> --- a/drivers/usb/host/Kconfig >> +++ b/drivers/usb/host/Kconfig >> @@ -42,6 +42,16 @@ config USB_XHCI_PCI >> depends on USB_PCI >> default y >> >> +config USB_XHCI_PCI_AUXDEV >> + bool "xHCI PCI auxiliary device support" >> + depends on USB_XHCI_PCI >> + select AUXILIARY_BUS >> + help >> + This enables xHCI PCI support for registering auxiliary devices >> + for selected controllers. It is used by optional child drivers >> + that bind to xHCI PCI controller-specific functionality through >> + the auxiliary bus. >> + >> config USB_XHCI_PCI_RENESAS >> tristate "Support for additional Renesas xHCI controller with firmware" >> depends on USB_XHCI_PCI >> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c >> index 585b2f3117b0..1ab27d2182eb 100644 >> --- a/drivers/usb/host/xhci-pci.c >> +++ b/drivers/usb/host/xhci-pci.c >> @@ -8,6 +8,8 @@ >> * Some code borrowed from the Linux EHCI driver. >> */ >> >> +#include <linux/auxiliary_bus.h> >> +#include <linux/device/devres.h> >> #include <linux/pci.h> >> #include <linux/slab.h> >> #include <linux/module.h> >> @@ -103,6 +105,114 @@ static int xhci_pci_run(struct usb_hcd *hcd); >> static int xhci_pci_update_hub_device(struct usb_hcd *hcd, struct usb_device *hdev, >> struct usb_tt *tt, gfp_t mem_flags); >> >> +#if IS_ENABLED(CONFIG_USB_XHCI_PCI_AUXDEV) >> +static const struct { >> + struct pci_device_id id; >> + const char *aux_dev_name; >> +} pci_ids_have_aux[] = { >> + { >> + .id = { PCI_DEVICE(PCI_VENDOR_ID_AMD, 0x43fd) }, /* PROM21 xHCI */ >> + .aux_dev_name = "hwmon", >> + }, >> + { /* end: all zeroes */ } >> +}; >> + >> +struct xhci_pci_aux_devres { >> + struct auxiliary_device *auxdev; >> +}; >> + >> +static bool xhci_pci_aux_match_id(const struct pci_device_id *id, >> + const struct pci_dev *pdev) >> +{ >> + if (id->vendor != PCI_ANY_ID && id->vendor != pdev->vendor) >> + return false; >> + if (id->device != PCI_ANY_ID && id->device != pdev->device) >> + return false; >> + if (id->subvendor != PCI_ANY_ID && >> + id->subvendor != pdev->subsystem_vendor) >> + return false; >> + if (id->subdevice != PCI_ANY_ID && >> + id->subdevice != pdev->subsystem_device) >> + return false; >> + >> + return !((id->class ^ pdev->class) & id->class_mask); >> +} >> + >> +static const char *xhci_pci_aux_dev_name(struct pci_dev *pdev) >> +{ >> + int i; >> + >> + for (i = 0; pci_ids_have_aux[i].aux_dev_name; i++) { >> + if (xhci_pci_aux_match_id(&pci_ids_have_aux[i].id, pdev)) >> + return pci_ids_have_aux[i].aux_dev_name; >> + } >> + >> + return NULL; >> +} >> + >> +static void xhci_pci_aux_devres_release(struct device *dev, void *res) >> +{ >> + struct xhci_pci_aux_devres *devres = res; >> + >> + if (devres->auxdev) >> + auxiliary_device_destroy(devres->auxdev); >> +} >> + >> +static void xhci_pci_try_add_aux_device(struct pci_dev *pdev) >> +{ >> + struct xhci_pci_aux_devres *devres; >> + struct auxiliary_device *auxdev; >> + const char *aux_dev_name; >> + >> + aux_dev_name = xhci_pci_aux_dev_name(pdev); >> + if (!aux_dev_name) >> + return; >> + >> + devres = devres_alloc(xhci_pci_aux_devres_release, sizeof(*devres), >> + GFP_KERNEL); >> + if (!devres) { >> + dev_warn(&pdev->dev, >> + "failed to allocate auxiliary device state\n"); >> + return; >> + } >> + >> + auxdev = auxiliary_device_create(&pdev->dev, KBUILD_MODNAME, >> + aux_dev_name, NULL, >> + (pci_domain_nr(pdev->bus) << 16) | >> + pci_dev_id(pdev)); >> + if (!auxdev) { >> + devres_free(devres); >> + dev_warn(&pdev->dev, "failed to add %s auxiliary device\n", >> + aux_dev_name); >> + return; >> + } >> + >> + devres->auxdev = auxdev; >> + devres_add(&pdev->dev, devres); >> +} >> + >> +static void xhci_pci_try_remove_aux_device(struct pci_dev *pdev) >> +{ >> + struct xhci_pci_aux_devres *devres; >> + >> + devres = devres_find(&pdev->dev, xhci_pci_aux_devres_release, NULL, >> + NULL); >> + if (!devres || !devres->auxdev) >> + return; >> + >> + auxiliary_device_destroy(devres->auxdev); >> + devres->auxdev = NULL; >> +} >> +#else >> +static inline void xhci_pci_try_add_aux_device(struct pci_dev *pdev) >> +{ >> +} >> + >> +static inline void xhci_pci_try_remove_aux_device(struct pci_dev *pdev) >> +{ >> +} >> +#endif >> + >> static const struct xhci_driver_overrides xhci_pci_overrides __initconst = { >> .reset = xhci_pci_setup, >> .start = xhci_pci_run, >> @@ -677,6 +787,8 @@ int xhci_pci_common_probe(struct pci_dev *dev, const struct pci_device_id *id) >> if (device_property_read_bool(&dev->dev, "ti,pwron-active-high")) >> pci_clear_and_set_config_dword(dev, 0xE0, 0, 1 << 22); >> >> + xhci_pci_try_add_aux_device(dev); > Is it considered acceptable to add > > if (IS_ENABLED(CONFIG_USB_XHCI_PCI_AUXDEV)) > > before this call, remove #ifdef around the definitions of the auxdev > functions and rely on dead code elimination to clean them up? > > We already have a similar trick with CONFIG_USB_XHCI_PCI_RENESAS here > and it seemed to be working, though the amount of conditional code is > much lower and so is the potential risk. > > The reason for doing it this way was because Greg doesn't like #ifdefs > in .c files, and neither do static analyzers like them. > >> + >> return 0; >> >> put_usb3_hcd: >> @@ -713,6 +825,8 @@ void xhci_pci_remove(struct pci_dev *dev) >> xhci = hcd_to_xhci(pci_get_drvdata(dev)); >> set_power_d3 = xhci->quirks & XHCI_SPURIOUS_WAKEUP; >> >> + xhci_pci_try_remove_aux_device(dev); >> + >> xhci->xhc_state |= XHCI_STATE_REMOVING; >> >> if (pci_choose_state(dev, PMSG_SUSPEND) == PCI_D0) >> -- >> 2.53.0 >>
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