From: Dmitry Torokhov <d...@chromium.org> USB devices permanently connected to USB ports may be described in ACPI tables and share ACPI devices with ports they are connected to. See [1] for details.
This will allow us to describe sideband resources for devices, such as, for example, hard reset line for BT USB controllers. [1] https://docs.microsoft.com/en-us/windows-hardware/drivers/bringup/other-acpi-namespace-objects#acpi-namespace-hierarchy-and-adr-for-embedded-usb-devices Signed-off-by: Dmitry Torokhov <d...@chromium.org> Signed-off-by: Rajat Jain <raja...@google.com> (changed how we get the usb_port) --- drivers/usb/core/usb-acpi.c | 44 +++++++++++++++++++++++++++++-------- 1 file changed, 35 insertions(+), 9 deletions(-) diff --git a/drivers/usb/core/usb-acpi.c b/drivers/usb/core/usb-acpi.c index 8ff73c83e8e8..9043d7242d67 100644 --- a/drivers/usb/core/usb-acpi.c +++ b/drivers/usb/core/usb-acpi.c @@ -200,30 +200,56 @@ static struct acpi_device * usb_acpi_find_companion_for_device(struct usb_device *udev) { struct acpi_device *adev; + struct usb_port *port_dev; + struct usb_hub *hub; + + if (!udev->parent) { + /* root hub is only child (_ADR=0) under its parent, the HC */ + adev = ACPI_COMPANION(udev->dev.parent); + return acpi_find_child_device(adev, 0, false); + } - if (!udev->parent) + hub = usb_hub_to_struct_hub(udev->parent); + if (!hub) return NULL; - /* root hub is only child (_ADR=0) under its parent, the HC */ - adev = ACPI_COMPANION(udev->dev.parent); - return acpi_find_child_device(adev, 0, false); + /* + * This is an embedded USB device connected to a port and such + * devices share port's ACPI companion. + */ + port_dev = hub->ports[udev->portnum - 1]; + return usb_acpi_get_companion_for_port(port_dev); } - static struct acpi_device *usb_acpi_find_companion(struct device *dev) { /* - * In the ACPI DSDT table, only usb root hub and usb ports are - * acpi device nodes. The hierarchy like following. + * The USB hierarchy like following: + * * Device (EHC1) * Device (HUBN) * Device (PR01) * Device (PR11) * Device (PR12) + * Device (FN12) + * Device (FN13) * Device (PR13) * ... - * So all binding process is divided into two parts. binding - * root hub and usb ports. + * where HUBN is root hub, and PRNN are USB ports and devices + * connected to them, and FNNN are individualk functions for + * connected composite USB devices. PRNN and FNNN may contain + * _CRS and other methods describing sideband resources for + * the connected device. + * + * On the kernel side both root hub and embedded USB devices are + * represented as instances of usb_device structure, and ports + * are represented as usb_port structures, so the whole process + * is split into 2 parts: finding companions for devices and + * finding companions for ports. + * + * Note that we do not handle individual functions of composite + * devices yet, for that we would need to assign companions to + * devices corresponding to USB interfaces. */ if (is_usb_device(dev)) return usb_acpi_find_companion_for_device(to_usb_device(dev)); -- 2.19.1.1215.g8438c0b245-goog
