[PATCH v5 0/2] AMD Promontory 21 xHCI temperature sensor support

[Jihong Min]

Hi,

This series adds temperature monitoring for AMD Promontory 21 (PROM21)
xHCI PCI functions.

Patch 1 adds a small PROM21-specific xHCI PCI glue driver. USB host
operation is delegated to the common xhci-pci code, while the PROM21 glue
publishes an auxiliary device for optional sensor support.

Patch 2 adds an auxiliary-bus hwmon driver that binds to that auxiliary
device and exposes the PROM21 xHCI temperature value as temp1_input.

The hwmon driver reads the sensor through a vendor index/data register pair
in the xHCI PCI MMIO BAR. It does not wake the parent PCI device for hwmon
reads; if the parent is suspended, the read returns -ENODATA.

Changes in v5:
- Add support for AMD 1022:43fc PROM21 xHCI controllers and document the
  new PCI ID.
- Make USB_XHCI_PCI_PROM21 depend on X86 and default to USB_XHCI_PCI.
- Keep the PROM21 PCI glue built-in-only when enabled, while allowing the
  hwmon sensor driver to be built as a separate module.
- Move PROM21 xHCI PCI device IDs to xhci-pci.h so xhci-pci.c and
  xhci-pci-prom21.c use shared definitions.
- Pass the parent PCI device, MMIO base, and resource length to the hwmon
  driver through platform data defined in a common header, instead of
  inspecting the parent driver's drvdata from the hwmon driver.
- Remove the private hwmon mutex and rely on hwmon core serialization for
  this driver's callbacks.
- Clarify that the driver only serializes its own hwmon callbacks and does
  not synchronize with firmware, SMM, ACPI AML, or other possible users of
  the PROM21 vendor index/data register pair.
- Use readb() for the temperature data register, validate the value before
  writing the output pointer, and drop the 0xff invalid-value check.
- Use pm_runtime_put() after successful reads with the parent device active
  so the PM core can re-evaluate the parent device's idle state.
- Simplify the documentation and use more precise terminology for the
  supported device.

Jihong Min (2):
  usb: xhci-pci: add AMD Promontory 21 PCI glue
  hwmon: add AMD Promontory 21 xHCI temperature sensor support

 Documentation/hwmon/index.rst                 |   1 +
 Documentation/hwmon/prom21-xhci.rst           | 101 ++++++++
 drivers/hwmon/Kconfig                         |  10 +
 drivers/hwmon/Makefile                        |   1 +
 drivers/hwmon/prom21-xhci.c                   | 238 ++++++++++++++++++
 drivers/usb/host/Kconfig                      |  20 ++
 drivers/usb/host/Makefile                     |   1 +
 drivers/usb/host/xhci-pci-prom21.c            | 123 +++++++++
 drivers/usb/host/xhci-pci.c                   |  11 +
 drivers/usb/host/xhci-pci.h                   |   3 +
 include/linux/platform_data/usb-xhci-prom21.h |  22 ++
 11 files changed, 531 insertions(+)
 create mode 100644 Documentation/hwmon/prom21-xhci.rst
 create mode 100644 drivers/hwmon/prom21-xhci.c
 create mode 100644 drivers/usb/host/xhci-pci-prom21.c
 create mode 100644 include/linux/platform_data/usb-xhci-prom21.h

-- 
2.53.0