[PATCH v4 0/2] AMD Promontory 21 xHCI temperature sensor support

[Jihong Min <hurryman2212@gmail.com>]

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 common xhci-pci code; the PROM21 glue only owns
the PCI binding and publishes an auxiliary "hwmon" child device for
optional sensor support. The glue is built-in only when enabled, matching
built-in xhci-pci, so PROM21 controllers are not left unbound during early
boot if an optional module is absent.

Patch 2 adds the auxiliary hwmon driver. It exposes temp1_input as
prom21_xhci, does not wake the parent PCI device for sensor reads, and
documents the register access and empirical observation method used to
identify the register pair and conversion formula.

Changes in v4:
- Move PROM21 PCI handling into a PROM21-specific xHCI PCI glue driver.
- Make USB_XHCI_PCI_PROM21 built-in only when enabled.
- Rename the hwmon driver/config/name to prom21-xhci,
  SENSORS_PROM21_XHCI, and prom21_xhci.
- Return -ENODATA for suspended parent devices and invalid raw values.
- Remove temp1_label and the runtime PM module parameter.
- Simplify hwmon remove/read lifetime handling.
- Expand hwmon documentation with register access, runtime PM behavior,
  sysfs lookup, and observation details.

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 |  99 +++++++++++
 drivers/hwmon/Kconfig               |  10 ++
 drivers/hwmon/Makefile              |   1 +
 drivers/hwmon/prom21-xhci.c         | 250 ++++++++++++++++++++++++++++
 drivers/usb/host/Kconfig            |  18 ++
 drivers/usb/host/Makefile           |   1 +
 drivers/usb/host/xhci-pci-prom21.c  | 111 ++++++++++++
 drivers/usb/host/xhci-pci.c         |  11 ++
 9 files changed, 502 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

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2.53.0