Message-Id: <20260127-cp2112-dt-v13-0-6448ddd4bf22@plexus.com>
Date: Tue, 27 Jan 2026 08:47:47 -0600
From: Danny Kaehn <danny.kaehn@...xus.com>
To: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Benjamin Tissoires <bentiss@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Danny Kaehn <danny.kaehn@...xus.com>,
        Andi Shyti <andi.shyti@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Cc: Jiri Kosina <jikos@...nel.org>, devicetree@...r.kernel.org,
        linux-input@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        Ethan Twardy <ethan.twardy@...xus.com>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, Leo Huang <leohu@...dia.com>,
        Arun D Patil <arundp@...dia.com>, Willie Thai <wthai@...dia.com>,
        Ting-Kai Chen <tingkaic@...dia.com>
Subject: [PATCH v13 0/3] Firmware Support for USB-HID Devices and CP2112

This patchset allows USB-HID devices to have Firmware bindings through sharing
the USB fwnode with the HID driver, and adds such a binding and driver
implementation for the CP2112 USB to SMBus Bridge (which necessitated the
USB-HID change). This change allows a CP2112 permanently attached in hardware to
be described in DT and ACPI and interoperate with other drivers.

Changes in v13:
- dt-binding changes:
  - drop scl-gpios and sda-gpios from binding, since they are included
      from the i2c-controller schena.
  - Set indentation to 4 spaces consistently for the DTS example
  - Fix alignment for gpio-line-names in the example
- Use dev_fwnode in hid-cp2112.c instead of directly accessing fwnode
- Immediately release the fwnode_handle from
    device_get_named_child_node() in hid-cp2112.c
- Link to v12: https://lore.kernel.org/r/20251126-cp2112-dt-v12-0-2cdba6481db3@plexus.com

Changes in v12:
- dt-binding changes:
  - Drop "on the host controller" from top-level description based on
      comment from Rob H.
  - Correct "Properties must precede subnodes" dt_binding_check error by
      moving gpio_chip-related properties above the i2c subnode in the
      binding and in the example.
  - Include `interrupt-controller` property in the example
- Modify hid-cp2112.c to support separate schemas for DT vs. ACPI - DT
  combines gpio subnode with the CP2112's node, but will have an I2C
  subnode; while ACPI will maintain separate child nodes for the GPIO
  I2C devices

Changes in v11:
- Eliminate 'gpio' subnode for DT and ACPI for the CP2112 per comment
    from Rob H.
- Edit hid-cp2112.c to match for ACPI index and fall back to matching by
    name (instead of the other way around)
- Separate CP2112 I2C bus speed configuration into a separate patch

Changes in v10:
- Define an enumeration and mapping for CP2112 ACPI _ADRs and devicetree
    child node names, and use these in the scanning of child nodes
- Address other miscellaneous

Changes in v9:
- Add _ADR-based ACPI binding of child nodes (I2C is _ADR Zero, GPIO is _ADR One)
- Use a loop-based approach for assigning child nodes within probe().
    As a consequence, hid-cp2112.c no longer maintains references to the
    child fwnodes during the lifetime of the device. (plese correct if this
    is actually needed for this use-case)

Changes in v8:
- Apply Review tags retroactively to patches previously reviewed

Changes in v7:
- Use dev_fwnode when calling fwnod_handle_put in i2c_adapter in hid-cp2112.c
- Capitalize I2C and GPIO in commit message for patch 0003

Changes in v6:
- Fix fwnode_handle reference leaks in hid-cp21112.c
- Simplify hog node pattern in silabs,cp2112.yaml

Changes in v5:
 - Use fwnode API instead of of_node api in hid-core.c and hid-cp2112.c
 - Include sda-gpios and scl-gpios in silabs,cp2112.yaml
 - Additional fixups to silabs,cp2112.yaml to address comments
   - Remove ngpios property
   - Constrain the hog pattern to a single naming scheme
   - Remove unneeded properties from the gpio hog which are provided by
       the parent schema
 - Submit threaded interrupt bugfix separately from this patchset, as requested

Changes in v4:
 - Moved silabs,cp2112.yaml to /Documentation/devicetree/bindings/i2c

Changes in v3:
 - Additional fixups to silabs,cp2112.yaml to address comments

Changes in v2:
 - Added more detail to silabs,cp2112.yaml dt-binding
 - Moved silabs,cp2112.yaml to /Documentation/devicetree/bindings/input
 - Added support for setting smbus clock-frequency from DT in hid-cp2112.c
 - Added freeing of of_nodes on error paths of _probe in hid-cp2112.c

Danny Kaehn (3):
  dt-bindings: i2c: Add CP2112 HID USB to SMBus Bridge
  HID: usbhid: Share USB device firmware node with child HID device
  HID: cp2112: Fwnode Support

 .../bindings/i2c/silabs,cp2112.yaml           | 113 ++++++++++++++++++
 drivers/hid/hid-cp2112.c                      |  50 ++++++++
 drivers/hid/usbhid/hid-core.c                 |   2 +
 3 files changed, 165 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/silabs,cp2112.yaml

--
2.25.1

---
Danny Kaehn (3):
      dt-bindings: i2c: Add CP2112 HID USB to SMBus Bridge
      HID: cp2112: Fwnode Support
      HID: cp2112: Configure I2C Bus Speed from Firmware

 .../devicetree/bindings/i2c/silabs,cp2112.yaml     | 100 +++++++++++++++++++++
 drivers/hid/hid-cp2112.c                           |  37 ++++++++
 2 files changed, 137 insertions(+)
---
base-commit: 1c772200c9dcb23a304f84a9334fe2e0d9529ab0
change-id: 20240605-cp2112-dt-7cdc95448e8a

Best regards,
-- 
Danny Kaehn <danny.kaehn@...xus.com>

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