[PATCH v3 1/2] dt-bindings: net: bluetooth: Add MediaTek MT7921S SDIO Bluetooth

[Chen-Yu Tsai]

The MediaTek MT7921S is a WiFi/Bluetooth combo chip that works over
SDIO. WiFi and Bluetooth are separate SDIO functions within the chip.
While the Bluetooth SDIO function is fully discoverable, the chip has
a pin that can reset just the Bluetooth core, as opposed to the full
chip. This should be described in the device tree.

Add a device tree binding for the Bluetooth SDIO function of the MT7921S
specifically to document the reset line. This binding is based on the MMC
controller binding, which specifies one device node per SDIO function.

Cc: Sean Wang <sean.wang at mediatek.com>
Signed-off-by: Chen-Yu Tsai <wenst at chromium.org>
---
Changes since v2:
- Expand description and commit message to clearly state that WiFi and
  Bluetooth are separate SDIO functions, and that each function should
  be a separate device node, as specified by the MMC binding.
- Change 'additionalProperties' to 'unevaluatedProperties'
- Add missing separating new line
- s/ot/to/

Angelo's reviewed-by was not picked up due to the above changes.

Changes since v1:
- Reworded descriptions
- Moved binding maintainer section before description
- Added missing reference to bluetooth-controller.yaml
- Added missing GPIO header to example
---
 .../bluetooth/mediatek,mt7921s-bluetooth.yaml | 55 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 56 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7921s-bluetooth.yaml

diff --git a/Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7921s-bluetooth.yaml b/Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7921s-bluetooth.yaml
new file mode 100644
index 000000000000..67ff7caad599
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7921s-bluetooth.yaml
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/bluetooth/mediatek,mt7921s-bluetooth.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek MT7921S Bluetooth
+
+maintainers:
+  - Sean Wang <sean.wang at mediatek.com>
+
+description:
+  MT7921S is an SDIO-attached dual-radio WiFi+Bluetooth Combo chip; each
+  function is its own SDIO function on a shared SDIO interface. The chip
+  has two dedicated reset lines, one for each function core.
+  This binding only covers the Bluetooth SDIO function, with one device
+  node describing only this SDIO function.
+
+allOf:
+  - $ref: bluetooth-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - mediatek,mt7921s-bluetooth
+
+  reg:
+    const: 2
+
+  reset-gpios:
+    maxItems: 1
+    description:
+      An active-low reset line for the Bluetooth core; on typical M.2
+      key E modules this is the W_DISABLE2# pin.
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    mmc {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        bluetooth at 2 {
+            compatible = "mediatek,mt7921s-bluetooth";
+            reg = <2>;
+            reset-gpios = <&pio 8 GPIO_ACTIVE_LOW>;
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 88981d9f3958..218bc2a21207 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13818,6 +13818,7 @@ M:	Sean Wang <sean.wang at mediatek.com>
 L:	linux-bluetooth at vger.kernel.org
 L:	linux-mediatek at lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
+F:	Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7921s-bluetooth.yaml
 F:	Documentation/devicetree/bindings/net/mediatek-bluetooth.txt
 F:	drivers/bluetooth/btmtkuart.c
 
-- 
2.44.0.683.g7961c838ac-goog