Reset BT via BT_KILL_1V2_L hardware pin.

On the M.2 standard hardware pin interface, the MTK chip
has a pin called BT_KILL_1V2_L or W_DISABLE#2, it uses
function-level device reset (FLDR) to reset Bluetooth.
When it is pulled low, it can external shut down the BT
function, it is defined as 5 on the MT7925 chip, and is
defined as 248 on the device tree pio controller.

Signed-off-by: Zhangchao Zhang <ot_zhangchao.zhang@mediatek.com>
---
 .../bluetooth/mediatek,mt7925-bluetooth.yaml  | 55 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 56 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7925-bluetooth.yaml

diff --git a/Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7925-bluetooth.yaml b/Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7925-bluetooth.yaml
new file mode 100644
index 000000000000..636b8b3d6a14
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7925-bluetooth.yaml
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/bluetooth/mediatek,mt7925-bluetooth.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Bluetooth mediatek use BT_KILL_1V2_L hardware pin to reset BT
+
+maintainers:
+  - Sean Wang <sean.wang@mediatek.com>
+
+description:
+  MT7925 chip uses the USB bus to communicate with the host.
+  Two methods are used to reset Bluetooth. It provide hardware
+  pin, when an exception occurs, resetting Bluetooth by hardware
+  pin is more stable than resetting Bluetooth by software. If the
+  corresponding pin is not found in dts, bluetooth can also be
+  reset successfully.
+
+allOf:
+  - $ref: bluetooth-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - mediatek,mt7925-bluetooth
+
+  "#gpio-cells":
+    const: 2
+
+  reset-gpios:
+    maxItems: 1
+    description:
+      Default high level, this pin can external shut down the BT function
+      when this pin is pull low, at the same time, USB interface will be also
+      disabled. When this function is not required, external pull high is not
+      required. After 200ms, it is pulled high to 3.3v and the next probe is
+      performed. On typical M.2 key E modules this is the W_DISABLE2# pin.
+
+required:
+  - compatible
+  - "#gpio-cells"
+  - reset-gpios
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    bluetooth {
+      compatible = "mediatek,mt7925-bluetooth";
+      #gpio-cells = <2>;
+      reset-gpios = <&pio 248 GPIO_ACTIVE_LOW>;
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 5959513a7359..d104a5821f20 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14676,6 +14676,7 @@ L:	linux-mediatek@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 F:	Documentation/devicetree/bindings/net/bluetooth/mediatek,bluetooth.txt
 F:	Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7921s-bluetooth.yaml
+F:	Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7925-bluetooth.yaml
 F:	drivers/bluetooth/btmtkuart.c
 
 MEDIATEK BOARD LEVEL SHUTDOWN DRIVERS
-- 
2.46.0

On 08/07/2025 08:01, Zhangchao Zhang wrote:
> Reset BT via BT_KILL_1V2_L hardware pin.
> 
> On the M.2 standard hardware pin interface, the MTK chip
> has a pin called BT_KILL_1V2_L or W_DISABLE#2, it uses
> function-level device reset (FLDR) to reset Bluetooth.
> When it is pulled low, it can external shut down the BT
> function, it is defined as 5 on the MT7925 chip, and is
> defined as 248 on the device tree pio controller.
> 
> Signed-off-by: Zhangchao Zhang <ot_zhangchao.zhang@mediatek.com>
> ---
>  .../bluetooth/mediatek,mt7925-bluetooth.yaml  | 55 +++++++++++++++++++
>  MAINTAINERS                                   |  1 +
>  2 files changed, 56 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7925-bluetooth.yaml
> 
> diff --git a/Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7925-bluetooth.yaml b/Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7925-bluetooth.yaml
> new file mode 100644
> index 000000000000..636b8b3d6a14
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/bluetooth/mediatek,mt7925-bluetooth.yaml
> @@ -0,0 +1,55 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/net/bluetooth/mediatek,mt7925-bluetooth.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Bluetooth mediatek use BT_KILL_1V2_L hardware pin to reset BT
> +
> +maintainers:
> +  - Sean Wang <sean.wang@mediatek.com>
> +
> +description:
> +  MT7925 chip uses the USB bus to communicate with the host.
> +  Two methods are used to reset Bluetooth. It provide hardware
> +  pin, when an exception occurs, resetting Bluetooth by hardware
> +  pin is more stable than resetting Bluetooth by software. If the
> +  corresponding pin is not found in dts, bluetooth can also be
> +  reset successfully.

Don't describe DTS, but the hardware.

> +
> +allOf:
> +  - $ref: bluetooth-controller.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - mediatek,mt7925-bluetooth
> +
> +  "#gpio-cells":
> +    const: 2

You did not say this is a GPIO controller.

> +
> +  reset-gpios:
> +    maxItems: 1
> +    description:
> +      Default high level, this pin can external shut down the BT function

How defaults matter?

> +      when this pin is pull low, at the same time, USB interface will be also
> +      disabled. When this function is not required, external pull high is not

So active low?

> +      required. After 200ms, it is pulled high to 3.3v and the next probe is
> +      performed. On typical M.2 key E modules this is the W_DISABLE2# pin.

So that's part of PCI slot? Sorry, but this does not fit here at all.


Best regards,
Krzysztof