From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-02.galae.net (smtpout-02.galae.net [185.246.84.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1EEC93A6EF1; Wed, 29 Apr 2026 07:44:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.84.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777448664; cv=none; b=aoDwQQvgB8dcy5A9LqwC4tPGbu+IU+2MSFygvp4Q4OVtLHryNei00NBsEDzi9qU2sDbW1xkAuJr5iqpk0BRHjNb0eShlGndPmJLVvHKGiMAcZresw+GWBdUxIY12avIbMcdwqbsaBbW7PzD2p6Vxh6UpqnGvBDRmkDwNvLESni0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777448664; c=relaxed/simple; bh=p66r+zCwkOwB1S0QW0mE5+VDJePu1ZvrY2w3dA98YBY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oUWK3Jg3QspK5ezVUbQWpKj1N1rZMwl+lYoJSuPCoH88mHFsgkLk1+0C9WuD/067A4Ym6hnEM52xNGLtxGubdKqJZ0DtJQApB+ubs5X/BURWZaqCEBD64EaU84T7Gv6WduqF7SeFHFn2pReRUGk6eq2x7rvA8tLmBx0FIhxiUpg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=fBvQl4xC; arc=none smtp.client-ip=185.246.84.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="fBvQl4xC" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id 9F9A71A347B; Wed, 29 Apr 2026 07:44:14 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 746E4601DF; Wed, 29 Apr 2026 07:44:14 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 3248010729898; Wed, 29 Apr 2026 09:44:11 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1777448653; h=from:subject:date:message-id:to:cc:mime-version: content-transfer-encoding:in-reply-to:references; bh=IxcuUJb+ByJPJw8uSLEtbL63MS3PIf1zV8Q9uCPz0+s=; b=fBvQl4xCao0eGGnMmPG2s1DuPaxy2W8fEM20BESEF93T/oo5E8tSoEmE3jZ3gbhYXk5DCP X5D56yJQMOvAbm+wQbTZFDHXGglNqq1DRQWeLjDfXodjgu8PTBMlrSVFYdlc4WwcR1jC2f zwp7o7O+Cj6d1rnQvRX3K6Hbomzi/KQcuarx8Zid8lQn8p8CPseWlU7V1GIo6bMczV3rkn hBE2K6YtF5rzxMRoh1vyrw1vqlDznRdci6PR3TxjPTGWQlXva5ERKzHmERzBOVFOizPdBG WzyKSiB2YUVac0EjVjR+p17J/fh1M76Mev/T7lohOgh5H7jCadPyvYcITGZ+JQ== From: Herve Codina To: Herve Codina , Bartosz Golaszewski , Linus Walleij , Liam Girdwood , Mark Brown , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Saravana Kannan , Jaroslav Kysela , Takashi Iwai Cc: linux-sound@vger.kernel.org, linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Christophe Leroy , Thomas Petazzoni Subject: [PATCH v2 02/17] ASoC: dt-bindings: Add support for the GPIOs driven amplifier Date: Wed, 29 Apr 2026 09:43:38 +0200 Message-ID: <20260429074356.118420-3-herve.codina@bootlin.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260429074356.118420-1-herve.codina@bootlin.com> References: <20260429074356.118420-1-herve.codina@bootlin.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Last-TLS-Session-Version: TLSv1.3 Some amplifiers based on analog switches and op-amps can be present in the audio path and can be driven by GPIOs in order to control their gain value, their mute and/or bypass functions. Those components needs to be viewed as audio components in order to be fully integrated in the audio path. gpio-audio-amp allows to consider these GPIO driven amplifiers as auxiliary audio devices. Signed-off-by: Herve Codina --- .../bindings/sound/gpio-audio-amp.yaml | 270 ++++++++++++++++++ 1 file changed, 270 insertions(+) create mode 100644 Documentation/devicetree/bindings/sound/gpio-audio-amp.yaml diff --git a/Documentation/devicetree/bindings/sound/gpio-audio-amp.yaml b/Documentation/devicetree/bindings/sound/gpio-audio-amp.yaml new file mode 100644 index 000000000000..46f99cdd2a97 --- /dev/null +++ b/Documentation/devicetree/bindings/sound/gpio-audio-amp.yaml @@ -0,0 +1,270 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/sound/gpio-audio-amp.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Audio amplifier driven by GPIOs + +maintainers: + - Herve Codina + +description: | + Audio GPIO amplifiers are driven by GPIO in order to control the gain value + of the amplifier, its mute function and/or its bypass function. + + Those amplifiers are based on discrete components (analog switches, op-amps + and more) where some of them, mostly analog switches, are controlled by GPIOs + to adjust the gain value of the whole amplifier and/or to control + the mute and/or bypass function. + + For instance, the following piece of hardware is a GPIO amplifier + + +5VA + ^ + |\ | + | \ + Vin >---------------------------|+ \ + | +-------+-----> Vout + .--\/\/\/--+------------|- / | + | | | / | + v | |/ | | + GND o v | + \ GND | + gpio >-----------> \ | + o o | + | | | + | '--\/\/\/--. | + | +--\/\/\/--' + '---------------' + +properties: + compatible: + oneOf: + - const: gpio-audio-amp-mono + description: + A single channel amplifier. All features apply to this sole channel. + + - const: gpio-audio-amp-stereo + description: + A dual channel amplifier (left and rignt). All features apply to both + channels producing the same effect on both channels at the same time. + + vdd-supply: + description: Main power supply of the amplifier + + vddio-supply: + description: Power supply related to the control path + + vdda1-supply: + description: Analog power supply + + vdda2-supply: + description: Additional analog power supply + + mute-gpios: + description: GPIO to control the mute function + maxItems: 1 + + bypass-gpios: + description: GPIO to control the bypass function + maxItems: 1 + + gain-gpios: + description: | + GPIOs to control the amplifier gain + + The gain value is computed from GPIOs value from 0 to 2^N-1 with N the + number of GPIO described. The first GPIO described is the lsb of the gain + value. + + For instance assuming 2 gpios + gain-gpios = <&gpio1 GPIO_ACTIVE_HIGH> <&gpio2 GPIO_ACTIVE_HIGH>; + The gain value will be the following: + + gpio1 | gpio2 | gain + ------+-------+----- + 0 | 0 | 0b00 -> 0 + 1 | 0 | 0b01 -> 1 + 0 | 1 | 0b10 -> 2 + 1 | 1 | 0b11 -> 3 + ------+-------+----- + + Note: The gain value, bits set to 1 or 0, indicate the state active (bit + set) or the state inactive (bit unset) of the related GPIO. The + physical voltage corresponding to this active/inactive state is + given by the GPIO_ACTIVE_HIGH and GPIO_ACTIVE_LOW flags. + + minItems: 1 + maxItems: 16 + + gain-ranges: + $ref: /schemas/types.yaml#/definitions/uint32-matrix + description: | + A list of one or more ranges of possible values. Each range is defined by + the first and last point in the range. Each point is defined by the pair + (GPIOs value, Gain in 0.01 dB unit). + + Ranges can be contiguous or holes can be present between ranges if some + gpios value should not be used. Also in a range the first point and the + last point can be identical. In that case, the range contains only one + item, the given point. + + items: + items: + - description: GPIOs value of the first point in the range + - description: Gain in 0.01 dB unit of the first point in the range + - description: GPIOs value of the last point in the range + - description: Gain in 0.01 dB unit of the last point in the range + description: | + A range defines a linear function (linear in dB) from the first point + to the last point, both included. The number of items in the range is + N = abs(first_point.gpio_value - last_point.gpio_value) + 1 + + It allows to define the gain range from the first_point.gain to + the last_point.gain, both points included. + + Gain (0.01 dB unit) + ^ + | last + +- - - - - - - - - - + point + | + . + | + . + | + . + +- - - - + . + | first . . + | point . . + | . . + +--------+-----------+---> gpios + value + + Note: Even if first_point.gpio_value is lower than last_point.gpio_value + and first_point.gain is lower than last_point.gain in the above + graphic, all combination of values are supported leading to an + increasing or a decreasing linear segment. + + minItems: 1 + maxItems: 65536 + + gain-labels: + $ref: /schemas/types.yaml#/definitions/string-array + minItems: 2 + maxItems: 65536 + description: | + List of the gain labels attached to the combination of GPIOs controlling + the gain. The first label is related to the gain value 0, the second label + is related to the gain value 1 and so on. + + With 2 GPIOs controlling the gain, GPIOs value can be 0, 1, 2 and 3. + Assuming that gain value set the hardware according to the following + table: + + GPIOs | Hardware + value | amplification + ------+-------------- + 0 | Low + 1 | Middle + 2 | High + 3 | Max + ------+-------------- + + The description using gain labels can be: + gain-labels = "Low", "Middle", "High", "Max"; + +dependencies: + gain-ranges: [ gain-gpios ] + gain-labels: [ gain-gpios ] + +required: + - compatible + - vdd-supply + +anyOf: + - required: + - gain-gpios + - required: + - mute-gpios + - required: + - bypass-gpios + +allOf: + - $ref: component-common.yaml# + - if: + required: + - gain-ranges + then: + properties: + gain-labels: false + - if: + required: + - gain-labels + then: + properties: + gain-ranges: false + +unevaluatedProperties: false + +examples: + - | + #include + + /* Gain controlled by gpios */ + amplifier-0 { + compatible = "gpio-audio-amp-mono"; + vdd-supply = <®ulator>; + gain-gpios = <&gpio 0 GPIO_ACTIVE_HIGH>, <&gpio 1 GPIO_ACTIVE_HIGH>; + }; + + /* Gain controlled by gpio using a simple range on a stereo amplifier */ + amplifier-1 { + compatible = "gpio-audio-amp-stereo"; + vdd-supply = <®ulator>; + gain-gpios = <&gpio 0 GPIO_ACTIVE_HIGH>, <&gpio 1 GPIO_ACTIVE_HIGH>; + gain-ranges = <0 (-300) 3 600>; + }; + + /* Gain controlled by gpio with labels */ + amplifier-3 { + compatible = "gpio-audio-amp-mono"; + vdd-supply = <®ulator>; + gain-gpios = <&gpio 0 GPIO_ACTIVE_HIGH>; + gain-labels = "Low", "High"; + }; + + /* A mutable stereo amplifier without any gain control */ + amplifier-4 { + compatible = "gpio-audio-amp-stereo"; + vdd-supply = <®ulator>; + mute-gpios = <&gpio 0 GPIO_ACTIVE_HIGH>; + }; + + /* + * Several supplies, gain controlled using more complex ranges, mute and + * bypass. + * + * Assuming 3 gpios for controlling the gain with the following table + * gpios value Gain + * 0b000 Do not use (gpios value not allowed) + * 0b001 - 3dB + * 0b010 + 3dB + * 0b011 + 10dB + * 0b100 Do not use (gpios value not allowed) + * 0b101 + 6dB + * 0b110 + 7dB + * 0b111 + 8dB + */ + amplifier-5 { + compatible = "gpio-audio-amp-mono"; + vdd-supply = <®ulator>; + vddio-supply = <®ulator1>; + vdda1-supply = <®ulator2>; + gain-gpios = <&gpio 0 GPIO_ACTIVE_HIGH>, + <&gpio 1 GPIO_ACTIVE_HIGH>, + <&gpio 2 GPIO_ACTIVE_HIGH>; + gain-ranges = <1 (-300) 2 300>, + <3 1000 3 1000>, + <5 600 7 800>; + mute-gpios = <&gpio 3 GPIO_ACTIVE_HIGH>; + bypass-gpios = <&gpio 4 GPIO_ACTIVE_HIGH>; + }; +... -- 2.53.0