From patchwork Thu Feb 20 09:56:51 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Quentin Schulz X-Patchwork-Id: 867569 Received: from smtp-190f.mail.infomaniak.ch (smtp-190f.mail.infomaniak.ch [185.125.25.15]) (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 BC1D71F03EE for ; Thu, 20 Feb 2025 09:57:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.125.25.15 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740045443; cv=none; b=fCWoodPuugQJFRwaNShcx5Mnbl7fKHTLCJzehmYLxgqup/51NFsgsEExl6dCreTMv0zVx4t6aANv+qja1IoahDLGr/No3UR9/ZWXUEN3jjwEQAO86B0N1GhNAKfu1JKgjMMCVwF7owhDYzYjSLFuaE5AsoKTyKw9nzlZ3p7PLtk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740045443; c=relaxed/simple; bh=bf8g/YXdtx1VUish3C6E+kFkY2PnMDnh+fkHBlxDPfk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=g5VxNjXS2lnvBgJ1xZl3zxIXg0Z1FqyUnvHlyfISpnO0SeZ8vJLFxoFsR4+c0Ra34P6qFpl04k6vSicHO349KoK67xoI4YZeq5fMQgqmbUaOiRUBA5iNzIE5nDMEXdP7S+iaeh0AHV6+ZZFLa2XMAtl07x1g3BGMLwJuJRSgdGA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=0leil.net; spf=pass smtp.mailfrom=0leil.net; arc=none smtp.client-ip=185.125.25.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=0leil.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=0leil.net Received: from smtp-4-0000.mail.infomaniak.ch (unknown [IPv6:2001:1600:7:10:40ca:feff:fe05:0]) by smtp-4-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4Yz7w86PKwzXcq; Thu, 20 Feb 2025 10:57:12 +0100 (CET) Received: from unknown by smtp-4-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4Yz7w82DM1zcNN; Thu, 20 Feb 2025 10:57:12 +0100 (CET) From: Quentin Schulz Date: Thu, 20 Feb 2025 10:56:51 +0100 Subject: [PATCH 1/2] dt-bindings: gpio: nxp,pcf8575: add reset GPIO Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250220-pca976x-reset-driver-v1-1-6abbf043050e@cherry.de> References: <20250220-pca976x-reset-driver-v1-0-6abbf043050e@cherry.de> In-Reply-To: <20250220-pca976x-reset-driver-v1-0-6abbf043050e@cherry.de> To: Linus Walleij , Bartosz Golaszewski , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Laurent Pinchart Cc: Heiko Stuebner , linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Quentin Schulz X-Mailer: b4 0.14.2 X-Infomaniak-Routing: alpha From: Quentin Schulz A few of the I2C GPIO expander chips supported by this binding have a RESETN pin to be able to reset the chip. The chip is held in reset while the pin is low, therefore the polarity of reset-gpios is expected to reflect that, i.e. a GPIO_ACTIVE_HIGH means the GPIO will be held low for reset and released high, GPIO_ACTIVE_LOW means the GPIO will be held high for reset and released low. Out of the supported chips, only PCA9670, PCA9671, PCA9672 and PCA9673 show a RESETN pin in their datasheets. They all share the same reset timings, that is 4+us reset pulse[0] and 100+us reset time[0]. When performing a reset, "The PCA9670 registers and I2C-bus state machine will be held in their default state until the RESET input is once again HIGH."[1] meaning we now know the state of each line controlled by the GPIO expander. Therefore, setting lines-initial-states and reset-gpios both does not make sense and their presence is XOR'ed. [0] https://www.nxp.com/docs/en/data-sheet/PCA9670.pdf Fig 22. [1] https://www.nxp.com/docs/en/data-sheet/PCA9670.pdf 8.5 Signed-off-by: Quentin Schulz --- .../devicetree/bindings/gpio/nxp,pcf8575.yaml | 33 ++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml b/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml index 3718103e966a13e1d77f73335ff73c18a3199469..d08d3f848f82e74de949da16d26a810dc52a74e5 100644 --- a/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml +++ b/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml @@ -73,6 +73,39 @@ properties: wakeup-source: true + reset-gpios: + maxItems: 1 + description: + GPIO controlling the (reset active LOW) RESET# pin. + + Performing a reset makes all lines initialized to their input (pulled-up) + state. + +allOf: + - if: + properties: + compatible: + not: + contains: + enum: + - nxp,pca9670 + - nxp,pca9671 + - nxp,pca9672 + - nxp,pca9673 + then: + properties: + reset-gpios: false + + # lines-initial-states XOR reset-gpios + # Performing a reset reinitializes all lines to a known state which + # may not match passed lines-initial-states + - if: + required: + - lines-initial-states + then: + properties: + reset-gpios: false + patternProperties: "^(.+-hog(-[0-9]+)?)$": type: object