From patchwork Tue Oct 26 19:15:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mauri Sandberg X-Patchwork-Id: 1546608 Return-Path: X-Original-To: incoming-dt@patchwork.ozlabs.org Delivered-To: patchwork-incoming-dt@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; secure) header.d=ext.kapsi.fi header.i=@ext.kapsi.fi header.a=rsa-sha256 header.s=20161220 header.b=fuevJs8Z; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=devicetree-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by bilbo.ozlabs.org (Postfix) with ESMTP id 4Hf1lK5K9Xz9sRN for ; Wed, 27 Oct 2021 06:16:29 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238609AbhJZTSw (ORCPT ); Tue, 26 Oct 2021 15:18:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37666 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238619AbhJZTSv (ORCPT ); Tue, 26 Oct 2021 15:18:51 -0400 Received: from mailserv1.kapsi.fi (mailserv1.kapsi.fi [IPv6:2001:67c:1be8::25:1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DAEBDC061570; Tue, 26 Oct 2021 12:16:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=ext.kapsi.fi; s=20161220; h=Subject:Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=6Z08zw8GPYqaS2TD7Ieq2MqRlSnLB18cTeBXjvmX1cE=; b=fuevJs8ZKtIKk8j4dkEoVZgI+f zp8N/Da06ZVJXCtywC+pv5gYTSKGd7+ZwHMEU5lxN4ivcZ0OJpMtJeuxzdwZ46vF4cChj0CDsQ6BH 4D8rtwblOpsZWe3QS6eYrL97Zw7mHmy/Cvr7YfFywDFyIJsFsH6AHOZsQHxMOkt8P2rRlgU3IUIyz 7RHGOrK7foAEbpKP9ZShTjYFpsqYkwcNOyuw8JXNMZ7njNStSJ0vCfZF91srV/LS1NxCXBq0s89lB r2452GxsoffFFjoYo70IGrBTa1dbe9P2zQ57R82Mvnx0SE0bRD1hvLrn3IBSd1CWrhZwWzjiq9oC/ 4eu2sPFg==; Received: from 153-106-191-90.dyn.estpak.ee ([90.191.106.153]:49199 helo=localdomain) by mailserv1.kapsi.fi with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1mfRvn-0000NE-9t; Tue, 26 Oct 2021 22:16:20 +0300 Received: by localdomain (sSMTP sendmail emulation); Tue, 26 Oct 2021 22:16:18 +0300 From: Mauri Sandberg To: sandberg@mailfence.com Cc: andy.shevchenko@gmail.com, bgolaszewski@baylibre.com, geert+renesas@glider.be, linus.walleij@linaro.org, linux-gpio@vger.kernel.org, robh+dt@kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, drew@beagleboard.org, Mauri Sandberg , Rob Herring Date: Tue, 26 Oct 2021 22:15:05 +0300 Message-Id: <20211026191506.3099-2-maukka@ext.kapsi.fi> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211026191506.3099-1-maukka@ext.kapsi.fi> References: <20210325122832.119147-1-sandberg@mailfence.com> <20211026191506.3099-1-maukka@ext.kapsi.fi> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 90.191.106.153 X-SA-Exim-Mail-From: maukka@ext.kapsi.fi X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on mailserv1.kapsi.fi X-Spam-Level: X-Spam-Status: No, score=-2.9 required=5.0 tests=ALL_TRUSTED,BAYES_00, TVD_RCVD_IP,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.2 Subject: [PATCH v8 1/2] dt-bindings: gpio-cascade: add documentation X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on mailserv1.kapsi.fi) Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Add documentation for a general GPIO cascade. It allows building one-to-many cascades of GPIO lines using multiplexer to choose the cascaded line. Signed-off-by: Mauri Sandberg Reviewed-by: Rob Herring Reviewed-by: Linus Walleij --- v7 -> v8: - added Reviewed-by tag by Linus v6 -> v7: - no changes v5 -> v6: - added Reviewed-by tag by Rob v4 -> v5: - renamed gpio-mux-input -> gpio-cascade - changed vague term 'pin' to 'upstream line' - added more verbose description for the module - added missing 'mux-controls' entry - dropped Tested-by and Reviewed-by due to changes in bindings v3 -> v4: - Changed author email - Included Tested-by and Reviewed-by from Drew v2 -> v3: added a complete example on dual 4-way multiplexer v1 -> v2: added a little bit more text in the binding documenation --- .../bindings/gpio/gpio-cascade.yaml | 103 ++++++++++++++++++ 1 file changed, 103 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/gpio-cascade.yaml diff --git a/Documentation/devicetree/bindings/gpio/gpio-cascade.yaml b/Documentation/devicetree/bindings/gpio/gpio-cascade.yaml new file mode 100644 index 000000000000..46248f8e2ba5 --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/gpio-cascade.yaml @@ -0,0 +1,103 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/gpio/gpio-cascade.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Generic GPIO cascade + +maintainers: + - Mauri Sandberg + +description: | + A generic GPIO cascade + + This hardware construction cascades (multiplexes) several GPIO lines from + one-to-many using a software controlled multiplexer. The most common use + case is probably reading several inputs by switching the multiplexer over + several input lines, which in practice works well since input lines has + high impedance. + + Constructions with multiplexed outputs are also possible using open drain + electronics. + + The number of cascaded GPIO lines is limited by the technology used to + switch over the cascaded lines. There are readily available dual/triple + 4-to-1 multiplexers, for example, and others. + + Illustration (pins used to drive the multiplexer are omitted for clarity) + + /|---- Cascaded GPIO line 0 + Upstream | |---- Cascaded GPIO line 1 + GPIO line ----+ | . + | | . + \|---- Cascaded GPIO line n + +properties: + compatible: + enum: + - gpio-cascade + + gpio-controller: true + + '#gpio-cells': + const: 2 + + mux-controls: + minItems: 1 + maxItems: 1 + description: | + The mux controller that will be driving the GPIO cascade. + + upstream-gpios: + description: | + The GPIO line used as the upstream line will convey the status to/from + cascaded GPIO lines. In an input mode, by using this line, it is + possible to read the status from selected cascaded GPIO line. + + In an output mode the status of the upstream GPIO will be conveyed to + the selected cascaded GPIO line. + +required: + - compatible + - gpio-controller + - "#gpio-cells" + - mux-controls + - upstream-gpios + +additionalProperties: false + +examples: + - | + #include + mux: mux-controller { + compatible = "gpio-mux"; + #mux-control-cells = <0>; + + mux-gpios = <&gpio 9 GPIO_ACTIVE_HIGH>, + <&gpio 11 GPIO_ACTIVE_HIGH>; + }; + + gpio2: key-mux1 { + compatible = "gpio-cascade"; + mux-controls = <&mux>; + + gpio-controller; + #gpio-cells = <2>; + + // GPIOs used by this node, upstream pin + upstream-gpios = <&gpio 12 GPIO_ACTIVE_HIGH>; + }; + + gpio3: key-mux2 { + compatible = "gpio-cascade"; + mux-controls = <&mux>; + + gpio-controller; + #gpio-cells = <2>; + + // GPIOs used by this node, upstream pin + upstream-gpios = <&gpio 14 GPIO_ACTIVE_HIGH>; + }; + +...