From patchwork Fri Apr 21 09:37:30 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matti Vaittinen X-Patchwork-Id: 13219699 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 952F7C77B7E for ; Fri, 21 Apr 2023 09:37:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231572AbjDUJhx (ORCPT ); Fri, 21 Apr 2023 05:37:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231809AbjDUJhw (ORCPT ); Fri, 21 Apr 2023 05:37:52 -0400 Received: from mail-lf1-x134.google.com (mail-lf1-x134.google.com [IPv6:2a00:1450:4864:20::134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AF8E9A5FF; Fri, 21 Apr 2023 02:37:50 -0700 (PDT) Received: by mail-lf1-x134.google.com with SMTP id 2adb3069b0e04-4ec81773cf7so1448512e87.2; Fri, 21 Apr 2023 02:37:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1682069869; x=1684661869; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :from:to:cc:subject:date:message-id:reply-to; bh=sz1OnOb0n4ydElkEDE6Ll6gkKnGXqAStKuCmUlNsLUM=; b=JNPU1i1i+zs2YwGELrf5uO3IjQoXrG/1jBjmt2UFd11jjG369OlmATIYpwa4tFD6PY l0Zmw6yVVeEBSPX7PFyanSY5oKhiibX8mPLWAzXTJLc7QpLhYXw0F/xCrEhFxcmXAWrv WVVVfzuJ8pCoWgy2SpqE9RIM2S+4MjZT9k78QznE829CQlRBg29ODvzsgro4oLX9WqFc lhFDxkBQ7oTv68WtW3cXxtlLxkJFtHTWHcqH9q2WRim/AmXlKrBnekD/gafml6rX/IkP /euo26e9sHW5PSJ2HOAkwK97t+zBXNVBYZVI5A6B8O65JZNwb1BTHAVjLzFJ3eihY8Ip E9oQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682069869; x=1684661869; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=sz1OnOb0n4ydElkEDE6Ll6gkKnGXqAStKuCmUlNsLUM=; b=PVdOI5RKOx072WhpADunhtGP4g3tB2Dgycg2N4jPIi7z52WVOjHKVUh292cForRYnl EDQO45eoXoYgg15/+JOV5j1ecTjqjQaDYjCHtygQTQM2mbZhhBAOEkMmVTdW92hsWBUQ 5GnjyGI/2cmDbfea4NveFn0s0vCvE4FenX8Synupy9tanbtE5v+FUGpcdG9xfF5aM6Sa Ij/aM3bwTgYajPdzawu4/ie3DkX2fNC3i+64Qku8Pqhbmwr13095duzJYHeOotVo6Emn Ksn1Su0VB8wlZCufEXmn8nxr9HJkeIqui8KFb+PDWxbEh1INVu4M2UdfgjPh1yWCi/wi 6LIg== X-Gm-Message-State: AAQBX9cS3rHIiZ8oaLrmg2TtTuZdTPbToZCM6VifjBxUvnkAIbslC+W9 +IctlNGLF25GgivP5qXLujs= X-Google-Smtp-Source: AKy350ZYkgij7NMRbdJJzs4P118dJbAD4yRBkU1YX+XBa0+WOYL78bHqCKH5yjice+HD8MNHnif6oA== X-Received: by 2002:ac2:5226:0:b0:4db:ebb3:b529 with SMTP id i6-20020ac25226000000b004dbebb3b529mr1224035lfl.46.1682069868926; Fri, 21 Apr 2023 02:37:48 -0700 (PDT) Received: from fedora (62-78-225-252.bb.dnainternet.fi. [62.78.225.252]) by smtp.gmail.com with ESMTPSA id y9-20020ac24e69000000b004eb44c2ab6bsm499025lfs.294.2023.04.21.02.37.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Apr 2023 02:37:48 -0700 (PDT) Date: Fri, 21 Apr 2023 12:37:30 +0300 From: Matti Vaittinen To: Matti Vaittinen , Matti Vaittinen Cc: Matti Vaittinen , Shreeya Patel , Krzysztof Kozlowski , Jonathan Cameron , devicetree@vger.kernel.org, Zhigang Shi , Lars-Peter Clausen , Paul Gazzillo , Rob Herring , Dmitry Osipenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Shevchenko Subject: [PATCH v1 0/3] Support ROHM BU27008 RGB sensor Message-ID: MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org Add support for ROHM BU27008 RGB sensor. The ROHM BU27008 is a sensor with 5 photodiodes (red, green, blue, clear and IR) with four configurable channels. Red and green being always available and two out of the rest three (blue, clear, IR) can be selected to be simultaneously measured. Typical application is adjusting LCD backlight of TVs, mobile phones and tablet PCs. This series supports reading the RGBC and IR channels using IIO frameeork. However, only two of the BC+IR can be enabled at the same time. Series adds also support for scale and integration time configuration, where scale consists of impact of both the integration time and hardware gain. The gain and time support is backed by the newly introduced IIO GTS helper. This series depends on GTS helper patches added in BU27034 support series which is already merged in iio/togreg which this series is based on. The hardware allows configuring gain setting by writing a 5-bit gain selector value to a register. Part of the gain setting is common for all channels (RGBC + IR) but part of the selector value can be set separately for RGBC and IR: MODE_CONTROL2 REG: bit 7 6 5 4 3 2 1 0 ----------------------------------------------------------------- | RGB selector | +---------------------------------------+ ----------------------------------------------------------------- | high bits IR | | low bits IR selector | +---------------+ +-----------------------+ In theory it would be possible to set certain separate gain values for RGBC and IR channels, but this gets pretty confusing because there are a few 'unsupported' selector values. If only RGBC or IR was set, some extra handling should be done to prevent the other channel from getting unsupported value due to change in high-bits. Furthermore, allowing the channels to be set different gain values (in some cases when gains are such the HW supports it) would make the cases where also integration time is changed to achieve correct scale ... interesting. It might also be confusing for user to try predicting when setting different scales succeeds and when it does not. Furthermore, if for example the scale setting for RGBC caused IR selector to be invalid - it could also cause the IR scale to "jump" very far from previous value. To make the code simpler and more predictable for users, the current logic is as follows: 1. Prevent setting IR scale. (My assumption is IR is less used than RGBC) 2. When RGBC scale is set, set also the IR-selector to the same value. This prevents unsupported selector values and makes the IR scale changes predictable. The 2) could mean we effectively have the same scale for all channels. Unfortunately, the HW design is slightly peculiar and selector 0 means gain 1X on RGBC but gain 2X on IR. Rest of the selectors equal same gain values on RGBC and IR. The result is that while changin selector from 0 => 1 causes RGBC gain to go from 1X => 4X, it causes IR gain to go from 2X => 4X. So, the driver provides separate scale entries for all channels (also RGB and C will have separate gain entries because these channels are of same type as IR channel). This makes it possible for user applications to go read the scales for all channels after setting scale for one (in order to detect the IR scale difference). Having the separate IR scale entry which applications can read to detect "arbitrary scale changes" makes it possible for applications to be written so they can cope if we need to implement the 'allow setting some different gains for IR and RGBC' - later. Finally, the scales_available is also provided for all other channels except the IR channel, which does not allow the scale to be changed. The sensor provides a data-ready IRQ and the driver implements a triggered buffer mode using this IRQ as a trigger. --- Matti Vaittinen (3): dt-bindings: iio: light: ROHM BU27008 iio: light: ROHM BU27008 color sensor MAINTAINERS: Add ROHM BU27008 .../bindings/iio/light/rohm-bu27008.yaml | 49 + MAINTAINERS | 3 +- drivers/iio/light/Kconfig | 14 + drivers/iio/light/Makefile | 1 + drivers/iio/light/rohm-bu27008.c | 1028 +++++++++++++++++ 5 files changed, 1094 insertions(+), 1 deletion(-) create mode 100644 Documentation/devicetree/bindings/iio/light/rohm-bu27008.yaml create mode 100644 drivers/iio/light/rohm-bu27008.c base-commit: 52cc189b4fc6af6accc45fe7b7053d76d8724059