From mboxrd@z Thu Jan 1 00:00:00 1970 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 955A1C433EF for ; Tue, 8 Mar 2022 01:18:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344235AbiCHBTi (ORCPT ); Mon, 7 Mar 2022 20:19:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238576AbiCHBT3 (ORCPT ); Mon, 7 Mar 2022 20:19:29 -0500 Received: from thorn.bewilderbeest.net (thorn.bewilderbeest.net [IPv6:2605:2700:0:5::4713:9cab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5CF836E22; Mon, 7 Mar 2022 17:18:31 -0800 (PST) Received: from hatter.bewilderbeest.net (174-21-187-98.tukw.qwest.net [174.21.187.98]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: zev) by thorn.bewilderbeest.net (Postfix) with ESMTPSA id 88DB04C8; Mon, 7 Mar 2022 17:18:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bewilderbeest.net; s=thorn; t=1646702310; bh=WA0g01ylI3uRFuxsoi3Sd/kmAWCJhNXmCT+GLDXKrng=; h=From:To:Cc:Subject:Date:From; b=SZNk3TyQOZhh0La1+PbuuAmh0QkAcMusjnejTEgP1Jtip5aWdNrM7TvXDaleiYAXK 4JfZiX5YIKSxw8wiHovUOS/eKTh9eXOjA57LYz/8irtXvFiiJ4WXyuJKSujRPfhW5R f09morTBdSS0o3gNVvohpJuseqFlC/PmNXZjwzRM= From: Zev Weiss To: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Arnd Bergmann Cc: Zev Weiss , openbmc@lists.ozlabs.org, Rob Herring , devicetree@vger.kernel.org, Mark Brown , Liam Girdwood Subject: [PATCH v2 0/2] misc: Add power-efuse driver Date: Mon, 7 Mar 2022 17:18:08 -0800 Message-Id: <20220308011811.10353-1-zev@bewilderbeest.net> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, This is a second revision of the v1 patch series posted previously [2]. Changes since v1: - dropped pmbus/lm25066 patches, submitted separately via hwmon tree [Guenter] - fixed indentation in power-efuse.yaml [Rob's bot] - added more detailed description in power-efuse.yaml [Rob] - added sysfs ABI documentation [Greg] - replaced manual struct attribute_group and sysfs_create_group() with ATTRIBUTE_GROUPS() and driver.dev_groups [Greg] A lightly edited version of the previous cover letter follows. This patch series is another incarnation of some previous efforts [0] at enabling userspace access to the OPERATION state (and now status flags) of PMBus devices, specifically with respect to efuses protecting general-purpose power outputs. This functionality is an important component enabling a port of OpenBMC to the Delta AHE-50DC Open19 power shelf [1]. The first patch adds dt-bindings, and the second adds the implementation of the power-efuse driver. The driver is fairly simple; it merely provides a sysfs interface to enable, disable, and retrieve error flags from an underlying regulator (which in the expected usage will most likely be a PMBus device). There is one aspect of its usage of the regulator API I'm a bit uncertain about, however: this driver seems like a case where an exclusive 'get' of the regulator (i.e. devm_regulator_get_exclusive() instead of devm_regulator_get() in efuse_probe()) would be appropriate, since in the intended usage no other device should be using an efuse's regulator. With an exclusive get though, the regulator's use_count and the consumer's enable_count don't balance out properly to allow the enable/disable operations to work properly (the former ending up one more than the latter, leading to enable_count underflows on attempts to disable the regulator). So at least for now it's using a non-exclusive get -- I'd be happy to hear any pointers on a way to allow an exclusive get to work here, though. Thanks, Zev [0] https://lore.kernel.org/openbmc/YGLepYLvtlO6Ikzs@hatter.bewilderbeest.net/ [1] https://www.open19.org/marketplace/delta-16kw-power-shelf/ [2] https://lore.kernel.org/openbmc/20220217104444.7695-1-zev@bewilderbeest.net/ Zev Weiss (2): dt-bindings: Add power-efuse binding misc: Add power-efuse driver .../ABI/testing/sysfs-driver-power-efuse | 32 +++ .../devicetree/bindings/misc/power-efuse.yaml | 49 ++++ MAINTAINERS | 5 + drivers/misc/Kconfig | 15 ++ drivers/misc/Makefile | 1 + drivers/misc/power-efuse.c | 212 ++++++++++++++++++ 6 files changed, 314 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-driver-power-efuse create mode 100644 Documentation/devicetree/bindings/misc/power-efuse.yaml create mode 100644 drivers/misc/power-efuse.c -- 2.35.1