From patchwork Thu Nov 12 23:00:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amjad Ouled-Ameur X-Patchwork-Id: 11902213 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EBB42138B for ; Thu, 12 Nov 2020 23:01:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C303D20797 for ; Thu, 12 Nov 2020 23:01:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=baylibre-com.20150623.gappssmtp.com header.i=@baylibre-com.20150623.gappssmtp.com header.b="l2Fb6GIr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726248AbgKLXBk (ORCPT ); Thu, 12 Nov 2020 18:01:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725973AbgKLXBj (ORCPT ); Thu, 12 Nov 2020 18:01:39 -0500 Received: from mail-wm1-x342.google.com (mail-wm1-x342.google.com [IPv6:2a00:1450:4864:20::342]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 100BBC0613D1 for ; Thu, 12 Nov 2020 15:01:39 -0800 (PST) Received: by mail-wm1-x342.google.com with SMTP id d142so6605025wmd.4 for ; Thu, 12 Nov 2020 15:01:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id; bh=Ay3g0WHJ5Z9sUFSsAiMtS3+CU9KxkEqczCaxCW1Xrgs=; b=l2Fb6GIrmV3NoRJY2y5tThITGKwdA6NgrUFo7qxhmNyIc+62ajsl9yBM9kBzY4kfI/ 6zrya4RPSp3Q1hopNqi5WabvuhTfkABp1kemsZhUgjmWeMy7KXQqJ5l4yM9ZqoBBn0tB y3gbvZ82PsUKTZfbw2zvaAl4WQfdlxYGD8fKkMmMlIxKv2U524dwT3OKIoY4lgkkNx0F ZweSwv4u5pdNR3c+tDswKLi/su1xzWR1gbZuzN3WQBCFHbpb6pGSdHJIRP1SImH9CcvK AynSSOMnnlOeB5G39R7YrCGg9++bWzW5O5E32YbNXKAt3cVZ6FlF3fQ2iITPdX3GTAH8 a7/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=Ay3g0WHJ5Z9sUFSsAiMtS3+CU9KxkEqczCaxCW1Xrgs=; b=LZJ2178eODcGi+lM8qAm3fXhG/AvjzW5sI69e8zIBGZOY/rPsjAcUwmD/zRSShoIUD tNsEYth4wiWbmb7iuQNconmva0p5qsdCT9yiJk69HmxURJ5NNVPhMVwFRCV4zhaxVMj1 714MWtMRH6VvtjwSwYeKU/d3VUc9Rgoe6lInYNTbMrcA1DoCJP0pzqdMbvyl/CMoiLNX LN1s7bnr9yBj5P6V7QX/fM7qoLLc9fIlICPFdeNl+BVa7/DHALZIxf+bGczOAcijSBpg /eCILdypw/QM453x2SoZGOCr5++sKYugsssKlUNeb0sznaRxYDcUbOMCgG4qGndQNgqW 44Fg== X-Gm-Message-State: AOAM533ZFB5QZLZcbnxz8msLI3Xp0vNq7lhZRxmn64LA3w/zeholqXms wSYFJWHG+HAmbLbKi0VFLoJUEQ== X-Google-Smtp-Source: ABdhPJxb0BlqXQvBwyt/FteBmLbQxyaS2N/LIBSC7x1esLzEKogJMph0rp55RJTnahob7LDMp4vhUA== X-Received: by 2002:a1c:b387:: with SMTP id c129mr124748wmf.66.1605222075499; Thu, 12 Nov 2020 15:01:15 -0800 (PST) Received: from localhost.localdomain ([2001:861:3a84:7260:5d3c:83d5:8524:33ca]) by smtp.googlemail.com with ESMTPSA id h4sm8185984wrq.3.2020.11.12.15.01.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Nov 2020 15:01:14 -0800 (PST) From: Amjad Ouled-Ameur To: Philipp Zabel Cc: Amjad Ouled-Ameur , linux-kernel@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-usb@vger.kernel.org, Jerome Brunet , Kevin Hilman , Jim Quinlan Subject: [PATCH v2] reset: make shared pulsed reset controls re-triggerable Date: Fri, 13 Nov 2020 00:00:43 +0100 Message-Id: <20201112230043.28987-1-aouledameur@baylibre.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org The current reset framework API does not allow to release what is done by reset_control_reset(), IOW decrement triggered_count. Add the new reset_control_rearm() call to do so. When reset_control_reset() has been called once, the counter triggered_count, in the reset framework, is incremented i.e the resource under the reset is in-use and the reset should not be done again. reset_control_rearm() would be the way to state that the resource is no longer used and, that from the caller's perspective, the reset can be fired again if necessary. Signed-off-by: Amjad Ouled-Ameur Reported-by: Jerome Brunet --- Change since v1: [0] * Renamed the new call from reset_control_(array_)resettable to reset_control_(array_)rearm * Open-coded reset_control_array_rearm to check for errors before decrementing triggered_count because we cannot roll back in case an error occurs while decrementing one of the rstc. * Reworded the new call's description. [0] https://lore.kernel.org/lkml/20201001132758.12280-1-aouledameur@baylibre.com drivers/reset/core.c | 73 +++++++++++++++++++++++++++++++++++++++++++ include/linux/reset.h | 1 + 2 files changed, 74 insertions(+) diff --git a/drivers/reset/core.c b/drivers/reset/core.c index a2df88e90011..34e89aa0fb5e 100644 --- a/drivers/reset/core.c +++ b/drivers/reset/core.c @@ -208,6 +208,39 @@ static int reset_control_array_reset(struct reset_control_array *resets) return 0; } +static int reset_control_array_rearm(struct reset_control_array *resets) +{ + struct reset_control *rstc; + int i; + + for (i = 0; i < resets->num_rstcs; i++) { + rstc = resets->rstc[i]; + + if (!rstc) + continue; + + if (WARN_ON(IS_ERR(rstc))) + return -EINVAL; + + if (rstc->shared) { + if (WARN_ON(atomic_read(&rstc->deassert_count) != 0)) + return -EINVAL; + } else { + if (!rstc->acquired) + return -EPERM; + } + } + + for (i = 0; i < resets->num_rstcs; i++) { + rstc = resets->rstc[i]; + + if (rstc && rstc->shared) + WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0); + } + + return 0; +} + static int reset_control_array_assert(struct reset_control_array *resets) { int ret, i; @@ -325,6 +358,46 @@ int reset_control_reset(struct reset_control *rstc) } EXPORT_SYMBOL_GPL(reset_control_reset); +/** + * reset_control_rearm - allow shared reset line to be re-triggered" + * @rstc: reset controller + * + * On a shared reset line the actual reset pulse is only triggered once for the + * lifetime of the reset_control instance, except if this call is used. + * + * Calls to this function must be balanced with calls to reset_control_reset, + * a warning is thrown in case triggered_count ever dips below 0. + * + * Consumers must not use reset_control_(de)assert on shared reset lines when + * reset_control_reset or reset_control_rearm have been used. + * + * If rstc is NULL the function will just return 0. + */ +int reset_control_rearm(struct reset_control *rstc) +{ + if (!rstc) + return 0; + + if (WARN_ON(IS_ERR(rstc))) + return -EINVAL; + + if (reset_control_is_array(rstc)) + return reset_control_array_rearm(rstc_to_array(rstc)); + + if (rstc->shared) { + if (WARN_ON(atomic_read(&rstc->deassert_count) != 0)) + return -EINVAL; + + WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0); + } else { + if (!rstc->acquired) + return -EPERM; + } + + return 0; +} +EXPORT_SYMBOL_GPL(reset_control_rearm); + /** * reset_control_assert - asserts the reset line * @rstc: reset controller diff --git a/include/linux/reset.h b/include/linux/reset.h index 05aa9f440f48..439fec7112a9 100644 --- a/include/linux/reset.h +++ b/include/linux/reset.h @@ -13,6 +13,7 @@ struct reset_control; #ifdef CONFIG_RESET_CONTROLLER int reset_control_reset(struct reset_control *rstc); +int reset_control_rearm(struct reset_control *rstc); int reset_control_assert(struct reset_control *rstc); int reset_control_deassert(struct reset_control *rstc); int reset_control_status(struct reset_control *rstc);