From nobody Tue Nov 18 16:55:14 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=linaro.org ARC-Seal: i=1; a=rsa-sha256; t=1611256186; cv=none; d=zohomail.com; s=zohoarc; b=TNsegncQ0Ki9UhReKroyAeEkZucVcb3VHUgUGsa8OG16iq5bmKhfeYO9bSuK6sc0w/R7adWsqGHBONu8NsiyjDENfjY6sUi2yz0gEW4Rg1rPsAvtrGO/SASoNOKGO8+M9SuzGoz3XPVe3ISnzYYYl/Y5xbvSu6shse4Bw2qZPCc= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1611256186; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=upN7NId7waDqdq/y54Hzrsu+F+aVKMHy5OMUTW9rDEw=; b=dAmzfgV9y3rCDNta6cjGWqLb6gWupJcHpllrYoBbpm1q4CG4Pcj5EUpa+00mw7orN9AB26FYuEV65NEIk+36KByPEaC2YoZv8yaCZ0E0iWuitAHjf1AXA069v/xAX6goWYVJxfxwTVHOX0F9uafAuefIEioCjImBS1kyQDwGlcs= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1611256186088249.87106177532394; Thu, 21 Jan 2021 11:09:46 -0800 (PST) Received: from localhost ([::1]:35086 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l2fKy-0004uX-Nz for importer@patchew.org; Thu, 21 Jan 2021 14:09:44 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:55444) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l2fI1-0002AP-F3 for qemu-devel@nongnu.org; Thu, 21 Jan 2021 14:06:41 -0500 Received: from mail-wr1-x42f.google.com ([2a00:1450:4864:20::42f]:32893) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1l2fHr-0005kk-G6 for qemu-devel@nongnu.org; Thu, 21 Jan 2021 14:06:41 -0500 Received: by mail-wr1-x42f.google.com with SMTP id 7so2830908wrz.0 for ; Thu, 21 Jan 2021 11:06:28 -0800 (PST) Received: from orth.archaic.org.uk (orth.archaic.org.uk. [81.2.115.148]) by smtp.gmail.com with ESMTPSA id m18sm9820686wrw.43.2021.01.21.11.06.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Jan 2021 11:06:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=upN7NId7waDqdq/y54Hzrsu+F+aVKMHy5OMUTW9rDEw=; b=sn0dGRtex5P42T3hk2ht1eoYTF/07UWBYlpSpd3RZbe8zb9QSZ4BIdtMinLn+Uxt0o 2bNlUqkjAroSzWDqS/6rvaOr93syDheLNOfwXaqpDFjyqAUzZMAx5n2I6Z77uZLuscUk 79N2daVjLwtxNHbJDblLS2TpjR3w5P9KnUV5VPFKJrJQ7oAQiln3Sdny6I03xtjWfSO4 t11S/3QGsYWV2BnugGlB8mLqViHSzPkgi6EKxlItt1LYZraJIecs90zfilH4+aWkuKq0 I38sTjrCwRakEVEfu/kfI4s5wa9437NhcOlDxG/8ZT3UcBb3cHFFCxvMmYFYNVHbi3hw VNlQ== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=upN7NId7waDqdq/y54Hzrsu+F+aVKMHy5OMUTW9rDEw=; b=UfiEIhXYJWr4Sip5PRkV0/WRpbLj5c7dERpHdEAS8zjMbXRO8dE3SbM4aUQbUba67r xhF+DL2zPOwvm6mn81ut3RCkjqVojR81t8vIKagJrVBPeVTMhu5Vcwf4kGXPIDk0kPm5 UUouPnUUEic0ita9AYwqW0IvMhsbnBrmZXV27NjNGAGLg/IEpBOtDIjI/5nglWUB5Gx5 Hubq6hMiL1y7CVivsvhQdeGovItEsKhIUw5Jxns0jmhaHiplqTPsAFFYkHRLZCtjce0Y rHAoEKfZXNScmIV2VQTKlPXF28x4L+PEQK+EUJul17Hhf36kuSGU1J4QziT4J6FF8DMi fgjg== X-Gm-Message-State: AOAM532nr3iw5a46/oo3sX6go6mXrbNHvjx6tzpl8RjpU3g+XCxxDJv7 AX+P3EXHXb6GlV7ZFErjdqgTDQ== X-Google-Smtp-Source: ABdhPJyYWPeD96pTaj0aV0nL8Ev8OprHynYHbCPzOpziSnqAewyJM8u5fh0paz6SPgIOA/xFqA9W+g== X-Received: by 2002:adf:cc81:: with SMTP id p1mr858184wrj.339.1611255987447; Thu, 21 Jan 2021 11:06:27 -0800 (PST) From: Peter Maydell To: qemu-arm@nongnu.org, qemu-devel@nongnu.org Subject: [PATCH 02/25] clock: Add new clock_has_source() function Date: Thu, 21 Jan 2021 19:05:59 +0000 Message-Id: <20210121190622.22000-3-peter.maydell@linaro.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210121190622.22000-1-peter.maydell@linaro.org> References: <20210121190622.22000-1-peter.maydell@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a00:1450:4864:20::42f; envelope-from=peter.maydell@linaro.org; helo=mail-wr1-x42f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Damien Hedde , Luc Michel , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Add a function for checking whether a clock has a source. This is useful for devices which have input clocks that must be wired up by the board as it allows them to fail in realize rather than ploughing on with a zero-period clock. Signed-off-by: Peter Maydell Reviewed-by: Luc Michel Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- docs/devel/clocks.rst | 16 ++++++++++++++++ include/hw/clock.h | 15 +++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/docs/devel/clocks.rst b/docs/devel/clocks.rst index 2548d842322..c54bbb82409 100644 --- a/docs/devel/clocks.rst +++ b/docs/devel/clocks.rst @@ -235,6 +235,22 @@ object during device instance init. For example: /* set initial value to 10ns / 100MHz */ clock_set_ns(clk, 10); =20 +To enforce that the clock is wired up by the board code, you can +call ``clock_has_source()`` in your device's realize method: + +.. code-block:: c + + if (!clock_has_source(s->clk)) { + error_setg(errp, "MyDevice: clk input must be connected"); + return; + } + +Note that this only checks that the clock has been wired up; it is +still possible that the output clock connected to it is disabled +or has not yet been configured, in which case the period will be +zero. You should use the clock callback to find out when the clock +period changes. + Fetching clock frequency/period ------------------------------- =20 diff --git a/include/hw/clock.h b/include/hw/clock.h index 6382f346569..e5f45e2626d 100644 --- a/include/hw/clock.h +++ b/include/hw/clock.h @@ -139,6 +139,21 @@ void clock_clear_callback(Clock *clk); */ void clock_set_source(Clock *clk, Clock *src); =20 +/** + * clock_has_source: + * @clk: the clock + * + * Returns true if the clock has a source clock connected to it. + * This is useful for devices which have input clocks which must + * be connected by the board/SoC code which creates them. The + * device code can use this to check in its realize method that + * the clock has been connected. + */ +static inline bool clock_has_source(const Clock *clk) +{ + return clk->source !=3D NULL; +} + /** * clock_set: * @clk: the clock to initialize. --=20 2.20.1