From nobody Wed May 7 10:15:20 2025
Delivered-To: importer@patchew.org
Authentication-Results: mx.zohomail.com;
dkim=pass;
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=pass(p=none dis=none) header.from=linaro.org
ARC-Seal: i=1; a=rsa-sha256; t=1611919020; cv=none;
d=zohomail.com; s=zohoarc;
b=ntoOi7LD/rX19diaapFSkRhrgu3ctNQnTBrSyWS93F+YT2avDUCV8qwKAXqKxrB7+Q37FilrgzY84A5K4KkIi/wL8rm0Vc32StS2AY0RABKdFZkI8b3spX6k1LrqPVfMQ5mBZj413mehMq1Ya977EjVT7qw1ajPWRqEVv/xBPZk=
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com;
s=zohoarc;
t=1611919020;
h=Content-Type:Content-Transfer-Encoding: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=iwK74lUuICgESOvqT1mx3LAnqkaSE1TGL5QtPXgrPPg=;
b=lzGWTLULVFRSzA5qPH8rtH5aMMMd7DvyuKaNQI8pfxmGhiHL2qiSpNt5eP+ze4ec/I89fdcXgwaeLei5mofapggLr7VP57Sc5fLmErSJjxFtpob6gwvhMx3yOCK4iiIIiBuefOGP28OXh1xRt5D11xbSl473vPfYyWrV/Oo5ZUI=
ARC-Authentication-Results: i=1; mx.zohomail.com;
dkim=pass;
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=pass header.from=<peter.maydell@linaro.org> (p=none dis=none)
header.from=<peter.maydell@linaro.org>
Return-Path: <qemu-devel-bounces+importer=patchew.org@nongnu.org>
Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by
mx.zohomail.com
with SMTPS id 1611919020716834.7731222587017;
Fri, 29 Jan 2021 03:17:00 -0800 (PST)
Received: from localhost ([::1]:56850 helo=lists1p.gnu.org)
by lists.gnu.org with esmtp (Exim 4.90_1)
(envelope-from <qemu-devel-bounces+importer=patchew.org@nongnu.org>)
id 1l5Rlr-0001WF-Km
for importer@patchew.org; Fri, 29 Jan 2021 06:16:59 -0500
Received: from eggs.gnu.org ([2001:470:142:3::10]:59886)
by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)
(Exim 4.90_1) (envelope-from <peter.maydell@linaro.org>)
id 1l5RWD-0004mQ-Tv
for qemu-devel@nongnu.org; Fri, 29 Jan 2021 06:00:49 -0500
Received: from mail-wr1-x436.google.com ([2a00:1450:4864:20::436]:36770)
by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)
(Exim 4.90_1) (envelope-from <peter.maydell@linaro.org>)
id 1l5RW1-00072Z-6L
for qemu-devel@nongnu.org; Fri, 29 Jan 2021 06:00:49 -0500
Received: by mail-wr1-x436.google.com with SMTP id 6so8390504wri.3
for <qemu-devel@nongnu.org>; Fri, 29 Jan 2021 03:00:36 -0800 (PST)
Received: from orth.archaic.org.uk (orth.archaic.org.uk. [81.2.115.148])
by smtp.gmail.com with ESMTPSA id w20sm9268761wmm.12.2021.01.29.03.00.35
for <qemu-devel@nongnu.org>
(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);
Fri, 29 Jan 2021 03:00:35 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google;
h=from:to:subject:date:message-id:in-reply-to:references:mime-version
:content-transfer-encoding;
bh=iwK74lUuICgESOvqT1mx3LAnqkaSE1TGL5QtPXgrPPg=;
b=U13BeTUygQH1XUvVHKP2dVtmcBwprYNBphmRFkmWXNHQJ/+cgbrS02dhqM02nER1aC
Fx5ELd1zxFTEF86SjQ24iDktV+/9n9h+a1fgP10AcNy15hutD4EF1FjithCskA1sEu2V
9/cDmOvghJwFACXolCishdhh4JQ7ImhQagYZEaNdnBMqm8Bc0DPiCj5l+pusSwUcWrJD
/q2YrXWygRHGocmZhaAPlX5Oiroh/nN3X3zIJiEAfccrcDcy6udHVn1+kagZd5iKdUHa
9SgrJ/7EXudk5JMK7vF8s/3l1h5ieidkBrRPHs43QbatogYHlMXRm9J9C7nWQXcqOqOL
3rwQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20161025;
h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to
:references:mime-version:content-transfer-encoding;
bh=iwK74lUuICgESOvqT1mx3LAnqkaSE1TGL5QtPXgrPPg=;
b=hnC7hqPiVytfl6qCwqDqIIRGIz2ix6DVo4oCTfnGDUKl/Oc4UU6bdgNtdHGQMnrG39
dmCWRPb14sKKrgXh7liZBkj7T71a17siVkPhoFkPMl8sSmGKKD+Vs50sRQV/2ebmxexX
Q9Vb13YXZQtvIj1jmHg+tqVO7x5m4jejHvltvfoKg3GkfZhN2X4mK+k8vN6SvhOjbSJo
zoWr762aGzq0Lm+vqEWvaap/nkWc/UxrFQ6Lv0ipUDn3YckHr5aKwz3Coa3HLAr+Wwbz
UR55QVv2EjvG9pEb4tufpaijIjv1MgC4symauZseIGAXPCzCRwqvYQdBj4vYZMc1hWVk
ky5g==
X-Gm-Message-State: AOAM532uxryEpSua8HkFAt+A61LDLknchYN4YrHHUhn1T43jCzkVYc5I
YIN3Js3PdcXPvD1Ue2GK7FBEScAqFcWkng==
X-Google-Smtp-Source:
ABdhPJw7z6tbK5vBfiWW8DsxuF0PpjyAotORFNwiLQK9Uz0RiZY3N8wD6ZSYdzMLlFhWlsCvJHcihQ==
X-Received: by 2002:a05:6000:1105:: with SMTP id
z5mr3875424wrw.15.1611918035941;
Fri, 29 Jan 2021 03:00:35 -0800 (PST)
From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-devel@nongnu.org
Subject: [PULL 23/46] clock: Add new clock_has_source() function
Date: Fri, 29 Jan 2021 10:59:49 +0000
Message-Id: <20210129110012.8660-24-peter.maydell@linaro.org>
X-Mailer: git-send-email 2.20.1
In-Reply-To: <20210129110012.8660-1-peter.maydell@linaro.org>
References: <20210129110012.8660-1-peter.maydell@linaro.org>
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
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::436;
envelope-from=peter.maydell@linaro.org; helo=mail-wr1-x436.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: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <https://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org
Sender: "Qemu-devel" <qemu-devel-bounces+importer=patchew.org@nongnu.org>
X-ZohoMail-DKIM: pass (identity @linaro.org)
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 <peter.maydell@linaro.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Philippe Mathieu-Daud=C3=A9 <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daud=C3=A9 <f4bug@amsat.org>
Message-id: 20210128114145.20536-3-peter.maydell@linaro.org
Message-id: 20210121190622.22000-3-peter.maydell@linaro.org
---
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