linux-kernel - [PATCH 06/13] clk: keep track if a clock is explicitly configured

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Message-Id: <20230918-imx8mp-dtsi-v1-6-1d008b3237c0@skidata.com>
Date:   Mon, 18 Sep 2023 00:40:02 +0200
From:   Benjamin Bara <bbara93@...il.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Abel Vesa <abelvesa@...nel.org>, Peng Fan <peng.fan@....com>
Cc:     Frank Oltmanns <frank@...manns.dev>,
        Maxime Ripard <mripard@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org,
        Benjamin Bara <benjamin.bara@...data.com>
Subject: [PATCH 06/13] clk: keep track if a clock is explicitly configured

From: Benjamin Bara <benjamin.bara@...data.com>

When we keep track if a clock has a given rate explicitly set by a
consumer, we can identify unintentional clock rate changes in an easy
way. This also helps during debugging, as one can see if a rate is set
by accident or due to a consumer-related change.

Signed-off-by: Benjamin Bara <benjamin.bara@...data.com>
---
 drivers/clk/clk.c            | 25 +++++++++++++++++++++++++
 include/linux/clk-provider.h |  1 +
 2 files changed, 26 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 8f4f92547768..82c65ed432c5 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -70,6 +70,7 @@ struct clk_core {
 	unsigned long		rate;
 	unsigned long		req_rate;
 	unsigned long		new_rate;
+	unsigned long		set_rate;
 	struct clk_core		*new_parent;
 	struct clk_core		*new_child;
 	unsigned long		flags;
@@ -541,6 +542,12 @@ bool __clk_is_enabled(struct clk *clk)
 }
 EXPORT_SYMBOL_GPL(__clk_is_enabled);
 
+bool __clk_is_rate_set(struct clk *clk)
+{
+	return clk->core->set_rate > 0;
+}
+EXPORT_SYMBOL_GPL(__clk_is_rate_set);
+
 static bool mux_is_better_rate(unsigned long rate, unsigned long now,
 			   unsigned long best, unsigned long flags)
 {
@@ -578,6 +585,19 @@ static bool clk_core_has_parent(struct clk_core *core, const struct clk_core *pa
 	return false;
 }
 
+static bool clk_core_is_ancestor(struct clk_core *core, const struct clk_core *ancestor)
+{
+	struct clk_core *tmp = core->parent;
+
+	while (tmp) {
+		if (tmp == ancestor)
+			return true;
+		tmp = tmp->parent;
+	}
+
+	return false;
+}
+
 static void
 clk_core_forward_rate_req(struct clk_core *core,
 			  const struct clk_rate_request *old_req,
@@ -2358,6 +2378,9 @@ static void clk_change_rate(struct clk_core *core)
 
 	trace_clk_set_rate_complete(core, core->new_rate);
 
+	if (rate_trigger_clk && clk_core_is_ancestor(rate_trigger_clk->core, core))
+		core->set_rate = core->new_rate;
+
 	core->rate = clk_recalc(core, best_parent_rate);
 
 	if (core->flags & CLK_SET_RATE_UNGATE) {
@@ -2528,6 +2551,7 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 		clk_core_rate_protect(clk->core);
 
 	rate_trigger_clk = NULL;
+	clk->core->set_rate = rate;
 
 	clk_prepare_unlock();
 
@@ -2579,6 +2603,7 @@ int clk_set_rate_exclusive(struct clk *clk, unsigned long rate)
 	}
 
 	rate_trigger_clk = NULL;
+	clk->core->set_rate = rate;
 
 	clk_prepare_unlock();
 
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 3fb99ed5e8d9..e3732e0bbed9 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -1325,6 +1325,7 @@ bool clk_hw_is_prepared(const struct clk_hw *hw);
 bool clk_hw_rate_is_protected(const struct clk_hw *hw);
 bool clk_hw_is_enabled(const struct clk_hw *hw);
 bool __clk_is_enabled(struct clk *clk);
+bool __clk_is_rate_set(struct clk *hw);
 struct clk *__clk_lookup(const char *name);
 int __clk_mux_determine_rate(struct clk_hw *hw,
 			     struct clk_rate_request *req);

-- 
2.34.1