linux-kernel - [PATCH 05/13] clk: keep track of the trigger of an ongoing clk_set

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Date:   Mon, 18 Sep 2023 00:40:01 +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 05/13] clk: keep track of the trigger of an ongoing
 clk_set_rate

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

When we keep track of the rate change trigger, we can easily check if an
affected clock is affiliated with the trigger. Additionally, the trigger
is added to the notify data, so that drivers can implement workarounds
that might be necessary if a shared parent changes.

Signed-off-by: Benjamin Bara <benjamin.bara@...data.com>
---
 drivers/clk/clk.c   | 12 ++++++++++++
 include/linux/clk.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 4954d31899ce..8f4f92547768 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -33,6 +33,9 @@ static struct task_struct *enable_owner;
 static int prepare_refcnt;
 static int enable_refcnt;
 
+/* responsible for ongoing rate change, protected by prepare_lock */
+static struct clk *rate_trigger_clk;
+
 static HLIST_HEAD(clk_root_list);
 static HLIST_HEAD(clk_orphan_list);
 static LIST_HEAD(clk_notifier_list);
@@ -1742,6 +1745,7 @@ static int __clk_notify(struct clk_core *core, unsigned long msg,
 
 	cnd.old_rate = old_rate;
 	cnd.new_rate = new_rate;
+	cnd.trigger = rate_trigger_clk ? : core->parent->hw->clk;
 
 	list_for_each_entry(cn, &clk_notifier_list, node) {
 		if (cn->clk->core == core) {
@@ -2513,6 +2517,8 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	/* prevent racing with updates to the clock topology */
 	clk_prepare_lock();
 
+	rate_trigger_clk = clk;
+
 	if (clk->exclusive_count)
 		clk_core_rate_unprotect(clk->core);
 
@@ -2521,6 +2527,8 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	if (clk->exclusive_count)
 		clk_core_rate_protect(clk->core);
 
+	rate_trigger_clk = NULL;
+
 	clk_prepare_unlock();
 
 	return ret;
@@ -2556,6 +2564,8 @@ int clk_set_rate_exclusive(struct clk *clk, unsigned long rate)
 	/* prevent racing with updates to the clock topology */
 	clk_prepare_lock();
 
+	rate_trigger_clk = clk;
+
 	/*
 	 * The temporary protection removal is not here, on purpose
 	 * This function is meant to be used instead of clk_rate_protect,
@@ -2568,6 +2578,8 @@ int clk_set_rate_exclusive(struct clk *clk, unsigned long rate)
 		clk->exclusive_count++;
 	}
 
+	rate_trigger_clk = NULL;
+
 	clk_prepare_unlock();
 
 	return ret;
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 06f1b292f8a0..f0fe78c7a0f1 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -60,6 +60,7 @@ struct clk_notifier {
 /**
  * struct clk_notifier_data - rate data to pass to the notifier callback
  * @clk: struct clk * being changed
+ * @trigger: struct clk * being responsible for the change
  * @old_rate: previous rate of this clk
  * @new_rate: new rate of this clk
  *
@@ -70,6 +71,7 @@ struct clk_notifier {
  */
 struct clk_notifier_data {
 	struct clk		*clk;
+	struct clk		*trigger;
 	unsigned long		old_rate;
 	unsigned long		new_rate;
 };

-- 
2.34.1