linux-kernel - [PATCH v13 4/9] clk: per-user clock accounting for debug

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Message-Id: <1411497857-24726-2-git-send-email-tomeu.vizoso@collabora.com>
Date:	Tue, 23 Sep 2014 20:44:12 +0200
From:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:	Mike Turquette <mturquette@...aro.org>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	tomasz.figa@...il.com,
	Peter De Schrijver <pdeschrijver@...dia.com>, rabin@....in,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	Russell King <linux@....linux.org.uk>,
	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Subject: [PATCH v13 4/9] clk: per-user clock accounting for debug

When a clock has multiple users, the WARNING on imbalance of
enable/disable may not show the guilty party since although they may
have commited the error earlier, the warning is emitted later when some
other user, presumably innocent, disables the clock.

Provide per-user clock enable/disable accounting and disabler tracking
in order to help debug these problems.

Based on previous work by Rabin Vincent <rabin@....in>.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
Tested-by: Heiko Stuebner <heiko@...ech.de>
---
 drivers/clk/clk.c           | 38 ++++++++++++++++++++++++++++++++++----
 drivers/clk/clk.h           |  3 ++-
 drivers/clk/clkdev.c        | 11 ++++++-----
 include/linux/clk-private.h |  5 +++++
 4 files changed, 47 insertions(+), 10 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index ffe58ec..b34922e 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -543,7 +543,8 @@ static int clk_disable_unused(void)
 }
 late_initcall_sync(clk_disable_unused);
 
-struct clk *__clk_create_clk(struct clk_core *clk_core)
+struct clk *__clk_create_clk(struct clk_core *clk_core, const char *dev,
+			     const char *con)
 {
 	struct clk *clk;
 
@@ -556,6 +557,8 @@ struct clk *__clk_create_clk(struct clk_core *clk_core)
 		return ERR_PTR(-ENOMEM);
 
 	clk->core = clk_core;
+	clk->dev_id = dev;
+	clk->con_id = con;
 
 	return clk;
 }
@@ -980,10 +983,25 @@ EXPORT_SYMBOL_GPL(clk_provider_disable);
  */
 void clk_disable(struct clk *clk_user)
 {
+	struct clk_core *clk;
+	unsigned long flags;
+
 	if (IS_ERR_OR_NULL(clk_user))
 		return;
 
-	clk_provider_disable(clk_to_clk_core(clk_user));
+	clk = clk_to_clk_core(clk_user);
+
+	flags = clk_enable_lock();
+	if (!WARN(clk_user->enable_count == 0,
+		  "incorrect disable clk dev %s con %s last disabler %pF\n",
+		  clk_user->dev_id, clk_user->con_id, clk_user->last_disable)) {
+
+		clk_user->last_disable = __builtin_return_address(0);
+		clk_user->enable_count--;
+
+		__clk_disable(clk);
+	}
+	clk_enable_unlock(flags);
 }
 EXPORT_SYMBOL_GPL(clk_disable);
 
@@ -1044,10 +1062,22 @@ EXPORT_SYMBOL_GPL(clk_provider_enable);
  */
 int clk_enable(struct clk *clk_user)
 {
+	struct clk_core *clk;
+	unsigned long flags;
+	int ret;
+
 	if (!clk_user)
 		return 0;
 
-	return clk_provider_enable(clk_to_clk_core(clk_user));
+	clk = clk_to_clk_core(clk_user);
+
+	flags = clk_enable_lock();
+	ret = __clk_enable(clk);
+	if (!ret)
+		clk_user->enable_count++;
+	clk_enable_unlock(flags);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(clk_enable);
 
@@ -1745,7 +1775,7 @@ struct clk *clk_get_parent(struct clk *clk_user)
 	if (IS_ERR(parent))
 		return (void *)parent;
 
-	parent_user = __clk_create_clk(parent);
+	parent_user = __clk_create_clk(parent, clk_user->dev_id, clk_user->con_id);
 	if (IS_ERR(parent_user))
 		__clk_put(parent);
 
diff --git a/drivers/clk/clk.h b/drivers/clk/clk.h
index 3b3068b..49eff38 100644
--- a/drivers/clk/clk.h
+++ b/drivers/clk/clk.h
@@ -19,5 +19,6 @@ void of_clk_unlock(void);
 #endif
 
 #if defined(CONFIG_COMMON_CLK)
-struct clk *__clk_create_clk(struct clk_core *clk_core);
+struct clk *__clk_create_clk(struct clk_core *clk_core, const char *dev,
+			     const char *con);
 #endif
diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index f99c1e4..8699a9b 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -36,7 +36,7 @@ static DEFINE_MUTEX(clocks_mutex);
 typedef struct clk_core clkdev_ret_t;
 #else
 typedef struct clk clkdev_ret_t;
-#define __clk_create_clk(clk) clk
+#define __clk_create_clk(clk, dev_id, con_id) clk
 #define clk_to_clk_core(clk) clk
 #endif
 
@@ -96,7 +96,7 @@ struct clk *of_clk_get(struct device_node *np, int index)
 	if (IS_ERR(clk))
 		return (void *)clk;
 
-	clk_user = __clk_create_clk(clk);
+	clk_user = __clk_create_clk(clk, np->full_name, NULL);
 	if (IS_ERR(clk_user))
 		__clk_put(clk);
 
@@ -160,7 +160,7 @@ struct clk *of_clk_get_by_name(struct device_node *np, const char *name)
 	if (IS_ERR(clk))
 		return (void *)clk;
 
-	clk_user = __clk_create_clk(clk);
+	clk_user = __clk_create_clk(clk, np->full_name, NULL);
 	if (IS_ERR(clk_user))
 		__clk_put(clk);
 
@@ -238,7 +238,7 @@ struct clk *clk_get_sys(const char *dev_id, const char *con_id)
 	if (IS_ERR(clk))
 		return (void *)clk;
 
-	clk_user = __clk_create_clk(clk);
+	clk_user = __clk_create_clk(clk, dev_id, con_id);
 	if (IS_ERR(clk_user))
 		__clk_put(clk);
 
@@ -265,6 +265,7 @@ EXPORT_SYMBOL(clk_provider_get);
 
 struct clk *clk_get(struct device *dev, const char *con_id)
 {
+	const char *dev_id = dev ? dev_name(dev) : NULL;
 	clkdev_ret_t *clk;
 	struct clk *clk_user;
 
@@ -272,7 +273,7 @@ struct clk *clk_get(struct device *dev, const char *con_id)
 	if (IS_ERR(clk))
 		return (void *)clk;
 
-	clk_user = __clk_create_clk(clk);
+	clk_user = __clk_create_clk(clk, dev_id, con_id);
 	if (IS_ERR(clk_user))
 		__clk_put(clk);
 
diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
index 2c1ece9..ce6a528 100644
--- a/include/linux/clk-private.h
+++ b/include/linux/clk-private.h
@@ -57,6 +57,11 @@ struct clk_core {
 
 struct clk {
 	struct clk_core	*core;
+	const char	*dev_id;
+	const char	*con_id;
+
+	unsigned int	enable_count;
+	void		*last_disable;
 };
 
 /*
-- 
1.9.3

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