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Subject[PATCH v4 6/6] clk: export the clk tree topology to debugfs
Date
Represents the clk tree as a directory hieraching in debugfs.  Each clk
is a directory filled with the following read-only entries:

clk_rate
clk_flags
clk_prepare_count
clk_enable_count
clk_notifier_count

This commit borrows some code from Yong Shen's patch to export clkdev
clk's to debugfs:
http://git.pengutronix.de/?p=imx/linux-2.6.git;a=commit;h=30aa15230747b3b92da16d841b1cf369f07192e7

Signed-off-by: Mike Turquette <mturquette@linaro.org>
Cc: Yong Shen <yong.shen@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
---
drivers/clk/Kconfig | 9 +++
drivers/clk/clk.c | 176 ++++++++++++++++++++++++++++++++++++++++++++++++++-
include/linux/clk.h | 3 +
3 files changed, 186 insertions(+), 2 deletions(-)
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index ba7eb8c..09cc198 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -19,3 +19,12 @@ config GENERIC_CLK_BASIC
help
Allow use of basic, single-function clock types. These
common definitions can be used across many platforms.
+
+config GENERIC_CLK_DEBUG
+ bool "Clock tree representation in debugs"
+ depends on GENERIC_CLK
+ help
+ Creates a directory hierchy in debugfs for visualizing the clk
+ tree structure as well. Each directory contains read-only
+ members that export information specific to that clk node:
+ clk_rate, clk_flags, clk_prepare_count & clk_enable_count.
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index f86cb98..a6ddbb1 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -23,6 +23,166 @@ static DEFINE_MUTEX(prepare_lock);
static HLIST_HEAD(clk_root_list);
static LIST_HEAD(clk_notifier_list);

+/*** debugfs support ***/
+
+#ifdef CONFIG_GENERIC_CLK_DEBUG
+#include <linux/debugfs.h>
+
+static struct dentry *rootdir;
+static int inited = 0;
+
+/* caller must hold prepare_lock */
+static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry)
+{
+ struct dentry *d;
+ int ret = -ENOMEM;
+
+ if (!clk || !pdentry) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ d = debugfs_create_dir(clk->name, pdentry);
+ if (!d)
+ goto out;
+
+ clk->dentry = d;
+
+ d = debugfs_create_u64("clk_rate", S_IRUGO, clk->dentry,
+ (u64 *)&clk->rate);
+ if (!d)
+ goto err_out;
+
+ d = debugfs_create_x32("clk_flags", S_IRUGO, clk->dentry,
+ (u32 *)&clk->flags);
+ if (!d)
+ goto err_out;
+
+ d = debugfs_create_u32("clk_prepare_count", S_IRUGO, clk->dentry,
+ (u32 *)&clk->prepare_count);
+ if (!d)
+ goto err_out;
+
+ d = debugfs_create_u32("clk_enable_count", S_IRUGO, clk->dentry,
+ (u32 *)&clk->enable_count);
+ if (!d)
+ goto err_out;
+
+ d = debugfs_create_u32("clk_notifier_count", S_IRUGO, clk->dentry,
+ (u32 *)&clk->notifier_count);
+ if (!d)
+ goto err_out;
+
+ ret = 0;
+ goto out;
+
+err_out:
+ debugfs_remove(clk->dentry);
+out:
+ return ret;
+}
+
+/* caller must hold prepare_lock */
+static int clk_debug_create_subtree(struct clk *clk, struct dentry *pdentry)
+{
+ struct clk *child;
+ struct hlist_node *tmp;
+ int ret = -EINVAL;;
+
+ if (!clk || !pdentry)
+ goto out;
+
+ ret = clk_debug_create_one(clk, pdentry);
+
+ if (ret)
+ goto out;
+
+ hlist_for_each_entry(child, tmp, &clk->children, child_node)
+ clk_debug_create_subtree(child, clk->dentry);
+
+ ret = 0;
+out:
+ return ret;
+}
+
+/**
+ * clk_debug_register - add a clk node to the debugfs clk tree
+ * @clk: the clk being added to the debugfs clk tree
+ *
+ * Dynamically adds a clk to the debugfs clk tree if debugfs has been
+ * initialized. Otherwise it bails out early since the debugfs clk tree
+ * will be created lazily by clk_debug_init as part of a late_initcall.
+ *
+ * Caller must hold prepare_lock. Only clk_init calls this function (so
+ * far) so this is taken care.
+ */
+static int clk_debug_register(struct clk *clk)
+{
+ struct clk *parent;
+ struct dentry *pdentry;
+ int ret = 0;
+
+ if (!inited)
+ goto out;
+
+ parent = clk->parent;
+
+ /*
+ * Check to see if a clk is a root clk. Also check that it is
+ * safe to add this clk to debugfs
+ */
+ if (!parent)
+ pdentry = rootdir;
+ else
+ if (parent->dentry)
+ pdentry = parent->dentry;
+ else
+ goto out;
+
+ ret = clk_debug_create_subtree(clk, pdentry);
+
+out:
+ return ret;
+}
+
+/**
+ * clk_debug_init - lazily create the debugfs clk tree visualization
+ *
+ * clks are often initialized very early during boot before memory can
+ * be dynamically allocated and well before debugfs is setup.
+ * clk_debug_init walks the clk tree hierarchy while holding
+ * prepare_lock and creates the topology as part of a late_initcall,
+ * thus insuring that clks initialized very early will still be
+ * represented in the debugfs clk tree. This function should only be
+ * called once at boot-time, and all other clks added dynamically will
+ * be done so with clk_debug_register.
+ */
+static int __init clk_debug_init(void)
+{
+ struct clk *root_clk;
+ struct hlist_node *tmp;
+
+ rootdir = debugfs_create_dir("clk", NULL);
+
+ if (!rootdir)
+ return -ENOMEM;
+
+ mutex_lock(&prepare_lock);
+
+ hlist_for_each_entry(root_clk, tmp, &clk_root_list, child_node)
+ clk_debug_create_subtree(root_clk, rootdir);
+
+ inited = 1;
+
+ mutex_unlock(&prepare_lock);
+
+ return 0;
+}
+late_initcall(clk_debug_init);
+#else
+static inline int clk_debug_register(struct clk *clk) { return 0; }
+#endif /* CONFIG_GENERIC_CLK_DEBUG */
+
/*** clk API ***/

void __clk_unprepare(struct clk *clk)
@@ -574,15 +734,25 @@ EXPORT_SYMBOL_GPL(clk_get_parent);

void __clk_reparent(struct clk *clk, struct clk *new_parent)
{
+ struct dentry *d;
+
if (!clk || !new_parent)
return;

hlist_del(&clk->child_node);
hlist_add_head(&clk->child_node, &new_parent->children);

- clk->parent = new_parent;
+#ifdef CONFIG_GENERIC_CLK_DEBUG
+ d = debugfs_rename(clk->parent->dentry, clk->dentry,
+ new_parent->dentry, clk->name);
+ if (d)
+ clk->dentry = d;
+ else
+ pr_debug("%s: failed to reparent debugfs entry for %s\n",
+ __func__, clk->name);
+#endif

- /* FIXME update sysfs clock topology */
+ clk->parent = new_parent;
}

/**
@@ -697,6 +867,8 @@ void clk_init(struct device *dev, struct clk *clk)
else
clk->rate = 0;

+ clk_debug_register(clk);
+
mutex_unlock(&prepare_lock);

return;
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 55049ee..6cf3e2b 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -46,6 +46,9 @@ struct clk {
struct hlist_head children;
struct hlist_node child_node;
unsigned int notifier_count;
+#ifdef CONFIG_GENERIC_CLK_DEBUG
+ struct dentry *dentry;
+#endif
};

/**
--
1.7.5.4


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