ARM: iMX51 BBG: add clock debug information

Expose clock debug information to debugfs, which makes it easier for clock
system debug by using tools like powerdebug developed by Linaro power
management group.
For long term, this can go into common clock framework, but so far it depends
on the process of common clk API development. Once the common clk API is
ready in upstream, the clock debug information will be based on it too.
The implementation based on common clk API had also been finished and
reviewed with Jeremy.

Signed-off-by: Yong Shen <yong.shen@linaro.org>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>

1 files changed, 121 insertions, 0 deletions

diff --git a/arch/arm/plat-mxc/clock.c b/arch/arm/plat-mxc/clock.c
index 2ed3ab173ad..190bce1221a 100644
--- a/arch/arm/plat-mxc/clock.c
+++ b/arch/arm/plat-mxc/clock.c
@@ -37,6 +37,8 @@
 #include <linux/proc_fs.h>
 #include <linux/semaphore.h>
 #include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/debugfs.h>
 
 #include <mach/clock.h>
 #include <mach/hardware.h>
@@ -244,3 +246,122 @@ unsigned long mxc_decode_pll(unsigned int reg_val, u32 freq)
 
 	return ll;
 }
+
+#ifdef CONFIG_CLK_DEBUG
+/*
+ *	debugfs support to trace clock tree hierarchy and attributes
+ */
+static int clk_debug_rate_get(void *data, u64 *val)
+{
+	struct clk *clk = data;
+
+	*val = (u64)clk_get_rate(clk);
+	return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(clk_debug_rate_fops, clk_debug_rate_get, NULL,
+		"%llu\n");
+
+
+static struct dentry *clk_root;
+static int clk_debug_register_one(struct clk *clk)
+{
+	int err;
+	struct dentry *d, *child, *child_tmp;
+	struct clk *pa = clk_get_parent(clk);
+
+	if (pa && !IS_ERR(pa))
+		d = debugfs_create_dir(clk->name, pa->dentry);
+	else {
+		if (!clk_root)
+			clk_root = debugfs_create_dir("clock", NULL);
+		if (!clk_root)
+			return -ENOMEM;
+		d = debugfs_create_dir(clk->name, clk_root);
+	}
+
+	if (!d)
+		return -ENOMEM;
+
+	clk->dentry = d;
+
+	d = debugfs_create_u32("enable_count", S_IRUGO, clk->dentry,
+			(u32 *)&clk->usecount);
+	if (!d) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	d = debugfs_create_file("rate", S_IRUGO, clk->dentry, (void *)clk,
+			&clk_debug_rate_fops);
+	if (!d) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	return 0;
+
+err_out:
+	d = clk->dentry;
+	list_for_each_entry_safe(child, child_tmp, &d->d_subdirs, d_u.d_child)
+		debugfs_remove(child);
+	debugfs_remove(clk->dentry);
+	return err;
+}
+
+struct preinit_clk {
+	struct list_head list;
+	struct clk *clk;
+};
+static LIST_HEAD(preinit_clks);
+static DEFINE_MUTEX(preinit_lock);
+static int init_done;
+
+void clk_debug_register(struct clk *clk)
+{
+	int err;
+	struct clk *pa;
+
+	if (init_done) {
+		pa = clk_get_parent(clk);
+
+		if (pa && !IS_ERR(pa) && !pa->dentry)
+			clk_debug_register(pa);
+
+		if (!clk->dentry) {
+			err = clk_debug_register_one(clk);
+			if (err)
+				return;
+		}
+	} else {
+		struct preinit_clk *p;
+		mutex_lock(&preinit_lock);
+		p = kmalloc(sizeof(*p), GFP_KERNEL);
+		if (p) {
+			p->clk = clk;
+			list_add(&p->list, &preinit_clks);
+		}
+		mutex_unlock(&preinit_lock);
+	}
+}
+EXPORT_SYMBOL_GPL(clk_debug_register);
+
+static int __init clk_debugfs_init(void)
+{
+	struct preinit_clk *pclk, *tmp;
+
+	init_done = 1;
+
+	mutex_lock(&preinit_lock);
+	list_for_each_entry(pclk, &preinit_clks, list) {
+		clk_debug_register(pclk->clk);
+	}
+
+	list_for_each_entry_safe(pclk, tmp, &preinit_clks, list) {
+		list_del(&pclk->list);
+		kfree(pclk);
+	}
+	mutex_unlock(&preinit_lock);
+	return 0;
+}
+late_initcall(clk_debugfs_init);
+#endif