ARM: SAMSUNG: Add support for clock debugging through debug-fs interface

This patch adds support for clock information exposed to debug-fs interface.

Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
[kgene.kim@samsung.com: removed useless empty lines]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/plat-samsung/clock.c

@@ -39,6 +39,9 @@
 #include <linux/clk.h>
 #include <linux/spinlock.h>
 #include <linux/io.h>
+#if defined(CONFIG_DEBUG_FS)
+#include <linux/debugfs.h>
+#endif
 
 #include <mach/hardware.h>
 #include <asm/irq.h>
@@ -447,3 +450,92 @@ int __init s3c24xx_register_baseclocks(unsigned long xtal)
 	return 0;
 }
 
+#if defined(CONFIG_PM_DEBUG) && defined(CONFIG_DEBUG_FS)
+/* debugfs support to trace clock tree hierarchy and attributes */
+
+static struct dentry *clk_debugfs_root;
+
+static int clk_debugfs_register_one(struct clk *c)
+{
+	int err;
+	struct dentry *d, *child, *child_tmp;
+	struct clk *pa = c->parent;
+	char s[255];
+	char *p = s;
+
+	p += sprintf(p, "%s", c->name);
+
+	if (c->id >= 0)
+		sprintf(p, ":%d", c->id);
+
+	d = debugfs_create_dir(s, pa ? pa->dent : clk_debugfs_root);
+	if (!d)
+		return -ENOMEM;
+
+	c->dent = d;
+
+	d = debugfs_create_u8("usecount", S_IRUGO, c->dent, (u8 *)&c->usage);
+	if (!d) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	d = debugfs_create_u32("rate", S_IRUGO, c->dent, (u32 *)&c->rate);
+	if (!d) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+	return 0;
+
+err_out:
+	d = c->dent;
+	list_for_each_entry_safe(child, child_tmp, &d->d_subdirs, d_u.d_child)
+		debugfs_remove(child);
+	debugfs_remove(c->dent);
+	return err;
+}
+
+static int clk_debugfs_register(struct clk *c)
+{
+	int err;
+	struct clk *pa = c->parent;
+
+	if (pa && !pa->dent) {
+		err = clk_debugfs_register(pa);
+		if (err)
+			return err;
+	}
+
+	if (!c->dent) {
+		err = clk_debugfs_register_one(c);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int __init clk_debugfs_init(void)
+{
+	struct clk *c;
+	struct dentry *d;
+	int err;
+
+	d = debugfs_create_dir("clock", NULL);
+	if (!d)
+		return -ENOMEM;
+	clk_debugfs_root = d;
+
+	list_for_each_entry(c, &clocks, list) {
+		err = clk_debugfs_register(c);
+		if (err)
+			goto err_out;
+	}
+	return 0;
+
+err_out:
+	debugfs_remove_recursive(clk_debugfs_root);
+	return err;
+}
+late_initcall(clk_debugfs_init);
+
+#endif /* defined(CONFIG_PM_DEBUG) && defined(CONFIG_DEBUG_FS) */

arch/arm/plat-samsung/include/plat/clock.h

@@ -47,6 +47,9 @@ struct clk {
 
 	struct clk_ops		*ops;
 	int		    (*enable)(struct clk *, int enable);
+#if defined(CONFIG_PM_DEBUG) && defined(CONFIG_DEBUG_FS)
+	struct dentry		*dent;	/* For visible tree hierarchy */
+#endif
 };
 
 /* other clocks which may be registered by board support */