clk: add/modify debugfs support for clocks

Update clock debugfs to support the below functionalities.
 - Allow enable/disable a clock.
 - Allow set_rate on a clock.
 - Display the list of enabled_clocks along with prepare_count,
   enable_count and rate.
 - Display the register contents of all the clocks which support
  this clock operation.

Change-Id: Ib67b3a3409c9e7d8adb710bb524f54f543abf712
Signed-off-by: Taniya Das <tdas@codeaurora.org>

drivers/clk/clk.c

@@ -2409,6 +2409,190 @@ static const struct file_operations clk_dump_fops = {
 	.release	= single_release,
 };
 
+static int clock_debug_rate_set(void *data, u64 val)
+{
+	struct clk_core *core = data;
+	int ret;
+
+	ret = clk_set_rate(core->hw->clk, val);
+	if (ret)
+		pr_err("clk_set_rate(%lu) failed (%d)\n",
+				(unsigned long)val, ret);
+
+	return ret;
+}
+
+static int clock_debug_rate_get(void *data, u64 *val)
+{
+	struct clk_core *core = data;
+
+	*val = core->hw->core->rate;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(clock_rate_fops, clock_debug_rate_get,
+			clock_debug_rate_set, "%llu\n");
+
+static ssize_t clock_parent_read(struct file *filp, char __user *ubuf,
+		size_t cnt, loff_t *ppos)
+{
+	char name[256] = {0};
+	struct clk_core *core = filp->private_data;
+	struct clk_core *p = core->hw->core->parent;
+
+	snprintf(name, sizeof(name), "%s\n", p ? p->name : "None\n");
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, name, strlen(name));
+}
+
+static const struct file_operations clock_parent_fops = {
+	.open	= simple_open,
+	.read	= clock_parent_read,
+};
+
+static int clock_debug_enable_set(void *data, u64 val)
+{
+	struct clk_core *core = data;
+	int rc = 0;
+
+	if (val)
+		rc = clk_prepare_enable(core->hw->clk);
+	else
+		clk_disable_unprepare(core->hw->clk);
+
+	return rc;
+}
+
+static int clock_debug_enable_get(void *data, u64 *val)
+{
+	struct clk_core *core = data;
+	int enabled = 0;
+
+	enabled = core->enable_count;
+
+	*val = enabled;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(clock_enable_fops, clock_debug_enable_get,
+			clock_debug_enable_set, "%lld\n");
+
+#define clock_debug_output(m, c, fmt, ...)		\
+do {							\
+	if (m)						\
+		seq_printf(m, fmt, ##__VA_ARGS__);	\
+	else if (c)					\
+		pr_cont(fmt, ##__VA_ARGS__);		\
+	else						\
+		pr_info(fmt, ##__VA_ARGS__);		\
+} while (0)
+
+int clock_debug_print_clock(struct clk_core *c, struct seq_file *s)
+{
+	char *start = "";
+	struct clk *clk;
+
+	if (!c || !c->prepare_count)
+		return 0;
+
+	clk = c->hw->clk;
+
+	clock_debug_output(s, 0, "\t");
+
+	do {
+		clock_debug_output(s, 1, "%s%s:%u:%u [%ld]", start,
+					clk->core->name,
+					clk->core->prepare_count,
+					clk->core->enable_count,
+					clk->core->rate);
+		start = " -> ";
+	} while ((clk = clk_get_parent(clk)));
+
+	clock_debug_output(s, 1, "\n");
+
+	return 1;
+}
+
+/*
+ * clock_debug_print_enabled_clocks() - Print names of enabled clocks
+ */
+static void clock_debug_print_enabled_clocks(struct seq_file *s)
+{
+	struct clk_core *core;
+	int cnt = 0;
+
+	clock_debug_output(s, 0, "Enabled clocks:\n");
+
+	mutex_lock(&clk_debug_lock);
+
+	hlist_for_each_entry(core, &clk_debug_list, debug_node)
+		cnt += clock_debug_print_clock(core, s);
+
+	mutex_unlock(&clk_debug_lock);
+
+	if (cnt)
+		clock_debug_output(s, 0, "Enabled clock count: %d\n", cnt);
+	else
+		clock_debug_output(s, 0, "No clocks enabled.\n");
+}
+
+static int enabled_clocks_show(struct seq_file *s, void *unused)
+{
+	clock_debug_print_enabled_clocks(s);
+
+	return 0;
+}
+
+static int enabled_clocks_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, enabled_clocks_show, inode->i_private);
+}
+
+static const struct file_operations clk_enabled_list_fops = {
+	.open		= enabled_clocks_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static void clk_debug_print_hw(struct clk_core *clk, struct seq_file *f)
+{
+	if (IS_ERR_OR_NULL(clk))
+		return;
+
+	clk_debug_print_hw(clk->parent, f);
+
+	clock_debug_output(f, false, "%s\n", clk->name);
+
+	if (!clk->ops->list_registers)
+		return;
+
+	clk->ops->list_registers(f, clk->hw);
+}
+
+static int print_hw_show(struct seq_file *m, void *unused)
+{
+	struct clk_core *c = m->private;
+
+	clk_debug_print_hw(c, m);
+
+	return 0;
+}
+
+static int print_hw_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, print_hw_show, inode->i_private);
+}
+
+static const struct file_operations clock_print_hw_fops = {
+	.open		= print_hw_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
 static int clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
 {
 	struct dentry *d;
@@ -2425,8 +2609,8 @@ static int clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
 
 	core->dentry = d;
 
-	d = debugfs_create_u32("clk_rate", S_IRUGO, core->dentry,
+	d = debugfs_create_file("clk_rate", S_IRUGO, core->dentry, core,
-			(u32 *)&core->rate);
+			&clock_rate_fops);
 	if (!d)
 		goto err_out;
 
@@ -2450,8 +2634,8 @@ static int clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
 	if (!d)
 		goto err_out;
 
-	d = debugfs_create_u32("clk_enable_count", S_IRUGO, core->dentry,
+	d = debugfs_create_file("clk_enable_count", S_IRUGO, core->dentry,
-			(u32 *)&core->enable_count);
+			core, &clock_enable_fops);
 	if (!d)
 		goto err_out;
 
@@ -2460,6 +2644,16 @@ static int clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
 	if (!d)
 		goto err_out;
 
+	d = debugfs_create_file("clk_parent", S_IRUGO, core->dentry, core,
+			&clock_parent_fops);
+	if (!d)
+		goto err_out;
+
+	d = debugfs_create_file("clk_print_regs", S_IRUGO, core->dentry,
+			core, &clock_print_hw_fops);
+	if (!d)
+		goto err_out;
+
 	if (core->ops->debug_init) {
 		ret = core->ops->debug_init(core->hw, core->dentry);
 		if (ret)
@@ -2570,6 +2764,11 @@ static int __init clk_debug_init(void)
 	if (!d)
 		return -ENOMEM;
 
+	d = debugfs_create_file("clk_enabled_list", S_IRUGO, rootdir,
+				&clk_debug_list, &clk_enabled_list_fops);
+	if (!d)
+		return -ENOMEM;
+
 	mutex_lock(&clk_debug_lock);
 	hlist_for_each_entry(core, &clk_debug_list, debug_node)
 		clk_debug_create_one(core, rootdir);

include/linux/clk-provider.h

@@ -177,6 +177,10 @@ struct clk_rate_request {
  * @set_flags: Set custom flags which deals with hardware specifics. Returns 0
  *	       on success, -EEROR otherwise.
  *
+ * @list_registers: Queries the hardware to get the current register contents.
+ *		    This callback is optional and required clocks could
+ *		    add this callback.
+ *
  * The clk_enable/clk_disable and clk_prepare/clk_unprepare pairs allow
  * implementations to split any work between atomic (enable) and sleepable
  * (prepare) contexts.  If enabling a clock requires code that might sleep,
@@ -217,6 +221,8 @@ struct clk_ops {
 	void		(*init)(struct clk_hw *hw);
 	int		(*debug_init)(struct clk_hw *hw, struct dentry *dentry);
 	int		(*set_flags)(struct clk_hw *hw, unsigned flags);
+	void		(*list_registers)(struct seq_file *f,
+							struct clk_hw *hw);
 };
 
 /**