[media] V4L: add CCF support to the v4l2_clk API

V4L2 clocks, e.g. used by camera sensors for their master clock, do not
have to be supplied by a different V4L2 driver, they can also be
supplied by an independent source. In this case the standart kernel
clock API should be used to handle such clocks. This patch adds support
for such cases.

Signed-off-by: Guennadi Liakhovetski <[e-mail]>
Acked-by: Laurent Pinchart <[e-mail]>
Tested-by: Josh Wu <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/v4l2-core/v4l2-clk.c

···
  */
 
 #include <linux/atomic.h>
+#include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/list.h>
···
 struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id)
 {
 	struct v4l2_clk *clk;
+	struct clk *ccf_clk = clk_get(dev, id);
+
+	if (PTR_ERR(ccf_clk) == -EPROBE_DEFER)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	if (!IS_ERR_OR_NULL(ccf_clk)) {
+		clk = kzalloc(sizeof(*clk), GFP_KERNEL);
+		if (!clk) {
+			clk_put(ccf_clk);
+			return ERR_PTR(-ENOMEM);
+		}
+		clk->clk = ccf_clk;
+
+		return clk;
+	}
 
 	mutex_lock(&clk_lock);
 	clk = v4l2_clk_find(dev_name(dev));
···
 
 	if (IS_ERR(clk))
 		return;
+
+	if (clk->clk) {
+		clk_put(clk->clk);
+		kfree(clk);
+		return;
+	}
 
 	mutex_lock(&clk_lock);
 
···
 
 int v4l2_clk_enable(struct v4l2_clk *clk)
 {
-	int ret = v4l2_clk_lock_driver(clk);
+	int ret;
 
+	if (clk->clk)
+		return clk_prepare_enable(clk->clk);
+
+	ret = v4l2_clk_lock_driver(clk);
 	if (ret < 0)
 		return ret;
 
···
 {
 	int enable;
 
+	if (clk->clk)
+		return clk_disable_unprepare(clk->clk);
+
 	mutex_lock(&clk->lock);
 
 	enable = --clk->enable;
···
 
 unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk)
 {
-	int ret = v4l2_clk_lock_driver(clk);
+	int ret;
 
+	if (clk->clk)
+		return clk_get_rate(clk->clk);
+
+	ret = v4l2_clk_lock_driver(clk);
 	if (ret < 0)
 		return ret;
 
···
 
 int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate)
 {
-	int ret = v4l2_clk_lock_driver(clk);
+	int ret;
+
+	if (clk->clk) {
+		long r = clk_round_rate(clk->clk, rate);
+		if (r < 0)
+			return r;
+		return clk_set_rate(clk->clk, r);
+	}
+
+	ret = v4l2_clk_lock_driver(clk);
 
 	if (ret < 0)
 		return ret;

include/media/v4l2-clk.h

···
 struct module;
 struct device;
 
+struct clk;
 struct v4l2_clk {
 	struct list_head list;
 	const struct v4l2_clk_ops *ops;
···
 	int enable;
 	struct mutex lock; /* Protect the enable count */
 	atomic_t use_count;
+	struct clk *clk;
 	void *priv;
 };