[PATCH 2/2] V4L2: add CCF support to the v4l2_clk API

[Guennadi Liakhovetski <g.liakhovetski@xxxxxx>]

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 <g.liakhovetski@xxxxxx>
---
 drivers/media/v4l2-core/v4l2-clk.c | 76 +++++++++++++++++++++++++++++++++-----
 include/media/v4l2-clk.h           |  2 +
 2 files changed, 68 insertions(+), 10 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-clk.c b/drivers/media/v4l2-core/v4l2-clk.c
index c210906..693e5a0 100644
--- a/drivers/media/v4l2-core/v4l2-clk.c
+++ b/drivers/media/v4l2-core/v4l2-clk.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/atomic.h>
+#include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/list.h>
@@ -39,9 +40,24 @@ static struct v4l2_clk *v4l2_clk_find(const char *dev_id, const char *id)
 	return ERR_PTR(-ENODEV);
 }
 
+static int v4l2_clk_add(struct v4l2_clk *clk, const char *dev_id,
+			const char *id)
+{
+	mutex_lock(&clk_lock);
+	if (!IS_ERR(v4l2_clk_find(dev_id, id))) {
+		mutex_unlock(&clk_lock);
+		return -EEXIST;
+	}
+	list_add_tail(&clk->list, &clk_list);
+	mutex_unlock(&clk_lock);
+
+	return 0;
+}
+
 struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id)
 {
 	struct v4l2_clk *clk;
+	struct clk *ccf_clk = clk_get(dev, id);
 
 	mutex_lock(&clk_lock);
 	clk = v4l2_clk_find(dev_name(dev), id);
@@ -50,6 +66,22 @@ struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id)
 		atomic_inc(&clk->use_count);
 	mutex_unlock(&clk_lock);
 
+	if (!IS_ERR(ccf_clk) && IS_ERR(clk)) {
+		/* not yet on the list */
+		clk = kzalloc(sizeof(struct v4l2_clk), GFP_KERNEL);
+		if (clk)
+			clk->id = kstrdup(id, GFP_KERNEL);
+		if (!clk || !clk->id) {
+			kfree(clk);
+			clk_put(ccf_clk);
+			return ERR_PTR(-ENOMEM);
+		}
+		clk->clk = ccf_clk;
+		atomic_set(&clk->use_count, 1);
+
+		v4l2_clk_add(clk, dev_name(dev), id);
+	}
+
 	return clk;
 }
 EXPORT_SYMBOL(v4l2_clk_get);
@@ -67,6 +99,15 @@ void v4l2_clk_put(struct v4l2_clk *clk)
 		if (tmp == clk)
 			atomic_dec(&clk->use_count);
 
+	if (clk->clk) {
+		clk_put(clk->clk);
+		if (!atomic_read(&clk->use_count)) {
+			list_del(&clk->list);
+			kfree(clk->id);
+			kfree(clk);
+		}
+	}
+
 	mutex_unlock(&clk_lock);
 }
 EXPORT_SYMBOL(v4l2_clk_put);
@@ -98,8 +139,12 @@ static void v4l2_clk_unlock_driver(struct v4l2_clk *clk)
 
 int v4l2_clk_enable(struct v4l2_clk *clk)
 {
-	int ret = v4l2_clk_lock_driver(clk);
+	int ret;
+
+	if (clk->clk)
+		return clk_enable(clk->clk);
 
+	ret = v4l2_clk_lock_driver(clk);
 	if (ret < 0)
 		return ret;
 
@@ -125,6 +170,9 @@ void v4l2_clk_disable(struct v4l2_clk *clk)
 {
 	int enable;
 
+	if (clk->clk)
+		return clk_disable(clk->clk);
+
 	mutex_lock(&clk->lock);
 
 	enable = --clk->enable;
@@ -142,8 +190,12 @@ EXPORT_SYMBOL(v4l2_clk_disable);
 
 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;
 
@@ -162,7 +214,16 @@ EXPORT_SYMBOL(v4l2_clk_get_rate);
 
 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;
@@ -204,14 +265,9 @@ struct v4l2_clk *v4l2_clk_register(const struct v4l2_clk_ops *ops,
 	atomic_set(&clk->use_count, 0);
 	mutex_init(&clk->lock);
 
-	mutex_lock(&clk_lock);
-	if (!IS_ERR(v4l2_clk_find(dev_id, NULL))) {
-		mutex_unlock(&clk_lock);
-		ret = -EEXIST;
+	ret = v4l2_clk_add(clk, dev_id, NULL);
+	if (ret < 0)
 		goto eexist;
-	}
-	list_add_tail(&clk->list, &clk_list);
-	mutex_unlock(&clk_lock);
 
 	return clk;
 
diff --git a/include/media/v4l2-clk.h b/include/media/v4l2-clk.h
index 8f06967..4402b2d 100644
--- a/include/media/v4l2-clk.h
+++ b/include/media/v4l2-clk.h
@@ -22,6 +22,7 @@
 struct module;
 struct device;
 
+struct clk;
 struct v4l2_clk {
 	struct list_head list;
 	const struct v4l2_clk_ops *ops;
@@ -30,6 +31,7 @@ struct v4l2_clk {
 	int enable;
 	struct mutex lock; /* Protect the enable count */
 	atomic_t use_count;
+	struct clk *clk;
 	void *priv;
 };
 
-- 
1.9.3

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