[media] V4L2: add v4l2-clock helpers to register and unregister a fixed-rate clock

Many bridges and video host controllers supply fixed rate always on clocks
to their I2C devices. This patch adds two simple helpers to register and
unregister such a clock.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/v4l2-clk.c b/drivers/media/v4l2-core/v4l2-clk.c
index b67de8642b5a..e18cc0469cf8 100644
--- a/drivers/media/v4l2-core/v4l2-clk.c
+++ b/drivers/media/v4l2-core/v4l2-clk.c
@@ -240,3 +240,42 @@ void v4l2_clk_unregister(struct v4l2_clk *clk)
         kfree(clk);
 }
 EXPORT_SYMBOL(v4l2_clk_unregister);
+
+struct v4l2_clk_fixed {
+        unsigned long rate;
+        struct v4l2_clk_ops ops;
+};
+
+static unsigned long fixed_get_rate(struct v4l2_clk *clk)
+{
+        struct v4l2_clk_fixed *priv = clk->priv;
+        return priv->rate;
+}
+
+struct v4l2_clk *__v4l2_clk_register_fixed(const char *dev_id,
+                const char *id, unsigned long rate, struct module *owner)
+{
+        struct v4l2_clk *clk;
+        struct v4l2_clk_fixed *priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+
+        if (!priv)
+                return ERR_PTR(-ENOMEM);
+
+        priv->rate = rate;
+        priv->ops.get_rate = fixed_get_rate;
+        priv->ops.owner = owner;
+
+        clk = v4l2_clk_register(&priv->ops, dev_id, id, priv);
+        if (IS_ERR(clk))
+                kfree(priv);
+
+        return clk;
+}
+EXPORT_SYMBOL(__v4l2_clk_register_fixed);
+
+void v4l2_clk_unregister_fixed(struct v4l2_clk *clk)
+{
+        kfree(clk->priv);
+        v4l2_clk_unregister(clk);
+}
+EXPORT_SYMBOL(v4l2_clk_unregister_fixed);