clk: Implement clk_unregister

clk_unregister() is currently not implemented and it is required when
a clock provider module needs to be unloaded.

Normally the clock supplier module is prevented to be unloaded by
taking reference on the module in clk_get().

For cases when the clock supplier module deinitializes despite the
consumers of its clocks holding a reference on the module, e.g. when
the driver is unbound through "unbind" sysfs attribute, there are
empty clock ops added. These ops are assigned temporarily to struct
clk and used until all consumers release the clock, to avoid invoking
callbacks from the module which just got removed.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
index 8cb1865e7d9..72c65e05450 100644
--- a/include/linux/clk-private.h
+++ b/include/linux/clk-private.h
@@ -12,6 +12,7 @@
 #define __LINUX_CLK_PRIVATE_H
 
 #include <linux/clk-provider.h>
+#include <linux/kref.h>
 #include <linux/list.h>
 
 /*
@@ -50,6 +51,7 @@ struct clk {
 #ifdef CONFIG_COMMON_CLK_DEBUG
 	struct dentry		*dentry;
 #endif
+	struct kref		ref;
 };
 
 /*