clk: Add common __clk_get(), __clk_put() implementations

This patch adds common __clk_get(), __clk_put() clkdev helpers that
replace their platform specific counterparts when the common clock
API is used.

The owner module pointer field is added to struct clk so a reference
to the clock supplier module can be taken by the clock consumers.

The owner module is assigned while the clock is being registered,
in functions _clk_register() and __clk_register().
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/clkdev.h

@@ -14,12 +14,14 @@
 
 #include <linux/slab.h>
 
+#ifndef CONFIG_COMMON_CLK
 #ifdef CONFIG_HAVE_MACH_CLKDEV
 #include <mach/clkdev.h>
 #else
 #define __clk_get(clk)	({ 1; })
 #define __clk_put(clk)	do { } while (0)
 #endif
+#endif
 
 static inline struct clk_lookup_alloc *__clkdev_alloc(size_t size)
 {

arch/blackfin/include/asm/clkdev.h

@@ -8,7 +8,9 @@ static inline struct clk_lookup_alloc *__clkdev_alloc(size_t size)
 	return kzalloc(size, GFP_KERNEL);
 }
 
+#ifndef CONFIG_COMMON_CLK
 #define __clk_put(clk)
 #define __clk_get(clk) ({ 1; })
+#endif
 
 #endif

arch/mips/include/asm/clkdev.h

@@ -14,8 +14,10 @@
 
 #include <linux/slab.h>
 
+#ifndef CONFIG_COMMON_CLK
 #define __clk_get(clk)	({ 1; })
 #define __clk_put(clk)	do { } while (0)
+#endif
 
 static inline struct clk_lookup_alloc *__clkdev_alloc(size_t size)
 {

arch/sh/include/asm/clkdev.h

@@ -25,7 +25,9 @@ static inline struct clk_lookup_alloc *__clkdev_alloc(size_t size)
 		return kzalloc(size, GFP_KERNEL);
 }
 
+#ifndef CONFIG_COMMON_CLK
 #define __clk_put(clk)
 #define __clk_get(clk) ({ 1; })
+#endif
 
 #endif /* __CLKDEV_H__ */

drivers/clk/clk.c

@@ -1813,6 +1813,10 @@ struct clk *__clk_register(struct device *dev, struct clk_hw *hw)
 	clk->flags = hw->init->flags;
 	clk->parent_names = hw->init->parent_names;
 	clk->num_parents = hw->init->num_parents;
+	if (dev && dev->driver)
+		clk->owner = dev->driver->owner;
+	else
+		clk->owner = NULL;
 
 	ret = __clk_init(dev, clk);
 	if (ret)
@@ -1833,6 +1837,8 @@ static int _clk_register(struct device *dev, struct clk_hw *hw, struct clk *clk)
 		goto fail_name;
 	}
 	clk->ops = hw->init->ops;
+	if (dev && dev->driver)
+		clk->owner = dev->driver->owner;
 	clk->hw = hw;
 	clk->flags = hw->init->flags;
 	clk->num_parents = hw->init->num_parents;
@@ -1973,6 +1979,26 @@ void devm_clk_unregister(struct device *dev, struct clk *clk)
 }
 EXPORT_SYMBOL_GPL(devm_clk_unregister);
 
+/*
+ * clkdev helpers
+ */
+int __clk_get(struct clk *clk)
+{
+	if (clk && !try_module_get(clk->owner))
+		return 0;
+
+	return 1;
+}
+
+void __clk_put(struct clk *clk)
+{
+	if (WARN_ON_ONCE(IS_ERR(clk)))
+		return;
+
+	if (clk)
+		module_put(clk->owner);
+}
+
 /***        clk rate change notifiers        ***/
 
 /**

include/linux/clk-private.h

@@ -25,10 +25,13 @@
 
 #ifdef CONFIG_COMMON_CLK
 
+struct module;
+
 struct clk {
 	const char		*name;
 	const struct clk_ops	*ops;
 	struct clk_hw		*hw;
+	struct module		*owner;
 	struct clk		*parent;
 	const char		**parent_names;
 	struct clk		**parents;

include/linux/clkdev.h

@@ -43,4 +43,9 @@ int clk_add_alias(const char *, const char *, char *, struct device *);
 int clk_register_clkdev(struct clk *, const char *, const char *, ...);
 int clk_register_clkdevs(struct clk *, struct clk_lookup *, size_t);
 
+#ifdef CONFIG_COMMON_CLK
+int __clk_get(struct clk *clk);
+void __clk_put(struct clk *clk);
+#endif
+
 #endif