drivers: of: add return value to of_reserved_mem_device_init()

Driver calling of_reserved_mem_device_init() might be interested if the
initialization has been successful or not, so add support for returning
error code.

This fixes a build warining caused by commit 7bfa5ab6fa1b ("drivers:
dma-coherent: add initialization from device tree"), which has been
merged without this change and without fixing function return value.

Fixes: 7bfa5ab6fa1b1 ("drivers: dma-coherent: add initialization from device tree")
Signed-off-by: Marek Szyprowski <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Cc: Michal Nazarewicz <[e-mail]>
Cc: Grant Likely <[e-mail]>
Cc: Laura Abbott <[e-mail]>
Cc: Josh Cartwright <[e-mail]>
Cc: Joonsoo Kim <[e-mail]>
Cc: Kyungmin Park <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Stephen Rothwell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/base/dma-contiguous.c

···
 #undef pr_fmt
 #define pr_fmt(fmt) fmt
 
-static void rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
+static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
 {
 	dev_set_cma_area(dev, rmem->priv);
+	return 0;
 }
 
 static void rmem_cma_device_release(struct reserved_mem *rmem,

drivers/of/of_reserved_mem.c

···
  * This function assign memory region pointed by "memory-region" device tree
  * property to the given device.
  */
-void of_reserved_mem_device_init(struct device *dev)
+int of_reserved_mem_device_init(struct device *dev)
 {
 	struct reserved_mem *rmem;
 	struct device_node *np;
+	int ret;
 
 	np = of_parse_phandle(dev->of_node, "memory-region", 0);
 	if (!np)
-		return;
+		return -ENODEV;
 
 	rmem = __find_rmem(np);
 	of_node_put(np);
 
 	if (!rmem || !rmem->ops || !rmem->ops->device_init)
-		return;
+		return -EINVAL;
 
-	rmem->ops->device_init(rmem, dev);
-	dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
+	ret = rmem->ops->device_init(rmem, dev);
+	if (ret == 0)
+		dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
+
+	return ret;
 }
 
 /**

include/linux/of_reserved_mem.h

···
 };
 
 struct reserved_mem_ops {
-	void	(*device_init)(struct reserved_mem *rmem,
+	int	(*device_init)(struct reserved_mem *rmem,
 			       struct device *dev);
 	void	(*device_release)(struct reserved_mem *rmem,
 				  struct device *dev);
···
 	_OF_DECLARE(reservedmem, name, compat, init, reservedmem_of_init_fn)
 
 #ifdef CONFIG_OF_RESERVED_MEM
-void of_reserved_mem_device_init(struct device *dev);
+int of_reserved_mem_device_init(struct device *dev);
 void of_reserved_mem_device_release(struct device *dev);
 
 void fdt_init_reserved_mem(void);
 void fdt_reserved_mem_save_node(unsigned long node, const char *uname,
 			       phys_addr_t base, phys_addr_t size);
 #else
-static inline void of_reserved_mem_device_init(struct device *dev) { }
+static inline int of_reserved_mem_device_init(struct device *dev)
+{
+	return -ENOSYS;
+}
 static inline void of_reserved_mem_device_release(struct device *pdev) { }
 
 static inline void fdt_init_reserved_mem(void) { }