of: reserved_mem: Remove the use of phandle from the reserved_mem APIs

The __find_rmem() function is the only place that references the phandle
field of the reserved_mem struct. __find_rmem() is used to match a
device_node object to its corresponding entry in the reserved_mem array
using its phandle value. But, there is already a function called
of_reserved_mem_lookup() which carries out the same action using the
name of the node.

Using the of_reserved_mem_lookup() function is more reliable because
every node is guaranteed to have a name, but not all nodes will have a
phandle.

Nodes are only assigned a phandle if they are explicitly defined in the
DT using "phandle = <phandle_number>", or if they are referenced by
another node in the DT. Hence, If the phandle field is empty, then
__find_rmem() will return a false negative.

Hence, delete the __find_rmem() function and switch to using the
of_reserved_mem_lookup() function to find the corresponding entry of a
device_node in the reserved_mem array. Since the phandle field of the
reserved_mem struct is now unused, delete that as well.

Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
Link: https://lore.kernel.org/r/20240502192403.3307277-1-quic_obabatun@quicinc.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Author: Oreoluwa Babatunde

drivers/of/of_reserved_mem.c

@@ -437,17 +437,10 @@ void __init fdt_init_reserved_mem(void)
 	for (i = 0; i < reserved_mem_count; i++) {
 		struct reserved_mem *rmem = &reserved_mem[i];
 		unsigned long node = rmem->fdt_node;
-		int len;
-		const __be32 *prop;
 		int err = 0;
 		bool nomap;
 
 		nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
-		prop = of_get_flat_dt_prop(node, "phandle", &len);
-		if (!prop)
-			prop = of_get_flat_dt_prop(node, "linux,phandle", &len);
-		if (prop)
-			rmem->phandle = of_read_number(prop, len/4);
 
 		if (rmem->size == 0)
 			err = __reserved_mem_alloc_size(node, rmem->name,
@@ -477,19 +470,6 @@ void __init fdt_init_reserved_mem(void)
 	}
 }
 
-static inline struct reserved_mem *__find_rmem(struct device_node *node)
-{
-	unsigned int i;
-
-	if (!node->phandle)
-		return NULL;
-
-	for (i = 0; i < reserved_mem_count; i++)
-		if (reserved_mem[i].phandle == node->phandle)
-			return &reserved_mem[i];
-	return NULL;
-}
-
 struct rmem_assigned_device {
 	struct device *dev;
 	struct reserved_mem *rmem;
@@ -534,7 +514,7 @@ int of_reserved_mem_device_init_by_idx(struct device *dev,
 		return 0;
 	}
 
-	rmem = __find_rmem(target);
+	rmem = of_reserved_mem_lookup(target);
 	of_node_put(target);
 
 	if (!rmem || !rmem->ops || !rmem->ops->device_init)

include/linux/of_reserved_mem.h

@@ -11,7 +11,6 @@ struct reserved_mem_ops;
 struct reserved_mem {
 	const char			*name;
 	unsigned long			fdt_node;
-	unsigned long			phandle;
 	const struct reserved_mem_ops	*ops;
 	phys_addr_t			base;
 	phys_addr_t			size;