of: fdt: Aggregate the processing of "linux,usable-memory-range"

Currently, we parse the "linux,usable-memory-range" property in
early_init_dt_scan_chosen(), to obtain the specified memory range of the
crash kernel. We then reserve the required memory after
early_init_dt_scan_memory() has identified all available physical memory.
Because the two pieces of code are separated far, the readability and
maintainability are reduced. So bring them together.

Suggested-by: Rob Herring <robh@kernel.org>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
(change the prototype of early_init_dt_check_for_usable_mem_range(), in
order to use it outside)
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Tested-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Acked-by: John Donnelly <john.p.donnelly@oracle.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
To: devicetree@vger.kernel.org
To: linux-efi@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

Author: Zhen Lei

drivers/of/fdt.c

@@ -965,18 +965,22 @@ static void __init early_init_dt_check_for_elfcorehdr(unsigned long node)
 		 elfcorehdr_addr, elfcorehdr_size);
 }
 
-static phys_addr_t cap_mem_addr;
-static phys_addr_t cap_mem_size;
+static unsigned long chosen_node_offset = -FDT_ERR_NOTFOUND;
 
 /**
  * early_init_dt_check_for_usable_mem_range - Decode usable memory range
  * location from flat tree
- * @node: reference to node containing usable memory range location ('chosen')
  */
-static void __init early_init_dt_check_for_usable_mem_range(unsigned long node)
+static void __init early_init_dt_check_for_usable_mem_range(void)
 {
 	const __be32 *prop;
 	int len;
+	phys_addr_t cap_mem_addr;
+	phys_addr_t cap_mem_size;
+	unsigned long node = chosen_node_offset;
+
+	if ((long)node < 0)
+		return;
 
 	pr_debug("Looking for usable-memory-range property... ");
 
@@ -989,6 +993,8 @@ static void __init early_init_dt_check_for_usable_mem_range(unsigned long node)
 
 	pr_debug("cap_mem_start=%pa cap_mem_size=%pa\n", &cap_mem_addr,
 		 &cap_mem_size);
+
+	memblock_cap_memory_range(cap_mem_addr, cap_mem_size);
 }
 
 #ifdef CONFIG_SERIAL_EARLYCON
@@ -1137,9 +1143,10 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 	    (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
 		return 0;
 
+	chosen_node_offset = node;
+
 	early_init_dt_check_for_initrd(node);
 	early_init_dt_check_for_elfcorehdr(node);
-	early_init_dt_check_for_usable_mem_range(node);
 
 	/* Retrieve command line */
 	p = of_get_flat_dt_prop(node, "bootargs", &l);
@@ -1275,7 +1282,7 @@ void __init early_init_dt_scan_nodes(void)
 	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
 
 	/* Handle linux,usable-memory-range property */
-	memblock_cap_memory_range(cap_mem_addr, cap_mem_size);
+	early_init_dt_check_for_usable_mem_range();
 }
 
 bool __init early_init_dt_scan(void *params)