x86: use FDT accessors for FDT blob header data

Remove the direct accesses to FDT header data using accessor
function instead. This makes the code more readable and makes the FDT
blob structure more opaque to the arch code. This also prepares for
removing struct boot_param_header completely.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Tested-by: Grant Likely <grant.likely@linaro.org>

1 files changed, 5 insertions, 7 deletions

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index d35078ea1446..7db54b5d5f86 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -206,23 +206,21 @@ static void __init dtb_apic_setup(void)
 static void __init x86_flattree_get_config(void)
 {
 	u32 size, map_len;
-	struct boot_param_header *dt;
+	void *dt;
 
 	if (!initial_dtb)
 		return;
 
-	map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK),
-			(u64)sizeof(struct boot_param_header));
+	map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK), (u64)128);
 
-	dt = early_memremap(initial_dtb, map_len);
-	size = be32_to_cpu(dt->totalsize);
+	initial_boot_params = dt = early_memremap(initial_dtb, map_len);
+	size = of_get_flat_dt_size();
 	if (map_len < size) {
 		early_iounmap(dt, map_len);
-		dt = early_memremap(initial_dtb, size);
+		initial_boot_params = dt = early_memremap(initial_dtb, size);
 		map_len = size;
 	}
 
-	initial_boot_params = dt;
 	unflatten_and_copy_device_tree();
 	early_iounmap(dt, map_len);
 }