[PATCH] ARM: rockchip: pass smaller device tree to OP-TEE

[Sascha Hauer]

From: Michael Tretter <m.tretter at pengutronix.de>

libfdt is slow on larger device tree, especially fdt_subnode_offset.

Adding the memory nodes to the ROCK 5T device tree takes about 2 seconds
on my machine.

OP-TEE doesn't need the entire tree, but only the memory nodes.

Create a fresh device tree, which is much smaller, and add the memory
nodes there to avoid the costly search through the device tree.

Since OP-TEE uses libfdt, too, this saves another 2.5 seconds in OP-TEE.

Signed-off-by: Michael Tretter <m.tretter at pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 arch/arm/mach-rockchip/atf.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-rockchip/atf.c b/arch/arm/mach-rockchip/atf.c
index 37f027740c..a60b55ae24 100644
--- a/arch/arm/mach-rockchip/atf.c
+++ b/arch/arm/mach-rockchip/atf.c
@@ -230,6 +230,20 @@ static int rk3588_fixup_mem(void *fdt)
 	return fdt_fixup_mem(fdt, base, size, i);
 }
 
+static int rk3588_open_fdt(const void *fdt, void *buf, int bufsize)
+{
+	int root;
+
+	if (fdt_create_empty_tree(buf, bufsize) != 0)
+		return -1;
+	root = fdt_path_offset(buf, "/");
+
+	fdt_setprop_u32(buf, root, "#address-cells", 2);
+	fdt_setprop_u32(buf, root, "#size-cells", 2);
+
+	return 0;
+}
+
 void __noreturn rk3588_barebox_entry(void *fdt)
 {
 	phys_addr_t membase, memend;
@@ -250,7 +264,7 @@ void __noreturn rk3588_barebox_entry(void *fdt)
 		if (IS_ENABLED(CONFIG_ARCH_ROCKCHIP_ATF_PASS_FDT)) {
 			pr_debug("Copy fdt to scratch area 0x%p (%zu bytes)\n",
 				 rk_scratch->fdt, sizeof(rk_scratch->fdt));
-			if (fdt_open_into(fdt, rk_scratch->fdt, sizeof(rk_scratch->fdt)) == 0)
+			if (rk3588_open_fdt(fdt, rk_scratch->fdt, sizeof(rk_scratch->fdt)) == 0)
 				fdt_scratch = rk_scratch->fdt;
 			else
 				pr_warn("Failed to copy fdt to scratch: Continue without fdt\n");
-- 
2.47.3