[PATCH 1/2] imx8m: implement armv8_el2_to_aarch32

[peng.fan at nxp.com]

From: Peng Fan <peng.fan at nxp.com>

Add iMX8M specific armv8_el2_to_aarch32 to let AArch64 mode U-Boot
could boot aarch32 mode linux with FIT image as below:

/dts-v1/;

/ {
        description = "Configuration to load ARM32 Linux";

        images {
                kernel at 1 {
                        description = "ARM32 Linux kernel";
                        data = /incbin/("./Image");
                        type = "kernel";
                        arch = "arm";
                        os = "linux";
                        compression = "none";
                        load = <0x40008000>;
                        entry = <0x40008000>;
                        hash at 1 {
                                algo = "md5";
                        };
                };
                fdt at 1 {
                        description = "Flattened Device Tree blob";
                        data = /incbin/("./imx8mm-evk.dtb");
                        type = "flat_dt";
                        arch = "arm";
                        compression = "none";
                        load = <0x43000000>;
                        hash at 1 {
                                algo = "md5";
                        };
                };
        };
        configurations {
                default = "config at 1";

                config at 1 {
                        description = "fsl-imx8mm-evk";
                        kernel = "kernel at 1";
                        fdt = "fdt at 1";
                };
        };
};

Signed-off-by: Peng Fan <peng.fan at nxp.com>
---
 arch/arm/mach-imx/imx8m/lowlevel_init.S | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm/mach-imx/imx8m/lowlevel_init.S b/arch/arm/mach-imx/imx8m/lowlevel_init.S
index a4c6466ca9..a49a9cdb35 100644
--- a/arch/arm/mach-imx/imx8m/lowlevel_init.S
+++ b/arch/arm/mach-imx/imx8m/lowlevel_init.S
@@ -60,3 +60,15 @@ restore_boot_params:
 	ldr	x0, [x0]
 	mov	sp, x0
 	ret
+
+.global armv8_el2_to_aarch32
+armv8_el2_to_aarch32:
+	cmp     x0, #0
+	bne     0f
+	mov     x3, x2
+	mov     x2, x1
+	mov     x1, x4
+	ldr x0, =0xc20000fd
+0:
+	smc #0
+	ret
-- 
2.16.4