To support loading a 32-bit OS, the execution state will change from
AArch64 to AArch32 when jumping to kernel.

The architecture information will be got through checking FIT
image, then U-Boot will load 32-bit OS or 64-bit OS automatically.

Signed-off-by: Ebony Zhu <ebony....@nxp.com>
Signed-off-by: Alison Wang <alison.w...@nxp.com>
Signed-off-by: Chenhui Zhao <chenhui.z...@nxp.com>
---
Changes in v2:
- armv8_switch_to_el2_aarch32() is removed. armv8_switch_to_el2_m is used
  to switch to AArch64 EL2 or AArch32 Hyp.
- armv8_switch_to_el1_aarch32() is removed. armv8_switch_to_el1_m is used
  to switch to AArch64 EL1 or AArch32 SVC.

 arch/arm/cpu/armv8/transition.S |  8 ++---
 arch/arm/include/asm/macro.h    | 80 +++++++++++++++++++++++++++++++++++++----
 arch/arm/include/asm/system.h   | 25 +++++++++++--
 arch/arm/lib/bootm.c            | 26 +++++++++++---
 common/image-fit.c              | 12 ++++++-
 5 files changed, 133 insertions(+), 18 deletions(-)

diff --git a/arch/arm/cpu/armv8/transition.S b/arch/arm/cpu/armv8/transition.S
index 253a39b..9fa3b59 100644
--- a/arch/arm/cpu/armv8/transition.S
+++ b/arch/arm/cpu/armv8/transition.S
@@ -11,13 +11,13 @@
 #include <asm/macro.h>
 
 ENTRY(armv8_switch_to_el2)
-       switch_el x0, 1f, 0f, 0f
+       switch_el x4, 1f, 0f, 0f
 0:     ret
-1:     armv8_switch_to_el2_m x0
+1:     armv8_switch_to_el2_m x0, x1, x2, x3, x4, x5, x6
 ENDPROC(armv8_switch_to_el2)
 
 ENTRY(armv8_switch_to_el1)
-       switch_el x0, 0f, 1f, 0f
+       switch_el x4, 0f, 1f, 0f
 0:     ret
-1:     armv8_switch_to_el1_m x0, x1
+1:     armv8_switch_to_el1_m x0, x1, x2, x3, x4, x5, x6
 ENDPROC(armv8_switch_to_el1)
diff --git a/arch/arm/include/asm/macro.h b/arch/arm/include/asm/macro.h
index 9bb0efa..56d77f6 100644
--- a/arch/arm/include/asm/macro.h
+++ b/arch/arm/include/asm/macro.h
@@ -8,6 +8,9 @@
 
 #ifndef __ASM_ARM_MACRO_H__
 #define __ASM_ARM_MACRO_H__
+
+#include <asm/system.h>
+
 #ifdef __ASSEMBLY__
 
 /*
@@ -135,9 +138,20 @@ lr .req    x30
 #endif
 .endm
 
-.macro armv8_switch_to_el2_m, xreg1
-       /* 64bit EL2 | HCE | SMD | RES1 (Bits[5:4]) | Non-secure EL0/EL1 */
-       mov     \xreg1, #0x5b1
+.macro armv8_switch_to_el2_m, xreg1, xreg2, xreg3, xreg4, xreg5, xreg6, xreg7
+       mov     \xreg5, \xreg1
+       mov     \xreg6, \xreg2
+       mov     \xreg7, \xreg3
+
+       /*
+        * If the next lower exception level is AArch64, 64bit EL2 | HCE | SMD |
+        * RES1 (Bits[5:4]) | Non-secure EL0/EL1. If the next lower exception
+        * level is AArch32, 32bit EL2 | HCE | SMD | RES1 (Bits[5:4]) |
+        * Non-secure EL0/EL1.
+        */
+       mov     \xreg1, #0x1b1
+       lsl     \xreg2, \xreg4, #10
+       orr     \xreg1, \xreg1, \xreg2
        msr     scr_el3, \xreg1
        msr     cptr_el3, xzr           /* Disable coprocessor traps to EL3 */
        mov     \xreg1, #0x33ff
@@ -156,18 +170,46 @@ lr        .req    x30
        movk    \xreg1, #0x30C5, lsl #16
        msr     sctlr_el2, \xreg1
 
-       /* Return to the EL2_SP2 mode from EL3 */
        mov     \xreg1, sp
        msr     sp_el2, \xreg1          /* Migrate SP */
        mrs     \xreg1, vbar_el3
        msr     vbar_el2, \xreg1        /* Migrate VBAR */
+
+       /* Check switch to AArch64 EL2 or AArch32 Hypervisor mode */
+       ldr     \xreg1, =ES_TO_AARCH64
+       cmp     \xreg4, \xreg1
+       b.eq    1f
+       b.ne    2f
+
+1:
+       /* Return to the EL2_SP2 mode from EL3 */
        mov     \xreg1, #0x3c9
        msr     spsr_el3, \xreg1        /* EL2_SP2 | D | A | I | F */
        msr     elr_el3, lr
+
+       mov     \xreg1, \xreg5
+       mov     \xreg2, \xreg6
+       mov     \xreg3, \xreg7
+       eret
+
+2:
+       /* Return to AArch32 Hypervisor mode */
+       mov     \xreg1, #0x1da
+       msr     spsr_el3, \xreg1        /* Hyp | D | A | I | F */
+       msr     elr_el3, \xreg5
+
+       mov     \xreg1, #0
+       mov     \xreg2, \xreg6
+       mov     \xreg3, \xreg7
        eret
+
 .endm
 
-.macro armv8_switch_to_el1_m, xreg1, xreg2
+.macro armv8_switch_to_el1_m, xreg1, xreg2, xreg3, xreg4, xreg5, xreg6, xreg7
+       mov     \xreg5, \xreg1
+       mov     \xreg6, \xreg2
+       mov     \xreg7, \xreg3
+
        /* Initialize Generic Timers */
        mrs     \xreg1, cnthctl_el2
        orr     \xreg1, \xreg1, #0x3    /* Enable EL1 access to timers */
@@ -188,7 +230,7 @@ lr  .req    x30
        msr     cpacr_el1, \xreg1       /* Enable FP/SIMD at EL1 */
 
        /* Initialize HCR_EL2 */
-       mov     \xreg1, #(1 << 31)              /* 64bit EL1 */
+       lsl     \xreg1, \xreg4, #31
        orr     \xreg1, \xreg1, #(1 << 29)      /* Disable HVC */
        msr     hcr_el2, \xreg1
 
@@ -203,15 +245,39 @@ lr        .req    x30
        movk    \xreg1, #0x30d0, lsl #16
        msr     sctlr_el1, \xreg1
 
-       /* Return to the EL1_SP1 mode from EL2 */
        mov     \xreg1, sp
        msr     sp_el1, \xreg1          /* Migrate SP */
        mrs     \xreg1, vbar_el2
        msr     vbar_el1, \xreg1        /* Migrate VBAR */
+
+       /* Check switch to AArch64 EL1 or AArch32 Supervisor mode */
+       ldr     \xreg1, =ES_TO_AARCH64
+       cmp     \xreg4, \xreg1
+       b.eq    1f
+       b.ne    2f
+
+1:
+       /* Return to the EL1_SP1 mode from EL2 */
        mov     \xreg1, #0x3c5
        msr     spsr_el2, \xreg1        /* EL1_SP1 | D | A | I | F */
        msr     elr_el2, lr
+
+       mov     \xreg1, \xreg5
+       mov     \xreg2, \xreg6
+       mov     \xreg3, \xreg7
+       eret
+
+2:
+       /* Return to the Supervisor mode from EL2 */
+       mov     \xreg1, #0x1d3
+       msr     spsr_el2, \xreg1        /* Supervisor | D | A | I | F */
+       msr     elr_el2, \xreg5
+
+       mov     \xreg1, #0
+       mov     \xreg2, \xreg6
+       mov     \xreg3, \xreg7
        eret
+
 .endm
 
 #if defined(CONFIG_GICV3)
diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index 9ae890a..fcfe3ae 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -17,6 +17,9 @@
 #define CR_WXN         (1 << 19)       /* Write Permision Imply XN     */
 #define CR_EE          (1 << 25)       /* Exception (Big) Endian       */
 
+#define ES_TO_AARCH64                  1
+#define ES_TO_AARCH32                  0
+
 #ifndef __ASSEMBLY__
 
 u64 get_page_table_size(void);
@@ -100,8 +103,26 @@ void __asm_invalidate_icache_all(void);
 int __asm_flush_l3_cache(void);
 void __asm_switch_ttbr(u64 new_ttbr);
 
-void armv8_switch_to_el2(void);
-void armv8_switch_to_el1(void);
+/*
+ * Switch from EL3 to EL2 for ARMv8
+ *
+ * @entry_point: kernel entry point
+ * @mach_nr:     machine nr
+ * @fdt_addr:    fdt address
+ * @es_flag:     execution state flag, ES_TO_AARCH64 or ES_TO_AARCH32
+ */
+void armv8_switch_to_el2(u64 entry_point, u64 mach_nr, u64 fdt_addr,
+                        u64 es_flag);
+/*
+ * Switch from EL2 to EL1 for ARMv8
+ *
+ * @entry_point: kernel entry point
+ * @mach_nr:     machine nr
+ * @fdt_addr:    fdt address
+ * @es_flag:     execution state flag, ES_TO_AARCH64 or ES_TO_AARCH32
+ */
+void armv8_switch_to_el1(u64 entry_point, u64 mach_nr, u64 fdt_addr,
+                        u64 es_flag);
 void gic_init(void);
 void gic_send_sgi(unsigned long sgino);
 void wait_for_wakeup(void);
diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index 0838d89..f6f685a 100644
--- a/arch/arm/lib/bootm.c
+++ b/arch/arm/lib/bootm.c
@@ -193,9 +193,9 @@ static void do_nonsec_virt_switch(void)
 {
        smp_kick_all_cpus();
        dcache_disable();       /* flush cache before swtiching to EL2 */
-       armv8_switch_to_el2();
+       armv8_switch_to_el2(0, 0, 0, ES_TO_AARCH64);
 #ifdef CONFIG_ARMV8_SWITCH_TO_EL1
-       armv8_switch_to_el1();
+       armv8_switch_to_el1(0, 0, 0, ES_TO_AARCH64);
 #endif
 }
 #endif
@@ -286,8 +286,26 @@ static void boot_jump_linux(bootm_headers_t *images, int 
flag)
        announce_and_cleanup(fake);
 
        if (!fake) {
-               do_nonsec_virt_switch();
-               kernel_entry(images->ft_addr, NULL, NULL, NULL);
+               if ((IH_ARCH_DEFAULT == IH_ARCH_ARM64) &&
+                   (images->os.arch == IH_ARCH_ARM)) {
+                       smp_kick_all_cpus();
+                       dcache_disable();
+#ifdef CONFIG_ARMV8_SWITCH_TO_EL1
+                       armv8_switch_to_el2(0, 0, 0, ES_TO_AARCH64);
+                       armv8_switch_to_el1((u64)images->ep,
+                                           (u64)gd->bd->bi_arch_number,
+                                           (u64)images->ft_addr,
+                                           ES_TO_AARCH32);
+#else
+                       armv8_switch_to_el2((u64)images->ep,
+                                           (u64)gd->bd->bi_arch_number,
+                                           (u64)images->ft_addr,
+                                           ES_TO_AARCH32);
+#endif
+               } else {
+                       do_nonsec_virt_switch();
+                       kernel_entry(images->ft_addr, NULL, NULL, NULL);
+               }
        }
 #else
        unsigned long machid = gd->bd->bi_arch_number;
diff --git a/common/image-fit.c b/common/image-fit.c
index 25f8a11..2986469 100644
--- a/common/image-fit.c
+++ b/common/image-fit.c
@@ -1163,7 +1163,8 @@ int fit_image_check_arch(const void *fit, int noffset, 
uint8_t arch)
        if (fit_image_get_arch(fit, noffset, &image_arch))
                return 0;
        return (arch == image_arch) ||
-               (arch == IH_ARCH_I386 && image_arch == IH_ARCH_X86_64);
+               (arch == IH_ARCH_I386 && image_arch == IH_ARCH_X86_64) ||
+               (arch == IH_ARCH_ARM64 && image_arch == IH_ARCH_ARM);
 }
 
 /**
@@ -1586,6 +1587,9 @@ int fit_image_load(bootm_headers_t *images, ulong addr,
        int type_ok, os_ok;
        ulong load, data, len;
        uint8_t os;
+#ifndef USE_HOSTCC
+       uint8_t os_arch;
+#endif
        const char *prop_name;
        int ret;
 
@@ -1669,6 +1673,12 @@ int fit_image_load(bootm_headers_t *images, ulong addr,
                return -ENOEXEC;
        }
 #endif
+
+#ifndef USE_HOSTCC
+       fit_image_get_arch(fit, noffset, &os_arch);
+       images->os.arch = os_arch;
+#endif
+
        if (image_type == IH_TYPE_FLATDT &&
            !fit_image_check_comp(fit, noffset, IH_COMP_NONE)) {
                puts("FDT image is compressed");
-- 
2.1.0.27.g96db324

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