[U-Boot] [RFC PATCH 1/2] Add Aarch32 option for ARMv8 CPUs

[Ryan Harkin]

This patch hacks some generic code used to allow the ARMv8 platform to
specify if it is booting in Aarch32 mode.

Some ARMv8 CPUs can be run in Aarch32 mode as well as Aarch64.  A good
example of this is ARM's AEMv8 FVP model which models the ARMv8
architecture rather than a specific CPU core.

This patch is co-authored with Soby Mathew <Soby.Mathew at arm.com>.

Signed-off-by: Ryan Harkin <ryan.harkin at linaro.org>
---
 Makefile                          | 5 +++++
 arch/arm/Kconfig                  | 6 ++++++
 arch/arm/cpu/armv7/virt-v7.c      | 2 ++
 arch/arm/cpu/armv8/u-boot-spl.lds | 5 +++++
 arch/arm/cpu/armv8/u-boot.lds     | 5 +++++
 arch/arm/include/asm/armv8/mmu.h  | 5 +++++
 6 files changed, 28 insertions(+)

diff --git a/Makefile b/Makefile
index 37cbcb2..b923ef7 100644
--- a/Makefile
+++ b/Makefile
@@ -1182,8 +1182,13 @@ u-boot-img-spl-at-end.bin: u-boot.img spl/u-boot-spl.bin FORCE
 # relocation).
 # FIXME refactor dts/Makefile to share target/arch detection
 u-boot.elf: u-boot.bin
+ifeq ($(CONFIG_ARMV8_AARCH32),y)
+	@$(OBJCOPY)  -B arm -I binary -O elf32-littlearm \
+		$< u-boot-elf.o
+else
 	@$(OBJCOPY)  -B aarch64 -I binary -O elf64-littleaarch64 \
 		$< u-boot-elf.o
+endif
 	@$(LD) u-boot-elf.o -o $@ \
 		--defsym=_start=$(CONFIG_SYS_TEXT_BASE) \
 		-Ttext=$(CONFIG_SYS_TEXT_BASE)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index d7a9b11..6475a21 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -44,6 +44,12 @@ config CPU_ARM1176
 	select HAS_VBAR
 	select SYS_CACHE_SHIFT_5
 
+
+config ARMV8_AARCH32
+	bool "some help"
+	help
+	  some better help
+
 config CPU_V7
 	bool
 	select HAS_VBAR
diff --git a/arch/arm/cpu/armv7/virt-v7.c b/arch/arm/cpu/armv7/virt-v7.c
index d33e5c6..b0f54e3 100644
--- a/arch/arm/cpu/armv7/virt-v7.c
+++ b/arch/arm/cpu/armv7/virt-v7.c
@@ -131,12 +131,14 @@ int armv7_init_nonsec(void)
 	 * ram, so need to relocate secure section before enabling other
 	 * cores.
 	 */
+#ifndef CONFIG_ARMV8_AARCH32
 	relocate_secure_section();
 
 #ifndef CONFIG_ARMV7_PSCI
 	smp_set_core_boot_addr((unsigned long)secure_ram_addr(_smp_pen), -1);
 	smp_kick_all_cpus();
 #endif
+#endif
 
 	/* call the non-sec switching code on this CPU also */
 	secure_ram_addr(_nonsec_init)();
diff --git a/arch/arm/cpu/armv8/u-boot-spl.lds b/arch/arm/cpu/armv8/u-boot-spl.lds
index cc427c3..bddfbe6 100644
--- a/arch/arm/cpu/armv8/u-boot-spl.lds
+++ b/arch/arm/cpu/armv8/u-boot-spl.lds
@@ -17,8 +17,13 @@ MEMORY { .sram : ORIGIN = CONFIG_SPL_TEXT_BASE,
 MEMORY { .sdram : ORIGIN = CONFIG_SPL_BSS_START_ADDR,
 		LENGTH = CONFIG_SPL_BSS_MAX_SIZE }
 
+#ifdef CONFIG_ARMV8_AARCH32
+OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
+OUTPUT_ARCH(arm)
+#else
 OUTPUT_FORMAT("elf64-littleaarch64", "elf64-littleaarch64", "elf64-littleaarch64")
 OUTPUT_ARCH(aarch64)
+#endif
 ENTRY(_start)
 SECTIONS
 {
diff --git a/arch/arm/cpu/armv8/u-boot.lds b/arch/arm/cpu/armv8/u-boot.lds
index fd15ad5..0543458 100644
--- a/arch/arm/cpu/armv8/u-boot.lds
+++ b/arch/arm/cpu/armv8/u-boot.lds
@@ -8,8 +8,13 @@
  * SPDX-License-Identifier:	GPL-2.0+
  */
 
+#ifdef CONFIG_ARMV8_AARCH32
+OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
+OUTPUT_ARCH(arm)
+#else
 OUTPUT_FORMAT("elf64-littleaarch64", "elf64-littleaarch64", "elf64-littleaarch64")
 OUTPUT_ARCH(aarch64)
+#endif
 ENTRY(_start)
 SECTIONS
 {
diff --git a/arch/arm/include/asm/armv8/mmu.h b/arch/arm/include/asm/armv8/mmu.h
index aa0f3c4..755c517 100644
--- a/arch/arm/include/asm/armv8/mmu.h
+++ b/arch/arm/include/asm/armv8/mmu.h
@@ -77,8 +77,13 @@
 #define PTE_BLOCK_INNER_SHARE	(3 << 8)
 #define PTE_BLOCK_AF		(1 << 10)
 #define PTE_BLOCK_NG		(1 << 11)
+#ifdef CONFIG_ARMV8_AARCH32
+#define PTE_BLOCK_PXN		((1ULL) << 53)
+#define PTE_BLOCK_UXN		((1ULL) << 54)
+#else
 #define PTE_BLOCK_PXN		(UL(1) << 53)
 #define PTE_BLOCK_UXN		(UL(1) << 54)
+#endif
 
 /*
  * AttrIndx[2:0]
-- 
1.9.1