[PATCH v2 5/6] arm: Use armv8_switch_to_el1 env to switch to EL1

[Peter Hoyes]

From: Peter Hoyes <Peter.Hoyes at arm.com>

Use the environment variable armv8_switch_to_el1 to determine whether
to switch to EL1 at runtime. This is an alternative to the
CONFIG_ARMV8_SWITCH_TO_EL1 compile-time option.

The environment variable will be ineffective if the ARMV8_MULTIENTRY
config is used.

This is required by the Armv8r64 architecture, which must be able to
boot at S-EL1 for Linux but may need to boot at other ELs for other
systems.

Signed-off-by: Peter Hoyes <Peter.Hoyes at arm.com>
---
 arch/arm/lib/bootm.c | 40 +++++++++++++++++++++++++---------------
 1 file changed, 25 insertions(+), 15 deletions(-)

diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index f60ee3a7e6..ea9bfe7570 100644
--- a/arch/arm/lib/bootm.c
+++ b/arch/arm/lib/bootm.c
@@ -317,7 +317,6 @@ __weak void update_os_arch_secondary_cores(uint8_t os_arch)
 {
 }
 
-#ifdef CONFIG_ARMV8_SWITCH_TO_EL1
 static void switch_to_el1(void)
 {
 	if ((IH_ARCH_DEFAULT == IH_ARCH_ARM64) &&
@@ -332,7 +331,6 @@ static void switch_to_el1(void)
 				    ES_TO_AARCH64);
 }
 #endif
-#endif
 
 /* Subcommand: GO */
 static void boot_jump_linux(bootm_headers_t *images, int flag)
@@ -359,21 +357,33 @@ static void boot_jump_linux(bootm_headers_t *images, int flag)
 
 		update_os_arch_secondary_cores(images->os.arch);
 
-#ifdef CONFIG_ARMV8_SWITCH_TO_EL1
-		armv8_switch_to_el2((u64)images->ft_addr, 0, 0, 0,
-				    (u64)switch_to_el1, ES_TO_AARCH64);
+#ifdef CONFIG_ARMV8_MULTIENTRY
+		int armv8_switch_to_el1 = -1;
 #else
-		if ((IH_ARCH_DEFAULT == IH_ARCH_ARM64) &&
-		    (images->os.arch == IH_ARCH_ARM))
-			armv8_switch_to_el2(0, (u64)gd->bd->bi_arch_number,
-					    (u64)images->ft_addr, 0,
-					    (u64)images->ep,
-					    ES_TO_AARCH32);
-		else
-			armv8_switch_to_el2((u64)images->ft_addr, 0, 0, 0,
-					    images->ep,
-					    ES_TO_AARCH64);
+		int armv8_switch_to_el1 = env_get_yesno("armv8_switch_to_el1");
 #endif
+#ifdef CONFIG_ARMV8_SWITCH_TO_EL1
+		if (armv8_switch_to_el1 == -1) {
+			armv8_switch_to_el1 = 1;
+		}
+#endif
+		if (armv8_switch_to_el1 == 1) {
+			armv8_switch_to_el2((u64)images->ft_addr, 0, 0, 0,
+					    (u64)switch_to_el1, ES_TO_AARCH64);
+		} else {
+			if ((IH_ARCH_DEFAULT == IH_ARCH_ARM64) &&
+					(images->os.arch == IH_ARCH_ARM))
+				armv8_switch_to_el2(0,
+						    (u64)gd->bd->bi_arch_number,
+						    (u64)images->ft_addr, 0,
+						    (u64)images->ep,
+						    ES_TO_AARCH32);
+			else
+				armv8_switch_to_el2((u64)images->ft_addr,
+						    0, 0, 0,
+						    images->ep,
+						    ES_TO_AARCH64);
+		}
 	}
 #else
 	unsigned long machid = gd->bd->bi_arch_number;
-- 
2.25.1