arm: Use armv8_switch_to_el1 env to switch to EL1

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@arm.com>

diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index f60ee3a..ea9bfe7 100644 (file)
--- 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;