armv8/vexpress64: make multientry conditional
While the Freescale ARMv8 board LS2085A will enter U-Boot both
on a master and a secondary (slave) CPU, this is not the common
behaviour on ARMv8 platforms. The norm is that U-Boot is entered
from the master CPU only, while the other CPUs are kept in
WFI (wait for interrupt) state.
The code determining which CPU we are running on is using the
MPIDR register, but the definition of that register varies with
platform to some extent, and handling multi-cluster platforms
(such as the Juno) will become cumbersome. It is better to only
enable the multiple entry code on machines that actually need
it and disable it by default.
Make the single entry default and add a special
ARMV8_MULTIENTRY KConfig option to be used by the
platforms that need multientry and set it for the LS2085A.
Delete all use of the CPU_RELEASE_ADDR from the Vexpress64
boards as it is just totally unused and misleading, and
make it conditional in the generic start.S code.
This makes the Juno platform start U-Boot properly.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
index 4b11aa4..df80a4e 100644
--- a/arch/arm/cpu/armv8/start.S
+++ b/arch/arm/cpu/armv8/start.S
@@ -77,6 +77,7 @@
/* Processor specific initialization */
bl lowlevel_init
+#ifdef CONFIG_ARMV8_MULTIENTRY
branch_if_master x0, x1, master_cpu
/*
@@ -88,11 +89,10 @@
ldr x0, [x1]
cbz x0, slave_cpu
br x0 /* branch to the given address */
-
- /*
- * Master CPU
- */
master_cpu:
+ /* On the master CPU */
+#endif /* CONFIG_ARMV8_MULTIENTRY */
+
bl _main
/*-----------------------------------------------------------------------*/
@@ -100,6 +100,15 @@
WEAK(lowlevel_init)
mov x29, lr /* Save LR */
+#ifndef CONFIG_ARMV8_MULTIENTRY
+ /*
+ * For single-entry systems the lowlevel init is very simple.
+ */
+ ldr x0, =GICD_BASE
+ bl gic_init_secure
+
+#else /* CONFIG_ARMV8_MULTIENTRY is set */
+
#if defined(CONFIG_GICV2) || defined(CONFIG_GICV3)
branch_if_slave x0, 1f
ldr x0, =GICD_BASE
@@ -137,6 +146,8 @@
bl armv8_switch_to_el1
#endif
+#endif /* CONFIG_ARMV8_MULTIENTRY */
+
2:
mov lr, x29 /* Restore LR */
ret