ARM: add SMP support for non-secure switch
Currently the non-secure switch is only done for the boot processor.
To enable full SMP support, we have to switch all secondary cores
into non-secure state also.
So we add an entry point for secondary CPUs coming out of low-power
state and make sure we put them into WFI again after having switched
to non-secure state.
For this we acknowledge and EOI the wake-up IPI, then go into WFI.
Once being kicked out of it later, we sanity check that the start
address has actually been changed (since another attempt to switch
to non-secure would block the core) and jump to the new address.
The actual CPU kick is done by sending an inter-processor interrupt
via the GIC to all CPU interfaces except the requesting processor.
The secondary cores will then setup their respective GIC CPU
interface.
While this approach is pretty universal across several ARMv7 boards,
we make this function weak in case someone needs to tweak this for
a specific board.
The way of setting the secondary's start address is board specific,
but mostly different only in the actual SMP pen address, so we also
provide a weak default implementation and just depend on the proper
address to be set in the config file.
Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
diff --git a/arch/arm/cpu/armv7/nonsec_virt.S b/arch/arm/cpu/armv7/nonsec_virt.S
index 3dd60b7..cbee8f7 100644
--- a/arch/arm/cpu/armv7/nonsec_virt.S
+++ b/arch/arm/cpu/armv7/nonsec_virt.S
@@ -58,6 +58,28 @@
movs pc, lr @ return to non-secure SVC
/*
+ * Secondary CPUs start here and call the code for the core specific parts
+ * of the non-secure and HYP mode transition. The GIC distributor specific
+ * code has already been executed by a C function before.
+ * Then they go back to wfi and wait to be woken up by the kernel again.
+ */
+ENTRY(_smp_pen)
+ mrs r0, cpsr
+ orr r0, r0, #0xc0
+ msr cpsr, r0 @ disable interrupts
+ ldr r1, =_start
+ mcr p15, 0, r1, c12, c0, 0 @ set VBAR
+
+ bl _nonsec_init
+
+ ldr r1, [r0, #GICC_IAR] @ acknowledge IPI
+ str r1, [r0, #GICC_EOIR] @ signal end of interrupt
+
+ adr r0, _smp_pen @ do not use this address again
+ b smp_waitloop @ wait for IPIs, board specific
+ENDPROC(_smp_pen)
+
+/*
* Switch a core to non-secure state.
*
* 1. initialize the GIC per-core interface
@@ -138,3 +160,16 @@
bx lr
ENDPROC(_nonsec_init)
+
+#ifdef CONFIG_SMP_PEN_ADDR
+/* void __weak smp_waitloop(unsigned previous_address); */
+ENTRY(smp_waitloop)
+ wfi
+ ldr r1, =CONFIG_SMP_PEN_ADDR @ load start address
+ ldr r1, [r1]
+ cmp r0, r1 @ make sure we dont execute this code
+ beq smp_waitloop @ again (due to a spurious wakeup)
+ mov pc, r1
+ENDPROC(smp_waitloop)
+.weak smp_waitloop
+#endif