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>
While actually switching to non-secure state is one thing, another
part of this process is to make sure that we still have full access
to the interrupt controller (GIC).
The GIC is fully aware of secure vs. non-secure state, some
registers are banked, others may be configured to be accessible from
secure state only.
To be as generic as possible, we get the GIC memory mapped address
based on the PERIPHBASE value in the CBAR register. Since this
register is not architecturally defined, we check the MIDR before to
be from an A15 or A7.
For CPUs not having the CBAR or boards with wrong information herein
we allow providing the base address as a configuration variable.
Now that we know the GIC address, we:
a) allow private interrupts to be delivered to the core
(GICD_IGROUPR0 = 0xFFFFFFFF)
b) enable the CPU interface (GICC_CTLR[0] = 1)
c) set the priority filter to allow non-secure interrupts
(GICC_PMR = 0xFF)
Also we allow access to all coprocessor interfaces from non-secure
state by writing the appropriate bits in the NSACR register.
The generic timer base frequency register is only accessible from
secure state, so we have to program it now. Actually this should be
done from primary firmware before, but some boards seems to omit
this, so if needed we do this here with a board specific value.
The Versatile Express board does not need this, so we remove the
frequency from the configuration file here.
After having switched to non-secure state, we also enable the
non-secure GIC CPU interface, since this register is banked.
Since we need to call this routine also directly from the smp_pen
later (where we don't have any stack), we can only use caller saved
registers r0-r3 and r12 to not mess with the compiler.
Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
Andre Przywara