This patch implements the power_down_finish() method for TC2, to
enable the kernel to confirm when CPUs are safely powered down.
The information required for determining when a CPU is parked
cannot be obtained from any single place, so a few sources of
information must be combined:
* mcpm_cpu_power_down() must be pending for the CPU, so that we
don't get confused by false STANDBYWFI positives arising from
CPUidle. This is detected by waiting for the tc2_pm use count
for the target CPU to reach 0.
* Either the SPC must report that the CPU has asserted
STANDBYWFI, or the TC2 tile's reset control logic must be
holding the CPU in reset.
Just checking for STANDBYWFI is not sufficient, because this
signal is not latched when the the cluster is clamped off and
powered down: the relevant status bits just drop to zero. This
means that STANDBYWFI status cannot be used for reliable
detection of the last CPU in a cluster reaching WFI.
This patch is required in order for kexec to work with MCPM on TC2.
MCPM code was changed in commit 0de0d64675 ('ARM: 7848/1: mcpm:
Implement cpu_kill() to synchronise on powerdown'), and since then it
will hit a WARN_ON_ONCE() due to power_down_finish not being implemented
on the TC2 platform.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Pawel Moll <pawel.moll@arm.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>
SPC(Serial Power Controller) on TC2 also controls the CPU performance
operating points which is essential to provide CPU DVFS. The M3
microcontroller provides two sets of eight performance values, one set
for each cluster (CA15 or CA7). Each of this value contains the
frequency(kHz) and voltage(mV) at that performance level. It expects
these performance level to be passed through the SPC PERF_LVL registers.
This patch adds support to populate these performance levels from M3,
build the mapping to CPU OPPs at the boot and then use it to get and
set the CPU performance level runtime.
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Pawel Moll <Pawel.Moll@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The TC2 versatile express core tile integrates a logic block that provides
the interface between the dual cluster test-chip and the M3 microcontroller
that carries out power management. The logic block, called Serial Power
Controller (SPC), contains several memory mapped registers to control among
other things low-power states, wake-up irqs and per-CPU jump addresses
registers.
This patch provides a driver that enables run-time control of features
implemented by the SPC power management control logic with an API to
be used by different subsystem drivers on top.
The SPC control logic is required to be programmed very early in the boot
process to reset secondary CPUs on the TC2 testchip, set-up jump addresses
and wake-up IRQs for power management. Hence, waiting for core changes to
be made in the device core code to enable early registration of platform
devices, the driver puts in place an early init scheme that allows kernel
drivers to initialize the SPC driver directly from the components requiring
it, if their initialization routine is called before this driver init
function during the boot process.
Device tree bindings documentation for the SPC component is also provided.
Cc: Olof Johansson <olof@lixom.net>
Cc: Amit Kucheria <amit.kucheria@linaro.org>
Cc: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Achin Gupta <achin.gupta@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@arm.com>
Acked-by: Pawel Moll <pawel.moll@arm.com>
[ np: moved from drivers/mfd/ to drivers/platform/vexpress/ ]
Signed-off-by: Nicolas Pitre <nico@linaro.org>
[ PM: moved again to arch/arm/mach-vexpress, requested by Olof ]
[ PM: removed useless printk, from Olof ]
[ PM: made the driver SPC-only ]
Signed-off-by: Pawel Moll <pawel.moll@arm.com>
