arm_pmu: ACPI support

Hi,

This series implements ACPI support in the ARM PMU code. It borrows some code from Jeremy's series [1], but takes a different approach to probing and association, using the usual hotplug state machine, minimising external changes required, and simplifying the relationship with the common arm_pmu code.

The first few patches are preparatory cleanup/refactoring, with the latter half of the series being specific to ACPI support.

The series is based on Will's perf/updates branch [2]. I've pushed the whole series out to the arm/perf/acpi branch [3] of my kernel.org repo.

Due to the innards of the hotplug callback framework, it's not entirely safe to register a PMU in a hotplug callback. Due to this, we can only associated hotplugged CPUs with a PMU if a matching CPU was around at probe time. A similar restriction already applies to DT systems. We may be able to relax this with some future work.

I've given this some testing on a Juno platform (using SPIs). To see that IRQs are correctly associated, I've tested with the following:

   $ taskset -c ${SOME_CPU_HERE} perf record \
     -e armv8_pmuv3_0/cpu_cycles/ \
     -e armv8_pmuv3_1/cpu_cycles/ \
     cat /proc/interrupts

I've also booted with nr_cpus temporarily capped (passing maxcpus=) to test the association logic. This has also been tested in a VM using PPIs; I do not have access to a host machine which itself uses PPIs.

Since v1 [4]:
* Fix up ACPI bits per Lorenzo's request
* Accumulate tags
* Check presence of PMUv3

Since v2 [5]:
* Clean up GSIs when a request fails
* Rename parse/unparse functions
* Use cpuid_feature_extract_unsigned_field() for PMUVer
* Drop parking protocol cleanups. I'll resend these later.

Thanks,
Mark.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-January/482397.html
[2] git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git perf/updates
[3] git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git arm/perf/acpi
[4] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-March/492897.html
[5] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/499982.html

Mark Rutland (14):
drivers/perf: arm_pmu: remove pointless PMU disabling drivers/perf: arm_pmu: define armpmu_init_fn drivers/perf: arm_pmu: fold init into alloc drivers/perf: arm_pmu: factor out pmu registration drivers/perf: arm_pmu: simplify cpu_pmu_request_irqs() drivers/perf: arm_pmu: handle no platform_device drivers/perf: arm_pmu: rename irq request/free functions drivers/perf: arm_pmu: split cpu-local irq request/free drivers/perf: arm_pmu: move irq request/free into probe drivers/perf: arm_pmu: split out platform device probe logic
arm64: add function to get a cpu's MADT GICC table drivers/perf: arm_pmu: add ACPI framework
arm64: pmuv3: handle !PMUv3 when probing
arm64: pmuv3: use arm_pmu ACPI framework

  arch/arm64/include/asm/acpi.h   |   2 +
  arch/arm64/kernel/perf_event.c  | 113 ++++++++----
  arch/arm64/kernel/smp.c         |  10 ++
  drivers/perf/Kconfig            |   4 +
  drivers/perf/Makefile           |   3 +-
  drivers/perf/arm_pmu.c          | 387 ++++++++++------------------------------
  drivers/perf/arm_pmu_acpi.c     | 256 ++++++++++++++++++++++++++
  drivers/perf/arm_pmu_platform.c | 235 ++++++++++++++++++++++++
  include/linux/cpuhotplug.h      |   1 +
  include/linux/perf/arm_pmu.h    |  22 ++-
  10 files changed, 708 insertions(+), 325 deletions(-)

create mode 100644 drivers/perf/arm_pmu_acpi.c create mode 100644 drivers/perf/arm_pmu_platform.c