[Xen-devel] [RFC PATCH v5 00/10] xen_cpufreq implementation in kernel

[Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>]

Hi to all.

Next series of patches implements xen-cpufreq driver in kernel.

Cpufreq core and registered cpufreq governors are located in xen. Hwdom has CPU
driver which can only change frequency of the physical CPUs. In addition this
driver can change CPUs regulator voltage. At start time xen-cpufreq driver
in hwdom reads an information about physical CPUs number and uploads to Xen
information about those physical cpus. Then hwdon uses XEN_SYSCTL_cpufreq_op
operation to start events from hwdom-cpufreq ddriver in Xen.
Changing frequency workflow:
 * hwdom-cpufreq driver in Xen wants to change the
   frequency of the physical CPU
 * hwdom-cpufreq in Xen sets parameters in the shared
   memory
 * hwdom-cpufreq driver in Xen sends an event via event channel
   to notify the xen-cpufreq driver in hwdom
 * xen-cpufreq driver in hwdom reads parameters from the shared
   memory, changes frequency and copies the result of
   the operation to the shared memory
 * xen-cpufreq driver in hwdom sends an event via event channel
   to notify the cpufreq driver in Xen

Next configs should be enabled to use xen-cpufreq driver:
CONFIG_GENERIC_CPUFREQ_CPU0
CONFIG_XEN_CPUFREQ

Changed since v1:
 * added cpufreq_drv_ops which allows to use more than one high-level
   cpufreq driver
 * reworked xen-cpufreq and drivers so the same kernel is able to run
   on bare metal and within Xen.

Changed since v2:
 * used VIRQ_CPUFREQ with number 14 instead of the 13
 * slightly reworked xen-cpufreq driver

Changed since v3:
 * documented /hypervisor/pcpus/ node
 * added cpufreq shared info definition to receive commands from the
   Xen cpufreq driver
 * config CONFIG_CPUMASK_OFFSTACK now is checked in the Kconfig

Changed since v4:
 * implemented an event channel between Xen and hwdom
 * restored XEN_SYSCTL_cpufreq_op definition (start/stop hwdom-cpufreq
   driver events)
 * extended comments for some patches (adding hypercalls, adding xen-cpufreq
   driver)
 * removed VIRQ_CPUFREQ

Oleksandr Dmytryshyn (10):
  PM / OPP: make cpufreq functions dependent on CONFIG_CPU_FREQ_TABLE
  xen/arm: add sysctl hypercall
  xen/arm: add dom0_op hypercall
  docs: Xen ARM DT bindings: document pcpus property
  cpufreq: cpufreq-cpu0: change cpus data path in devtree for hwdom
    kernel
  cpufreq: introduce cpufreq_drv_ops
  cpufreq: make cpufreq low-level drivers visible for CPUFREQ_DRV_OPS
    config
  xen: arm: add cpufreq shared info definition
  xen/arm: add XEN_SYSCTL_cpufreq_op definition
  xen/arm: cpufreq: add xen-cpufreq driver

 Documentation/devicetree/bindings/arm/xen.txt |  20 +-
 arch/arm/include/asm/xen/hypercall.h          |   2 +
 arch/arm/include/asm/xen/interface.h          |  17 +-
 arch/arm/xen/enlighten.c                      |   2 +
 arch/arm/xen/hypercall.S                      |   2 +
 drivers/Makefile                              |   2 +-
 drivers/base/power/opp.c                      |   4 +-
 drivers/cpufreq/Kconfig                       |  40 +-
 drivers/cpufreq/Makefile                      |   2 +
 drivers/cpufreq/acpi-cpufreq.c                |   5 +-
 drivers/cpufreq/cpufreq-cpu0.c                |   8 +-
 drivers/cpufreq/cpufreq.c                     | 116 ++--
 drivers/cpufreq/cpufreq_drv_ops.c             | 196 ++++++
 drivers/cpufreq/cpufreq_drv_ops.h             |  54 ++
 drivers/cpufreq/cpufreq_governor.c            |   4 +-
 drivers/cpufreq/xen-cpufreq.c                 | 917 ++++++++++++++++++++++++++
 include/linux/cpufreq.h                       |   2 +-
 include/linux/opp.h                           |   2 +-
 include/xen/interface/platform.h              |   1 +
 include/xen/interface/sysctl.h                |  89 +++
 include/xen/interface/xen.h                   |   6 +
 21 files changed, 1423 insertions(+), 68 deletions(-)
 create mode 100644 drivers/cpufreq/cpufreq_drv_ops.c
 create mode 100644 drivers/cpufreq/cpufreq_drv_ops.h
 create mode 100644 drivers/cpufreq/xen-cpufreq.c
 create mode 100644 include/xen/interface/sysctl.h

-- 
1.9.1


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