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From: Nicolas Pitre <nicolas.pitre <at> linaro.org>
Subject: [PATCH 00/16] big.LITTLE low-level CPU and cluster power management
Newsgroups: gmane.linux.ports.arm.kernel
Date: Thursday 10th January 2013 00:20:35 UTC (over 5 years ago)
This is the initial public posting of the initial support for big.LITTLE.
Included here is the code required to safely power up and down CPUs in a
b.L system, whether this is via CPU hotplug, a cpuidle driver or the
Linaro b.L in-kernel switcher[*] on top of this.  Only  SMP secondary
boot and CPU hotplug support is included at this time.  Getting to this
point already represents a significcant chunk of code as illustrated by
the diffstat below.

This work was presented at Linaro Connect in Copenhagen by Dave Martin and
myself.  The presentation slides are available here:


The code is now stable on both Fast Models as well as Virtual Express TC2
and ready for public review.

Platform support is included for Fast Models implementing the
Cortex-A15x4-A7x4 and Cortex-A15x1-A7x1 configurations.  To allow
successful compilation, I also included a preliminary version of the
CCI400 driver from Lorenzo Pieralisi.

Support for actual hardware such as Vexpress TC2 should come later,
once the basic infrastructure from this series is merged.  A few DT
bindings are used but not yet documented.

This series is made of the following parts:

Low-level support code:
[PATCH 01/16] ARM: b.L: secondary kernel entry code
[PATCH 02/16] ARM: b.L: introduce the CPU/cluster power API
[PATCH 03/16] ARM: b.L: introduce helpers for platform coherency
[PATCH 04/16] ARM: b.L: Add baremetal voting mutexes
[PATCH 05/16] ARM: bL_head: vlock-based first man election

Adaptation layer to hook with the generic kernel infrastructure:
[PATCH 06/16] ARM: b.L: generic SMP secondary bringup and hotplug
[PATCH 07/16] ARM: bL_platsmp.c: close the kernel entry gate before
[PATCH 08/16] ARM: bL_platsmp.c: make sure the GIC interface of a
[PATCH 09/16] ARM: vexpress: Select the correct SMP operations at

Fast Models support:
[PATCH 10/16] ARM: vexpress: introduce DCSCB support
[PATCH 11/16] ARM: vexpress/dcscb: add CPU use counts to the power
[PATCH 12/16] ARM: vexpress/dcscb: do not hardcode number of CPUs
[PATCH 13/16] drivers: misc: add ARM CCI support
[PATCH 14/16] ARM: TC2: ensure powerdown-time data is flushed from
[PATCH 15/16] ARM: vexpress/dcscb: handle platform coherency
[PATCH 16/16] ARM: vexpress/dcscb: probe via device tree

Here's the diffstat:

 .../big.LITTLE/cluster-pm-race-avoidance.txt    | 498 ++++++++++++++++++
 Documentation/arm/big.LITTLE/vlocks.txt         | 211 ++++++++
 arch/arm/Kconfig                                |   6 +
 arch/arm/common/Makefile                        |   3 +
 arch/arm/common/bL_entry.c                      | 278 ++++++++++
 arch/arm/common/bL_head.S                       | 232 ++++++++
 arch/arm/common/bL_platsmp.c                    |  85 +++
 arch/arm/common/gic.c                           |   6 +
 arch/arm/common/vlock.S                         | 108 ++++
 arch/arm/common/vlock.h                         |  43 ++
 arch/arm/include/asm/bL_entry.h                 | 189 +++++++
 arch/arm/include/asm/hardware/gic.h             |   2 +
 arch/arm/include/asm/mach/arch.h                |   3 +
 arch/arm/kernel/setup.c                         |   5 +-
 arch/arm/mach-vexpress/Kconfig                  |   9 +
 arch/arm/mach-vexpress/Makefile                 |   1 +
 arch/arm/mach-vexpress/core.h                   |   2 +
 arch/arm/mach-vexpress/dcscb.c                  | 257 +++++++++
 arch/arm/mach-vexpress/dcscb_setup.S            |  77 +++
 arch/arm/mach-vexpress/platsmp.c                |  12 +
 arch/arm/mach-vexpress/v2m.c                    |   2 +-
 drivers/misc/Kconfig                            |   4 +
 drivers/misc/Makefile                           |   1 +
 drivers/misc/arm-cci.c                          | 124 +++++
 include/linux/arm-cci.h                         |  30 ++
 25 files changed, 2186 insertions(+), 2 deletions(-)

Review comments are welcome!

[*] General design information on the b.L switcher can be found here:
    However the code is only accessible to Linaro members for the
    time being.
CD: 3ms