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Gmane
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 4 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:

http://www.linaro.org/documents/download/f3569407bb1fb8bde0d6da80e285b832508f92f57223c

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:
    http://lwn.net/Articles/481055/
    However the code is only accessible to Linaro members for the
    time being.
 
CD: 3ms