This patchset adds support for booting the secondary CPU cores (and
taking them offline again) on Amlogic Meson8 and Meson8b SoCs.
It is based on an earlier version from Carlo Caione - this helped me
a lot to get a better understanding of how SMP/CPU hotplug works
(compared to the code found in Amlogic's GPL kernel sources from
year 2015).
Changes since v6 from [6]:
- rebased on top of v4.14-rc1 (which only corrected some line
numbers in the SCU patches)
Changes since v5 from [5]:
- dropped dependency on another patch series (for the clock
controller's embedded reset controller, which is needed to boot
the secondary CPUs) from the cover-letter as that series is now
merged
- fix incorrect documentation of scu_cpu_power_enable (thanks to
Russell King for spotting these). removed the paragraph about
preemption, cache coherency and interrupts as we're powering on
a CPU core (the text was copied from the original scu_power_mode
but simply not adjusted). also changed "Set the executing CPUs"
to "Set the given (logical) CPU's" as we're not modifying the
current CPU. this affects only patch #2
- extended the commit message of patch #3 with a short sentence
about why SCU_CPU_STATUS_MASK was introduced
Changes since v4 from [4]:
- use __pa_symbol(secondary_startup) instead of
virt_to_phys(secondary_startup) as suggested by Florian Fainelli
(affects patch #4)
- (cover-letter) removed dependency on my other patch
"ARM: dts: meson: add a node which describes the SRAM" [2] as that
was merged into Kevin's Amlogic repo today
- dropped patch #5 ("clk: meson: meson8b: export the CPU soft reset
lines") again because the reset controller series exposes the
preprocessor macros now directly, see [1]
- refreshed the .dts patches so they now include the new header for
the reset line preprocessor macros
Changes since v3 from [3]:
- added Rob's ACK to patch #1
- replaced a msleep(10) with usleep_range(10000, 15000) in patch #4
- removed all "pen" code from patch #4 as that code was not needed
at all (it was left-over while trying to fix Meson8 secondary CPU
boot - which turned out to have nothing to do with this "pen" code)
- removed all memory barrier operations as they were added based on
the code in the Amlogic GPL kernel tree (while trying to fix the
Meson8 secondary CPU boot - just like the "pen" code). Everything
still works fine with these on my Meson8m2 and Meson8b boards.
- added PATCH #5 as we now have to export the reset identifiers
(just like we do it with the clock identifiers / preprocessor
macros) - this is the result of a change in the reset controller
patch in version 2, see [1]
- use the reset line preprocessor macros (from patch #5) in patches
#6 and #7
Changes since v2 from [0]:
- added support for Meson8 (which requires a slightly different
enable-method)
- implemented CPU hotplug support which allows taking a CPU core
offline for both, Meson8 and Meson8b
- add a function to smp_scu.c which allows enabling a CPU core from
a different CPU (previously only the power mode for the current CPU
could be changed). Without this the CPU cores on Meson8 won't come
up (Amlogic's vendor GPL kernel sources also enable power through
SCU as very first step for Meson8b as well)
- add a function to smp_scu.c to get the power status of a CPU core
(which is needed because the code in .cpu_kill needs to wait until
the core is actually powered off)
- dropped patch "ARM: DTS: meson8b: Extend L2 cache controller node"
as it is already applied (for both, Meson8 and Meson8b)
- dropped the patches which implement the reset controller which is
built into the clock-controller, these are a separate series: [1]
- moved the enable-method property to each CPU node
[0] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-December/390355.html
[1] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004456.html
[2] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004282.html
[3] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004297.html
[4] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004354.html
[5] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004460.html
[6] http://lists.infradead.org/pipermail/linux-amlogic/2017-August/004588.html
Carlo Caione (2):
dt-bindings: Amlogic: Add Meson8 and Meson8b SMP related documentation
ARM: dts: meson8b: add support for booting the secondary CPU cores
Martin Blumenstingl (4):
ARM: smp_scu: add a helper for powering on a specific CPU
ARM: smp_scu: allow the platform code to read the SCU CPU status
ARM: meson: Add SMP bringup code for Meson8 and Meson8b
ARM: dts: meson8: add support for booting the secondary CPU cores
.../devicetree/bindings/arm/amlogic/pmu.txt | 18 +
.../devicetree/bindings/arm/amlogic/smp-sram.txt | 32 ++
Documentation/devicetree/bindings/arm/cpus.txt | 2 +
arch/arm/Makefile | 1 +
arch/arm/boot/dts/meson8.dtsi | 21 +
arch/arm/boot/dts/meson8b.dtsi | 21 +
arch/arm/include/asm/smp_scu.h | 12 +
arch/arm/kernel/smp_scu.c | 43 +-
arch/arm/mach-meson/Kconfig | 1 +
arch/arm/mach-meson/Makefile | 1 +
arch/arm/mach-meson/platsmp.c | 440 +++++++++++++++++++++
11 files changed, 586 insertions(+), 6 deletions(-)
create mode 100644 Documentation/devicetree/bindings/arm/amlogic/pmu.txt
create mode 100644 Documentation/devicetree/bindings/arm/amlogic/smp-sram.txt
create mode 100644 arch/arm/mach-meson/platsmp.c
--
2.14.1
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