[PATCHv2 00/16] Suspend to RAM support for Armada XP
Thomas Petazzoni
thomas.petazzoni at free-electrons.com
Fri Nov 14 07:21:20 PST 2014
Hello,
This is the second version of the patches implementing suspend to RAM
for the Marvell Armada XP platform, and specifically for the Armada XP
GP board.
If possible, I'd like this patch series to be considered as 3.19
material.
For now, it does not implement suspend/resume for all device drivers,
it only implements the core of the suspend/resume functionality:
enough to make sure that the system can enter suspend and resume from
suspend, restart all CPUs, and get back to a shell prompt. Additional
work in individual device drivers will be needed, and provided as
follow-up patches.
There are three important things to understand about the hardware
before reading this patch series:
- The Armada XP SoC cannot put itself into a suspend to RAM state. It
requires an external circuit, which in most cases, is a PIC
micro-controller, to turn off the SoC. This PIC is connected to the
SoC using a set of GPIOs, which allow the SoC to talk to the PIC
and request certain things to be done.
This means that the Armada XP suspend/resume logic has some
board-specific code, which is fairly uncommon for suspend/resume
code in the ARM world.
We have chosen to represent the PIC and the fact that it's
connected to the SoC using 3 GPIOs in the Device
Tree.
- When exiting from suspend, the SoC is actually powered up again
completely from scratch, so it goes through the bootloader. The
kernel has to fill a bootloader-specific structure at a fixed
physical address to pass information to the bootloader that will
tell the bootloader to do a resume and therefore jump back directly
into the kernel resume entry point, instead of doing a normal boot.
- The bootloader has to reconfigure the DRAM controller, which
involves executing some DDR3 training code that has the unfortunate
side effect of overwriting the first 10 KB of each DRAM
chip-select. We therefore have to ensure that the kernel does not
use the first 10 KB of each DRAM chip select.
So, in sequence:
* PATCH 1 and 2 are mainly preparation patches: Device Tree binding
documentation, fixing an errata of the Armada XP.
* PATCH 3 to 8 add suspend/resume support to some core drivers:
irqchip, clocksource, gpio, mvebu-mbus and clock.
Note that the gpio suspend/resume patch was said to be applied by
Linus Walleij in
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-November/299201.html,
but I don't see it present in
https://git.kernel.org/cgit/linux/kernel/git/linusw/linux-gpio.git/log/?h=for-next,
so I've kept it for now in this patch series.
* PATCH 9 implements the core of the SoC suspend/resume logic.
* PATCH 10 makes sure the first 10 KB of each DRAM chip select isn't
used by the kernel.
* PATCH 11 implements the board-specific suspend/resume logic,
especially talking with the PIC micro-controller over GPIOs.
* PATCH 12 and 13 make some other additional changes to the Armada XP
SoC support to make suspend/resume work properly.
* PATCH 14 to 16 modify the Armada XP and Armada XP GP Device Tree
description to add the relevant hardware blocks that are needed for
suspend/resume: description of the PIC micro-controller and the 3
GPIOs connecting it to the SoC, an additional set of the register
for mvebu-mbus, and the registers for the SDRAM controller.
Changes since v1:
- Add Reviewed-by from Grégory Clement on
Documentation: dt-bindings: minimal documentation for MVEBU SDRAM controller
gpio: mvebu: add suspend/resume support
bus: mvebu-mbus: provide a mechanism to save SDRAM window configuration
- Added Acked-by from Grégory Clement on
ARM: mvebu: enable strex backoff delay
ARM: mvebu: reserve the first 10 KB of each memory bank for suspend/resume
ARM: mvebu: make sure MMU is disabled in armada_370_xp_cpu_resume
ARM: mvebu: synchronize secondary CPU clocks on resume
ARM: mvebu: add suspend/resume DT information for Armada XP GP
ARM: mvebu: adjust mbus controller description on Armada 370/XP
ARM: mvebu: add SDRAM controller description for Armada XP
clk: mvebu: add suspend/resume for gatable clocks
- Add Acked-by from Alexandre Courbot on
gpio: mvebu: add suspend/resume support
- Drop patch "irqchip: irq-armada-370-xp: use proper return value for
->set_affinity()" as it was applied by Jason Cooper.
- Fix typo in commit log of "clocksource: time-armada-370-xp: add
suspend/resume support", noticed by Grégory Clement.
- Adjust the name of the new variables used in "clocksource:
time-armada-370-xp: add suspend/resume support" to save the state
of timer 0, to make it clear only the state of timer 0 is
preserved. Suggested by Grégory Clement.
- In the suspend/resume code of the mvebu-mbus driver, make sure to
fail (and therefore abort the suspend) if the MBus bridge registers
were not mapped, instead of continuing with the suspend procedure
and later on have a system that we know cannot resume
properly. Suggested by Grégory Clement.
- Remove cpu_pm_cluster_{enter,exit} calls from
mach-mvebu/pm.c. Suggested by Grégory Clement.
- In patch "ARM: mvebu: Armada XP GP specific suspend/resume code",
fixup the wait loop of 100 cycles before entering suspend to
actually initialize the r1 register before entering the wait
loop. Before that, r1 was uninitialized, and a JTAG has shown that
it was generally defined to 0, so the loop started by decrementing
it by 1, making r1 equal 0xFFFFFFFF. So we had 2^32 iterations of a
two instructions loop, at 1.2 Ghz, about a 7 seconds
delay. Switching to the 100 cycles loop that is needed showed that
the previous mdelay of 250 ms was way too short: the PIC needs
several seconds before the two GPIO toggles. The Marvell vendor
kernel uses a bit more than 3 seconds delay, and experience has
shown that a 3 seconds delay works fine, while shorter delays
sometimes lead to a system that doesn't enter suspend. Noticed by
Grégory Clement.
Best regards,
Thomas
Nadav Haklai (1):
ARM: mvebu: enable strex backoff delay
Thomas Petazzoni (15):
Documentation: dt-bindings: minimal documentation for MVEBU SDRAM
controller
irqchip: irq-armada-370-xp: suspend/resume support
clocksource: time-armada-370-xp: add suspend/resume support
gpio: mvebu: add suspend/resume support
bus: mvebu-mbus: suspend/resume support
bus: mvebu-mbus: provide a mechanism to save SDRAM window
configuration
clk: mvebu: add suspend/resume for gatable clocks
ARM: mvebu: implement suspend/resume support for Armada XP
ARM: mvebu: reserve the first 10 KB of each memory bank for
suspend/resume
ARM: mvebu: Armada XP GP specific suspend/resume code
ARM: mvebu: make sure MMU is disabled in armada_370_xp_cpu_resume
ARM: mvebu: synchronize secondary CPU clocks on resume
ARM: mvebu: add suspend/resume DT information for Armada XP GP
ARM: mvebu: adjust mbus controller description on Armada 370/XP
ARM: mvebu: add SDRAM controller description for Armada XP
.../devicetree/bindings/bus/mvebu-mbus.txt | 17 +-
.../memory-controllers/mvebu-sdram-controller.txt | 21 ++
arch/arm/boot/dts/armada-370-xp.dtsi | 3 +-
arch/arm/boot/dts/armada-xp-gp.dts | 19 +-
arch/arm/boot/dts/armada-xp.dtsi | 5 +
arch/arm/mach-mvebu/Makefile | 2 +-
arch/arm/mach-mvebu/board-v7.c | 51 +++++
arch/arm/mach-mvebu/common.h | 2 +
arch/arm/mach-mvebu/platsmp.c | 31 ++-
arch/arm/mach-mvebu/pm-board.c | 141 +++++++++++++
arch/arm/mach-mvebu/pm.c | 218 +++++++++++++++++++++
arch/arm/mach-mvebu/pmsu.h | 1 +
arch/arm/mach-mvebu/pmsu_ll.S | 8 +
arch/arm/mm/proc-v7.S | 2 -
drivers/bus/mvebu-mbus.c | 180 ++++++++++++++++-
drivers/clk/mvebu/common.c | 30 ++-
drivers/clocksource/time-armada-370-xp.c | 25 +++
drivers/gpio/gpio-mvebu.c | 99 ++++++++++
drivers/irqchip/irq-armada-370-xp.c | 52 +++++
include/linux/mbus.h | 1 +
20 files changed, 874 insertions(+), 34 deletions(-)
create mode 100644 Documentation/devicetree/bindings/memory-controllers/mvebu-sdram-controller.txt
create mode 100644 arch/arm/mach-mvebu/pm-board.c
create mode 100644 arch/arm/mach-mvebu/pm.c
--
2.1.0
More information about the linux-arm-kernel
mailing list