[PATCH/RFC 0/5] ARM: shmobile: rcar-gen2: Add CPG Clock Domain

[Geert Uytterhoeven <geert+renesas@glider.be>]

	Hi,

This RFC patch series adds Clock Domain support to the R-Car Gen2 Clock
Pulse Generator (CPG) driver using the generic PM Domain.  This allows
to power-manage the module clocks of SoC devices that are part of the
CPG Clock Domain using Runtime PM, or for system suspend/resume.

SoC devices that are part of the CPG Clock Domain and can be
power-managed through their primary clock are tagged in DT with a proper
"power-domains" property. Drivers for devices with multiple clocks
(notably du and rcar-sound) still have to manage their (multiple module)
clocks themselves.

Finally, the legacy default PM domain hack in drivers/sh/pm_runtime.c is
disabled when running on an R-Car Gen2 SoC with genpd support.

Compared to the legacy default PM domain hack, the CPG Clock Domain has
several advantages:
  - It only affects on-SoC devices, not all platform devices,
  - It only affects the on-SoC devices we want, as specified in DT,
  - Allmost all module clocks of all on-SoC devices (barring devices
    needed for wake-up[*]) are now gated during s2ram, saving more
    power.

Here's a list of all devices in the CPG Clock Domain on r8a7791:

root@koelsch:~# cat /sys/kernel/debug/pm_genpd/pm_genpd_summary
    domain                      status         slaves
           /device                                      runtime status
----------------------------------------------------------------------
cpg_clocks                      on
    /devices/platform/e61c0000.interrupt-controller     active
    /devices/platform/e60b0000.i2c                      suspended
    /devices/platform/ffca0000.timer                    suspended
    /devices/platform/e6050000.gpio                     active
    /devices/platform/e6051000.gpio                     active
    /devices/platform/e6052000.gpio                     active
    /devices/platform/e6053000.gpio                     active
    /devices/platform/e6054000.gpio                     active
    /devices/platform/e6055000.gpio                     active
    /devices/platform/e6055400.gpio                     active
    /devices/platform/e6055800.gpio                     active
    /devices/platform/ee090000.pci                      active
    /devices/platform/ee0d0000.pci                      active
    /devices/platform/fe000000.pcie                     unsupported
    /devices/platform/e6700000.dma-controller           active
    /devices/platform/e6720000.dma-controller           active
    /devices/platform/ec700000.dma-controller           active
    /devices/platform/ec720000.dma-controller           suspended
    /devices/platform/e6e60000.serial                   active
    /devices/platform/e6e68000.serial                   active
    /devices/platform/ee300000.sata                     unsupported
    /devices/platform/e6b10000.spi                      suspended
    /devices/platform/e6e20000.spi                      suspended
    /devices/platform/ee700000.ethernet                 active
    /devices/platform/e6530000.i2c                      suspended
    /devices/platform/e6ef1000.video                    suspended
    /devices/platform/e61f0000.thermal                  active
    /devices/platform/ee100000.sd                       active
    /devices/platform/ee140000.sd                       active
    /devices/platform/ee160000.sd                       active
root@koelsch:~#

Logically, the CPG Clock Domain operates on the SoC CPG/MSTP block.
As there's no single device node in DT representing this block (there
are separate device nodes for the CPG and for the individual MSTP
clocks), I bound the logic to the CPG device node.
Perhaps this is something we should change for future SoCs?

As usual when involving clocks and/or PM Domains, the DTS changes depend
stricly on the driver change. The final patch must be applied last.

The DTS changes also depend on the series "[PATCH 0/5] ARM: shmobile:
Add INTC-SYS clock to device tree" I've just sent.

This was tested on r8a7791/koelsch.

Thanks for your comments!

[*] GPIO wake-up requires "[PATCH 0/3] gpio: rcar: Fix wake up using
gpio-keys with PM domain").

Geert Uytterhoeven (5):
  [RFC] clk: shmobile: rcar-gen2: Add CPG Clock Domain support
  [RFC] ARM: shmobile: r8a7790 dtsi: Add CPG Clock Domain
  [RFC] ARM: shmobile: r8a7791 dtsi: Add CPG Clock Domain
  [RFC] ARM: shmobile: r8a7794 dtsi: Add CPG Clock Domain
  drivers: sh: Disable PM runtime for multi-platform R-Car Gen2 with
    genpd

 .../clock/renesas,rcar-gen2-cpg-clocks.txt         | 26 ++++++-
 arch/arm/boot/dts/r8a7790.dtsi                     | 77 +++++++++++++++++++--
 arch/arm/boot/dts/r8a7791.dtsi                     | 80 ++++++++++++++++++++--
 arch/arm/boot/dts/r8a7794.dtsi                     | 29 ++++++++
 arch/arm/mach-shmobile/Kconfig                     |  1 +
 drivers/clk/shmobile/clk-rcar-gen2.c               | 63 +++++++++++++++++
 drivers/sh/pm_runtime.c                            | 10 +--
 7 files changed, 268 insertions(+), 18 deletions(-)

-- 
1.9.1

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds