[PATCH] ARM: EXYNOS: add power domains support for EXYNOS5440
Mark Rutland
mark.rutland at arm.com
Thu Aug 8 10:29:44 EDT 2013
On Tue, Aug 06, 2013 at 05:16:56PM +0100, Bartlomiej Zolnierkiewicz wrote:
>
> Hi,
>
> On Saturday, August 03, 2013 09:14:11 PM Mark Rutland wrote:
> > On Fri, Aug 02, 2013 at 10:01:52PM +0100, Stephen Warren wrote:
> > > (CCing the other DT maintainers, hence quoting binding in full)
> > >
> > > On 08/02/2013 07:23 AM, Bartlomiej Zolnierkiewicz wrote:
> > > > On EXYNOS5440 power domains are handled in a different way than on
> > > > the previous EXYNOS SoCs. Add support for them to EXYNOS pm_domains
> > > > driver. Then add device tree nodes for PCIe (controlling power for
> > > > PCIe host controller) and Conn2 (controlling power for Ethernet,
> > > > SATA and USB controllers) power domains to exynos5440.dtsi.
> > > >
> > > > Currently if runtime Power Management is enabled and the driver
> > > > for devices under power domain is disabled then the power domain
> > > > will be disabled by EXYNOS pm_domains driver. To make more active
> > > > use of power domains (dynamically enable and disabled them as
> > > > needed) it is required to add runtime PM support to pci-exynos,
> > > > stmmac, ahci_platform, ohci-exynos and ehci-s5p drivers (to be
> > > > done later).
> > > >
> > > > Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie at samsung.com>
> > > > Signed-off-by: Myungjoo Ham <myungjoo.ham at samsung.com>
> > > > Cc: Tomasz Figa <t.figa at samsung.com>
> > > > Cc: Stephen Warren <swarren at wwwdotorg.org>
> > > > ---
> > > > Documentation/devicetree/bindings/arm/exynos/power_domain.txt | 33 ++
> > > > arch/arm/boot/dts/exynos5440.dtsi | 23 +
> > > > arch/arm/mach-exynos/Kconfig | 1
> > > > arch/arm/mach-exynos/common.c | 4
> > > > arch/arm/mach-exynos/pm_domains.c | 138 +++++++++-
> > > > 5 files changed, 190 insertions(+), 9 deletions(-)
> > > >
> > > > Index: b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
> > > > ===================================================================
> > > > --- a/Documentation/devicetree/bindings/arm/exynos/power_domain.txt 2013-08-02 14:45:53.551392396 +0200
> > > > +++ b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt 2013-08-02 14:46:29.799391845 +0200
> > > > @@ -5,20 +5,47 @@ to gate power to one or more peripherals
> > > >
> > > > Required Properties:
> > > > - compatible: should be one of the following.
> > > > - * samsung,exynos4210-pd - for exynos4210 type power domain.
> > > > + * samsung,exynos4210-pd - for Exynos4210 type power domain.
> > > > + * samsung,exynos5440-pd - for Exynos5440 type power domain.
> > > > - reg: physical base address of the controller and length of memory mapped
> > > > - region.
> > > > + region (Exynos4210 type power domain) or bit offset in the control
> > > > + register (Exynos5440 type power domain).
> > > > +
> > > > +Additional parent node must be created for Exynos5440 power domains with
> > > > +the following required properties:
> > > > +- compatible: samsung,exynos5440-power-domains, simple-bus
> > > > +- reg: physical base address of the XMU controller and length of memory
> > > > + mapped region
> > >
> > > It's a little odd to describe the child nodes first. Given the 4210 and
> > > 5440 bindings work so differently, I'd suggest making separate binding
> > > files for the two; samsung,exynos4210-pd.txt and samsung,exynos5440-pd.txt.
>
> OK, I'll fix it.
>
> > > The node being describe here clearly is not a simple-bus; the child
> > > nodes appear to have a specific need that their parent be compatible =
> > > "samsung,exynos5440-power-domains", hence they aren't the independent
> > > devices that simple-bus would usually contain.
> >
> > +1. This is most definitely not a simple-bus, the child nodes reg
> > properties cdon't represent the same address space as the
> > parent's reg property.
>
> What does in mean in the practice? What should I do instead?
The driver for the parent nodes should probe for the child nodes via
some mechanism. The "simple-bus" compatible property should be removed
from the parent node as it's simply not true.
Simple-bus should only be used where the child nodes make sense and are
useable on their own, regardless of the parent node.
>
> > How much does the association of bit-offsets to power domains vary?
>
> On EXYNOS5440 power domains are controlled by control and status registers
> which are shared among all power domains. On other EXYNOS SoCs there are
> separate control/status registers for each power domain.
Ok.
>
> > > Note that I only briefly reviewed the low-level structural aspects of
> > > the binding that I mentioned above; I haven't thought about the binding
> > > at a higher level of e.g. "does this binding conceptually make sense".
> >
> > This is unfortunately difficult to do :(
> >
> > >
> > > > Node of a device using power domains must have a samsung,power-domain property
> > > > defined with a phandle to respective power domain.
> > > >
> > > > -Example:
> > > > +Example for Exynos4210 compatible power domain:
> > > >
> > > > lcd0: power-domain-lcd0 {
> > > > compatible = "samsung,exynos4210-pd";
> > > > reg = <0x10023C00 0x10>;
> > > > };
> > > >
> > > > +Example for Exynos5440 compatible power domains:
> > > > +
> > > > + power-domains at 00160000 {
> > > > + compatible = "samsung,exynos5440-power-domains", "simple-bus";
> > > > + reg = <0x00160000 0x1000>;
> > > > + #address-cells = <1>;
> > > > + #size-cells = <0>;
> > > > +
> > > > + pd_pcie: pcie-power-domain at 6 {
> > > > + compatible = "samsung,exynos5440-pd";
> > > > + reg = <6>;
> > > > + };
> > > > +
> > > > + pd_conn2: conn2-power-domain at 7 {
> > > > + compatible = "samsung,exynos5440-pd";
> > > > + reg = <7>;
> > > > + };
> > > > + };
> > > > +
> > > > Example of the node using power domain:
> > > >
> > > > node {
> > > > Index: b/arch/arm/boot/dts/exynos5440.dtsi
> > > > ===================================================================
> > > > --- a/arch/arm/boot/dts/exynos5440.dtsi 2013-08-02 14:45:53.599392397 +0200
> > > > +++ b/arch/arm/boot/dts/exynos5440.dtsi 2013-08-02 14:46:29.815391842 +0200
> > > > @@ -29,6 +29,23 @@
> > > > #clock-cells = <1>;
> > > > };
> > > >
> > > > + power-domains at 00160000 {
> > > > + compatible = "samsung,exynos5440-power-domains", "simple-bus";
> > > > + reg = <0x00160000 0x1000>;
> > > > + #address-cells = <1>;
> > > > + #size-cells = <0>;
> > > > +
> > > > + pd_pcie: pcie-power-domain at 6 {
> > > > + compatible = "samsung,exynos5440-pd";
> > > > + reg = <6>;
> > > > + };
> > > > +
> > > > + pd_conn2: conn2-power-domain at 7 {
> > > > + compatible = "samsung,exynos5440-pd";
> > > > + reg = <7>;
> > > > + };
> > > > + };
> > > > +
> > > > gic:interrupt-controller at 2E0000 {
> > > > compatible = "arm,cortex-a15-gic";
> > > > #interrupt-cells = <3>;
> > > > @@ -192,6 +209,7 @@
> > > > phy-mode = "sgmii";
> > > > clocks = <&clock 25>;
> > > > clock-names = "stmmaceth";
> > > > + samsung,power-domain = <&pd_conn2>;
> > > > };
> >
> > This feels like a clock style binding would fit better:
> > samsung,power-domain = <&pwr 7>;
> >
> > But there may be a better, more general way of handling this. I'm not
> > sure how this relates to regulators and so on, and how other vendors
> > handle this stuff...
>
> Other vendors don't implement device tree for their power domains yet.
>
> Also there is not much power domain users in the tree currently:
>
> $ git grep pm_genpd_init
> arch/arm/mach-exynos/pm_domains.c: pm_genpd_init(&pd->pd, NULL, !on);
> arch/arm/mach-s3c64xx/pm.c: pm_genpd_init(&s3c64xx_always_on_pm_domains[i]->pd,
> arch/arm/mach-s3c64xx/pm.c: pm_genpd_init(&s3c64xx_pm_domains[i]->pd, NULL, false);
> arch/arm/mach-shmobile/pm-r8a7779.c: pm_genpd_init(genpd, NULL, false);
> arch/arm/mach-shmobile/pm-rmobile.c: pm_genpd_init(genpd, gov ? : &simple_qos_governor, false);
> drivers/base/power/domain.c: * pm_genpd_init - Initialize a generic I/O PM domain object.
> drivers/base/power/domain.c:void pm_genpd_init(struct generic_pm_domain *genpd,
> include/linux/pm_domain.h:extern void pm_genpd_init(struct generic_pm_domain *genpd,
> include/linux/pm_domain.h:static inline void pm_genpd_init(struct generic_pm_domain *genpd,
Ok. How do you feel about for clock style binding I suggested above? Is
there any information you might need to membed in teh child *-pd nodes
in future?
Thanks,
Mark.
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