[PATCH] ARM: cache-l2x0: add device tree support for power control

[Chao Xie]

>Hi,

>On Wed, Feb 27, 2013 at 03:20:37AM +0000, Chao Xie wrote:
> After version r3p0, cache pl310 has the power control register.
> Adding the device tree support for power control.
> So it can parse the power control register settings.
> 
> Signed-off-by: Chao Xie <chao.xie at marvell.com>
> ---
>  Documentation/devicetree/bindings/arm/l2cc.txt |    6 ++++++
>  arch/arm/mm/cache-l2x0.c                       |   16 ++++++++++++++++
>  2 files changed, 22 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/arm/l2cc.txt b/Documentation/devicetree/bindings/arm/l2cc.txt
> index cbef09b..435ead2 100644
> --- a/Documentation/devicetree/bindings/arm/l2cc.txt
> +++ b/Documentation/devicetree/bindings/arm/l2cc.txt
> @@ -34,6 +34,10 @@ Optional properties:
>  - arm,filter-ranges : <start length> Starting address and length of window to
>    filter. Addresses in the filter window are directed to the M1 port. Other
>    addresses will go to the M0 port.
> +- arm,pwr-dynamic-clk-gating: If it is defined. The dynamic clock gating for
> +  better power is enabled. Only availabe after r3p0.
>
> This appears to be a configuration option rather than a description of the
> hardware.
>
> If we're able to know that this feature is present by reading the id register,
> we shouldn't need to describe it in the dt. We should simply work out if and
> when we want it enabled within the kernel.

So do you mean that I need directly enable these features and do not need provide the choice at DT?

> +- arm,pwr-standby-mode: If it is defined, standby mode is enabled. On available
> +  after r3p0.

> This looks like it depends on an additional signal being wired up, so it may be
> worth describing.

In fact I do know the details. I can only see PL310 spec that it added these features since r3p0.

>  - interrupts : 1 combined interrupt.
>  - cache-id-part: cache id part number to be used if it is not present
>    on hardware
> @@ -47,6 +51,8 @@ L2: cache-controller {
>          arm,data-latency = <1 1 1>;
>          arm,tag-latency = <2 2 2>;
>          arm,filter-ranges = <0x80000000 0x8000000>;
> +        arm,pwr-dynamic-clk-gating;
> +        arm,pwr-standby-mode;
>          cache-unified;
>          cache-level = <2>;
>  	interrupts = <45>;
> diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
> index c2f3739..95a338a 100644
> --- a/arch/arm/mm/cache-l2x0.c
> +++ b/arch/arm/mm/cache-l2x0.c
> @@ -564,6 +564,9 @@ static void __init pl310_of_setup(const struct device_node *np,
>  	u32 data[3] = { 0, 0, 0 };
>  	u32 tag[3] = { 0, 0, 0 };
>  	u32 filter[2] = { 0, 0 };
> +	u32 l2x0_revision;
> +	u32 power;
> +	const unsigned char *prop;
>  
>  	of_property_read_u32_array(np, "arm,tag-latency", tag, ARRAY_SIZE(tag));
>  	if (tag[0] && tag[1] && tag[2])
> @@ -590,6 +593,19 @@ static void __init pl310_of_setup(const struct device_node *np,
>  		writel_relaxed((filter[0] & ~(SZ_1M - 1)) | L2X0_ADDR_FILTER_EN,
>  			       l2x0_base + L2X0_ADDR_FILTER_START);
>  	}
> +
> +	l2x0_revision = readl_relaxed(l2x0_base + L2X0_CACHE_ID) &
> +		L2X0_CACHE_ID_RTL_MASK;
> +	if (l2x0_revision >= L2X0_CACHE_ID_RTL_R3P0) {
> +		power = 0;
> +		prop = of_get_property(np, "arm,pwr-dynamic-clk-gating", NULL);
> +		if (prop)
> +			power |= L2X0_DYNAMIC_CLK_GATING_EN;
> +		prop = of_get_property(np, "arm,pwr-standby-mode", NULL);
> +		if (prop)
> +			power |= L2X0_STNDBY_MODE_EN;

> You can use of_property_read_bool for both of the above cases (and you won't
> need prop any more):

> if (of_property_read_bool(np, "arm,pwr-standby-mode"))
>	power |= L2X0_STNDBY_MODE_EN;

> If dt info isn't needed, this can probably be moved into l2x0_init.

Sure. If everyone want the power feature enabled, it can be moved to l2x0_init.

> Mark.