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

[Mark Rutland]

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.

> +- 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.

>  - 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.

Mark.