[PATCH v3 2/3] PM / OPP: Initialize OPP table from device tree

[rjw@sisk.pl (Rafael J. Wysocki)]

On Friday, August 10, 2012, Shawn Guo wrote:
> With a lot of devices booting from device tree nowadays, it requires
> that OPP table can be initialized from device tree.  The patch adds
> a helper function of_init_opp_table together with a binding doc for
> that purpose.
> 
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

I need an ACK from whoever maintains the DT bindings for that.

Thanks,
Rafael


> ---
>  Documentation/devicetree/bindings/power/opp.txt |   25 ++++++++++++
>  drivers/base/power/opp.c                        |   47 +++++++++++++++++++++++
>  include/linux/opp.h                             |    8 ++++
>  3 files changed, 80 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/power/opp.txt
> 
> diff --git a/Documentation/devicetree/bindings/power/opp.txt b/Documentation/devicetree/bindings/power/opp.txt
> new file mode 100644
> index 0000000..74499e5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/opp.txt
> @@ -0,0 +1,25 @@
> +* Generic OPP Interface
> +
> +SoCs have a standard set of tuples consisting of frequency and
> +voltage pairs that the device will support per voltage domain. These
> +are called Operating Performance Points or OPPs.
> +
> +Properties:
> +- operating-points: An array of 2-tuples items, and each item consists
> +  of frequency and voltage like <freq-kHz vol-uV>.
> +	freq: clock frequency in kHz
> +	vol: voltage in microvolt
> +
> +Examples:
> +
> +cpu at 0 {
> +	compatible = "arm,cortex-a9";
> +	reg = <0>;
> +	next-level-cache = <&L2>;
> +	operating-points = <
> +		/* kHz    uV */
> +		792000  1100000
> +		396000  950000
> +		198000  850000
> +	>;
> +};
> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index ac993ea..d946864 100644
> --- a/drivers/base/power/opp.c
> +++ b/drivers/base/power/opp.c
> @@ -22,6 +22,7 @@
>  #include <linux/rculist.h>
>  #include <linux/rcupdate.h>
>  #include <linux/opp.h>
> +#include <linux/of.h>
>  
>  /*
>   * Internal data structure organization with the OPP layer library is as
> @@ -674,3 +675,49 @@ struct srcu_notifier_head *opp_get_notifier(struct device *dev)
>  
>  	return &dev_opp->head;
>  }
> +
> +#ifdef CONFIG_OF
> +/**
> + * of_init_opp_table() - Initialize opp table from device tree
> + * @dev:	device pointer used to lookup device OPPs.
> + *
> + * Register the initial OPP table with the OPP library for given device.
> + */
> +int of_init_opp_table(struct device *dev)
> +{
> +	const struct property *prop;
> +	const __be32 *val;
> +	int nr;
> +
> +	prop = of_find_property(dev->of_node, "operating-points", NULL);
> +	if (!prop)
> +		return -ENODEV;
> +	if (!prop->value)
> +		return -ENODATA;
> +
> +	/*
> +	 * Each OPP is a set of tuples consisting of frequency and
> +	 * voltage like <freq-kHz vol-uV>.
> +	 */
> +	nr = prop->length / sizeof(u32);
> +	if (nr % 2) {
> +		dev_err(dev, "%s: Invalid OPP list\n", __func__);
> +		return -EINVAL;
> +	}
> +
> +	val = prop->value;
> +	while (nr) {
> +		unsigned long freq = be32_to_cpup(val++) * 1000;
> +		unsigned long volt = be32_to_cpup(val++);
> +
> +		if (opp_add(dev, freq, volt)) {
> +			dev_warn(dev, "%s: Failed to add OPP %ld\n",
> +				 __func__, freq);
> +			continue;
> +		}
> +		nr -= 2;
> +	}
> +
> +	return 0;
> +}
> +#endif
> diff --git a/include/linux/opp.h b/include/linux/opp.h
> index 2a4e5fa..214e0eb 100644
> --- a/include/linux/opp.h
> +++ b/include/linux/opp.h
> @@ -48,6 +48,14 @@ int opp_disable(struct device *dev, unsigned long freq);
>  
>  struct srcu_notifier_head *opp_get_notifier(struct device *dev);
>  
> +#ifdef CONFIG_OF
> +int of_init_opp_table(struct device *dev);
> +#else
> +static inline int of_init_opp_table(struct device *dev)
> +{
> +	return -EINVAL;
> +}
> +#endif /* CONFIG_OF */
>  #else
>  static inline unsigned long opp_get_voltage(struct opp *opp)
>  {
>