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

[Rafael J. Wysocki]

On Wednesday, July 18, 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 at linaro.org>

While I can take it, I'm not going to include it into my v3.6 pull request.

If no one has objections, it will show up in linux-next after v3.6-rc1.

Thanks,
Rafael


> ---
>  Documentation/devicetree/bindings/power/opp.txt |   29 ++++++++++
>  drivers/base/power/opp.c                        |   66 +++++++++++++++++++++++
>  include/linux/opp.h                             |    4 ++
>  3 files changed, 99 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..1dd0db2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/opp.txt
> @@ -0,0 +1,29 @@
> +* 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 3-tuples items, and each item consists
> +  of frequency, voltage and enabling like <freq vol en>.
> +	freq: clock frequency in kHz
> +	vol: voltage in microvolt
> +	en: initially enabled (1) or not (0)
> +
> +Examples:
> +
> +cpu at 0 {
> +	compatible = "arm,cortex-a9";
> +	reg = <0>;
> +	next-level-cache = <&L2>;
> +	operating-points = <
> +		/* kHz    uV    en */
> +		1200000 1275000 0
> +		996000  1225000 1
> +		792000  1100000 1
> +		672000  1100000 0
> +		396000  950000  1
> +		198000  850000  1
> +	>;
> +};
> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index ac993ea..2d750f9 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 +675,68 @@ 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)
> +{
> +	struct device_node *np = dev->of_node;
> +	const char *propname = "operating-points";
> +	const struct property *pp;
> +	u32 *opp;
> +	int ret, i, nr;
> +
> +	pp = of_find_property(np, propname, NULL);
> +	if (!pp) {
> +		dev_err(dev, "%s: Unable to find property", __func__);
> +		return -ENODEV;
> +	}
> +
> +	opp = kzalloc(pp->length, GFP_KERNEL);
> +	if (!opp) {
> +		dev_err(dev, "%s: Unable to allocate array\n", __func__);
> +		return -ENOMEM;
> +	}
> +
> +	nr = pp->length / sizeof(u32);
> +	ret = of_property_read_u32_array(np, propname, opp, nr);
> +	if (ret) {
> +		dev_err(dev, "%s: Unable to read OPPs\n", __func__);
> +		goto out;
> +	}
> +
> +	nr /= 3;
> +	for (i = 0; i < nr; i++) {
> +		/*
> +		 * Each OPP is a set of tuples consisting of frequency,
> +		 * voltage and availability like <freq-kHz vol-uV enable>.
> +		 */
> +		u32 *val = opp + i * 3;
> +
> +		val[0] *= 1000;
> +		ret = opp_add(dev, val[0], val[1]);
> +		if (ret) {
> +			dev_warn(dev, "%s: Failed to add OPP %d: %d\n",
> +				 __func__, val[0], ret);
> +			continue;
> +		}
> +
> +		if (!val[2]) {
> +			ret = opp_disable(dev, val[0]);
> +			if (ret)
> +				dev_warn(dev, "%s: Failed to disable OPP %d: %d\n",
> +					 __func__, val[0], ret);
> +		}
> +	}
> +
> +	ret = 0;
> +out:
> +	kfree(opp);
> +	return ret;
> +}
> +#endif
> diff --git a/include/linux/opp.h b/include/linux/opp.h
> index 2a4e5fa..fd165ad 100644
> --- a/include/linux/opp.h
> +++ b/include/linux/opp.h
> @@ -48,6 +48,10 @@ 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);
> +#endif
> +
>  #else
>  static inline unsigned long opp_get_voltage(struct opp *opp)
>  {
>