linux-kernel - Re: [1/2] cpufreq: dt-platdev: Automatically create cpufreq device with OPP v2

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Date:   Mon, 21 Aug 2017 15:17:35 +0200
From:   Simon Horman <horms@...ge.net.au>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        geert@...ux-m68k.org, maxime.ripard@...e-electrons.com,
        wens@...e.org, xuwei5@...ilicon.com, kgene@...nel.org,
        krzk@...nel.org, yamada.masahiro@...ionext.com, jun.nie@...aro.org,
        baoyou.xie@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [1/2] cpufreq: dt-platdev: Automatically create cpufreq device
 with OPP v2

On Mon, Aug 21, 2017 at 03:13:32PM +0200, Viresh Kumar wrote:
> The initial idea of creating the cpufreq-dt-platdev.c file was to keep a
> list of platforms that use the "operating-points" (V1) bindings and
> create cpufreq device for them only, as we weren't sure which platforms
> would want the device to get created automatically as some had their own
> cpufreq drivers as well, or wanted to initialize cpufreq after doing
> some stuff from platform code.
> 
> But that wasn't the case with platforms using "operating-points-v2"
> property. We wanted the device to get created automatically without the
> need of adding them to the whitelist. Though, we will still have some
> exceptions where we don't want to create the device automatically.
> 
> Rename the earlier platform list as *whitelist* and create a new
> *blacklist* as well.
> 
> The cpufreq-dt device will get created if:
> - The platform is there in the whitelist OR
> - The platform has "operating-points-v2" property in CPU0's DT node and
>   isn't part of the blacklist .
> 
> Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> 
> I have exercised this on the r8a7795 and r8a7795 with the following reverted:
> 
> * 034def597bb7 ("cpufreq: rcar: Add support for R8A7795 SoC")
> * bea2ebca6b91 ("cpufreq: dt: Add r8a7796 support to to use generic cpufreq driver")
> 
> Tested-by: Simon Horman <horms+renesas@...ge.net.au>

Sorry, I seem to have accidently sent this email as Virish rather than
myself. I will try again.

> 
> 
> ---
>  drivers/cpufreq/cpufreq-dt-platdev.c | 45 ++++++++++++++++++++++++++++++++----
>  1 file changed, 40 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
> index bcee384b3251..061b468512a2 100644
> --- a/drivers/cpufreq/cpufreq-dt-platdev.c
> +++ b/drivers/cpufreq/cpufreq-dt-platdev.c
> @@ -9,11 +9,16 @@
>  
>  #include <linux/err.h>
>  #include <linux/of.h>
> +#include <linux/of_device.h>
>  #include <linux/platform_device.h>
>  
>  #include "cpufreq-dt.h"
>  
> -static const struct of_device_id machines[] __initconst = {
> +/*
> + * Machines for which the cpufreq device is *always* created, mostly used for
> + * platforms using "operating-points" (V1) property.
> + */
> +static const struct of_device_id whitelist[] __initconst = {
>  	{ .compatible = "allwinner,sun4i-a10", },
>  	{ .compatible = "allwinner,sun5i-a10s", },
>  	{ .compatible = "allwinner,sun5i-a13", },
> @@ -101,21 +106,51 @@ static const struct of_device_id machines[] __initconst = {
>  	{ }
>  };
>  
> +/*
> + * Machines for which the cpufreq device is *not* created, mostly used for
> + * platforms using "operating-points-v2" property.
> + */
> +static const struct of_device_id blacklist[] __initconst = {
> +	{ }
> +};
> +
> +static bool __init cpu0_node_has_opp_v2_prop(void)
> +{
> +	struct device_node *np = of_cpu_device_node_get(0);
> +	bool ret = false;
> +
> +	if (of_get_property(np, "operating-points-v2", NULL))
> +		ret = true;
> +
> +	of_node_put(np);
> +	return ret;
> +}
> +
>  static int __init cpufreq_dt_platdev_init(void)
>  {
>  	struct device_node *np = of_find_node_by_path("/");
>  	const struct of_device_id *match;
> +	const void *data = NULL;
>  
>  	if (!np)
>  		return -ENODEV;
>  
> -	match = of_match_node(machines, np);
> +	match = of_match_node(whitelist, np);
> +	if (match) {
> +		data = match->data;
> +		goto create_pdev;
> +	}
> +
> +	if (cpu0_node_has_opp_v2_prop() && !of_match_node(blacklist, np))
> +		goto create_pdev;
> +
>  	of_node_put(np);
> -	if (!match)
> -		return -ENODEV;
> +	return -ENODEV;
>  
> +create_pdev:
> +	of_node_put(np);
>  	return PTR_ERR_OR_ZERO(platform_device_register_data(NULL, "cpufreq-dt",
> -			       -1, match->data,
> +			       -1, data,
>  			       sizeof(struct cpufreq_dt_platform_data)));
>  }
>  device_initcall(cpufreq_dt_platdev_init);