[PATCH] cpufreq: instantiate cpufreq-cpu0 as a platform_driver

[Rafael J. Wysocki]

On Saturday, January 26, 2013 09:55:50 PM Shawn Guo wrote:
> As multiplatform build is being adopted by more and more ARM platforms,
> initcall function should be used very carefully.  For example, when
> GENERIC_CPUFREQ_CPU0 is built in the kernel, cpu0_cpufreq_driver_init()
> will be called on all the platforms to initialize cpufreq-cpu0 driver.
> 
> To eliminate this undesired the effect, the patch changes cpufreq-cpu0
> driver to have it instantiated as a platform_driver.  Then it will only
> run on platforms that create the platform_device "cpufreq-cpu0".
> 
> Along with the change, it also changes cpu_dev to be &pdev->dev,
> so that managed functions can start working, and module build gets
> supported too.
> 
> Signed-off-by: Shawn Guo <shawn.guo at linaro.org>
> ---
> Rafael,
> 
> The patch depends patch "power: export opp cpufreq functions".
> https://patchwork.kernel.org/patch/1847261/

That one should use EXPORT_SYMBOL_GPL() for exporting symbols, though.

Care to add a fixed version to the patch set along with the $subject one?

> AnilKumar,
> 
> Unfortunately, the change will require some platform level adoption
> to have cpufreq-cpu0 driver continue working for am33xx.  But it should
> be as simple as something like below.
> 
> 	struct platform_device_info devinfo = { .name = "cpufreq-cpu0", };
> 	platform_device_register_full(&devinfo);

That should be included in your patch, then.

Thanks,
Rafael


>  drivers/cpufreq/Kconfig        |    2 +-
>  drivers/cpufreq/cpufreq-cpu0.c |   35 +++++++++++++++++++++++------------
>  2 files changed, 24 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
> index ea512f4..774dc1c 100644
> --- a/drivers/cpufreq/Kconfig
> +++ b/drivers/cpufreq/Kconfig
> @@ -180,7 +180,7 @@ config CPU_FREQ_GOV_CONSERVATIVE
>  	  If in doubt, say N.
>  
>  config GENERIC_CPUFREQ_CPU0
> -	bool "Generic CPU0 cpufreq driver"
> +	tristate "Generic CPU0 cpufreq driver"
>  	depends on HAVE_CLK && REGULATOR && PM_OPP && OF
>  	select CPU_FREQ_TABLE
>  	help
> diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
> index debc5a7..dae0667 100644
> --- a/drivers/cpufreq/cpufreq-cpu0.c
> +++ b/drivers/cpufreq/cpufreq-cpu0.c
> @@ -12,12 +12,12 @@
>  #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
>  
>  #include <linux/clk.h>
> -#include <linux/cpu.h>
>  #include <linux/cpufreq.h>
>  #include <linux/err.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/opp.h>
> +#include <linux/platform_device.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/slab.h>
>  
> @@ -177,7 +177,7 @@ static struct cpufreq_driver cpu0_cpufreq_driver = {
>  	.attr = cpu0_cpufreq_attr,
>  };
>  
> -static int cpu0_cpufreq_driver_init(void)
> +static int cpu0_cpufreq_probe(struct platform_device *pdev)
>  {
>  	struct device_node *np;
>  	int ret;
> @@ -188,23 +188,17 @@ static int cpu0_cpufreq_driver_init(void)
>  		return -ENOENT;
>  	}
>  
> -	cpu_dev = get_cpu_device(0);
> -	if (!cpu_dev) {
> -		pr_err("failed to get cpu0 device\n");
> -		ret = -ENODEV;
> -		goto out_put_node;
> -	}
> -
> +	cpu_dev = &pdev->dev;
>  	cpu_dev->of_node = np;
>  
> -	cpu_clk = clk_get(cpu_dev, NULL);
> +	cpu_clk = devm_clk_get(cpu_dev, NULL);
>  	if (IS_ERR(cpu_clk)) {
>  		ret = PTR_ERR(cpu_clk);
>  		pr_err("failed to get cpu0 clock: %d\n", ret);
>  		goto out_put_node;
>  	}
>  
> -	cpu_reg = regulator_get(cpu_dev, "cpu0");
> +	cpu_reg = devm_regulator_get(cpu_dev, "cpu0");
>  	if (IS_ERR(cpu_reg)) {
>  		pr_warn("failed to get cpu0 regulator\n");
>  		cpu_reg = NULL;
> @@ -267,7 +261,24 @@ out_put_node:
>  	of_node_put(np);
>  	return ret;
>  }
> -late_initcall(cpu0_cpufreq_driver_init);
> +
> +static int cpu0_cpufreq_remove(struct platform_device *pdev)
> +{
> +	cpufreq_unregister_driver(&cpu0_cpufreq_driver);
> +	opp_free_cpufreq_table(cpu_dev, &freq_table);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver cpu0_cpufreq_platdrv = {
> +	.driver = {
> +		.name	= "cpufreq-cpu0",
> +		.owner	= THIS_MODULE,
> +	},
> +	.probe		= cpu0_cpufreq_probe,
> +	.remove		= cpu0_cpufreq_remove,
> +};
> +module_platform_driver(cpu0_cpufreq_platdrv);
>  
>  MODULE_AUTHOR("Shawn Guo <shawn.guo at linaro.org>");
>  MODULE_DESCRIPTION("Generic CPU0 cpufreq driver");
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.