linux-kernel - Re: [PATCH v5 3/3] cpufreq: tegra124: Allow building as a module

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Message-ID: <640f7ba1-c016-4d77-a65b-93477be9cf3b@nvidia.com>
Date: Fri, 4 Jul 2025 12:53:16 +0100
From: Jon Hunter <jonathanh@...dia.com>
To: webgeek1234@...il.com, "Rafael J. Wysocki" <rafael@...nel.org>,
 Viresh Kumar <viresh.kumar@...aro.org>,
 Thierry Reding <thierry.reding@...il.com>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-tegra@...r.kernel.org
Subject: Re: [PATCH v5 3/3] cpufreq: tegra124: Allow building as a module



On 02/07/2025 08:46, Aaron Kling via B4 Relay wrote:
> From: Aaron Kling <webgeek1234@...il.com>
> 
> This requires three changes:
> * Using the cpufreq-dt register helper to establish a hard dependency
>    for depmod to track
> * Adding a remove routine to remove the cpufreq-dt device
> * Adding a exit routine to handle cleaning up the driver

And populate the license?

> 
> Signed-off-by: Aaron Kling <webgeek1234@...il.com>
> ---
>   drivers/cpufreq/Kconfig.arm        |  2 +-
>   drivers/cpufreq/tegra124-cpufreq.c | 44 +++++++++++++++++++++++++++++---------
>   2 files changed, 35 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 4f9cb943d945c244eb2b29f543d14df6cac4e5d4..625f6fbdaaf5fd774e3b0bb996eb7ce980da41ee 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -238,7 +238,7 @@ config ARM_TEGRA20_CPUFREQ
>   	  This adds the CPUFreq driver support for Tegra20/30 SOCs.
>   
>   config ARM_TEGRA124_CPUFREQ
> -	bool "Tegra124 CPUFreq support"
> +	tristate "Tegra124 CPUFreq support"
>   	depends on ARCH_TEGRA || COMPILE_TEST
>   	depends on CPUFREQ_DT
>   	default y
> diff --git a/drivers/cpufreq/tegra124-cpufreq.c b/drivers/cpufreq/tegra124-cpufreq.c
> index 514146d98bca2d8aa59980a14dff3487cd8045f6..ebce62be9a9c17724d50dadeea1bb2ec81538421 100644
> --- a/drivers/cpufreq/tegra124-cpufreq.c
> +++ b/drivers/cpufreq/tegra124-cpufreq.c
> @@ -16,6 +16,10 @@
>   #include <linux/pm_opp.h>
>   #include <linux/types.h>
>   
> +#include "cpufreq-dt.h"
> +
> +static struct platform_device *platform_device;

I think that this could do with a better name than just 
'platform_device'. Maybe something like tegra124_cpufreq_pdev?

> +
>   struct tegra124_cpufreq_priv {
>   	struct clk *cpu_clk;
>   	struct clk *pllp_clk;
> @@ -55,7 +59,6 @@ static int tegra124_cpufreq_probe(struct platform_device *pdev)
>   	struct device_node *np __free(device_node) = of_cpu_device_node_get(0);
>   	struct tegra124_cpufreq_priv *priv;
>   	struct device *cpu_dev;
> -	struct platform_device_info cpufreq_dt_devinfo = {};
>   	int ret;
>   
>   	if (!np)
> @@ -95,11 +98,7 @@ static int tegra124_cpufreq_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto out_put_pllp_clk;
>   
> -	cpufreq_dt_devinfo.name = "cpufreq-dt";
> -	cpufreq_dt_devinfo.parent = &pdev->dev;
> -
> -	priv->cpufreq_dt_pdev =
> -		platform_device_register_full(&cpufreq_dt_devinfo);
> +	priv->cpufreq_dt_pdev = cpufreq_dt_pdev_register(&pdev->dev);
>   	if (IS_ERR(priv->cpufreq_dt_pdev)) {
>   		ret = PTR_ERR(priv->cpufreq_dt_pdev);
>   		goto out_put_pllp_clk;
> @@ -173,6 +172,21 @@ static int __maybe_unused tegra124_cpufreq_resume(struct device *dev)
>   	return err;
>   }
>   
> +static void tegra124_cpufreq_remove(struct platform_device *pdev)
> +{
> +	struct tegra124_cpufreq_priv *priv = dev_get_drvdata(&pdev->dev);
> +
> +	if (!IS_ERR(priv->cpufreq_dt_pdev)) {
> +		platform_device_unregister(priv->cpufreq_dt_pdev);
> +		priv->cpufreq_dt_pdev = ERR_PTR(-ENODEV);
> +	}
> +
> +	clk_put(priv->pllp_clk);
> +	clk_put(priv->pllx_clk);
> +	clk_put(priv->dfll_clk);
> +	clk_put(priv->cpu_clk);
> +}
> +
>   static const struct dev_pm_ops tegra124_cpufreq_pm_ops = {
>   	SET_SYSTEM_SLEEP_PM_OPS(tegra124_cpufreq_suspend,
>   				tegra124_cpufreq_resume)
> @@ -182,12 +196,12 @@ static struct platform_driver tegra124_cpufreq_platdrv = {
>   	.driver.name	= "cpufreq-tegra124",
>   	.driver.pm	= &tegra124_cpufreq_pm_ops,
>   	.probe		= tegra124_cpufreq_probe,
> +	.remove		= tegra124_cpufreq_remove,
>   };
>   
>   static int __init tegra_cpufreq_init(void)
>   {
>   	int ret;
> -	struct platform_device *pdev;
>   
>   	if (!(of_machine_is_compatible("nvidia,tegra124") ||
>   		of_machine_is_compatible("nvidia,tegra210")))
> @@ -201,15 +215,25 @@ static int __init tegra_cpufreq_init(void)
>   	if (ret)
>   		return ret;
>   
> -	pdev = platform_device_register_simple("cpufreq-tegra124", -1, NULL, 0);
> -	if (IS_ERR(pdev)) {
> +	platform_device = platform_device_register_simple("cpufreq-tegra124", -1, NULL, 0);
> +	if (IS_ERR(platform_device)) {
>   		platform_driver_unregister(&tegra124_cpufreq_platdrv);
> -		return PTR_ERR(pdev);
> +		return PTR_ERR(platform_device);
>   	}
>   
>   	return 0;
>   }
>   module_init(tegra_cpufreq_init);
>   
> +static void __exit tegra_cpufreq_module_exit(void)
> +{
> +	if (platform_device && !IS_ERR(platform_device))
> +		platform_device_unregister(platform_device);
> +
> +	platform_driver_unregister(&tegra124_cpufreq_platdrv);
> +}
> +module_exit(tegra_cpufreq_module_exit);
> +
>   MODULE_AUTHOR("Tuomas Tynkkynen <ttynkkynen@...dia.com>");
>   MODULE_DESCRIPTION("cpufreq driver for NVIDIA Tegra124");
> +MODULE_LICENSE("GPL");
> 

-- 
nvpublic