Re: [PATCH v4 2/2] cpufreq: tegra124: Allow building as a module

Jon Hunter
2025-05-09T13:38:02Z

On 09/05/2025 01:04, Aaron Kling via B4 Relay wrote:
> From: Aaron Kling <webgeek1234@gmail.com>
>
> This requires three changes:
> * A soft dependency on cpufreq-dt as this driver only handles power
> management and cpufreq-dt does the real operations

Hmmm .. how is this handled for other drivers using the cpufreq-dt
driver? I see the imx driver has a dependency on this.

> * Adding a remove routine to remove the cpufreq-dt device
> * Adding a exit routine to handle cleaning up the driver
>
> Signed-off-by: Aaron Kling <webgeek1234@gmail.com>
> ---
> drivers/cpufreq/Kconfig.arm | 2 +-
> drivers/cpufreq/tegra124-cpufreq.c | 36 ++++++++++++++++++++++++++++++++----
> 2 files changed, 33 insertions(+), 5 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 bc0691e8971f9454def37f489e4a3e244100b9f4..b6059c91f2474c56809c403eca94eacf51df734f 100644
> --- a/drivers/cpufreq/tegra124-cpufreq.c
> +++ b/drivers/cpufreq/tegra124-cpufreq.c
> @@ -16,6 +16,8 @@
> #include <linux/pm_opp.h>
> #include <linux/types.h>
>
> +static struct platform_device *platform_device;

Do we need this?

> +
> struct tegra124_cpufreq_priv {
> struct clk *cpu_clk;
> struct clk *pllp_clk;
> @@ -176,6 +178,21 @@ 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)
> @@ -185,12 +202,12 @@ 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")))
> @@ -204,15 +221,26 @@ 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);

The device is unregistered in the remove. Why do we need this?

> +
> + platform_driver_unregister(&tegra124_cpufreq_platdrv);
> +}
> +module_exit(tegra_cpufreq_module_exit);
> +
> +MODULE_SOFTDEP("pre: cpufreq-dt");
> MODULE_AUTHOR("Tuomas Tynkkynen <ttynkkynen@nvidia.com>");
> MODULE_DESCRIPTION("cpufreq driver for NVIDIA Tegra124");
> +MODULE_LICENSE("GPL");
>

--
nvpublic