linux-kernel - [PATCH v3 2/2] cpufreq: tegra124: Allow building as a module

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Message-Id: <20250421-tegra124-cpufreq-v3-2-95eaba968467@gmail.com>
Date: Mon, 21 Apr 2025 12:33:54 -0500
From: Aaron Kling via B4 Relay <devnull+webgeek1234.gmail.com@...nel.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>, 
 Viresh Kumar <viresh.kumar@...aro.org>, 
 Thierry Reding <thierry.reding@...il.com>, 
 Jonathan Hunter <jonathanh@...dia.com>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-tegra@...r.kernel.org, Aaron Kling <webgeek1234@...il.com>
Subject: [PATCH v3 2/2] cpufreq: tegra124: Allow building as a module

From: Aaron Kling <webgeek1234@...il.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
* 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@...il.com>
---
 drivers/cpufreq/Kconfig.arm        |  2 +-
 drivers/cpufreq/tegra124-cpufreq.c | 41 ++++++++++++++++++++++++++++++++++----
 2 files changed, 38 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..b1de59a6bd5009981f4739456e08f5b110f1540f 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;
+
 struct tegra124_cpufreq_priv {
 	struct clk *cpu_clk;
 	struct clk *pllp_clk;
@@ -176,6 +178,16 @@ 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);
+	}
+}
+
 static const struct dev_pm_ops tegra124_cpufreq_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(tegra124_cpufreq_suspend,
 				tegra124_cpufreq_resume)
@@ -185,12 +197,12 @@ 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 +216,36 @@ 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)
+{
+	struct tegra124_cpufreq_priv *priv;
+
+	if (platform_device && !IS_ERR(platform_device)) {
+		priv = dev_get_drvdata(&platform_device->dev);
+
+		clk_put(priv->pllp_clk);
+		clk_put(priv->pllx_clk);
+		clk_put(priv->dfll_clk);
+		clk_put(priv->cpu_clk);
+
+		platform_device_unregister(platform_device);
+	}
+
+	platform_driver_unregister(&tegra124_cpufreq_platdrv);
+}
+module_exit(tegra_cpufreq_module_exit);
+
+MODULE_SOFTDEP("pre: cpufreq-dt");
 MODULE_AUTHOR("Tuomas Tynkkynen <ttynkkynen@...dia.com>");
 MODULE_DESCRIPTION("cpufreq driver for NVIDIA Tegra124");
+MODULE_LICENSE("GPL");

-- 
2.48.1