[PATCH v4 2/3] pmdomain: imx: scu-pd: allow building as a module

[Zhipeng.wang_1@oss.nxp.com]

From: Zhipeng Wang <zhipeng.wang_1@nxp.com>

Convert CONFIG_IMX_SCU_PD from bool to tristate to allow building as a
loadable module. This is needed on Android devices using the Generic
Kernel Image (GKI), where SoC-specific drivers must be built as modules
rather than built into the core kernel image.

For i.MX8Q devices running Android with a GKI kernel, the SCU power
domain driver must be loadable. Without tristate support, power domains
cannot be properly initialized, preventing these systems from
functioning under GKI.

Use subsys_initcall() so that when built-in the power domain provider
probes before its consumers (e.g. the SCU clock driver at
device_initcall level), fixing "failed to attached the power domain"
warnings at boot. When built as a module, subsys_initcall() is
equivalent to module_init(). No module_exit() is provided because the
SCU power domain provider is a system-level resource that cannot be
safely removed at runtime.

Add MODULE_DEVICE_TABLE() for OF-based module autoloading.

Signed-off-by: Zhipeng Wang <zhipeng.wang_1@nxp.com>
---
 drivers/pmdomain/imx/Kconfig  | 2 +-
 drivers/pmdomain/imx/scu-pd.c | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/pmdomain/imx/Kconfig b/drivers/pmdomain/imx/Kconfig
index 00203615c65e..472e9dec6bd4 100644
--- a/drivers/pmdomain/imx/Kconfig
+++ b/drivers/pmdomain/imx/Kconfig
@@ -21,7 +21,7 @@ config IMX9_BLK_CTRL
 	depends on PM_GENERIC_DOMAINS
 
 config IMX_SCU_PD
-	bool "IMX SCU Power Domain driver"
+	tristate "IMX SCU Power Domain driver"
 	depends on IMX_SCU
 	help
 	  The System Controller Firmware (SCFW) based power domain driver.
diff --git a/drivers/pmdomain/imx/scu-pd.c b/drivers/pmdomain/imx/scu-pd.c
index 3ec33667a308..e3f9e741daf7 100644
--- a/drivers/pmdomain/imx/scu-pd.c
+++ b/drivers/pmdomain/imx/scu-pd.c
@@ -531,6 +531,7 @@ static const struct of_device_id imx_sc_pd_match[] = {
 	{ .compatible = "fsl,scu-pd", &imx8qxp_scu_pd},
 	{ /* sentinel */ }
 };
+MODULE_DEVICE_TABLE(of, imx_sc_pd_match);
 
 static struct platform_driver imx_sc_pd_driver = {
 	.driver = {
@@ -540,7 +541,12 @@ static struct platform_driver imx_sc_pd_driver = {
 	},
 	.probe = imx_sc_pd_probe,
 };
-builtin_platform_driver(imx_sc_pd_driver);
+
+static int __init imx_sc_pd_driver_init(void)
+{
+	return platform_driver_register(&imx_sc_pd_driver);
+}
+subsys_initcall(imx_sc_pd_driver_init);
 
 MODULE_AUTHOR("Dong Aisheng <aisheng.dong@nxp.com>");
 MODULE_DESCRIPTION("IMX SCU Power Domain driver");
-- 
2.34.1