clk: imx95-blk-ctl: Save/restore registers when RPM routines are called

When runtime PM is used for clock providers that are part of a power
domain, the power domain supply is cut off during runtime suspend. This
causes all BLK CTL registers belonging to that power domain to reset. To
prevent this, save the state of the registers before entering suspend
and restore them on resume. Additionally, disable the APB clock during
suspend to minimize power consumption.

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250804131450.3918846-3-laurentiu.palcu@oss.nxp.com
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>

diff --git a/drivers/clk/imx/clk-imx95-blk-ctl.c b/drivers/clk/imx/clk-imx95-blk-ctl.c
index c72debaf3a60bd9182c71197e5a7790dedde7fff..56bed44719954d6a644606914b61dad672cd82cf 100644 (file)
--- a/drivers/clk/imx/clk-imx95-blk-ctl.c
+++ b/drivers/clk/imx/clk-imx95-blk-ctl.c
@@ -453,15 +453,24 @@ static int imx95_bc_runtime_suspend(struct device *dev)
 {
        struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
 
+       bc->clk_reg_restore = readl(bc->base + bc->pdata->clk_reg_offset);
        clk_disable_unprepare(bc->clk_apb);
+
        return 0;
 }
 
 static int imx95_bc_runtime_resume(struct device *dev)
 {
        struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
+       int ret;
 
-       return clk_prepare_enable(bc->clk_apb);
+       ret = clk_prepare_enable(bc->clk_apb);
+       if (ret)
+               return ret;
+
+       writel(bc->clk_reg_restore, bc->base + bc->pdata->clk_reg_offset);
+
+       return 0;
 }
 #endif
 
@@ -469,17 +478,12 @@ static int imx95_bc_runtime_resume(struct device *dev)
 static int imx95_bc_suspend(struct device *dev)
 {
        struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
-       int ret;
 
-       if (bc->pdata->rpm_enabled) {
-               ret = pm_runtime_get_sync(bc->dev);
-               if (ret < 0) {
-                       pm_runtime_put_noidle(bc->dev);
-                       return ret;
-               }
-       }
+       if (pm_runtime_suspended(dev))
+               return 0;
 
        bc->clk_reg_restore = readl(bc->base + bc->pdata->clk_reg_offset);
+       clk_disable_unprepare(bc->clk_apb);
 
        return 0;
 }
@@ -487,11 +491,16 @@ static int imx95_bc_suspend(struct device *dev)
 static int imx95_bc_resume(struct device *dev)
 {
        struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
+       int ret;
 
-       writel(bc->clk_reg_restore, bc->base + bc->pdata->clk_reg_offset);
+       if (pm_runtime_suspended(dev))
+               return 0;
 
-       if (bc->pdata->rpm_enabled)
-               pm_runtime_put(bc->dev);
+       ret = clk_prepare_enable(bc->clk_apb);
+       if (ret)
+               return ret;
+
+       writel(bc->clk_reg_restore, bc->base + bc->pdata->clk_reg_offset);
 
        return 0;
 }