linux-kernel - [PATCH 2/2] clk: imx95-blk-ctl: Save/restore registers when RPM routines are called

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Message-Id: <20250730125932.357379-3-laurentiu.palcu@oss.nxp.com>
Date: Wed, 30 Jul 2025 15:59:31 +0300
From: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
To: Abel Vesa <abelvesa@...nel.org>,
	Peng Fan <peng.fan@....com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>
Cc: Laurentiu Palcu <laurentiu.palcu@....nxp.com>,
	linux-clk@...r.kernel.org,
	imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] clk: imx95-blk-ctl: Save/restore registers when RPM routines are called

If runtime PM is used for the clock providers and they're part of a
power domain, then the power domain supply will be cut off when runtime
suspended. That means all BLK CTL registers belonging to that power
domain will be reset. Save the registers, then, before entering suspend
and restore them in resume.

Also, fix the suspend/resume routines and make sure we disable/enable
the clock correctly.

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
---
 drivers/clk/imx/clk-imx95-blk-ctl.c | 33 ++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/clk/imx/clk-imx95-blk-ctl.c b/drivers/clk/imx/clk-imx95-blk-ctl.c
index c72debaf3a60b..56bed44719954 100644
--- 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;
 }
-- 
2.46.1