phy: fsl-imx8mq-usb: add runtime PM support

Add runtime PM support to ensure the PHY clocks are properly gated
when the PHY is not in use, reducing power consumption.

Clock management is moved from power_on()/power_off() callbacks into
the runtime_resume()/runtime_suspend() callbacks respectively. The PHY
subsystem core already holds a runtime PM reference around init() and
power_on/off() calls, so no explicit clock handling is needed there.

Use devm_clk_get_enabled() and devm_clk_get_optional_enabled() in
probe() to keep clocks enabled initially. This ensures the PHY remains
functional when CONFIG_PM is disabled, where runtime suspend/resume
callbacks are never invoked.

In tca_blk_typec_switch_set(), replace the manual clk_prepare_enable()
/ clk_disable_unprepare() pair with PM_RUNTIME_ACQUIRE_IF_ENABLED() to
guard register access against a concurrently suspended PHY.

Move devm_regulator_get() before pm_runtime_enable() to avoid having
to clean up runtime PM state on regulator acquisition failure.

In remove(), call pm_runtime_get_sync() before pm_runtime_disable() to
ensure the PHY is resumed and clocks are enabled before the devres
teardown disables them.

Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260731-imx8mp-usb-phy-improvement-v8-3-2ec8d6b3854d@nxp.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 74 insertions, 29 deletions

diff --git a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
index 3a5788c609e1..42de2cff4d5f 100644
--- a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
+++ b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
@@ -9,6 +9,7 @@
 #include <linux/of.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 #include <linux/usb/typec_mux.h>
 
@@ -136,17 +137,15 @@ static int tca_blk_typec_switch_set(struct typec_switch_dev *sw,
 {
 	struct imx8mq_usb_phy *imx_phy = typec_switch_get_drvdata(sw);
 	struct tca_blk *tca = imx_phy->tca;
-	int ret;
 
 	if (tca->orientation == orientation)
 		return 0;
 
-	ret = clk_prepare_enable(imx_phy->clk);
-	if (ret)
-		return ret;
+	PM_RUNTIME_ACQUIRE_IF_ENABLED(&imx_phy->phy->dev, pm);
+	if (PM_RUNTIME_ACQUIRE_ERR(&pm))
+		return -ENXIO;
 
 	tca_blk_orientation_set(tca, orientation);
-	clk_disable_unprepare(imx_phy->clk);
 
 	return 0;
 }
@@ -620,16 +619,6 @@ static int imx8mq_phy_power_on(struct phy *phy)
 	if (ret)
 		return ret;
 
-	ret = clk_prepare_enable(imx_phy->clk);
-	if (ret)
-		return ret;
-
-	ret = clk_prepare_enable(imx_phy->alt_clk);
-	if (ret) {
-		clk_disable_unprepare(imx_phy->clk);
-		return ret;
-	}
-
 	/* Disable rx term override */
 	value = readl(imx_phy->base + PHY_CTRL6);
 	value &= ~PHY_CTRL6_RXTERM_OVERRIDE_SEL;
@@ -648,8 +637,6 @@ static int imx8mq_phy_power_off(struct phy *phy)
 	value |= PHY_CTRL6_RXTERM_OVERRIDE_SEL;
 	writel(value, imx_phy->base + PHY_CTRL6);
 
-	clk_disable_unprepare(imx_phy->alt_clk);
-	clk_disable_unprepare(imx_phy->clk);
 	regulator_disable(imx_phy->vbus);
 
 	return 0;
@@ -686,6 +673,7 @@ static int imx8mq_usb_phy_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct imx8mq_usb_phy *imx_phy;
 	const struct phy_ops *phy_ops;
+	int ret;
 
 	imx_phy = devm_kzalloc(dev, sizeof(*imx_phy), GFP_KERNEL);
 	if (!imx_phy)
@@ -693,13 +681,13 @@ static int imx8mq_usb_phy_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, imx_phy);
 
-	imx_phy->clk = devm_clk_get(dev, "phy");
+	imx_phy->clk = devm_clk_get_enabled(dev, "phy");
 	if (IS_ERR(imx_phy->clk)) {
 		dev_err(dev, "failed to get imx8mq usb phy clock\n");
 		return PTR_ERR(imx_phy->clk);
 	}
 
-	imx_phy->alt_clk = devm_clk_get_optional(dev, "alt");
+	imx_phy->alt_clk = devm_clk_get_optional_enabled(dev, "alt");
 	if (IS_ERR(imx_phy->alt_clk))
 		return dev_err_probe(dev, PTR_ERR(imx_phy->alt_clk),
 				    "Failed to get alt clk\n");
@@ -708,44 +696,101 @@ static int imx8mq_usb_phy_probe(struct platform_device *pdev)
 	if (IS_ERR(imx_phy->base))
 		return PTR_ERR(imx_phy->base);
 
+	imx_phy->vbus = devm_regulator_get(dev, "vbus");
+	if (IS_ERR(imx_phy->vbus))
+		return dev_err_probe(dev, PTR_ERR(imx_phy->vbus), "failed to get vbus\n");
+
 	phy_ops = of_device_get_match_data(dev);
 	if (!phy_ops)
 		return -EINVAL;
 
-	imx_phy->phy = devm_phy_create(dev, NULL, phy_ops);
-	if (IS_ERR(imx_phy->phy))
-		return PTR_ERR(imx_phy->phy);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
 
-	imx_phy->vbus = devm_regulator_get(dev, "vbus");
-	if (IS_ERR(imx_phy->vbus))
-		return dev_err_probe(dev, PTR_ERR(imx_phy->vbus), "failed to get vbus\n");
+	imx_phy->phy = devm_phy_create(dev, NULL, phy_ops);
+	if (IS_ERR(imx_phy->phy)) {
+		ret = dev_err_probe(dev, PTR_ERR(imx_phy->phy),
+				    "failed to create PHY\n");
+		goto disable_rpm;
+	}
 
 	phy_set_drvdata(imx_phy->phy, imx_phy);
 
 	imx_phy->tca = imx95_usb_phy_get_tca(pdev, imx_phy);
-	if (IS_ERR(imx_phy->tca))
-		return dev_err_probe(dev, PTR_ERR(imx_phy->tca),
-					"failed to get tca\n");
+	if (IS_ERR(imx_phy->tca)) {
+		ret = dev_err_probe(dev, PTR_ERR(imx_phy->tca),
+				    "failed to get tca\n");
+		goto disable_rpm;
+	}
 
 	imx8m_get_phy_tuning_data(imx_phy);
 	device_set_wakeup_capable(dev, true);
 
 	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+	if (IS_ERR(phy_provider)) {
+		ret = dev_err_probe(dev, PTR_ERR(phy_provider),
+				    "failed to register phy provider\n");
+		goto disable_rpm;
+	}
 
-	return PTR_ERR_OR_ZERO(phy_provider);
+	return 0;
+
+disable_rpm:
+	pm_runtime_disable(dev);
+	return ret;
 }
 
 static void imx8mq_usb_phy_remove(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	ret = pm_runtime_get_sync(dev);
+	if (ret < 0)
+		dev_warn(dev, "failed to resume on remove: %d\n", ret);
+
+	pm_runtime_disable(dev);
+	pm_runtime_put_noidle(dev);
+}
+
+static int imx8mq_usb_phy_runtime_suspend(struct device *dev)
+{
+	struct imx8mq_usb_phy *imx_phy = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(imx_phy->alt_clk);
+	clk_disable_unprepare(imx_phy->clk);
+
+	return 0;
+}
+
+static int imx8mq_usb_phy_runtime_resume(struct device *dev)
+{
+	struct imx8mq_usb_phy *imx_phy = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare_enable(imx_phy->clk);
+	if (ret)
+		return ret;
 
+	ret = clk_prepare_enable(imx_phy->alt_clk);
+	if (ret) {
+		clk_disable_unprepare(imx_phy->clk);
+		return ret;
+	}
+
+	return 0;
 }
 
+static DEFINE_RUNTIME_DEV_PM_OPS(imx8mq_usb_phy_pm_ops, imx8mq_usb_phy_runtime_suspend,
+				 imx8mq_usb_phy_runtime_resume, NULL);
+
 static struct platform_driver imx8mq_usb_phy_driver = {
 	.probe	= imx8mq_usb_phy_probe,
 	.remove = imx8mq_usb_phy_remove,
 	.driver = {
 		.name	= "imx8mq-usb-phy",
 		.of_match_table	= imx8mq_usb_phy_of_match,
+		.pm = pm_ptr(&imx8mq_usb_phy_pm_ops),
 		.suppress_bind_attrs = true,
 	}
 };