[PATCH v6 6/9] irqchip/imx-irqsteer: Let devres own the clock

[Zhipeng.wang_1 at oss.nxp.com]

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

Let the driver core own the clock lifetime so that the probe() error
path and remove() do not have to hand-balance it:

 - acquire the clock with devm_clk_get_enabled() instead of a bare
   devm_clk_get() followed by a manual clk_prepare_enable(), so it is
   prepared/enabled for the device lifetime and released on unbind;
 - keep only clk_enable()/clk_disable() in the runtime PM callbacks,
   since prepare/unprepare is now handled once by devres.

Signed-off-by: Zhipeng Wang <zhipeng.wang_1 at nxp.com>
---
 drivers/irqchip/irq-imx-irqsteer.c | 37 +++++++++++++++---------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/drivers/irqchip/irq-imx-irqsteer.c b/drivers/irqchip/irq-imx-irqsteer.c
index fa233de9bc2b..15ee50f65d54 100644
--- a/drivers/irqchip/irq-imx-irqsteer.c
+++ b/drivers/irqchip/irq-imx-irqsteer.c
@@ -194,7 +194,7 @@ static int imx_irqsteer_probe(struct platform_device *pdev)
 		return PTR_ERR(data->regs);
 	}
 
-	data->ipg_clk = devm_clk_get(&pdev->dev, "ipg");
+	data->ipg_clk = devm_clk_get_enabled(&pdev->dev, "ipg");
 	if (IS_ERR(data->ipg_clk))
 		return dev_err_probe(&pdev->dev, PTR_ERR(data->ipg_clk),
 				     "failed to get ipg clk\n");
@@ -229,12 +229,6 @@ static int imx_irqsteer_probe(struct platform_device *pdev)
 			return -ENOMEM;
 	}
 
-	ret = clk_prepare_enable(data->ipg_clk);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to enable ipg clk: %d\n", ret);
-		return ret;
-	}
-
 	/* steer all IRQs into configured channel */
 	if (irqsteer_has_chanctrl(data->devtype_data))
 		writel_relaxed(BIT(data->channel), data->regs + CHANCTRL);
@@ -249,14 +243,13 @@ static int imx_irqsteer_probe(struct platform_device *pdev)
 
 	ret = devm_pm_runtime_set_active_enabled(&pdev->dev);
 	if (ret)
-		goto out;
+		return ret;
 
 	data->domain = irq_domain_create_linear(dev_fwnode(&pdev->dev), data->reg_num * 32,
 						&imx_irqsteer_domain_ops, data);
 	if (!data->domain) {
 		dev_err(&pdev->dev, "failed to create IRQ domain\n");
-		ret = -ENOMEM;
-		goto out;
+		return -ENOMEM;
 	}
 	irq_domain_set_pm_device(data->domain, &pdev->dev);
 
@@ -273,15 +266,23 @@ static int imx_irqsteer_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, data);
 
 	return 0;
-out:
-	clk_disable_unprepare(data->ipg_clk);
-	return ret;
 }
 
 static void imx_irqsteer_remove(struct platform_device *pdev)
 {
 	struct irqsteer_data *irqsteer_data = platform_get_drvdata(pdev);
-	int i;
+	int i, ret;
+
+	/*
+	 * The device may be runtime-suspended here, in which case the runtime
+	 * suspend callback has already dropped the clock enable count. Resume
+	 * it so the devres clk_disable_unprepare(), which runs after remove(),
+	 * finds the clock enabled and stays balanced. On success drop the
+	 * usage count again with pm_runtime_put_noidle(): it must not trigger a
+	 * suspend (which would re-disable the clock) and must not leak to the
+	 * next probe of this persistent device.
+	 */
+	ret = pm_runtime_resume_and_get(&pdev->dev);
 
 	for (i = 0; i < irqsteer_data->irq_count; i++) {
 		if (!irqsteer_data->irq[i])
@@ -294,8 +295,8 @@ static void imx_irqsteer_remove(struct platform_device *pdev)
 
 	irq_domain_remove(irqsteer_data->domain);
 
-	if (!pm_runtime_status_suspended(&pdev->dev))
-		clk_disable_unprepare(irqsteer_data->ipg_clk);
+	if (ret >= 0)
+		pm_runtime_put_noidle(&pdev->dev);
 }
 
 #ifdef CONFIG_PM
@@ -325,7 +326,7 @@ static int imx_irqsteer_suspend(struct device *dev)
 	struct irqsteer_data *irqsteer_data = dev_get_drvdata(dev);
 
 	imx_irqsteer_save_regs(irqsteer_data);
-	clk_disable_unprepare(irqsteer_data->ipg_clk);
+	clk_disable(irqsteer_data->ipg_clk);
 
 	return 0;
 }
@@ -335,7 +336,7 @@ static int imx_irqsteer_resume(struct device *dev)
 	struct irqsteer_data *irqsteer_data = dev_get_drvdata(dev);
 	int ret;
 
-	ret = clk_prepare_enable(irqsteer_data->ipg_clk);
+	ret = clk_enable(irqsteer_data->ipg_clk);
 	if (ret) {
 		dev_err(dev, "failed to enable ipg clk: %d\n", ret);
 		return ret;
-- 
2.34.1