[PATCH v5 6/9] irqchip/imx-irqsteer: Let devres own the clock and runtime PM

[Zhipeng.wang_1@oss.nxp.com]

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

In preparation for making the driver unbindable/reloadable, let the
driver core own the clock and runtime PM lifetime so that the probe()
error path and remove() do not have to hand-balance them:

 - 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;
 - enable runtime PM with devm_pm_runtime_set_active_enabled(), which
   marks the device active (matching the enabled clock) and disables
   runtime PM on unbind.

The device may be runtime-suspended at unbind time (autosuspend), in
which case the runtime suspend callback has already dropped the clock
enable count. The devres clk_disable_unprepare() that runs after
remove() would then underflow the enable count. Resume the device in
remove() so the clock is enabled when devres tears it down, keeping the
count balanced.

With the clock and runtime PM owned by devres, remove() and the probe()
error path only have to dispose of the parent IRQ mappings.

Suggested-by: Fabio Estevam <festevam@nabladev.com>
Signed-off-by: Zhipeng Wang <zhipeng.wang_1@nxp.com>
---
 drivers/irqchip/irq-imx-irqsteer.c | 37 +++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/drivers/irqchip/irq-imx-irqsteer.c b/drivers/irqchip/irq-imx-irqsteer.c
index b63bf957ab88..c2f58787f9a8 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);
@@ -275,12 +269,21 @@ static int imx_irqsteer_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, data);
 
-	pm_runtime_set_active(&pdev->dev);
-	pm_runtime_enable(&pdev->dev);
+	ret = devm_pm_runtime_set_active_enabled(&pdev->dev);
+	if (ret)
+		goto err_irq;
 
 	return 0;
+
+err_irq:
+	for (i = 0; i < data->irq_count; i++) {
+		if (!data->irq[i])
+			break;
+
+		irq_set_chained_handler_and_data(data->irq[i], NULL, NULL);
+		irq_dispose_mapping(data->irq[i]);
+	}
 out:
-	clk_disable_unprepare(data->ipg_clk);
 	return ret;
 }
 
@@ -289,6 +292,14 @@ static void imx_irqsteer_remove(struct platform_device *pdev)
 	struct irqsteer_data *irqsteer_data = platform_get_drvdata(pdev);
 	int i;
 
+	/*
+	 * 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.
+	 */
+	pm_runtime_resume_and_get(&pdev->dev);
+
 	for (i = 0; i < irqsteer_data->irq_count; i++) {
 		if (!irqsteer_data->irq[i])
 			break;
@@ -297,8 +308,6 @@ static void imx_irqsteer_remove(struct platform_device *pdev)
 						 NULL, NULL);
 		irq_dispose_mapping(irqsteer_data->irq[i]);
 	}
-
-	clk_disable_unprepare(irqsteer_data->ipg_clk);
 }
 
 #ifdef CONFIG_PM
@@ -328,7 +337,7 @@ 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;
 }
@@ -338,7 +347,7 @@ 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