amba: Make use of bus_type functions

Instead of assigning the needed functions for each driver separately do it
only once in amba_bustype. Move the definition of the functions to their
proper place among the other callbacks used there. Note that the bus's
shutdown function might be called for unbound devices, too, so it needs
additional guarding.

This prepares getting rid of these callbacks in struct device_driver.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210126165835.687514-6-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/amba/bus.c

@@ -174,83 +174,6 @@ static int amba_uevent(struct device *dev, struct kobj_uevent_env *env)
 	return retval;
 }
 
-#ifdef CONFIG_PM
-/*
- * Hooks to provide runtime PM of the pclk (bus clock).  It is safe to
- * enable/disable the bus clock at runtime PM suspend/resume as this
- * does not result in loss of context.
- */
-static int amba_pm_runtime_suspend(struct device *dev)
-{
-	struct amba_device *pcdev = to_amba_device(dev);
-	int ret = pm_generic_runtime_suspend(dev);
-
-	if (ret == 0 && dev->driver) {
-		if (pm_runtime_is_irq_safe(dev))
-			clk_disable(pcdev->pclk);
-		else
-			clk_disable_unprepare(pcdev->pclk);
-	}
-
-	return ret;
-}
-
-static int amba_pm_runtime_resume(struct device *dev)
-{
-	struct amba_device *pcdev = to_amba_device(dev);
-	int ret;
-
-	if (dev->driver) {
-		if (pm_runtime_is_irq_safe(dev))
-			ret = clk_enable(pcdev->pclk);
-		else
-			ret = clk_prepare_enable(pcdev->pclk);
-		/* Failure is probably fatal to the system, but... */
-		if (ret)
-			return ret;
-	}
-
-	return pm_generic_runtime_resume(dev);
-}
-#endif /* CONFIG_PM */
-
-static const struct dev_pm_ops amba_pm = {
-	.suspend	= pm_generic_suspend,
-	.resume		= pm_generic_resume,
-	.freeze		= pm_generic_freeze,
-	.thaw		= pm_generic_thaw,
-	.poweroff	= pm_generic_poweroff,
-	.restore	= pm_generic_restore,
-	SET_RUNTIME_PM_OPS(
-		amba_pm_runtime_suspend,
-		amba_pm_runtime_resume,
-		NULL
-	)
-};
-
-/*
- * Primecells are part of the Advanced Microcontroller Bus Architecture,
- * so we call the bus "amba".
- * DMA configuration for platform and AMBA bus is same. So here we reuse
- * platform's DMA config routine.
- */
-struct bus_type amba_bustype = {
-	.name		= "amba",
-	.dev_groups	= amba_dev_groups,
-	.match		= amba_match,
-	.uevent		= amba_uevent,
-	.dma_configure	= platform_dma_configure,
-	.pm		= &amba_pm,
-};
-EXPORT_SYMBOL_GPL(amba_bustype);
-
-static int __init amba_init(void)
-{
-	return bus_register(&amba_bustype);
-}
-
-postcore_initcall(amba_init);
-
 /*
  * These are the device model conversion veneers; they convert the
  * device model structures to our more specific structures.
@@ -319,12 +242,96 @@ static int amba_remove(struct device *dev)
 
 static void amba_shutdown(struct device *dev)
 {
-	struct amba_driver *drv = to_amba_driver(dev->driver);
+	struct amba_driver *drv;
 
+	if (!dev->driver)
+		return;
+
+	drv = to_amba_driver(dev->driver);
 	if (drv->shutdown)
 		drv->shutdown(to_amba_device(dev));
 }
 
+#ifdef CONFIG_PM
+/*
+ * Hooks to provide runtime PM of the pclk (bus clock).  It is safe to
+ * enable/disable the bus clock at runtime PM suspend/resume as this
+ * does not result in loss of context.
+ */
+static int amba_pm_runtime_suspend(struct device *dev)
+{
+	struct amba_device *pcdev = to_amba_device(dev);
+	int ret = pm_generic_runtime_suspend(dev);
+
+	if (ret == 0 && dev->driver) {
+		if (pm_runtime_is_irq_safe(dev))
+			clk_disable(pcdev->pclk);
+		else
+			clk_disable_unprepare(pcdev->pclk);
+	}
+
+	return ret;
+}
+
+static int amba_pm_runtime_resume(struct device *dev)
+{
+	struct amba_device *pcdev = to_amba_device(dev);
+	int ret;
+
+	if (dev->driver) {
+		if (pm_runtime_is_irq_safe(dev))
+			ret = clk_enable(pcdev->pclk);
+		else
+			ret = clk_prepare_enable(pcdev->pclk);
+		/* Failure is probably fatal to the system, but... */
+		if (ret)
+			return ret;
+	}
+
+	return pm_generic_runtime_resume(dev);
+}
+#endif /* CONFIG_PM */
+
+static const struct dev_pm_ops amba_pm = {
+	.suspend	= pm_generic_suspend,
+	.resume		= pm_generic_resume,
+	.freeze		= pm_generic_freeze,
+	.thaw		= pm_generic_thaw,
+	.poweroff	= pm_generic_poweroff,
+	.restore	= pm_generic_restore,
+	SET_RUNTIME_PM_OPS(
+		amba_pm_runtime_suspend,
+		amba_pm_runtime_resume,
+		NULL
+	)
+};
+
+/*
+ * Primecells are part of the Advanced Microcontroller Bus Architecture,
+ * so we call the bus "amba".
+ * DMA configuration for platform and AMBA bus is same. So here we reuse
+ * platform's DMA config routine.
+ */
+struct bus_type amba_bustype = {
+	.name		= "amba",
+	.dev_groups	= amba_dev_groups,
+	.match		= amba_match,
+	.uevent		= amba_uevent,
+	.probe		= amba_probe,
+	.remove		= amba_remove,
+	.shutdown	= amba_shutdown,
+	.dma_configure	= platform_dma_configure,
+	.pm		= &amba_pm,
+};
+EXPORT_SYMBOL_GPL(amba_bustype);
+
+static int __init amba_init(void)
+{
+	return bus_register(&amba_bustype);
+}
+
+postcore_initcall(amba_init);
+
 /**
  *	amba_driver_register - register an AMBA device driver
  *	@drv: amba device driver structure
@@ -339,9 +346,6 @@ int amba_driver_register(struct amba_driver *drv)
 		return -EINVAL;
 
 	drv->drv.bus = &amba_bustype;
-	drv->drv.probe = amba_probe;
-	drv->drv.remove = amba_remove;
-	drv->drv.shutdown = amba_shutdown;
 
 	return driver_register(&drv->drv);
 }