powerpc/eeh: Move EEH initialisation to an arch initcall

The initialisation of EEH mostly happens in a core_initcall_sync initcall,
followed by registering a bus notifier later on in an arch_initcall.
Anything involving initcall dependecies is mostly incomprehensible unless
you've spent a while staring at code so here's the full sequence:

ppc_md.setup_arch       <-- pci_controllers are created here

...time passes...

core_initcall           <-- pci_dns are created from DT nodes
core_initcall_sync      <-- platforms call eeh_init()
postcore_initcall       <-- PCI bus type is registered
postcore_initcall_sync
arch_initcall           <-- EEH pci_bus notifier registered
subsys_initcall         <-- PHBs are scanned here

There's no real requirement to do the EEH setup at the core_initcall_sync
level. It just needs to be done after pci_dn's are created and before we
start scanning PHBs. Simplify the flow a bit by moving the platform EEH
inititalisation to an arch_initcall so we can fold the bus notifier
registration into eeh_init().
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200918093050.37344-5-oohall@gmail.com

arch/powerpc/kernel/eeh.c

@@ -940,6 +940,30 @@ static struct notifier_block eeh_reboot_nb = {
 	.notifier_call = eeh_reboot_notifier,
 };
 
+static int eeh_device_notifier(struct notifier_block *nb,
+			       unsigned long action, void *data)
+{
+	struct device *dev = data;
+
+	switch (action) {
+	/*
+	 * Note: It's not possible to perform EEH device addition (i.e.
+	 * {pseries,pnv}_pcibios_bus_add_device()) here because it depends on
+	 * the device's resources, which have not yet been set up.
+	 */
+	case BUS_NOTIFY_DEL_DEVICE:
+		eeh_remove_device(to_pci_dev(dev));
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block eeh_device_nb = {
+	.notifier_call = eeh_device_notifier,
+};
+
 /**
  * eeh_init - System wide EEH initialization
  *
@@ -960,7 +984,14 @@ int eeh_init(struct eeh_ops *ops)
 	/* Register reboot notifier */
 	ret = register_reboot_notifier(&eeh_reboot_nb);
 	if (ret) {
-		pr_warn("%s: Failed to register notifier (%d)\n",
+		pr_warn("%s: Failed to register reboot notifier (%d)\n",
+			__func__, ret);
+		return ret;
+	}
+
+	ret = bus_register_notifier(&pci_bus_type, &eeh_device_nb);
+	if (ret) {
+		pr_warn("%s: Failed to register bus notifier (%d)\n",
 			__func__, ret);
 		return ret;
 	}
@@ -975,37 +1006,6 @@ int eeh_init(struct eeh_ops *ops)
 	return eeh_event_init();
 }
 
-static int eeh_device_notifier(struct notifier_block *nb,
-			       unsigned long action, void *data)
-{
-	struct device *dev = data;
-
-	switch (action) {
-	/*
-	 * Note: It's not possible to perform EEH device addition (i.e.
-	 * {pseries,pnv}_pcibios_bus_add_device()) here because it depends on
-	 * the device's resources, which have not yet been set up.
-	 */
-	case BUS_NOTIFY_DEL_DEVICE:
-		eeh_remove_device(to_pci_dev(dev));
-		break;
-	default:
-		break;
-	}
-	return NOTIFY_DONE;
-}
-
-static struct notifier_block eeh_device_nb = {
-	.notifier_call = eeh_device_notifier,
-};
-
-static __init int eeh_set_bus_notifier(void)
-{
-	bus_register_notifier(&pci_bus_type, &eeh_device_nb);
-	return 0;
-}
-arch_initcall(eeh_set_bus_notifier);
-
 /**
  * eeh_probe_device() - Perform EEH initialization for the indicated pci device
  * @dev: pci device for which to set up EEH

arch/powerpc/platforms/powernv/eeh-powernv.c

@@ -1721,4 +1721,4 @@ static int __init eeh_powernv_init(void)
 
 	return ret;
 }
-machine_core_initcall_sync(powernv, eeh_powernv_init);
+machine_arch_initcall(powernv, eeh_powernv_init);

arch/powerpc/platforms/pseries/eeh_pseries.c

@@ -985,4 +985,4 @@ static int __init eeh_pseries_init(void)
 			ret);
 	return ret;
 }
-machine_core_initcall_sync(pseries, eeh_pseries_init);
+machine_arch_initcall(pseries, eeh_pseries_init);