powerpc/eeh: Register OPAL notifier for PCI error

The patch registers OPAL event notifier and process the PCI errors
from firmware. If we have pending PCI errors, special EEH event
(without binding PE) will be sent to EEH core for processing.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

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

@@ -18,6 +18,7 @@
 #include <linux/irq.h>
 #include <linux/kernel.h>
 #include <linux/msi.h>
+#include <linux/notifier.h>
 #include <linux/pci.h>
 #include <linux/string.h>
 
@@ -42,6 +43,26 @@
 #endif
 
 static char *hub_diag = NULL;
+static int ioda_eeh_nb_init = 0;
+
+static int ioda_eeh_event(struct notifier_block *nb,
+			  unsigned long events, void *change)
+{
+	uint64_t changed_evts = (uint64_t)change;
+
+	/* We simply send special EEH event */
+	if ((changed_evts & OPAL_EVENT_PCI_ERROR) &&
+	    (events & OPAL_EVENT_PCI_ERROR))
+		eeh_send_failure_event(NULL);
+
+	return 0;
+}
+
+static struct notifier_block ioda_eeh_nb = {
+	.notifier_call	= ioda_eeh_event,
+	.next		= NULL,
+	.priority	= 0
+};
 
 /**
  * ioda_eeh_post_init - Chip dependent post initialization
@@ -54,6 +75,19 @@ static char *hub_diag = NULL;
 static int ioda_eeh_post_init(struct pci_controller *hose)
 {
 	struct pnv_phb *phb = hose->private_data;
+	int ret;
+
+	/* Register OPAL event notifier */
+	if (!ioda_eeh_nb_init) {
+		ret = opal_notifier_register(&ioda_eeh_nb);
+		if (ret) {
+			pr_err("%s: Can't register OPAL event notifier (%d)\n",
+			       __func__, ret);
+			return ret;
+		}
+
+		ioda_eeh_nb_init = 1;
+	}
 
 	/* FIXME: Enable it for PHB3 later */
 	if (phb->type == PNV_PHB_IODA1) {
@@ -736,8 +770,13 @@ static int ioda_eeh_next_error(struct eeh_pe **pe)
 	long rc;
 	int ret = 1;
 
-	/* While running here, it's safe to purge the event queue */
+	/*
+	 * While running here, it's safe to purge the event queue.
+	 * And we should keep the cached OPAL notifier event sychronized
+	 * between the kernel and firmware.
+	 */
 	eeh_remove_event(NULL);
+	opal_notifier_update_evt(OPAL_EVENT_PCI_ERROR, 0x0ul);
 
 	list_for_each_entry_safe(hose, tmp, &hose_list, list_node) {
 		/*