powerpc/powernv/opal: Use standard interrupts property when available

For (bad) historical reasons, OPAL used to create a non-standard pair
of properties "opal-interrupts" and "opal-interrupts-names" for
representing the list of interrupts it wants Linux to request on its
behalf.

Among other issues, the opal-interrupts doesn't have a way to carry
the type of interrupts, and they were assumed to be all level
sensitive.

This is wrong on some recent systems where some of them are edge
sensitive causing warnings in the XIVE code and possible misbehaviours
if they need to be retriggered (typically the NPU2 TCE error
interrupts).

This makes Linux switch to using the standard "interrupts" and
"interrupt-names" properties instead when they are available, using
standard of_irq helpers, which can carry all the desired type
information.

Newer versions of OPAL will generate those properties in addition to
the legacy ones.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[mpe: Fixup prefix logic to check strlen(r->name). Reinstate setting
 of start = 0 in opal_event_shutdown() to avoid double free warnings]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/powernv/opal-irqchip.c

@@ -22,6 +22,7 @@
 #include <linux/kthread.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
+#include <linux/of_irq.h>
 
 #include <asm/machdep.h>
 #include <asm/opal.h>
@@ -38,8 +39,8 @@ struct opal_event_irqchip {
 };
 static struct opal_event_irqchip opal_event_irqchip;
 static u64 last_outstanding_events;
-static unsigned int opal_irq_count;
-static unsigned int *opal_irqs;
+static int opal_irq_count;
+static struct resource *opal_irqs;
 
 void opal_handle_events(void)
 {
@@ -165,24 +166,23 @@ void opal_event_shutdown(void)
 
 	/* First free interrupts, which will also mask them */
 	for (i = 0; i < opal_irq_count; i++) {
-		if (!opal_irqs[i])
+		if (!opal_irqs || !opal_irqs[i].start)
 			continue;
 
 		if (in_interrupt() || irqs_disabled())
-			disable_irq_nosync(opal_irqs[i]);
+			disable_irq_nosync(opal_irqs[i].start);
 		else
-			free_irq(opal_irqs[i], NULL);
+			free_irq(opal_irqs[i].start, NULL);
 
-		opal_irqs[i] = 0;
+		opal_irqs[i].start = 0;
 	}
 }
 
 int __init opal_event_init(void)
 {
 	struct device_node *dn, *opal_node;
-	const char **names;
-	u32 *irqs;
-	int i, rc;
+	bool old_style = false;
+	int i, rc = 0;
 
 	opal_node = of_find_node_by_path("/ibm,opal");
 	if (!opal_node) {
@@ -207,67 +207,91 @@ int __init opal_event_init(void)
 		goto out;
 	}
 
-	/* Get opal-interrupts property and names if present */
-	rc = of_property_count_u32_elems(opal_node, "opal-interrupts");
-	if (rc < 0)
-		goto out;
+	/* Look for new-style (standard) "interrupts" property */
+	opal_irq_count = of_irq_count(opal_node);
 
-	opal_irq_count = rc;
-	pr_debug("Found %d interrupts reserved for OPAL\n", opal_irq_count);
+	/* Absent ? Look for the old one */
+	if (opal_irq_count < 1) {
+		/* Get opal-interrupts property and names if present */
+		rc = of_property_count_u32_elems(opal_node, "opal-interrupts");
+		if (rc > 0)
+			opal_irq_count = rc;
+		old_style = true;
+	}
 
-	irqs = kcalloc(opal_irq_count, sizeof(*irqs), GFP_KERNEL);
-	names = kcalloc(opal_irq_count, sizeof(*names), GFP_KERNEL);
-	opal_irqs = kcalloc(opal_irq_count, sizeof(*opal_irqs), GFP_KERNEL);
+	/* No interrupts ? Bail out */
+	if (!opal_irq_count)
+		goto out;
 
-	if (WARN_ON(!irqs || !names || !opal_irqs))
-		goto out_free;
+	pr_debug("OPAL: Found %d interrupts reserved for OPAL using %s scheme\n",
+		 opal_irq_count, old_style ? "old" : "new");
 
-	rc = of_property_read_u32_array(opal_node, "opal-interrupts",
-					irqs, opal_irq_count);
-	if (rc < 0) {
-		pr_err("Error %d reading opal-interrupts array\n", rc);
-		goto out_free;
+	/* Allocate an IRQ resources array */
+	opal_irqs = kcalloc(opal_irq_count, sizeof(struct resource), GFP_KERNEL);
+	if (WARN_ON(!opal_irqs)) {
+		rc = -ENOMEM;
+		goto out;
 	}
 
-	/* It's not an error for the names to be missing */
-	of_property_read_string_array(opal_node, "opal-interrupts-names",
-				      names, opal_irq_count);
+	/* Build the resources array */
+	if (old_style) {
+		/* Old style "opal-interrupts" property */
+		for (i = 0; i < opal_irq_count; i++) {
+			struct resource *r = &opal_irqs[i];
+			const char *name = NULL;
+			u32 hw_irq;
+			int virq;
+
+			rc = of_property_read_u32_index(opal_node, "opal-interrupts",
+							i, &hw_irq);
+			if (WARN_ON(rc < 0)) {
+				opal_irq_count = i;
+				break;
+			}
+			of_property_read_string_index(opal_node, "opal-interrupts-names",
+						      i, &name);
+			virq = irq_create_mapping(NULL, hw_irq);
+			if (!virq) {
+				pr_warn("Failed to map OPAL irq 0x%x\n", hw_irq);
+				continue;
+			}
+			r->start = r->end = virq;
+			r->flags = IORESOURCE_IRQ | IRQ_TYPE_LEVEL_LOW;
+			r->name = name;
+		}
+	} else {
+		/* new style standard "interrupts" property */
+		rc = of_irq_to_resource_table(opal_node, opal_irqs, opal_irq_count);
+		if (WARN_ON(rc < 0)) {
+			opal_irq_count = 0;
+			kfree(opal_irqs);
+			goto out;
+		}
+		if (WARN_ON(rc < opal_irq_count))
+			opal_irq_count = rc;
+	}
 
 	/* Install interrupt handlers */
 	for (i = 0; i < opal_irq_count; i++) {
-		unsigned int virq;
-		char *name;
-
-		/* Get hardware and virtual IRQ */
-		virq = irq_create_mapping(NULL, irqs[i]);
-		if (!virq) {
-			pr_warn("Failed to map irq 0x%x\n", irqs[i]);
-			continue;
-		}
+		struct resource *r = &opal_irqs[i];
+		const char *name;
 
-		if (names[i] && strlen(names[i]))
-			name = kasprintf(GFP_KERNEL, "opal-%s", names[i]);
+		/* Prefix name */
+		if (r->name && strlen(r->name))
+			name = kasprintf(GFP_KERNEL, "opal-%s", r->name);
 		else
 			name = kasprintf(GFP_KERNEL, "opal");
 
 		/* Install interrupt handler */
-		rc = request_irq(virq, opal_interrupt, IRQF_TRIGGER_LOW,
+		rc = request_irq(r->start, opal_interrupt, r->flags & IRQD_TRIGGER_MASK,
 				 name, NULL);
 		if (rc) {
-			irq_dispose_mapping(virq);
-			pr_warn("Error %d requesting irq %d (0x%x)\n",
-				 rc, virq, irqs[i]);
+			pr_warn("Error %d requesting OPAL irq %d\n", rc, (int)r->start);
 			continue;
 		}
-
-		/* Cache IRQ */
-		opal_irqs[i] = virq;
 	}
-
-out_free:
-	kfree(irqs);
-	kfree(names);
-out:
+	rc = 0;
+ out:
 	of_node_put(opal_node);
 	return rc;
 }