+/* For hooking up the cascace we have a problem. Our device-tree is
+ * crap and we don't know on which BE iic interrupt we are hooked on at
+ * least not the "standard" way. We can reconstitute it based on two
+ * informations though: which BE node we are connected to and wether
+ * we are connected to IOIF0 or IOIF1. Right now, we really only care
+ * about the IBM cell blade and we know that its firmware gives us an
+ * interrupt-map property which is pretty strange.
+ */
+static unsigned int __init spider_find_cascade_and_node(struct spider_pic *pic)
+{
+ unsigned int virq;
+ const u32 *imap, *tmp;
+ int imaplen, intsize, unit;
+ struct device_node *iic;
+ struct irq_host *iic_host;
+
+#if 0 /* Enable that when we have a way to retreive the node as well */
+ /* First, we check wether we have a real "interrupts" in the device
+ * tree in case the device-tree is ever fixed
+ */
+ struct of_irq oirq;
+ if (of_irq_map_one(pic->of_node, 0, &oirq) == 0) {
+ virq = irq_create_of_mapping(oirq.controller, oirq.specifier,
+ oirq.size);
+ goto bail;
+ }
+#endif
+
+ /* Now do the horrible hacks */
+ tmp = get_property(pic->of_node, "#interrupt-cells", NULL);
+ if (tmp == NULL)
+ return NO_IRQ;
+ intsize = *tmp;
+ imap = get_property(pic->of_node, "interrupt-map", &imaplen);
+ if (imap == NULL || imaplen < (intsize + 1))
+ return NO_IRQ;
+ iic = of_find_node_by_phandle(imap[intsize]);
+ if (iic == NULL)
+ return NO_IRQ;
+ imap += intsize + 1;
+ tmp = get_property(iic, "#interrupt-cells", NULL);
+ if (tmp == NULL)
+ return NO_IRQ;
+ intsize = *tmp;
+ /* Assume unit is last entry of interrupt specifier */
+ unit = imap[intsize - 1];
+ /* Ok, we have a unit, now let's try to get the node */
+ tmp = get_property(iic, "ibm,interrupt-server-ranges", NULL);
+ if (tmp == NULL) {
+ of_node_put(iic);
+ return NO_IRQ;
+ }
+ /* ugly as hell but works for now */
+ pic->node_id = (*tmp) >> 1;
+ of_node_put(iic);
+
+ /* Ok, now let's get cracking. You may ask me why I just didn't match
+ * the iic host from the iic OF node, but that way I'm still compatible
+ * with really really old old firmwares for which we don't have a node
+ */
+ iic_host = iic_get_irq_host(pic->node_id);
+ if (iic_host == NULL)
+ return NO_IRQ;
+ /* Manufacture an IIC interrupt number of class 2 */
+ virq = irq_create_mapping(iic_host, 0x20 | unit);
+ if (virq == NO_IRQ)
+ printk(KERN_ERR "spider_pic: failed to map cascade !");
+ return virq;
+}