[POWERPC] Fix CHRP platforms with only 8259

On CHRP platforms with only a 8259 controller, we should set the
default IRQ host to the 8259 driver's one for the IRQ probing
fallbacks to work in case the IRQ tree is incorrect (like on
Pegasos for example). Without this fix, we get a bunch of WARN_ON's
during boot.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/chrp/setup.c

@@ -477,8 +477,10 @@ static void __init chrp_find_8259(void)
 		       " address, polling\n");
 
 	i8259_init(pic, chrp_int_ack);
-	if (ppc_md.get_irq == NULL)
+	if (ppc_md.get_irq == NULL) {
 		ppc_md.get_irq = i8259_irq;
+		irq_set_default_host(i8259_get_host());
+	}
 	if (chrp_mpic != NULL) {
 		cascade_irq = irq_of_parse_and_map(pic, 0);
 		if (cascade_irq == NO_IRQ)

arch/powerpc/sysdev/i8259.c

@@ -224,6 +224,11 @@ static struct irq_host_ops i8259_host_ops = {
 	.xlate = i8259_host_xlate,
 };
 
+struct irq_host *i8259_get_host(void)
+{
+	return i8259_host;
+}
+
 /**
  * i8259_init - Initialize the legacy controller
  * @node: device node of the legacy PIC (can be NULL, but then, it will match

include/asm-powerpc/i8259.h

@@ -7,6 +7,7 @@
 #ifdef CONFIG_PPC_MERGE
 extern void i8259_init(struct device_node *node, unsigned long intack_addr);
 extern unsigned int i8259_irq(void);
+extern struct irq_host *i8259_get_host(void);
 #else
 extern void i8259_init(unsigned long intack_addr, int offset);
 extern int i8259_irq(void);