[POWERPC] Add new interrupt mapping core and change platforms to use it

This adds the new irq remapper core and removes the old one.  Because
there are some fundamental conflicts with the old code, like the value
of NO_IRQ which I'm now setting to 0 (as per discussions with Linus),
etc..., this commit also changes the relevant platform and driver code
over to use the new remapper (so as not to cause difficulties later
in bisecting).

This patch removes the old pre-parsing of the open firmware interrupt
tree along with all the bogus assumptions it made to try to renumber
interrupts according to the platform. This is all to be handled by the
new code now.

For the pSeries XICS interrupt controller, a single remapper host is
created for the whole machine regardless of how many interrupt
presentation and source controllers are found, and it's set to match
any device node that isn't a 8259.  That works fine on pSeries and
avoids having to deal with some of the complexities of split source
controllers vs. presentation controllers in the pSeries device trees.

The powerpc i8259 PIC driver now always requests the legacy interrupt
range. It also has the feature of being able to match any device node
(including NULL) if passed no device node as an input. That will help
porting over platforms with broken device-trees like Pegasos who don't
have a proper interrupt tree.

Signed-off-by: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Paul Mackerras <[email protected]>

arch/powerpc/kernel/ibmebus.c

@@ -323,26 +323,21 @@ int ibmebus_request_irq(struct ibmebus_dev *dev,
 			unsigned long irq_flags, const char * devname,
 			void *dev_id)
 {
-	unsigned int irq = virt_irq_create_mapping(ist);
+	unsigned int irq = irq_create_mapping(NULL, ist, 0);
 
 	if (irq == NO_IRQ)
 		return -EINVAL;
 
-	irq = irq_offset_up(irq);
-
 	return request_irq(irq, handler,
 			   irq_flags, devname, dev_id);
 }
 EXPORT_SYMBOL(ibmebus_request_irq);
 
 void ibmebus_free_irq(struct ibmebus_dev *dev, u32 ist, void *dev_id)
 {
-	unsigned int irq = virt_irq_create_mapping(ist);
+	unsigned int irq = irq_find_mapping(NULL, ist);
 
-	irq = irq_offset_up(irq);
 	free_irq(irq, dev_id);
-
-	return;
 }
 EXPORT_SYMBOL(ibmebus_free_irq);