msi: Kill the msi_desc array.

We need to be able to get from an irq number to a struct msi_desc.
The msi_desc array in msi.c had several short comings the big one was
that it could not be used outside of msi.c.  Using irq_data in struct
irq_desc almost worked except on some architectures irq_data needs to
be used for something else.

So this patch adds a msi_desc pointer to irq_desc, adds the appropriate
wrappers and changes all of the msi code to use them.

The dynamic_irq_init/cleanup code was tweaked to ensure the new
field is left in a well defined state.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index d27b258..475e8a7 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -39,6 +39,7 @@
 	desc->chip = &no_irq_chip;
 	desc->handle_irq = handle_bad_irq;
 	desc->depth = 1;
+	desc->msi_desc = NULL;
 	desc->handler_data = NULL;
 	desc->chip_data = NULL;
 	desc->action = NULL;
@@ -74,6 +75,9 @@
 		WARN_ON(1);
 		return;
 	}
+	desc->msi_desc = NULL;
+	desc->handler_data = NULL;
+	desc->chip_data = NULL;
 	desc->handle_irq = handle_bad_irq;
 	desc->chip = &no_irq_chip;
 	spin_unlock_irqrestore(&desc->lock, flags);
@@ -162,6 +166,30 @@
 EXPORT_SYMBOL(set_irq_data);
 
 /**
+ *	set_irq_data - set irq type data for an irq
+ *	@irq:	Interrupt number
+ *	@data:	Pointer to interrupt specific data
+ *
+ *	Set the hardware irq controller data for an irq
+ */
+int set_irq_msi(unsigned int irq, struct msi_desc *entry)
+{
+	struct irq_desc *desc;
+	unsigned long flags;
+
+	if (irq >= NR_IRQS) {
+		printk(KERN_ERR
+		       "Trying to install msi data for IRQ%d\n", irq);
+		return -EINVAL;
+	}
+	desc = irq_desc + irq;
+	spin_lock_irqsave(&desc->lock, flags);
+	desc->msi_desc = entry;
+	spin_unlock_irqrestore(&desc->lock, flags);
+	return 0;
+}
+
+/**
  *	set_irq_chip_data - set irq chip data for an irq
  *	@irq:	Interrupt number
  *	@data:	Pointer to chip specific data