x86/devicetree: Fix device IRQ settings in DT

IRQ parameters for the SoC devices connected directly to I/O APIC lines
(without PCI IRQ routing) may be specified in the Device Tree.

Called from DT IRQ parser, irq_create_fwspec_mapping() calls
irq_domain_alloc_irqs() with a pointer to irq_fwspec structure as @arg.

But x86-specific DT IRQ allocation code casts @arg to of_phandle_args
structure pointer and crashes trying to read the IRQ parameters. The
function was not converted when the mapping descriptor was changed to
irq_fwspec in the generic irqdomain code.

Fixes: 11e4438e ("irqdomain: Introduce a firmware-specific IRQ specifier structure")
Signed-off-by: Ivan Gorinov <ivan.gorinov@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Link: https://lkml.kernel.org/r/a234dee27ea60ce76141872da0d6bdb378b2a9ee.1520450752.git.ivan.gorinov@intel.com

arch/x86/kernel/devicetree.c

@@ -195,19 +195,22 @@ static struct of_ioapic_type of_ioapic_type[] =
 static int dt_irqdomain_alloc(struct irq_domain *domain, unsigned int virq,
 			      unsigned int nr_irqs, void *arg)
 {
-	struct of_phandle_args *irq_data = (void *)arg;
+	struct irq_fwspec *fwspec = (struct irq_fwspec *)arg;
 	struct of_ioapic_type *it;
 	struct irq_alloc_info tmp;
+	int type_index;
 
-	if (WARN_ON(irq_data->args_count < 2))
+	if (WARN_ON(fwspec->param_count < 2))
 		return -EINVAL;
-	if (irq_data->args[1] >= ARRAY_SIZE(of_ioapic_type))
+
+	type_index = fwspec->param[1];
+	if (type_index >= ARRAY_SIZE(of_ioapic_type))
 		return -EINVAL;
 
-	it = &of_ioapic_type[irq_data->args[1]];
+	it = &of_ioapic_type[type_index];
 	ioapic_set_alloc_attr(&tmp, NUMA_NO_NODE, it->trigger, it->polarity);
 	tmp.ioapic_id = mpc_ioapic_id(mp_irqdomain_ioapic_idx(domain));
-	tmp.ioapic_pin = irq_data->args[0];
+	tmp.ioapic_pin = fwspec->param[0];
 
 	return mp_irqdomain_alloc(domain, virq, nr_irqs, &tmp);
 }