x86: Implement arch_setup/teardown_hwirq()

This is just a cleanup to get rid of the create/destroy_irq variants
which were designed in hell.

The long term solution for x86 is to switch over to irq domains and
cleanup the whole vector allocation mess.

The generic irq_alloc_hwirqs() interface deliberately prevents
multi-MSI vector allocation to further enforce the irq domain
conversion (aside of the desire to support ioapic hotplug).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Grant Likely <grant.likely@linaro.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20140507154334.482904047@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/Kconfig

@@ -831,6 +831,7 @@ config X86_LOCAL_APIC
 config X86_IO_APIC
 	def_bool y
 	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC || PCI_MSI
+	select GENERIC_IRQ_LEGACY_ALLOC_HWIRQ
 
 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
 	bool "Reroute for broken boot IRQs"

arch/x86/kernel/apic/io_apic.c

@@ -3010,6 +3010,39 @@ void destroy_irqs(unsigned int irq, unsigned int count)
 		destroy_irq(irq + i);
 }
 
+int arch_setup_hwirq(unsigned int irq, int node)
+{
+	struct irq_cfg *cfg;
+	unsigned long flags;
+	int ret;
+
+	cfg = alloc_irq_cfg(irq, node);
+	if (!cfg)
+		return -ENOMEM;
+
+	raw_spin_lock_irqsave(&vector_lock, flags);
+	ret = __assign_irq_vector(irq, cfg, apic->target_cpus());
+	raw_spin_unlock_irqrestore(&vector_lock, flags);
+
+	if (!ret)
+		irq_set_chip_data(irq, cfg);
+	else
+		free_irq_cfg(irq, cfg);
+	return ret;
+}
+
+void arch_teardown_hwirq(unsigned int irq)
+{
+	struct irq_cfg *cfg = irq_get_chip_data(irq);
+	unsigned long flags;
+
+	free_remapped_irq(irq);
+	raw_spin_lock_irqsave(&vector_lock, flags);
+	__clear_irq_vector(irq, cfg);
+	raw_spin_unlock_irqrestore(&vector_lock, flags);
+	free_irq_cfg(irq, cfg);
+}
+
 /*
  * MSI message composition
  */