x86/irq: Refine the way to allocate irq_cfg for legacy IRQs

To support legacy ISA IRQs, we need to preallocate irq_cfg structures
for legacy ISA IRQs. Refine the way to allocate irq_cfg for legacy ISA
IRQs, so it's more friendly for the hierarchical irqdomain
implementation.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Tested-by: Joerg Roedel <jroedel@suse.de>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Cohen <david.a.cohen@linux.intel.com>
Cc: Sander Eikelenboom <linux@eikelenboom.it>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Grant Likely <grant.likely@linaro.org>
Link: http://lkml.kernel.org/r/1428905519-23704-35-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/apic/io_apic.c

@@ -254,8 +254,7 @@ static void free_ioapic_saved_registers(int idx)
 
 int __init arch_early_ioapic_init(void)
 {
-	struct irq_cfg *cfg;
-	int i, node = cpu_to_node(0);
+	int i;
 
 	if (!nr_legacy_irqs())
 		io_apic_irqs = ~0UL;
@@ -263,16 +262,6 @@ int __init arch_early_ioapic_init(void)
 	for_each_ioapic(i)
 		alloc_ioapic_saved_registers(i);
 
-	/*
-	 * For legacy IRQ's, start with assigning irq0 to irq15 to
-	 * IRQ0_VECTOR to IRQ15_VECTOR for all cpu's.
-	 */
-	for (i = 0; i < nr_legacy_irqs(); i++) {
-		cfg = alloc_irq_and_cfg_at(i, node);
-		cfg->vector = IRQ0_VECTOR + i;
-		cpumask_setall(cfg->domain);
-	}
-
 	return 0;
 }
 

arch/x86/kernel/apic/vector.c

@@ -24,6 +24,9 @@
 struct irq_domain *x86_vector_domain;
 static DEFINE_RAW_SPINLOCK(vector_lock);
 static struct irq_chip lapic_controller;
+#ifdef	CONFIG_X86_IO_APIC
+static struct irq_cfg *legacy_irq_cfgs[NR_IRQS_LEGACY];
+#endif
 
 void lock_vector_lock(void)
 {
@@ -283,6 +286,10 @@ static void x86_vector_free_irqs(struct irq_domain *domain,
 			free_remapped_irq(virq);
 			clear_irq_vector(virq + i, irq_data->chip_data);
 			free_irq_cfg(irq_data->chip_data);
+#ifdef	CONFIG_X86_IO_APIC
+			if (virq + i < nr_legacy_irqs())
+				legacy_irq_cfgs[virq + i] = NULL;
+#endif
 			irq_domain_reset_irq_data(irq_data);
 		}
 	}
@@ -308,7 +315,12 @@ static int x86_vector_alloc_irqs(struct irq_domain *domain, unsigned int virq,
 	for (i = 0; i < nr_irqs; i++) {
 		irq_data = irq_domain_get_irq_data(domain, virq + i);
 		BUG_ON(!irq_data);
-		cfg = alloc_irq_cfg(irq_data->node);
+#ifdef	CONFIG_X86_IO_APIC
+		if (virq + i < nr_legacy_irqs() && legacy_irq_cfgs[virq + i])
+			cfg = legacy_irq_cfgs[virq + i];
+		else
+#endif
+			cfg = alloc_irq_cfg(irq_data->node);
 		if (!cfg) {
 			err = -ENOMEM;
 			goto error;
@@ -357,8 +369,36 @@ int __init arch_probe_nr_irqs(void)
 	return nr_legacy_irqs();
 }
 
+#ifdef	CONFIG_X86_IO_APIC
+static void init_legacy_irqs(void)
+{
+	int i, node = cpu_to_node(0);
+	struct irq_cfg *cfg;
+
+	/*
+	 * For legacy IRQ's, start with assigning irq0 to irq15 to
+	 * IRQ0_VECTOR to IRQ15_VECTOR for all cpu's.
+	 */
+	for (i = 0; i < nr_legacy_irqs(); i++) {
+		cfg = legacy_irq_cfgs[i] = alloc_irq_cfg(node);
+		BUG_ON(!cfg);
+		/*
+		 * For legacy IRQ's, start with assigning irq0 to irq15 to
+		 * IRQ0_VECTOR to IRQ15_VECTOR for all cpu's.
+		 */
+		cfg->vector = IRQ0_VECTOR + i;
+		cpumask_setall(cfg->domain);
+		irq_set_chip_data(i, cfg);
+	}
+}
+#else
+static void init_legacy_irqs(void) { }
+#endif
+
 int __init arch_early_irq_init(void)
 {
+	init_legacy_irqs();
+
 	x86_vector_domain = irq_domain_add_tree(NULL, &x86_vector_domain_ops,
 						NULL);
 	BUG_ON(x86_vector_domain == NULL);