powerpc/irqdomain: Fix broken NR_IRQ references

The switch from using irq_map to irq_alloc_desc*() for managing irq
number allocations introduced new bugs in some of the powerpc
interrupt code. Several functions rely on the value of NR_IRQS to
determine the maximum irq number that could get allocated. However,
with sparse_irq and using irq_alloc_desc*() the maximum possible irq
number is now specified with 'nr_irqs' which may be a number larger
than NR_IRQS. This has caused breakage on powermac when
CONFIG_NR_IRQS is set to 32.

This patch removes most of the direct references to NR_IRQS in the
powerpc code and replaces them with either a nr_irqs reference or by
using the common for_each_irq_desc() macro. The powerpc-specific
for_each_irq() macro is removed at the same time.

Also, the Cell axon_msi driver is refactored to remove the global
build assumption on the size of NR_IRQS and instead add a limit to the
maximum irq number when calling irq_domain_add_nomap().

Signed-off-by: Grant Likely <[e-mail]>
Signed-off-by: Benjamin Herrenschmidt <[e-mail]>

arch/powerpc/include/asm/irq.h

···
 #include <linux/atomic.h>
 
 
-/* Define a way to iterate across irqs. */
-#define for_each_irq(i) \
-	for ((i) = 0; (i) < NR_IRQS; ++(i))
-
 extern atomic_t ppc_n_lost_interrupts;
 
 /* This number is used when no interrupt has been assigned */

arch/powerpc/kernel/irq.c

···
 
 	alloc_cpumask_var(&mask, GFP_KERNEL);
 
-	for_each_irq(irq) {
+	for_each_irq_desc(irq, desc) {
 		struct irq_data *data;
 		struct irq_chip *chip;
-
-		desc = irq_to_desc(irq);
-		if (!desc)
-			continue;
 
 		data = irq_desc_get_irq_data(desc);
 		if (irqd_is_per_cpu(data))

arch/powerpc/kernel/machine_kexec.c

···
 
 void machine_kexec_mask_interrupts(void) {
 	unsigned int i;
+	struct irq_desc *desc;
 
-	for_each_irq(i) {
-		struct irq_desc *desc = irq_to_desc(i);
+	for_each_irq_desc(i, desc) {
 		struct irq_chip *chip;
-
-		if (!desc)
-			continue;
 
 		chip = irq_desc_get_chip(desc);
 		if (!chip)

arch/powerpc/platforms/cell/axon_msi.c

···
 		pr_devel("axon_msi: woff %x roff %x msi %x\n",
 			  write_offset, msic->read_offset, msi);
 
-		if (msi < NR_IRQS && irq_get_chip_data(msi) == msic) {
+		if (msi < nr_irqs && irq_get_chip_data(msi) == msic) {
 			generic_handle_irq(msi);
 			msic->fifo_virt[idx] = cpu_to_le32(0xffffffff);
 		} else {
···
 	if (rc)
 		return rc;
 
-	/* We rely on being able to stash a virq in a u16 */
-	BUILD_BUG_ON(NR_IRQS > 65536);
-
 	list_for_each_entry(entry, &dev->msi_list, list) {
 		virq = irq_create_direct_mapping(msic->irq_domain);
 		if (virq == NO_IRQ) {
···
 	}
 	memset(msic->fifo_virt, 0xff, MSIC_FIFO_SIZE_BYTES);
 
-	msic->irq_domain = irq_domain_add_nomap(dn, 0, &msic_host_ops, msic);
+	/* We rely on being able to stash a virq in a u16, so limit irqs to < 65536 */
+	msic->irq_domain = irq_domain_add_nomap(dn, 65536, &msic_host_ops, msic);
 	if (!msic->irq_domain) {
 		printk(KERN_ERR "axon_msi: couldn't allocate irq_domain for %s\n",
 		       dn->full_name);

arch/powerpc/platforms/cell/beat_interrupt.c

···
 {
 	int	i;
 
-	for (i = 1; i < NR_IRQS; i++)
+	for (i = 1; i < nr_irqs; i++)
 		beat_destruct_irq_plug(i);
 }

arch/powerpc/platforms/powermac/pic.c

···
 
 static DEFINE_RAW_SPINLOCK(pmac_pic_lock);
 
-#define NR_MASK_WORDS	((NR_IRQS + 31) / 32)
-static unsigned long ppc_lost_interrupts[NR_MASK_WORDS];
-static unsigned long ppc_cached_irq_mask[NR_MASK_WORDS];
+/* The max irq number this driver deals with is 128; see max_irqs */
+static DECLARE_BITMAP(ppc_lost_interrupts, 128);
+static DECLARE_BITMAP(ppc_cached_irq_mask, 128);
 static int pmac_irq_cascade = -1;
 static struct irq_domain *pmac_pic_host;
 

arch/powerpc/sysdev/cpm2_pic.c

···
 static intctl_cpm2_t __iomem *cpm2_intctl;
 
 static struct irq_domain *cpm2_pic_host;
-#define NR_MASK_WORDS   ((NR_IRQS + 31) / 32)
-static unsigned long ppc_cached_irq_mask[NR_MASK_WORDS];
+static unsigned long ppc_cached_irq_mask[2]; /* 2 32-bit registers */
 
 static const u_char irq_to_siureg[] = {
 	1, 1, 1, 1, 1, 1, 1, 1,

arch/powerpc/sysdev/xics/xics-common.c

···
 {
 	int cpu = smp_processor_id(), hw_cpu = hard_smp_processor_id();
 	unsigned int irq, virq;
+	struct irq_desc *desc;
 
 	/* If we used to be the default server, move to the new "boot_cpuid" */
 	if (hw_cpu == xics_default_server)
···
 	/* Allow IPIs again... */
 	icp_ops->set_priority(DEFAULT_PRIORITY);
 
-	for_each_irq(virq) {
-		struct irq_desc *desc;
+	for_each_irq_desc(virq, desc) {
 		struct irq_chip *chip;
 		long server;
 		unsigned long flags;
···
 		/* We can't set affinity on ISA interrupts */
 		if (virq < NUM_ISA_INTERRUPTS)
 			continue;
-		desc = irq_to_desc(virq);
 		/* We only need to migrate enabled IRQS */
-		if (!desc || !desc->action)
+		if (!desc->action)
 			continue;
 		if (desc->irq_data.domain != xics_host)
 			continue;