generic: sparse irqs: use irq_desc() together with dyn_array, instead of irq_desc[]

add CONFIG_HAVE_SPARSE_IRQ to for use condensed array.
Get rid of irq_desc[] array assumptions.

Preallocate 32 irq_desc, and irq_desc() will try to get more.

( No change in functionality is expected anywhere, except the odd build
  failure where we missed a code site or where a crossing commit itroduces
  new irq_desc[] usage. )

v2: according to Eric, change get_irq_desc() to irq_desc()

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/parisc/gsc.c b/drivers/parisc/gsc.c
index f7d088b897ee..e76db9e4d504 100644
--- a/drivers/parisc/gsc.c
+++ b/drivers/parisc/gsc.c
@@ -108,7 +108,8 @@ int gsc_find_local_irq(unsigned int irq, int *global_irqs, int limit)
 
 static void gsc_asic_disable_irq(unsigned int irq)
 {
-        struct gsc_asic *irq_dev = irq_desc[irq].chip_data;
+        struct irq_desc *desc = irq_to_desc(irq);
+        struct gsc_asic *irq_dev = desc->chip_data;
         int local_irq = gsc_find_local_irq(irq, irq_dev->global_irq, 32);
         u32 imr;
 
@@ -123,7 +124,8 @@ static void gsc_asic_disable_irq(unsigned int irq)
 
 static void gsc_asic_enable_irq(unsigned int irq)
 {
-        struct gsc_asic *irq_dev = irq_desc[irq].chip_data;
+        struct irq_desc *desc = irq_to_desc(irq);
+        struct gsc_asic *irq_dev = desc->chip_data;
         int local_irq = gsc_find_local_irq(irq, irq_dev->global_irq, 32);
         u32 imr;
 
@@ -159,12 +161,14 @@ static struct hw_interrupt_type gsc_asic_interrupt_type = {
 int gsc_assign_irq(struct hw_interrupt_type *type, void *data)
 {
         static int irq = GSC_IRQ_BASE;
+        struct irq_desc *desc;
 
         if (irq > GSC_IRQ_MAX)
                 return NO_IRQ;
 
-        irq_desc[irq].chip = type;
-        irq_desc[irq].chip_data = data;
+        desc = irq_to_desc(irq);
+        desc->chip = type;
+        desc->chip_data = data;
         return irq++;
 }