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>

10 files changed, 38 insertions, 20 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 8d2940517c99..572d372899d3 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1058,7 +1058,7 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 
                 if (!is_out) {
                         int             irq = gpio_to_irq(gpio);
-                        struct irq_desc *desc = irq_desc + irq;
+                        struct irq_desc *desc = irq_to_desc(irq);
 
                         /* This races with request_irq(), set_irq_type(),
                          * and set_irq_wake() ... but those are "rare".
diff --git a/drivers/mfd/asic3.c b/drivers/mfd/asic3.c
index ba5aa2008273..e4c0db4dc7b1 100644
--- a/drivers/mfd/asic3.c
+++ b/drivers/mfd/asic3.c
@@ -123,7 +123,7 @@ static void asic3_irq_demux(unsigned int irq, struct irq_desc *desc)
                                         irqnr = asic->irq_base +
                                                 (ASIC3_GPIOS_PER_BANK * bank)
                                                 + i;
-                                        desc = irq_desc + irqnr;
+                                        desc = irq_to_desc(irqnr);
                                         desc->handle_irq(irqnr, desc);
                                         if (asic->irq_bothedge[bank] & bit)
                                                 asic3_irq_flip_edge(asic, base,
@@ -136,7 +136,7 @@ static void asic3_irq_demux(unsigned int irq, struct irq_desc *desc)
                 for (i = ASIC3_NUM_GPIOS; i < ASIC3_NR_IRQS; i++) {
                         /* They start at bit 4 and go up */
                         if (status & (1 << (i - ASIC3_NUM_GPIOS + 4))) {
-                                desc = irq_desc + asic->irq_base + i;
+                                desc = irq_to_desc(asic->irq_base + i);
                                 desc->handle_irq(asic->irq_base + i,
                                                  desc);
                         }
diff --git a/drivers/mfd/htc-egpio.c b/drivers/mfd/htc-egpio.c
index 6be43172dc65..ad3379fcd194 100644
--- a/drivers/mfd/htc-egpio.c
+++ b/drivers/mfd/htc-egpio.c
@@ -112,7 +112,7 @@ static void egpio_handler(unsigned int irq, struct irq_desc *desc)
                 /* Run irq handler */
                 pr_debug("got IRQ %d\n", irqpin);
                 irq = ei->irq_start + irqpin;
-                desc = &irq_desc[irq];
+                desc = irq_to_desc(irq);
                 desc->handle_irq(irq, desc);
         }
 }
diff --git a/drivers/parisc/dino.c b/drivers/parisc/dino.c
index fd56128525d1..3bc54b30c3a1 100644
--- a/drivers/parisc/dino.c
+++ b/drivers/parisc/dino.c
@@ -298,7 +298,8 @@ struct pci_port_ops dino_port_ops = {
 
 static void dino_disable_irq(unsigned int irq)
 {
-        struct dino_device *dino_dev = irq_desc[irq].chip_data;
+        struct irq_desc *desc = irq_to_desc(irq);
+        struct dino_device *dino_dev = desc->chip_data;
         int local_irq = gsc_find_local_irq(irq, dino_dev->global_irq, DINO_LOCAL_IRQS);
 
         DBG(KERN_WARNING "%s(0x%p, %d)\n", __func__, dino_dev, irq);
@@ -310,7 +311,8 @@ static void dino_disable_irq(unsigned int irq)
 
 static void dino_enable_irq(unsigned int irq)
 {
-        struct dino_device *dino_dev = irq_desc[irq].chip_data;
+        struct irq_desc *desc = irq_to_desc(irq);
+        struct dino_device *dino_dev = desc->chip_data;
         int local_irq = gsc_find_local_irq(irq, dino_dev->global_irq, DINO_LOCAL_IRQS);
         u32 tmp;
 
diff --git a/drivers/parisc/eisa.c b/drivers/parisc/eisa.c
index 771cef592542..7891db50c483 100644
--- a/drivers/parisc/eisa.c
+++ b/drivers/parisc/eisa.c
@@ -346,10 +346,10 @@ static int __init eisa_probe(struct parisc_device *dev)
         }
         
         /* Reserve IRQ2 */
-        irq_desc[2].action = &irq2_action;
+        irq_to_desc(2)->action = &irq2_action;
         
         for (i = 0; i < 16; i++) {
-                irq_desc[i].chip = &eisa_interrupt_type;
+                irq_to_desc(i)->chip = &eisa_interrupt_type;
         }
         
         EISA_bus = 1;
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++;
 }
 
diff --git a/drivers/parisc/iosapic.c b/drivers/parisc/iosapic.c
index 6fb3f7979f21..7beffcab2745 100644
--- a/drivers/parisc/iosapic.c
+++ b/drivers/parisc/iosapic.c
@@ -619,7 +619,9 @@ iosapic_set_irt_data( struct vector_info *vi, u32 *dp0, u32 *dp1)
 
 static struct vector_info *iosapic_get_vector(unsigned int irq)
 {
-        return irq_desc[irq].chip_data;
+        struct irq_desc *desc = irq_to_desc(irq);
+
+        return desc->chip_data;
 }
 
 static void iosapic_disable_irq(unsigned int irq)
diff --git a/drivers/parisc/superio.c b/drivers/parisc/superio.c
index 1e8d2d17f04c..1e93c837514f 100644
--- a/drivers/parisc/superio.c
+++ b/drivers/parisc/superio.c
@@ -363,7 +363,9 @@ int superio_fixup_irq(struct pci_dev *pcidev)
 #endif
 
         for (i = 0; i < 16; i++) {
-                irq_desc[i].chip = &superio_interrupt_type;
+                struct irq_desc *desc = irq_to_desc(i);
+
+                desc->chip = &superio_interrupt_type;
         }
 
         /*
diff --git a/drivers/pcmcia/hd64465_ss.c b/drivers/pcmcia/hd64465_ss.c
index 117dc12ab438..9ef69cdb3183 100644
--- a/drivers/pcmcia/hd64465_ss.c
+++ b/drivers/pcmcia/hd64465_ss.c
@@ -233,15 +233,18 @@ static struct hw_interrupt_type hd64465_ss_irq_type = {
  */
 static void hs_map_irq(hs_socket_t *sp, unsigned int irq)
 {
+        struct irq_desc *desc;
+
         DPRINTK("hs_map_irq(sock=%d irq=%d)\n", sp->number, irq);
         
         if (irq >= HS_NUM_MAPPED_IRQS)
             return;
 
+        desc = irq_to_desc(irq);
         hs_mapped_irq[irq].sock = sp;
         /* insert ourselves as the irq controller */
-        hs_mapped_irq[irq].old_handler = irq_desc[irq].chip;
-        irq_desc[irq].chip = &hd64465_ss_irq_type;
+        hs_mapped_irq[irq].old_handler = desc->chip;
+        desc->chip = &hd64465_ss_irq_type;
 }
 
 
@@ -250,13 +253,16 @@ static void hs_map_irq(hs_socket_t *sp, unsigned int irq)
  */
 static void hs_unmap_irq(hs_socket_t *sp, unsigned int irq)
 {
+        struct irq_desc *desc;
+
         DPRINTK("hs_unmap_irq(sock=%d irq=%d)\n", sp->number, irq);
         
         if (irq >= HS_NUM_MAPPED_IRQS)
             return;
                 
+        desc = irq_to_desc(irq);
         /* restore the original irq controller */
-        irq_desc[irq].chip = hs_mapped_irq[irq].old_handler;
+        desc->chip = hs_mapped_irq[irq].old_handler;
 }
 
 /*============================================================*/
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index ed8235187dc0..56ace47f24d6 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -125,7 +125,7 @@ static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
 
         BUG_ON(irq == -1);
 #ifdef CONFIG_SMP
-        irq_desc[irq].affinity = cpumask_of_cpu(cpu);
+        irq_to_desc(irq)->affinity = cpumask_of_cpu(cpu);
 #endif
 
         __clear_bit(chn, cpu_evtchn_mask[cpu_evtchn[chn]]);
@@ -139,8 +139,10 @@ static void init_evtchn_cpu_bindings(void)
 #ifdef CONFIG_SMP
         int i;
         /* By default all event channels notify CPU#0. */
-        for (i = 0; i < nr_irqs; i++)
-                irq_desc[i].affinity = cpumask_of_cpu(0);
+        for (i = 0; i < nr_irqs; i++) {
+                struct irq_desc *desc = irq_to_desc(i);
+                desc->affinity = cpumask_of_cpu(0);
+        }
 #endif
 
         memset(cpu_evtchn, 0, sizeof(cpu_evtchn));