Blackfin: SIC: cut down on IAR MMR reads a bit

Tweak the for loops that operate on the SIC IAR system MMRs to avoid
re-reading them multiple times in a row.  System MMRs are a little
slower to access, so avoid the penalty when possible.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 18 insertions, 15 deletions

diff --git a/arch/blackfin/mach-common/ints-priority.c b/arch/blackfin/mach-common/ints-priority.c
index ce988713445d..1c8c4c7245c3 100644
--- a/arch/blackfin/mach-common/ints-priority.c
+++ b/arch/blackfin/mach-common/ints-priority.c
@@ -92,26 +92,29 @@ static void __init search_IAR(void)
 {
         unsigned ivg, irq_pos = 0;
         for (ivg = 0; ivg <= IVG13 - IVG7; ivg++) {
-                int irqn;
+                int irqN;
 
                 ivg7_13[ivg].istop = ivg7_13[ivg].ifirst = &ivg_table[irq_pos];
 
-                for (irqn = 0; irqn < NR_PERI_INTS; irqn++) {
-                        int iar_shift = (irqn & 7) * 4;
-                                if (ivg == (0xf &
-#if defined(CONFIG_BF52x) || defined(CONFIG_BF538) \
-        || defined(CONFIG_BF539) || defined(CONFIG_BF51x)
-                             bfin_read32((unsigned long *)SIC_IAR0 +
-                                         ((irqn % 32) >> 3) + ((irqn / 32) *
-                                         ((SIC_IAR4 - SIC_IAR0) / 4))) >> iar_shift)) {
+                for (irqN = 0; irqN < NR_PERI_INTS; irqN += 4) {
+                        int irqn;
+                        u32 iar = bfin_read32((unsigned long *)SIC_IAR0 +
+#if defined(CONFIG_BF51x) || defined(CONFIG_BF52x) || \
+        defined(CONFIG_BF538) || defined(CONFIG_BF539)
+                                ((irqN % 32) >> 3) + ((irqN / 32) * ((SIC_IAR4 - SIC_IAR0) / 4))
 #else
-                             bfin_read32((unsigned long *)SIC_IAR0 +
-                                         (irqn >> 3)) >> iar_shift)) {
+                                (irqN >> 3)
 #endif
-                                ivg_table[irq_pos].irqno = IVG7 + irqn;
-                                ivg_table[irq_pos].isrflag = 1 << (irqn % 32);
-                                ivg7_13[ivg].istop++;
-                                irq_pos++;
+                                );
+
+                        for (irqn = irqN; irqn < irqN + 4; ++irqn) {
+                                int iar_shift = (irqn & 7) * 4;
+                                if (ivg == (0xf & (iar >> iar_shift))) {
+                                        ivg_table[irq_pos].irqno = IVG7 + irqn;
+                                        ivg_table[irq_pos].isrflag = 1 << (irqn % 32);
+                                        ivg7_13[ivg].istop++;
+                                        irq_pos++;
+                                }
                         }
                 }
         }