rtc-bfin: shrink/optimize interrupt handler a bit
Mike Frysinger [Wed, 27 Oct 2010 22:33:03 +0000 (15:33 -0700)]
By unifying the RTC_ISTAT clearing steps, we shrink the interrupt handler
and avoid multiple writes to the hardware registers.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-bfin.c

index d4fb82d..3506f33 100644 (file)
@@ -183,29 +183,33 @@ static irqreturn_t bfin_rtc_interrupt(int irq, void *dev_id)
        struct bfin_rtc *rtc = dev_get_drvdata(dev);
        unsigned long events = 0;
        bool write_complete = false;
-       u16 rtc_istat, rtc_ictl;
+       u16 rtc_istat, rtc_istat_clear, rtc_ictl, bits;
 
        dev_dbg_stamp(dev);
 
        rtc_istat = bfin_read_RTC_ISTAT();
        rtc_ictl = bfin_read_RTC_ICTL();
+       rtc_istat_clear = 0;
 
-       if (rtc_istat & RTC_ISTAT_WRITE_COMPLETE) {
-               bfin_write_RTC_ISTAT(RTC_ISTAT_WRITE_COMPLETE);
+       bits = RTC_ISTAT_WRITE_COMPLETE;
+       if (rtc_istat & bits) {
+               rtc_istat_clear |= bits;
                write_complete = true;
                complete(&bfin_write_complete);
        }
 
-       if (rtc_ictl & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)) {
-               if (rtc_istat & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)) {
-                       bfin_write_RTC_ISTAT(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY);
+       bits = (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY);
+       if (rtc_ictl & bits) {
+               if (rtc_istat & bits) {
+                       rtc_istat_clear |= bits;
                        events |= RTC_AF | RTC_IRQF;
                }
        }
 
-       if (rtc_ictl & RTC_ISTAT_SEC) {
-               if (rtc_istat & RTC_ISTAT_SEC) {
-                       bfin_write_RTC_ISTAT(RTC_ISTAT_SEC);
+       bits = RTC_ISTAT_SEC;
+       if (rtc_ictl & bits) {
+               if (rtc_istat & bits) {
+                       rtc_istat_clear |= bits;
                        events |= RTC_UF | RTC_IRQF;
                }
        }
@@ -213,9 +217,10 @@ static irqreturn_t bfin_rtc_interrupt(int irq, void *dev_id)
        if (events)
                rtc_update_irq(rtc->rtc_dev, 1, events);
 
-       if (write_complete || events)
+       if (write_complete || events) {
+               bfin_write_RTC_ISTAT(rtc_istat_clear);
                return IRQ_HANDLED;
-       else
+       } else
                return IRQ_NONE;
 }