Merge branch 'consolidate-clksrc-i8253' of master.kernel.org:~rmk/linux-2.6-arm into...

[pandora-kernel.git] / arch / blackfin / kernel / time-ts.c

diff --git a/arch/blackfin/kernel/time-ts.c b/arch/blackfin/kernel/time-ts.c
index 8c9a43d..9e9b60d 100644 (file)
--- a/arch/blackfin/kernel/time-ts.c
+++ b/arch/blackfin/kernel/time-ts.c
@@ -23,29 +23,6 @@
 #include <asm/gptimers.h>
 #include <asm/nmi.h>
 
-/* Accelerators for sched_clock()
- * convert from cycles(64bits) => nanoseconds (64bits)
- *  basic equation:
- *             ns = cycles / (freq / ns_per_sec)
- *             ns = cycles * (ns_per_sec / freq)
- *             ns = cycles * (10^9 / (cpu_khz * 10^3))
- *             ns = cycles * (10^6 / cpu_khz)
- *
- *     Then we use scaling math (suggested by george@mvista.com) to get:
- *             ns = cycles * (10^6 * SC / cpu_khz) / SC
- *             ns = cycles * cyc2ns_scale / SC
- *
- *     And since SC is a constant power of two, we can convert the div
- *  into a shift.
- *
- *  We can use khz divisor instead of mhz to keep a better precision, since
- *  cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
- *  (mathieu.desnoyers@polymtl.ca)
- *
- *                     -johnstul@us.ibm.com "math is hard, lets go shopping!"
- */
-
-#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
 
 #if defined(CONFIG_CYCLES_CLOCKSOURCE)
 
@@ -63,7 +40,6 @@ static struct clocksource bfin_cs_cycles = {
        .rating         = 400,
        .read           = bfin_read_cycles,
        .mask           = CLOCKSOURCE_MASK(64),
-       .shift          = CYC2NS_SCALE_FACTOR,
        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
@@ -75,10 +51,7 @@ static inline unsigned long long bfin_cs_cycles_sched_clock(void)
 
 static int __init bfin_cs_cycles_init(void)
 {
-       bfin_cs_cycles.mult = \
-               clocksource_hz2mult(get_cclk(), bfin_cs_cycles.shift);
-
-       if (clocksource_register(&bfin_cs_cycles))
+       if (clocksource_register_hz(&bfin_cs_cycles, get_cclk()))
                panic("failed to register clocksource");
 
        return 0;
@@ -111,7 +84,6 @@ static struct clocksource bfin_cs_gptimer0 = {
        .rating         = 350,
        .read           = bfin_read_gptimer0,
        .mask           = CLOCKSOURCE_MASK(32),
-       .shift          = CYC2NS_SCALE_FACTOR,
        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
@@ -125,10 +97,7 @@ static int __init bfin_cs_gptimer0_init(void)
 {
        setup_gptimer0();
 
-       bfin_cs_gptimer0.mult = \
-               clocksource_hz2mult(get_sclk(), bfin_cs_gptimer0.shift);
-
-       if (clocksource_register(&bfin_cs_gptimer0))
+       if (clocksource_register_hz(&bfin_cs_gptimer0, get_sclk()))
                panic("failed to register clocksource");
 
        return 0;
@@ -206,8 +175,14 @@ irqreturn_t bfin_gptmr0_interrupt(int irq, void *dev_id)
 {
        struct clock_event_device *evt = dev_id;
        smp_mb();
-       evt->event_handler(evt);
+       /*
+        * We want to ACK before we handle so that we can handle smaller timer
+        * intervals.  This way if the timer expires again while we're handling
+        * things, we're more likely to see that 2nd int rather than swallowing
+        * it by ACKing the int at the end of this handler.
+        */
        bfin_gptmr0_ack();
+       evt->event_handler(evt);
        return IRQ_HANDLED;
 }