Merge branch 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[deliverable/linux.git] / arch / arm / lib / delay.c

diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c
index 5306de35013397994ec6873f2a713af5d47867a4..312d43eb686a0254543258efdc3185c340bde82c 100644 (file)
--- a/arch/arm/lib/delay.c
+++ b/arch/arm/lib/delay.c
@@ -19,6 +19,7 @@
  * Author: Will Deacon <will.deacon@arm.com>
  */
 
+#include <linux/clocksource.h>
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -36,6 +37,7 @@ struct arm_delay_ops arm_delay_ops = {
 
 static const struct delay_timer *delay_timer;
 static bool delay_calibrated;
+static u64 delay_res;
 
 int read_current_timer(unsigned long *timer_val)
 {
@@ -47,6 +49,11 @@ int read_current_timer(unsigned long *timer_val)
 }
 EXPORT_SYMBOL_GPL(read_current_timer);
 
+static inline u64 cyc_to_ns(u64 cyc, u32 mult, u32 shift)
+{
+       return (cyc * mult) >> shift;
+}
+
 static void __timer_delay(unsigned long cycles)
 {
        cycles_t start = get_cycles();
@@ -69,18 +76,24 @@ static void __timer_udelay(unsigned long usecs)
 
 void __init register_current_timer_delay(const struct delay_timer *timer)
 {
-       if (!delay_calibrated) {
-               pr_info("Switching to timer-based delay loop\n");
+       u32 new_mult, new_shift;
+       u64 res;
+
+       clocks_calc_mult_shift(&new_mult, &new_shift, timer->freq,
+                              NSEC_PER_SEC, 3600);
+       res = cyc_to_ns(1ULL, new_mult, new_shift);
+
+       if (!delay_calibrated && (!delay_res || (res < delay_res))) {
+               pr_info("Switching to timer-based delay loop, resolution %lluns\n", res);
                delay_timer                     = timer;
                lpj_fine                        = timer->freq / HZ;
+               delay_res                       = res;
 
                /* cpufreq may scale loops_per_jiffy, so keep a private copy */
                arm_delay_ops.ticks_per_jiffy   = lpj_fine;
                arm_delay_ops.delay             = __timer_delay;
                arm_delay_ops.const_udelay      = __timer_const_udelay;
                arm_delay_ops.udelay            = __timer_udelay;
-
-               delay_calibrated                = true;
        } else {
                pr_info("Ignoring duplicate/late registration of read_current_timer delay\n");
        }
@@ -91,3 +104,8 @@ unsigned long calibrate_delay_is_known(void)
        delay_calibrated = true;
        return lpj_fine;
 }
+
+void calibration_delay_done(void)
+{
+       delay_calibrated = true;
+}