[PATCH 04/21] ARM: OMAP: 32k counter: Provide y2038-safe omap_read_persistent_clock() replacement

John Stultz
2015-04-02T03:39:26Z

From: Xunlei Pang <pang.xunlei@linaro.org>

As part of addressing "y2038 problem" for in-kernel uses, this
patch adds the y2038-safe omap_read_persistent_clock64() using
timespec64.

Because we rely on some subsequent changes to convert arm multiarch
support, omap_read_persistent_clock() will be removed then.

Also remove the needless spinlock, because read_persistent_clock()
doesn't run simultaneously.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
arch/arm/plat-omap/counter_32k.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
index 43cf745..b7b7b07 100644
--- a/arch/arm/plat-omap/counter_32k.c
+++ b/arch/arm/plat-omap/counter_32k.c
@@ -44,24 +44,20 @@ static u64 notrace omap_32k_read_sched_clock(void)
}

/**
- * omap_read_persistent_clock - Return time from a persistent clock.
+ * omap_read_persistent_clock64 - Return time from a persistent clock.
*
* Reads the time from a source which isn't disabled during PM, the
* 32k sync timer. Convert the cycles elapsed since last read into
- * nsecs and adds to a monotonically increasing timespec.
+ * nsecs and adds to a monotonically increasing timespec64.
*/
-static struct timespec persistent_ts;
+static struct timespec64 persistent_ts;
static cycles_t cycles;
static unsigned int persistent_mult, persistent_shift;
-static DEFINE_SPINLOCK(read_persistent_clock_lock);

-static void omap_read_persistent_clock(struct timespec *ts)
+static void omap_read_persistent_clock64(struct timespec64 *ts)
{
unsigned long long nsecs;
cycles_t last_cycles;
- unsigned long flags;
-
- spin_lock_irqsave(&read_persistent_clock_lock, flags);

last_cycles = cycles;
cycles = sync32k_cnt_reg ? readl_relaxed(sync32k_cnt_reg) : 0;
@@ -69,11 +65,17 @@ static void omap_read_persistent_clock(struct timespec *ts)
nsecs = clocksource_cyc2ns(cycles - last_cycles,
persistent_mult, persistent_shift);

- timespec_add_ns(&persistent_ts, nsecs);
+ timespec64_add_ns(&persistent_ts, nsecs);

*ts = persistent_ts;
+}
+
+static void omap_read_persistent_clock(struct timespec *ts)
+{
+ struct timespec64 ts64;

- spin_unlock_irqrestore(&read_persistent_clock_lock, flags);
+ omap_read_persistent_clock64(&ts64);
+ *ts = timespec64_to_timespec(ts64);
}

/**
--
1.9.1