[PATCH v2 01/10] ARC: timer: rtc: implement read loop in "C" vs. inline asm

Vineet Gupta
2016-11-03T21:33:37Z

The current code doesn't even compile ....

CC: stable@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/kernel/time.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/arc/kernel/time.c b/arch/arc/kernel/time.c
index f927b8dc6edd..1a117b999c0c 100644
--- a/arch/arc/kernel/time.c
+++ b/arch/arc/kernel/time.c
@@ -152,14 +152,17 @@ static cycle_t arc_read_rtc(struct clocksource *cs)
cycle_t full;
} stamp;

-
- __asm__ __volatile(
- "1: \n"
- " lr %0, [AUX_RTC_LOW] \n"
- " lr %1, [AUX_RTC_HIGH] \n"
- " lr %2, [AUX_RTC_CTRL] \n"
- " bbit0.nt %2, 31, 1b \n"
- : "=r" (stamp.low), "=r" (stamp.high), "=r" (status));
+ /*
+ * hardware has an internal state machine which tracks readout of
+ * low/high and updates the CTRL.status if
+ * - interrupt/exception taken between the two reads
+ * - high increments after low has been read
+ */
+ do {
+ stamp.low = read_aux_reg(AUX_RTC_LOW);
+ stamp.high = read_aux_reg(AUX_RTC_HIGH);
+ status = read_aux_reg(AUX_RTC_CTRL);
+ } while (!(status & _BITUL(31)));

return stamp.full;
}
--
2.7.4