From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vineet.Gupta1@synopsys.com (Vineet Gupta) Date: Thu, 3 Nov 2016 16:33:26 -0700 Subject: [PATCH v3 01/10] ARC: timer: rtc: implement read loop in "C" vs. inline asm In-Reply-To: <1478216015-18931-1-git-send-email-vgupta@synopsys.com> References: <1478216015-18931-1-git-send-email-vgupta@synopsys.com> List-ID: Message-ID: <1478216015-18931-2-git-send-email-vgupta@synopsys.com> To: linux-snps-arc@lists.infradead.org The current code doesn't even compile as somehow the inline assembly can't see the register names defined as ARC_RTC_* I'm pretty sure It worked when I first got it merged, but the tools were definitely different then. So better to write this in "C" anyways. CC: stable at vger.kernel.org Acked-by: Daniel Lezcano Signed-off-by: Vineet Gupta --- 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..c10390d1ddb6 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