From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:48198 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941543AbcKQKjf (ORCPT ); Thu, 17 Nov 2016 05:39:35 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Lezcano , Vineet Gupta Subject: [PATCH 4.4 08/38] ARC: timer: rtc: implement read loop in "C" vs. inline asm Date: Thu, 17 Nov 2016 11:32:46 +0100 Message-Id: <20161117103236.743986236@linuxfoundation.org> In-Reply-To: <20161117103236.423602981@linuxfoundation.org> References: <20161117103236.423602981@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vineet Gupta commit 922cc171998ac3dbe74d57011ef7ed57e9b0d7df upstream. 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. Acked-by: Daniel Lezcano Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman --- arch/arc/kernel/time.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) --- a/arch/arc/kernel/time.c +++ b/arch/arc/kernel/time.c @@ -130,14 +130,17 @@ static cycle_t arc_counter_read(struct c 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; }