From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50158) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZMGAY-0002wl-T6 for qemu-devel@nongnu.org; Mon, 03 Aug 2015 09:52:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZMGAU-0007FY-Sb for qemu-devel@nongnu.org; Mon, 03 Aug 2015 09:52:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42375) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZMGAU-0007Et-Nm for qemu-devel@nongnu.org; Mon, 03 Aug 2015 09:52:42 -0400 From: Laurent Vivier Date: Mon, 3 Aug 2015 15:52:28 +0200 Message-Id: <1438609948-3744-1-git-send-email-lvivier@redhat.com> Subject: [Qemu-devel] [PATCH] i6300esb: correctly convert watchdog clock ticks into nanoseconds List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Laurent Vivier , Paolo Bonzini , "Richard W.M. Jones" , David Gibson Originally, qemu_mod_timer() was using ticks to count time. And i6300esb was converting internal clock ticks (33 MHz) to QEMU timer ticks. The timer has been changed by a script to use nanoseconds: 7447545 change all other clock references to use nanosecond resolution accessors As i6300esb takes nanoseconds, we don't need anymore to multiply counter by get_ticks_per_sec()/33MHz, but instead we must convert watchdog ticks into nanoseconds. Signed-off-by: Laurent Vivier --- hw/watchdog/wdt_i6300esb.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/hw/watchdog/wdt_i6300esb.c b/hw/watchdog/wdt_i6300esb.c index cfa2b1b..21119ab 100644 --- a/hw/watchdog/wdt_i6300esb.c +++ b/hw/watchdog/wdt_i6300esb.c @@ -124,19 +124,24 @@ static void i6300esb_restart_timer(I6300State *d, int stage) else timeout = d->timer2_preload; - if (d->clock_scale == CLOCK_SCALE_1KHZ) + /* convert timeout to 33Mhz clock ticks */ + if (d->clock_scale == CLOCK_SCALE_1KHZ) { + /* The 20-bit Preload Value is loaded into bits 34:15 of the + * main down counter. [...] The approximate clock generated + * is 1 KHz, (Default) + */ timeout <<= 15; - else + } else { + /* The 20-bit Preload Value is loaded into bits 24:5 of the + * main down counter. [...] The approximate clock generated + * is 1 MHz. + */ timeout <<= 5; - - /* Get the timeout in units of ticks_per_sec. - * - * ticks_per_sec is typically 10^9 == 0x3B9ACA00 (30 bits), with - * 20 bits of user supplied preload, and 15 bits of scale, the - * multiply here can exceed 64-bits, before we divide by 33MHz, so - * we use a higher-precision intermediate result. + } + /* A 33 Mhz clock gives a 30 ns tick, + * convert timeout from ticks to ns */ - timeout = muldiv64(get_ticks_per_sec(), timeout, 33000000); + timeout *= 30; i6300esb_debug("stage %d, timeout %" PRIi64 "\n", d->stage, timeout); -- 2.1.0