From patchwork Tue Mar 19 13:05:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "D, Lakshmi Sowjanya" X-Patchwork-Id: 13596643 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E73F980033; Tue, 19 Mar 2024 13:06:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710853572; cv=none; b=FLXMcEzFhUTzH0KeWR4CRDEn8UoWdeKvsZQzCAz4G/ZR16Wrea/RtId+wHuEI/qzsXKUOsJEUA/ZzciwLTqqUZ4BcJOCsKAmI6IMLQnwDlwrsP1Cy1cQ62jTHbpYaJ5tQrnlBKGv7CJCyL3c7L/UfXvO/H3iZPzz+FoHOFqyPgM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710853572; c=relaxed/simple; bh=f4BFmpOnOflQZ26qIp5VZktFRxTUYvqOxJjovMonJwY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=HiiDPI+LwDw6x3QfKehZD1e4EfEAKTcvrWi7DwHC6H1Yhiy2xI6S4bgr0ENxHIYnZu+8V0nNUeSMyAPsNUgDh4e+KUUagMQKJUtrCpWaDB09z4VgmAoTeVtrtsLMhQtipFCX/RPkCsoM9KLCOp163oSx4fM+q8kNBPuBH3vIXg0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=dZOHsth6; arc=none smtp.client-ip=198.175.65.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="dZOHsth6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1710853571; x=1742389571; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=f4BFmpOnOflQZ26qIp5VZktFRxTUYvqOxJjovMonJwY=; b=dZOHsth6dV6L3Al83jHTffN5x7e0ZY0bzEDbfX0K6Wg6MfAfeAenk7c5 Bx4TY7PMDQURuHlxwu1m2QJg2km9ya5wVLXPI7eKcJ1SbZB6lGgoA26H/ QgilGuyFCZHv06hc0I0Om52leLFIvO3VBzd20eRKTVl8zSsnnLO53eg4E hQ6M5UuUfm+Iy9A+H5+CgpFCVYoa/aEYDfAnxWf6sTOJYGbKDe4LI3kyB pjkdrj8VLmZgQkjqSni+Js5nl5ibV2th8nIkf6h2OU8xE6yb5Q278DOks GDSosr5fTPmzNh9IYdj3XHiqvZ1iHlZVsXaM1JQw6yflbsy6j6f8DrAC3 Q==; X-IronPort-AV: E=McAfee;i="6600,9927,11017"; a="5842914" X-IronPort-AV: E=Sophos;i="6.07,137,1708416000"; d="scan'208";a="5842914" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2024 06:06:10 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,137,1708416000"; d="scan'208";a="44883186" Received: from inlubt0316.iind.intel.com ([10.191.20.213]) by fmviesa001.fm.intel.com with ESMTP; 19 Mar 2024 06:06:02 -0700 From: lakshmi.sowjanya.d@intel.com To: tglx@linutronix.de, jstultz@google.com, giometti@enneenne.com, corbet@lwn.net, linux-kernel@vger.kernel.org Cc: x86@kernel.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, intel-wired-lan@lists.osuosl.org, andriy.shevchenko@linux.intel.com, eddie.dong@intel.com, christopher.s.hall@intel.com, jesse.brandeburg@intel.com, davem@davemloft.net, alexandre.torgue@foss.st.com, joabreu@synopsys.com, mcoquelin.stm32@gmail.com, perex@perex.cz, linux-sound@vger.kernel.org, anthony.l.nguyen@intel.com, peter.hilber@opensynergy.com, pandith.n@intel.com, mallikarjunappa.sangannavar@intel.com, subramanian.mohan@intel.com, basavaraj.goudar@intel.com, thejesh.reddy.t.r@intel.com, lakshmi.sowjanya.d@intel.com Subject: [PATCH v5 02/11] timekeeping: Add function to convert realtime to base clock Date: Tue, 19 Mar 2024 18:35:38 +0530 Message-Id: <20240319130547.4195-3-lakshmi.sowjanya.d@intel.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20240319130547.4195-1-lakshmi.sowjanya.d@intel.com> References: <20240319130547.4195-1-lakshmi.sowjanya.d@intel.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Lakshmi Sowjanya D PPS(Pulse Per Second) generates signals in realtime, but Timed IO hardware understands time in base clock reference. Add an interface, ktime_real_to_base_clock() to convert realtime to base clock. Convert the base clock to the system clock using convert_base_to_cs() in get_device_system_crosststamp(). Add the helper function timekeeping_clocksource_has_base(), to check whether the current clocksource has the same base clock. This will be used by Timed IO device to check if the base clock is X86_ART(Always Running Timer). Co-developed-by: Thomas Gleixner Signed-off-by: Thomas Gleixner Co-developed-by: Christopher S. Hall Signed-off-by: Christopher S. Hall Signed-off-by: Lakshmi Sowjanya D --- include/linux/timekeeping.h | 6 +++ kernel/time/timekeeping.c | 105 +++++++++++++++++++++++++++++++++++- 2 files changed, 109 insertions(+), 2 deletions(-) diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index 7e50cbd97f86..1b2a4a37bf93 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -275,12 +275,18 @@ struct system_device_crosststamp { * timekeeping code to verify comparability of two cycle values. * The default ID, CSID_GENERIC, does not identify a specific * clocksource. + * @nsecs: @cycles is in nanoseconds. */ struct system_counterval_t { u64 cycles; enum clocksource_ids cs_id; + bool nsecs; }; +extern bool ktime_real_to_base_clock(ktime_t treal, + enum clocksource_ids base_id, u64 *cycles); +extern bool timekeeping_clocksource_has_base(enum clocksource_ids id); + /* * Get cross timestamp between system clock and device clock */ diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index b58dffc58a8f..78836c7712dd 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1193,6 +1193,82 @@ static bool timestamp_in_interval(u64 start, u64 end, u64 ts) return false; } +static bool convert_clock(u64 *val, u32 numerator, u32 denominator) +{ + u64 rem, res; + + if (!numerator || !denominator) + return false; + + res = div64_u64_rem(*val, denominator, &rem) * numerator; + *val = res + div_u64(rem * numerator, denominator); + return true; +} + +static bool convert_base_to_cs(struct system_counterval_t *scv) +{ + struct clocksource *cs = tk_core.timekeeper.tkr_mono.clock; + struct clocksource_base *base = cs->base; + u32 num, den; + + /* The timestamp was taken from the time keeper clock source */ + if (cs->id == scv->cs_id) + return true; + + /* Check whether cs_id matches the base clock */ + if (!base || base->id != scv->cs_id) + return false; + + num = scv->nsecs ? cs->freq_khz : base->numerator; + den = scv->nsecs ? USEC_PER_SEC : base->denominator; + + convert_clock(&scv->cycles, num, den); + scv->cycles += base->offset; + return true; +} + +static bool convert_cs_to_base(u64 *cycles, enum clocksource_ids base_id) +{ + struct clocksource *cs = tk_core.timekeeper.tkr_mono.clock; + struct clocksource_base *base = cs->base; + + /* Check whether base_id matches the base clock */ + if (!base || base->id != base_id) + return false; + + *cycles -= base->offset; + if (!convert_clock(cycles, base->denominator, base->numerator)) + return false; + return true; +} + +static u64 convert_ns_to_cs(u64 delta) +{ + struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono; + + return div_u64((delta << tkr->shift) - tkr->xtime_nsec, tkr->mult); +} + +bool ktime_real_to_base_clock(ktime_t treal, enum clocksource_ids base_id, u64 *cycles) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + u64 delta; + + do { + seq = read_seqcount_begin(&tk_core.seq); + delta = (u64)treal - tk->tkr_mono.base_real; + if (delta > tk->tkr_mono.clock->max_idle_ns) + return false; + *cycles = tk->tkr_mono.cycle_last + convert_ns_to_cs(delta); + if (!convert_cs_to_base(cycles, base_id)) + return false; + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return true; +} +EXPORT_SYMBOL_GPL(ktime_real_to_base_clock); + /** * get_device_system_crosststamp - Synchronously capture system/device timestamp * @get_time_fn: Callback to get simultaneous device time and @@ -1238,8 +1314,7 @@ int get_device_system_crosststamp(int (*get_time_fn) * system counter value is the same as for the currently * installed timekeeper clocksource */ - if (system_counterval.cs_id == CSID_GENERIC || - tk->tkr_mono.clock->id != system_counterval.cs_id) + if (!convert_base_to_cs(&system_counterval)) return -ENODEV; cycles = system_counterval.cycles; @@ -1304,6 +1379,32 @@ int get_device_system_crosststamp(int (*get_time_fn) } EXPORT_SYMBOL_GPL(get_device_system_crosststamp); +/** + * timekeeping_clocksource_has_base - Check whether the current clocksource + * has a base clock + * @id: The clocksource ID to check for + * + * Note: The return value is a snapshot which can become invalid right + * after the function returns. + * + * Return: true if the timekeeper clocksource has a base clock with @id, + * false otherwise + */ +bool timekeeping_clocksource_has_base(enum clocksource_ids id) +{ + unsigned int seq; + bool ret; + + do { + seq = read_seqcount_begin(&tk_core.seq); + ret = tk_core.timekeeper.tkr_mono.clock->base ? + tk_core.timekeeper.tkr_mono.clock->base->id == id : false; + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ret; +} +EXPORT_SYMBOL_GPL(timekeeping_clocksource_has_base); + /** * do_settimeofday64 - Sets the time of day. * @ts: pointer to the timespec64 variable containing the new time