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bh=Ime50F3RKb2m1VV+ZMtTLz8M9K+YfMpKUU6CJBgWeTE=; b=kzONTKUOi+Z17NPfYeq6Ad+PbLvIwjVnkHGn0EeWUnmaOi61sczXeW8x yIREfTbK86/U2Pw4xxkUAJ4E8fFdd9xAM/RqXYozWC0LVpKxU9XwT8ajs 4xJykyw3B5Y6s9ZwqNAkgmDF0T6ch9dWMAkcZf+sqqTaAIR65IJJjtPZH b/lJ5ULfOtVhQiZ4Wy5BhGiHCANegp6UchHL/yolCQq2Wb9F2rsV1LZiK GhJIgWYygLnQVYwFDcvdBSL0VOymx7KaAD4c2Gb1OexAIK6YyMKugPko/ Gm0F8zEbGTlhznUVpz4rW/SYRGpjQHurg9JFzjNZ20ENxBW3qwtvrs3rv A==; X-IronPort-AV: E=McAfee;i="6600,9927,10976"; a="436053956" X-IronPort-AV: E=Sophos;i="6.05,250,1701158400"; d="scan'208";a="436053956" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Feb 2024 22:09:15 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.05,250,1701158400"; d="scan'208";a="5849731" Received: from inlubt0316.iind.intel.com ([10.191.20.213]) by fmviesa004.fm.intel.com with ESMTP; 06 Feb 2024 22:09:09 -0800 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, thejesh.reddy.t.r@intel.com, lakshmi.sowjanya.d@intel.com Subject: [PATCH v4 02/11] timekeeping: Add function to convert realtime to base clock Date: Wed, 7 Feb 2024 11:38:45 +0530 Message-Id: <20240207060854.6524-3-lakshmi.sowjanya.d@intel.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20240207060854.6524-1-lakshmi.sowjanya.d@intel.com> References: <20240207060854.6524-1-lakshmi.sowjanya.d@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1790219355469405557 X-GMAIL-MSGID: 1790219355469405557 From: Lakshmi Sowjanya D Introduce 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. 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 | 112 +++++++++++++++++++++++++++++++++++- 2 files changed, 116 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 0ff065c5d25b..e68ecd77ee34 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1191,6 +1191,89 @@ static bool cycle_between(u64 before, u64 test, u64 after) return false; } +static bool convert_clock(u64 *val, u32 numerator, u32 denominator) +{ + u64 rem, res; + + if (numerator == 0 || denominator == 0) + 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; + + /* 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; + + /* Avoid conversion to a less precise clock */ + if (scv->nsecs && cs->freq_khz != 0 && base->freq_khz < cs->freq_khz) { + if (!convert_clock(&scv->cycles, cs->freq_khz, USEC_PER_SEC)) + return false; + } else { + if (scv->nsecs) { + if (!convert_clock(&scv->cycles, base->freq_khz, USEC_PER_SEC)) + return false; + } + if (!convert_clock(&scv->cycles, base->numerator, base->denominator)) + return false; + } + 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 @@ -1236,8 +1319,7 @@ 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 +1386,32 @@ 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