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From: lakshmi.sowjanya.d@intel.com
To: linus.walleij@linaro.org
Cc: linux-gpio@vger.kernel.org, bgolaszewski@baylibre.com,
	linux-kernel@vger.kernel.org, mgross@linux.intel.com,
	andriy.shevchenko@linux.intel.com, tamal.saha@intel.com,
	bala.senthil@intel.com, lakshmi.sowjanya.d@intel.com
Subject: [RFC PATCH v1 14/20] arch/x86: Add ART nanosecond to ART conversion
Date: Tue, 24 Aug 2021 22:17:55 +0530	[thread overview]
Message-ID: <20210824164801.28896-15-lakshmi.sowjanya.d@intel.com> (raw)
In-Reply-To: <20210824164801.28896-1-lakshmi.sowjanya.d@intel.com>

From: Christopher Hall <christopher.s.hall@intel.com>

The PWM 'apply' interface uses units of nominal nanoseconds for period and
the Intel(R) PMC Timed I/O hardware requires a period in terms of ART
cycles. Add a function using ART conversion coefficients determined at boot
time by the TSC initialization code to convert from ART in nominal
nanoseconds to ART cycles.

Signed-off-by: Christopher Hall <christopher.s.hall@intel.com>
Signed-off-by: Tamal Saha <tamal.saha@intel.com>
Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
Reviewed-by: Mark Gross <mgross@linux.intel.com>
---
 arch/x86/include/asm/tsc.h |  1 +
 arch/x86/kernel/tsc.c      | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index f1de7ede3ec9..e53507df92e1 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -34,6 +34,7 @@ extern u64 read_art_time(void);
 extern int convert_tsc_to_art(const struct system_counterval_t *tsc, u64 *art);
 extern struct system_counterval_t convert_art_to_tsc(u64 art);
 extern struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns);
+extern u64 convert_art_ns_to_art(u64 art_ns);
 
 extern void tsc_early_init(void);
 extern void tsc_init(void);
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 040109228100..381d15894dd2 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1329,6 +1329,38 @@ struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns)
 }
 EXPORT_SYMBOL(convert_art_ns_to_tsc);
 
+/*
+ * convert_art_ns_to_art() - Convert ART in nanoseconds to ART
+ * @art_ns: ART (Always Running Timer) in nominal nanoseconds
+ *
+ * Computes the ART cycles given the duration in nominal nanoseconds
+ *
+ * This is valid when CPU feature flag X86_FEATURE_TSC_KNOWN_FREQ is set
+ * indicating the tsc_khz is derived from CPUID[15H]. Drivers should check
+ * that this flag is set before conversion to ART is attempted.
+ *
+ * Return:
+ *	u64 ART value rounded to nearest cycle corresponding to nanosecond
+ *	duration input
+ */
+u64 convert_art_ns_to_art(u64 art_ns)
+{
+	u64 tmp, res, rem;
+	u32 crystal_khz;
+
+	crystal_khz = (tsc_khz * art_to_tsc_denominator) /
+		art_to_tsc_numerator;
+
+	rem = do_div(art_ns, USEC_PER_SEC);
+	res = art_ns * crystal_khz;
+	tmp = rem * crystal_khz;
+
+	rem = do_div(tmp, USEC_PER_SEC);
+	res += rem < USEC_PER_SEC / 2 ? tmp : tmp + 1;
+
+	return res;
+}
+EXPORT_SYMBOL(convert_art_ns_to_art);
 
 static void tsc_refine_calibration_work(struct work_struct *work);
 static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
-- 
2.17.1


  parent reply	other threads:[~2021-08-24 16:49 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-24 16:47 [RFC PATCH v1 00/20] Review Request: Add support for Intel PMC lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 01/20] gpio: Add basic GPIO driver for Intel PMC Timed I/O device lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 02/20] gpio: Add GPIO polling interface to GPIO lib lakshmi.sowjanya.d
2021-09-22 10:03   ` Bartosz Golaszewski
2021-10-07  2:14     ` Kent Gibson
2021-08-24 16:47 ` [RFC PATCH v1 03/20] arch: x86: Add ART support function to tsc code lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 04/20] gpio: Add input code to Intel PMC Timed I/O Driver lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 05/20] tools: gpio: Add additional polling support to gpio-event-mon lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 06/20] gpio: Add set_input and polling interface to GPIO lib code lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 07/20] gpio: Add output event generation method to GPIOLIB and PMC Driver lakshmi.sowjanya.d
2021-09-16 21:42   ` Linus Walleij
2021-09-17  7:27     ` Uwe Kleine-König
2021-09-19 19:38       ` Linus Walleij
2021-09-19 21:21         ` Clemens Gruber
2021-09-20  7:14           ` Uwe Kleine-König
2021-08-24 16:47 ` [RFC PATCH v1 08/20] kernel: time: Add system time to system counter translation lakshmi.sowjanya.d
2021-09-16 21:48   ` Linus Walleij
2021-08-24 16:47 ` [RFC PATCH v1 09/20] arch: x86: Add TSC to ART translation lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 10/20] tools: gpio: Add GPIO output generation user application lakshmi.sowjanya.d
2021-09-16 21:52   ` Linus Walleij
2021-08-24 16:47 ` [RFC PATCH v1 11/20] gpio: Add event count interface to gpiolib lakshmi.sowjanya.d
2021-09-22  9:53   ` Bartosz Golaszewski
2021-08-24 16:47 ` [RFC PATCH v1 12/20] gpio: Add event count to Intel(R) PMC Timed I/O driver lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 13/20] tools: gpio: Add event count capability to event monitor application lakshmi.sowjanya.d
2021-09-16 21:57   ` Linus Walleij
2021-08-24 16:47 ` lakshmi.sowjanya.d [this message]
2021-08-24 16:47 ` [RFC PATCH v1 15/20] pwm: Add capability for PWM Driver managed state lakshmi.sowjanya.d
2021-09-16 22:00   ` Linus Walleij
2021-08-24 16:47 ` [RFC PATCH v1 16/20] gpio: Add PWM capabilities to Intel(R) PMC TIO driver lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 17/20] pwm: Add second alignment to the core PWM interface lakshmi.sowjanya.d
2021-08-24 16:47 ` [RFC PATCH v1 18/20] gpio: Add PWM alignment support to the Intel(R) PMC Timed I/O driver lakshmi.sowjanya.d
2021-08-24 16:48 ` [RFC PATCH v1 19/20] gpio: Add GPIO monitor line to Intel(R) Timed I/O Driver lakshmi.sowjanya.d
2021-08-24 16:48 ` [RFC PATCH v1 20/20] tools: gpio: Add PWM monitor application lakshmi.sowjanya.d
2021-09-16 21:21 ` [RFC PATCH v1 00/20] Review Request: Add support for Intel PMC Linus Walleij
2021-10-11 21:14   ` Dipen Patel

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