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Message-Id: <20240103115602.19044-2-lakshmi.sowjanya.d@intel.com>
Date: Wed, 3 Jan 2024 17:25:52 +0530
From: lakshmi.sowjanya.d@...el.com
To: tglx@...utronix.de,
jstultz@...gle.com,
giometti@...eenne.com,
corbet@....net,
linux-kernel@...r.kernel.org
Cc: x86@...nel.org,
netdev@...r.kernel.org,
linux-doc@...r.kernel.org,
intel-wired-lan@...ts.osuosl.org,
andriy.shevchenko@...ux.intel.com,
eddie.dong@...el.com,
christopher.s.hall@...el.com,
jesse.brandeburg@...el.com,
davem@...emloft.net,
alexandre.torgue@...s.st.com,
joabreu@...opsys.com,
mcoquelin.stm32@...il.com,
perex@...ex.cz,
linux-sound@...r.kernel.org,
anthony.l.nguyen@...el.com,
pandith.n@...el.com,
mallikarjunappa.sangannavar@...el.com,
thejesh.reddy.t.r@...el.com,
lakshmi.sowjanya.d@...el.com
Subject: [RFC PATCH v3 01/11] x86/tsc: Add base clock properties in clocksource structure
From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@...el.com>
Add hardware abstraction, struct clocksource_base in clocksource.
Add clocksource ID for x86 ART(Always Running Timer).
Co-developed-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Co-developed-by: Christopher S. Hall <christopher.s.hall@...el.com>
Signed-off-by: Christopher S. Hall <christopher.s.hall@...el.com>
Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@...el.com>
---
arch/x86/kernel/tsc.c | 43 ++++++++++++++++++---------------
include/linux/clocksource.h | 27 +++++++++++++++++++++
include/linux/clocksource_ids.h | 1 +
3 files changed, 52 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 868f09966b0f..035ae5bec2e8 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -51,9 +51,9 @@ int tsc_clocksource_reliable;
static int __read_mostly tsc_force_recalibrate;
-static u32 art_to_tsc_numerator;
-static u32 art_to_tsc_denominator;
-static u64 art_to_tsc_offset;
+static struct clocksource_base art_base_clk = {
+ .id = CSID_X86_ART,
+};
static bool have_art;
struct cyc2ns {
@@ -1075,7 +1075,7 @@ core_initcall(cpufreq_register_tsc_scaling);
*/
static void __init detect_art(void)
{
- unsigned int unused[2];
+ unsigned int unused;
if (boot_cpu_data.cpuid_level < ART_CPUID_LEAF)
return;
@@ -1090,13 +1090,14 @@ static void __init detect_art(void)
tsc_async_resets)
return;
- cpuid(ART_CPUID_LEAF, &art_to_tsc_denominator,
- &art_to_tsc_numerator, unused, unused+1);
+ cpuid(ART_CPUID_LEAF, &art_base_clk.denominator,
+ &art_base_clk.numerator, &art_base_clk.freq_khz, &unused);
- if (art_to_tsc_denominator < ART_MIN_DENOMINATOR)
+ art_base_clk.freq_khz /= KHZ;
+ if (art_base_clk.denominator < ART_MIN_DENOMINATOR)
return;
- rdmsrl(MSR_IA32_TSC_ADJUST, art_to_tsc_offset);
+ rdmsrl(MSR_IA32_TSC_ADJUST, art_base_clk.offset);
/* Make this sticky over multiple CPU init calls */
setup_force_cpu_cap(X86_FEATURE_ART);
@@ -1304,13 +1305,13 @@ struct system_counterval_t convert_art_to_tsc(u64 art)
{
u64 tmp, res, rem;
- rem = do_div(art, art_to_tsc_denominator);
+ rem = do_div(art, art_base_clk.denominator);
- res = art * art_to_tsc_numerator;
- tmp = rem * art_to_tsc_numerator;
+ res = art * art_base_clk.numerator;
+ tmp = rem * art_base_clk.numerator;
- do_div(tmp, art_to_tsc_denominator);
- res += tmp + art_to_tsc_offset;
+ do_div(tmp, art_base_clk.denominator);
+ res += tmp + art_base_clk.offset;
return (struct system_counterval_t) {
.cs_id = have_art ? CSID_X86_TSC : CSID_GENERIC,
@@ -1351,7 +1352,6 @@ struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns)
do_div(tmp, USEC_PER_SEC);
res += tmp;
-
return (struct system_counterval_t) {
.cs_id = have_art ? CSID_X86_TSC : CSID_GENERIC,
.cycles = res
@@ -1359,7 +1359,6 @@ struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns)
}
EXPORT_SYMBOL(convert_art_ns_to_tsc);
-
static void tsc_refine_calibration_work(struct work_struct *work);
static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
/**
@@ -1461,8 +1460,10 @@ static void tsc_refine_calibration_work(struct work_struct *work)
if (tsc_unstable)
goto unreg;
- if (boot_cpu_has(X86_FEATURE_ART))
+ if (boot_cpu_has(X86_FEATURE_ART)) {
have_art = true;
+ clocksource_tsc.base = &art_base_clk;
+ }
clocksource_register_khz(&clocksource_tsc, tsc_khz);
unreg:
clocksource_unregister(&clocksource_tsc_early);
@@ -1487,8 +1488,10 @@ static int __init init_tsc_clocksource(void)
* the refined calibration and directly register it as a clocksource.
*/
if (boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) {
- if (boot_cpu_has(X86_FEATURE_ART))
+ if (boot_cpu_has(X86_FEATURE_ART)) {
have_art = true;
+ clocksource_tsc.base = &art_base_clk;
+ }
clocksource_register_khz(&clocksource_tsc, tsc_khz);
clocksource_unregister(&clocksource_tsc_early);
@@ -1512,10 +1515,12 @@ static bool __init determine_cpu_tsc_frequencies(bool early)
if (early) {
cpu_khz = x86_platform.calibrate_cpu();
- if (tsc_early_khz)
+ if (tsc_early_khz) {
tsc_khz = tsc_early_khz;
- else
+ } else {
tsc_khz = x86_platform.calibrate_tsc();
+ clocksource_tsc.freq_khz = tsc_khz;
+ }
} else {
/* We should not be here with non-native cpu calibration */
WARN_ON(x86_platform.calibrate_cpu != native_calibrate_cpu);
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 1d42d4b17327..0a1110a0e660 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -21,6 +21,7 @@
#include <asm/div64.h>
#include <asm/io.h>
+struct clocksource_base;
struct clocksource;
struct module;
@@ -48,6 +49,7 @@ struct module;
* @archdata: Optional arch-specific data
* @max_cycles: Maximum safe cycle value which won't overflow on
* multiplication
+ * @freq_khz: Clocksource frequency in khz.
* @name: Pointer to clocksource name
* @list: List head for registration (internal)
* @rating: Rating value for selection (higher is better)
@@ -70,6 +72,8 @@ struct module;
* validate the clocksource from which the snapshot was
* taken.
* @flags: Flags describing special properties
+ * @base: Hardware abstraction for clock on which a clocksource
+ * is based
* @enable: Optional function to enable the clocksource
* @disable: Optional function to disable the clocksource
* @suspend: Optional suspend function for the clocksource
@@ -105,12 +109,14 @@ struct clocksource {
struct arch_clocksource_data archdata;
#endif
u64 max_cycles;
+ u32 freq_khz;
const char *name;
struct list_head list;
int rating;
enum clocksource_ids id;
enum vdso_clock_mode vdso_clock_mode;
unsigned long flags;
+ struct clocksource_base *base;
int (*enable)(struct clocksource *cs);
void (*disable)(struct clocksource *cs);
@@ -294,4 +300,25 @@ static inline void timer_probe(void) {}
extern ulong max_cswd_read_retries;
void clocksource_verify_percpu(struct clocksource *cs);
+/**
+ * struct clocksource_base - hardware abstraction for clock on which a clocksource
+ * is based
+ * @id: Defaults to CSID_GENERIC. The id value is used for conversion
+ * functions which require that the current clocksource is based
+ * on a clocksource_base with a particular ID in certain snapshot
+ * functions to allow callers to validate the clocksource from
+ * which the snapshot was taken.
+ * @freq_khz: Nominal frequency of the base clock in kHz
+ * @offset: Offset between the base clock and the clocksource
+ * @numerator: Numerator of the clock ratio between base clock and the clocksource
+ * @denominator: Denominator of the clock ratio between base clock and the clocksource
+ */
+struct clocksource_base {
+ enum clocksource_ids id;
+ u32 freq_khz;
+ u64 offset;
+ u32 numerator;
+ u32 denominator;
+};
+
#endif /* _LINUX_CLOCKSOURCE_H */
diff --git a/include/linux/clocksource_ids.h b/include/linux/clocksource_ids.h
index a4fa3436940c..2bb4d8c2f1b0 100644
--- a/include/linux/clocksource_ids.h
+++ b/include/linux/clocksource_ids.h
@@ -9,6 +9,7 @@ enum clocksource_ids {
CSID_X86_TSC_EARLY,
CSID_X86_TSC,
CSID_X86_KVM_CLK,
+ CSID_X86_ART,
CSID_MAX,
};
--
2.35.3
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