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| author | Marc Zyngier <marc.zyngier@arm.com> | 2017-01-27 12:52:31 +0000 |
|---|---|---|
| committer | Marc Zyngier <marc.zyngier@arm.com> | 2017-04-07 11:22:10 +0100 |
| commit | fa8d815fac96e7c9247783d5a1f8fa4685b3c543 (patch) | |
| tree | 2bf8488d8d20bdcbfba0f69cd30999e96d365c35 /drivers/clocksource | |
| parent | a86bd139f2ae02f960caeb0c1dd5f871d3e087cd (diff) | |
| download | linux-fa8d815fac96e7c9247783d5a1f8fa4685b3c543.tar.bz2 | |
arm64: arch_timer: Workaround for Cortex-A73 erratum 858921
Cortex-A73 (all versions) counter read can return a wrong value
when the counter crosses a 32bit boundary.
The workaround involves performing the read twice, and to return
one or the other depending on whether a transition has taken place.
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'drivers/clocksource')
| -rw-r--r-- | drivers/clocksource/Kconfig | 11 | ||||
| -rw-r--r-- | drivers/clocksource/arm_arch_timer.c | 19 |
2 files changed, 30 insertions, 0 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 3356ab821624..af80a7c44faf 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -366,6 +366,17 @@ config HISILICON_ERRATUM_161010101 161010101. The workaround will be active if the hisilicon,erratum-161010101 property is found in the timer node. +config ARM64_ERRATUM_858921 + bool "Workaround for Cortex-A73 erratum 858921" + default y + select ARM_ARCH_TIMER_OOL_WORKAROUND + depends on ARM_ARCH_TIMER && ARM64 + help + This option enables a workaround applicable to Cortex-A73 + (all versions), whose counter may return incorrect values. + The workaround will be dynamically enabled when an affected + core is detected. + config ARM_GLOBAL_TIMER bool "Support for the ARM global timer" if COMPILE_TEST select CLKSRC_OF if OF diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index f8adea258cf0..8459d19a84f5 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -266,6 +266,17 @@ static u64 notrace hisi_161010101_read_cntvct_el0(void) } #endif +#ifdef CONFIG_ARM64_ERRATUM_858921 +static u64 notrace arm64_858921_read_cntvct_el0(void) +{ + u64 old, new; + + old = read_sysreg(cntvct_el0); + new = read_sysreg(cntvct_el0); + return (((old ^ new) >> 32) & 1) ? old : new; +} +#endif + #ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND DEFINE_PER_CPU(const struct arch_timer_erratum_workaround *, timer_unstable_counter_workaround); @@ -331,6 +342,14 @@ static const struct arch_timer_erratum_workaround ool_workarounds[] = { .set_next_event_virt = erratum_set_next_event_tval_virt, }, #endif +#ifdef CONFIG_ARM64_ERRATUM_858921 + { + .match_type = ate_match_local_cap_id, + .id = (void *)ARM64_WORKAROUND_858921, + .desc = "ARM erratum 858921", + .read_cntvct_el0 = arm64_858921_read_cntvct_el0, + }, +#endif }; typedef bool (*ate_match_fn_t)(const struct arch_timer_erratum_workaround *, |