| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | #include <linux/nmi.h> |
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| 3 | #include <linux/cpufreq.h> |
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| 4 | #include <linux/perf/arm_pmu.h> |
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| 5 | |
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| 6 | /* |
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| 7 | * Safe maximum CPU frequency in case a particular platform doesn't implement |
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| 8 | * cpufreq driver. Although, architecture doesn't put any restrictions on |
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| 9 | * maximum frequency but 5 GHz seems to be safe maximum given the available |
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| 10 | * Arm CPUs in the market which are clocked much less than 5 GHz. On the other |
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| 11 | * hand, we can't make it much higher as it would lead to a large hard-lockup |
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| 12 | * detection timeout on parts which are running slower (eg. 1GHz on |
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| 13 | * Developerbox) and doesn't possess a cpufreq driver. |
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| 14 | */ |
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| 15 | #define SAFE_MAX_CPU_FREQ 5000000000UL // 5 GHz |
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| 16 | u64 hw_nmi_get_sample_period(int watchdog_thresh) |
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| 17 | { |
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| 18 | unsigned int cpu = smp_processor_id(); |
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| 19 | unsigned long max_cpu_freq; |
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| 20 | |
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| 21 | max_cpu_freq = cpufreq_get_hw_max_freq(cpu) * 1000UL; |
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| 22 | if (!max_cpu_freq) |
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| 23 | max_cpu_freq = SAFE_MAX_CPU_FREQ; |
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| 24 | |
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| 25 | return (u64)max_cpu_freq * watchdog_thresh; |
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| 26 | } |
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| 27 | |
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| 28 | bool __init arch_perf_nmi_is_available(void) |
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| 29 | { |
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| 30 | /* |
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| 31 | * hardlockup_detector_perf_init() will success even if Pseudo-NMI turns off, |
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| 32 | * however, the pmu interrupts will act like a normal interrupt instead of |
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| 33 | * NMI and the hardlockup detector would be broken. |
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| 34 | */ |
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| 35 | return arm_pmu_irq_is_nmi(); |
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| 36 | } |
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| 37 | |
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