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