diff options
Diffstat (limited to 'arch/mips/kernel/time.c')
| -rw-r--r-- | arch/mips/kernel/time.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c new file mode 100644 index 000000000..ed339d797 --- /dev/null +++ b/arch/mips/kernel/time.c @@ -0,0 +1,167 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 2001 MontaVista Software Inc. + * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net + * Copyright (c) 2003, 2004 Maciej W. Rozycki + * + * Common time service routines for MIPS machines. + */ +#include <linux/bug.h> +#include <linux/clockchips.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/sched.h> +#include <linux/param.h> +#include <linux/time.h> +#include <linux/timex.h> +#include <linux/smp.h> +#include <linux/spinlock.h> +#include <linux/export.h> +#include <linux/cpufreq.h> +#include <linux/delay.h> + +#include <asm/cpu-features.h> +#include <asm/cpu-type.h> +#include <asm/div64.h> +#include <asm/time.h> + +#ifdef CONFIG_CPU_FREQ + +static DEFINE_PER_CPU(unsigned long, pcp_lpj_ref); +static DEFINE_PER_CPU(unsigned long, pcp_lpj_ref_freq); +static unsigned long glb_lpj_ref; +static unsigned long glb_lpj_ref_freq; + +static int cpufreq_callback(struct notifier_block *nb, + unsigned long val, void *data) +{ + struct cpufreq_freqs *freq = data; + struct cpumask *cpus = freq->policy->cpus; + unsigned long lpj; + int cpu; + + /* + * Skip lpj numbers adjustment if the CPU-freq transition is safe for + * the loops delay. (Is this possible?) + */ + if (freq->flags & CPUFREQ_CONST_LOOPS) + return NOTIFY_OK; + + /* Save the initial values of the lpjes for future scaling. */ + if (!glb_lpj_ref) { + glb_lpj_ref = boot_cpu_data.udelay_val; + glb_lpj_ref_freq = freq->old; + + for_each_online_cpu(cpu) { + per_cpu(pcp_lpj_ref, cpu) = + cpu_data[cpu].udelay_val; + per_cpu(pcp_lpj_ref_freq, cpu) = freq->old; + } + } + + /* + * Adjust global lpj variable and per-CPU udelay_val number in + * accordance with the new CPU frequency. + */ + if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || + (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) { + loops_per_jiffy = cpufreq_scale(glb_lpj_ref, + glb_lpj_ref_freq, + freq->new); + + for_each_cpu(cpu, cpus) { + lpj = cpufreq_scale(per_cpu(pcp_lpj_ref, cpu), + per_cpu(pcp_lpj_ref_freq, cpu), + freq->new); + cpu_data[cpu].udelay_val = (unsigned int)lpj; + } + } + + return NOTIFY_OK; +} + +static struct notifier_block cpufreq_notifier = { + .notifier_call = cpufreq_callback, +}; + +static int __init register_cpufreq_notifier(void) +{ + return cpufreq_register_notifier(&cpufreq_notifier, + CPUFREQ_TRANSITION_NOTIFIER); +} +core_initcall(register_cpufreq_notifier); + +#endif /* CONFIG_CPU_FREQ */ + +/* + * forward reference + */ +DEFINE_SPINLOCK(rtc_lock); +EXPORT_SYMBOL(rtc_lock); + +static int null_perf_irq(void) +{ + return 0; +} + +int (*perf_irq)(void) = null_perf_irq; + +EXPORT_SYMBOL(perf_irq); + +/* + * time_init() - it does the following things. + * + * 1) plat_time_init() - + * a) (optional) set up RTC routines, + * b) (optional) calibrate and set the mips_hpt_frequency + * (only needed if you intended to use cpu counter as timer interrupt + * source) + * 2) calculate a couple of cached variables for later usage + */ + +unsigned int mips_hpt_frequency; +EXPORT_SYMBOL_GPL(mips_hpt_frequency); + +static __init int cpu_has_mfc0_count_bug(void) +{ + switch (current_cpu_type()) { + case CPU_R4000PC: + case CPU_R4000SC: + case CPU_R4000MC: + /* + * V3.0 is documented as suffering from the mfc0 from count bug. + * Afaik this is the last version of the R4000. Later versions + * were marketed as R4400. + */ + return 1; + + case CPU_R4400PC: + case CPU_R4400SC: + case CPU_R4400MC: + /* + * The published errata for the R4400 up to 3.0 say the CPU + * has the mfc0 from count bug. This seems the last version + * produced. + */ + return 1; + } + + return 0; +} + +void __init time_init(void) +{ + plat_time_init(); + + /* + * The use of the R4k timer as a clock event takes precedence; + * if reading the Count register might interfere with the timer + * interrupt, then we don't use the timer as a clock source. + * We may still use the timer as a clock source though if the + * timer interrupt isn't reliable; the interference doesn't + * matter then, because we don't use the interrupt. + */ + if (mips_clockevent_init() != 0 || !cpu_has_mfc0_count_bug()) + init_mips_clocksource(); +} |