| /* |
| * linux/arch/ia64/kernel/time.c |
| * |
| * Copyright (C) 1998-2003 Hewlett-Packard Co |
| * Stephane Eranian <eranian@hpl.hp.com> |
| * David Mosberger <davidm@hpl.hp.com> |
| * Copyright (C) 1999 Don Dugger <don.dugger@intel.com> |
| * Copyright (C) 1999-2000 VA Linux Systems |
| * Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com> |
| */ |
| #include <linux/config.h> |
| |
| #include <linux/cpu.h> |
| #include <linux/init.h> |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/profile.h> |
| #include <linux/sched.h> |
| #include <linux/time.h> |
| #include <linux/interrupt.h> |
| #include <linux/efi.h> |
| #include <linux/profile.h> |
| #include <linux/timex.h> |
| |
| #include <asm/machvec.h> |
| #include <asm/delay.h> |
| #include <asm/hw_irq.h> |
| #include <asm/ptrace.h> |
| #include <asm/sal.h> |
| #include <asm/sections.h> |
| #include <asm/system.h> |
| |
| extern unsigned long wall_jiffies; |
| |
| u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES; |
| |
| EXPORT_SYMBOL(jiffies_64); |
| |
| #define TIME_KEEPER_ID 0 /* smp_processor_id() of time-keeper */ |
| |
| #ifdef CONFIG_IA64_DEBUG_IRQ |
| |
| unsigned long last_cli_ip; |
| EXPORT_SYMBOL(last_cli_ip); |
| |
| #endif |
| |
| static struct time_interpolator itc_interpolator = { |
| .shift = 16, |
| .mask = 0xffffffffffffffffLL, |
| .source = TIME_SOURCE_CPU |
| }; |
| |
| static irqreturn_t |
| timer_interrupt (int irq, void *dev_id, struct pt_regs *regs) |
| { |
| unsigned long new_itm; |
| |
| if (unlikely(cpu_is_offline(smp_processor_id()))) { |
| return IRQ_HANDLED; |
| } |
| |
| platform_timer_interrupt(irq, dev_id, regs); |
| |
| new_itm = local_cpu_data->itm_next; |
| |
| if (!time_after(ia64_get_itc(), new_itm)) |
| printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n", |
| ia64_get_itc(), new_itm); |
| |
| profile_tick(CPU_PROFILING, regs); |
| |
| while (1) { |
| update_process_times(user_mode(regs)); |
| |
| new_itm += local_cpu_data->itm_delta; |
| |
| if (smp_processor_id() == TIME_KEEPER_ID) { |
| /* |
| * Here we are in the timer irq handler. We have irqs locally |
| * disabled, but we don't know if the timer_bh is running on |
| * another CPU. We need to avoid to SMP race by acquiring the |
| * xtime_lock. |
| */ |
| write_seqlock(&xtime_lock); |
| do_timer(regs); |
| local_cpu_data->itm_next = new_itm; |
| write_sequnlock(&xtime_lock); |
| } else |
| local_cpu_data->itm_next = new_itm; |
| |
| if (time_after(new_itm, ia64_get_itc())) |
| break; |
| } |
| |
| do { |
| /* |
| * If we're too close to the next clock tick for |
| * comfort, we increase the safety margin by |
| * intentionally dropping the next tick(s). We do NOT |
| * update itm.next because that would force us to call |
| * do_timer() which in turn would let our clock run |
| * too fast (with the potentially devastating effect |
| * of losing monotony of time). |
| */ |
| while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2)) |
| new_itm += local_cpu_data->itm_delta; |
| ia64_set_itm(new_itm); |
| /* double check, in case we got hit by a (slow) PMI: */ |
| } while (time_after_eq(ia64_get_itc(), new_itm)); |
| return IRQ_HANDLED; |
| } |
| |
| /* |
| * Encapsulate access to the itm structure for SMP. |
| */ |
| void |
| ia64_cpu_local_tick (void) |
| { |
| int cpu = smp_processor_id(); |
| unsigned long shift = 0, delta; |
| |
| /* arrange for the cycle counter to generate a timer interrupt: */ |
| ia64_set_itv(IA64_TIMER_VECTOR); |
| |
| delta = local_cpu_data->itm_delta; |
| /* |
| * Stagger the timer tick for each CPU so they don't occur all at (almost) the |
| * same time: |
| */ |
| if (cpu) { |
| unsigned long hi = 1UL << ia64_fls(cpu); |
| shift = (2*(cpu - hi) + 1) * delta/hi/2; |
| } |
| local_cpu_data->itm_next = ia64_get_itc() + delta + shift; |
| ia64_set_itm(local_cpu_data->itm_next); |
| } |
| |
| static int nojitter; |
| |
| static int __init nojitter_setup(char *str) |
| { |
| nojitter = 1; |
| printk("Jitter checking for ITC timers disabled\n"); |
| return 1; |
| } |
| |
| __setup("nojitter", nojitter_setup); |
| |
| |
| void __devinit |
| ia64_init_itm (void) |
| { |
| unsigned long platform_base_freq, itc_freq; |
| struct pal_freq_ratio itc_ratio, proc_ratio; |
| long status, platform_base_drift, itc_drift; |
| |
| /* |
| * According to SAL v2.6, we need to use a SAL call to determine the platform base |
| * frequency and then a PAL call to determine the frequency ratio between the ITC |
| * and the base frequency. |
| */ |
| status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM, |
| &platform_base_freq, &platform_base_drift); |
| if (status != 0) { |
| printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status)); |
| } else { |
| status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio); |
| if (status != 0) |
| printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status); |
| } |
| if (status != 0) { |
| /* invent "random" values */ |
| printk(KERN_ERR |
| "SAL/PAL failed to obtain frequency info---inventing reasonable values\n"); |
| platform_base_freq = 100000000; |
| platform_base_drift = -1; /* no drift info */ |
| itc_ratio.num = 3; |
| itc_ratio.den = 1; |
| } |
| if (platform_base_freq < 40000000) { |
| printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n", |
| platform_base_freq); |
| platform_base_freq = 75000000; |
| platform_base_drift = -1; |
| } |
| if (!proc_ratio.den) |
| proc_ratio.den = 1; /* avoid division by zero */ |
| if (!itc_ratio.den) |
| itc_ratio.den = 1; /* avoid division by zero */ |
| |
| itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den; |
| |
| local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ; |
| printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%lu/%lu, " |
| "ITC freq=%lu.%03luMHz", smp_processor_id(), |
| platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000, |
| itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000); |
| |
| if (platform_base_drift != -1) { |
| itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den; |
| printk("+/-%ldppm\n", itc_drift); |
| } else { |
| itc_drift = -1; |
| printk("\n"); |
| } |
| |
| local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den; |
| local_cpu_data->itc_freq = itc_freq; |
| local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC; |
| local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT) |
| + itc_freq/2)/itc_freq; |
| |
| if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) { |
| itc_interpolator.frequency = local_cpu_data->itc_freq; |
| itc_interpolator.drift = itc_drift; |
| #ifdef CONFIG_SMP |
| /* On IA64 in an SMP configuration ITCs are never accurately synchronized. |
| * Jitter compensation requires a cmpxchg which may limit |
| * the scalability of the syscalls for retrieving time. |
| * The ITC synchronization is usually successful to within a few |
| * ITC ticks but this is not a sure thing. If you need to improve |
| * timer performance in SMP situations then boot the kernel with the |
| * "nojitter" option. However, doing so may result in time fluctuating (maybe |
| * even going backward) if the ITC offsets between the individual CPUs |
| * are too large. |
| */ |
| if (!nojitter) itc_interpolator.jitter = 1; |
| #endif |
| register_time_interpolator(&itc_interpolator); |
| } |
| |
| /* Setup the CPU local timer tick */ |
| ia64_cpu_local_tick(); |
| } |
| |
| static struct irqaction timer_irqaction = { |
| .handler = timer_interrupt, |
| .flags = SA_INTERRUPT, |
| .name = "timer" |
| }; |
| |
| void __init |
| time_init (void) |
| { |
| register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction); |
| efi_gettimeofday(&xtime); |
| ia64_init_itm(); |
| |
| /* |
| * Initialize wall_to_monotonic such that adding it to xtime will yield zero, the |
| * tv_nsec field must be normalized (i.e., 0 <= nsec < NSEC_PER_SEC). |
| */ |
| set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec); |
| } |