OSCL-LXR linux-6.0.1/​arch/​powerpc/​kernel/​time.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Common time routines among all ppc machines.
  *
  * Written by Cort Dougan (cort@cs.nmt.edu) to merge
  * Paul Mackerras' version and mine for PReP and Pmac.
  * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
  * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
  *
  * First round of bugfixes by Gabriel Paubert (paubert@iram.es)
  * to make clock more stable (2.4.0-test5). The only thing
  * that this code assumes is that the timebases have been synchronized
  * by firmware on SMP and are never stopped (never do sleep
  * on SMP then, nap and doze are OK).
  * 
  * Speeded up do_gettimeofday by getting rid of references to
  * xtime (which required locks for consistency). (mikejc@us.ibm.com)
  *
  * TODO (not necessarily in this file):
  * - improve precision and reproducibility of timebase frequency
  * measurement at boot time.
  * - for astronomical applications: add a new function to get
  * non ambiguous timestamps even around leap seconds. This needs
  * a new timestamp format and a good name.
  *
  * 1997-09-10  Updated NTP code according to technical memorandum Jan '96
  *             "A Kernel Model for Precision Timekeeping" by Dave Mills
  */
 
 #include <linux/errno.h>
 #include <linux/export.h>
 #include <linux/sched.h>
 #include <linux/sched/clock.h>
 #include <linux/sched/cputime.h>
 #include <linux/kernel.h>
 #include <linux/param.h>
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/timex.h>
 #include <linux/kernel_stat.h>
 #include <linux/time.h>
 #include <linux/init.h>
 #include <linux/profile.h>
 #include <linux/cpu.h>
 #include <linux/security.h>
 #include <linux/percpu.h>
 #include <linux/rtc.h>
 #include <linux/jiffies.h>
 #include <linux/posix-timers.h>
 #include <linux/irq.h>
 #include <linux/delay.h>
 #include <linux/irq_work.h>
 #include <linux/of_clk.h>
 #include <linux/suspend.h>
 #include <linux/processor.h>
 #include <linux/mc146818rtc.h>
 #include <linux/platform_device.h>
 
 #include <asm/trace.h>
 #include <asm/interrupt.h>
 #include <asm/io.h>
 #include <asm/nvram.h>
 #include <asm/cache.h>
 #include <asm/machdep.h>
 #include <linux/uaccess.h>
 #include <asm/time.h>
 #include <asm/irq.h>
 #include <asm/div64.h>
 #include <asm/smp.h>
 #include <asm/vdso_datapage.h>
 #include <asm/firmware.h>
 #include <asm/mce.h>
 
 /* powerpc clocksource/clockevent code */
 
 #include <linux/clockchips.h>
 #include <linux/timekeeper_internal.h>
 
 static u64 timebase_read(struct clocksource *);
 static struct clocksource clocksource_timebase = {
     .name         = "timebase",
     .rating       = 400,
     .flags        = CLOCK_SOURCE_IS_CONTINUOUS,
     .mask         = CLOCKSOURCE_MASK(64),
     .read         = timebase_read,
     .vdso_clock_mode    = VDSO_CLOCKMODE_ARCHTIMER,
 };
 
 #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF
 u64 decrementer_max = DECREMENTER_DEFAULT_MAX;
 EXPORT_SYMBOL_GPL(decrementer_max); /* for KVM HDEC */
 
 static int decrementer_set_next_event(unsigned long evt,
                       struct clock_event_device *dev);
 static int decrementer_shutdown(struct clock_event_device *evt);
 
 struct clock_event_device decrementer_clockevent = {
     .name           = "decrementer",
     .rating         = 200,
     .irq            = 0,
     .set_next_event     = decrementer_set_next_event,
     .set_state_oneshot_stopped = decrementer_shutdown,
     .set_state_shutdown = decrementer_shutdown,
     .tick_resume        = decrementer_shutdown,
     .features       = CLOCK_EVT_FEAT_ONESHOT |
                   CLOCK_EVT_FEAT_C3STOP,
 };
 EXPORT_SYMBOL(decrementer_clockevent);
 
 /*
  * This always puts next_tb beyond now, so the clock event will never fire
  * with the usual comparison, no need for a separate test for stopped.
  */
 #define DEC_CLOCKEVENT_STOPPED ~0ULL
 DEFINE_PER_CPU(u64, decrementers_next_tb) = DEC_CLOCKEVENT_STOPPED;
 EXPORT_SYMBOL_GPL(decrementers_next_tb);
 static DEFINE_PER_CPU(struct clock_event_device, decrementers);
 
 #define XSEC_PER_SEC (1024*1024)
 
 #ifdef CONFIG_PPC64
 #define SCALE_XSEC(xsec, max)   (((xsec) * max) / XSEC_PER_SEC)
 #else
 /* compute ((xsec << 12) * max) >> 32 */
 #define SCALE_XSEC(xsec, max)   mulhwu((xsec) << 12, max)
 #endif
 
 unsigned long tb_ticks_per_jiffy;
 unsigned long tb_ticks_per_usec = 100; /* sane default */
 EXPORT_SYMBOL(tb_ticks_per_usec);
 unsigned long tb_ticks_per_sec;
 EXPORT_SYMBOL(tb_ticks_per_sec);    /* for cputime_t conversions */
 
 DEFINE_SPINLOCK(rtc_lock);
 EXPORT_SYMBOL_GPL(rtc_lock);
 
 static u64 tb_to_ns_scale __read_mostly;
 static unsigned tb_to_ns_shift __read_mostly;
 static u64 boot_tb __read_mostly;
 
 extern struct timezone sys_tz;
 static long timezone_offset;
 
 unsigned long ppc_proc_freq;
 EXPORT_SYMBOL_GPL(ppc_proc_freq);
 unsigned long ppc_tb_freq;
 EXPORT_SYMBOL_GPL(ppc_tb_freq);
 
 bool tb_invalid;
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 /*
  * Factor for converting from cputime_t (timebase ticks) to
  * microseconds. This is stored as 0.64 fixed-point binary fraction.
  */
 u64 __cputime_usec_factor;
 EXPORT_SYMBOL(__cputime_usec_factor);
 
 static void calc_cputime_factors(void)
 {
     struct div_result res;
 
     div128_by_32(1000000, 0, tb_ticks_per_sec, &res);
     __cputime_usec_factor = res.result_low;
 }
 
 /*
  * Read the SPURR on systems that have it, otherwise the PURR,
  * or if that doesn't exist return the timebase value passed in.
  */
 static inline unsigned long read_spurr(unsigned long tb)
 {
     if (cpu_has_feature(CPU_FTR_SPURR))
         return mfspr(SPRN_SPURR);
     if (cpu_has_feature(CPU_FTR_PURR))
         return mfspr(SPRN_PURR);
     return tb;
 }
 
 #ifdef CONFIG_PPC_SPLPAR
 
 #include <asm/dtl.h>
 
 void (*dtl_consumer)(struct dtl_entry *, u64);
 
 /*
  * Scan the dispatch trace log and count up the stolen time.
  * Should be called with interrupts disabled.
  */
 static u64 scan_dispatch_log(u64 stop_tb)
 {
     u64 i = local_paca->dtl_ridx;
     struct dtl_entry *dtl = local_paca->dtl_curr;
     struct dtl_entry *dtl_end = local_paca->dispatch_log_end;
     struct lppaca *vpa = local_paca->lppaca_ptr;
     u64 tb_delta;
     u64 stolen = 0;
     u64 dtb;
 
     if (!dtl)
         return 0;
 
     if (i == be64_to_cpu(vpa->dtl_idx))
         return 0;
     while (i < be64_to_cpu(vpa->dtl_idx)) {
         dtb = be64_to_cpu(dtl->timebase);
         tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) +
             be32_to_cpu(dtl->ready_to_enqueue_time);
         barrier();
         if (i + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) {
             /* buffer has overflowed */
             i = be64_to_cpu(vpa->dtl_idx) - N_DISPATCH_LOG;
             dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG);
             continue;
         }
         if (dtb > stop_tb)
             break;
         if (dtl_consumer)
             dtl_consumer(dtl, i);
         stolen += tb_delta;
         ++i;
         ++dtl;
         if (dtl == dtl_end)
             dtl = local_paca->dispatch_log;
     }
     local_paca->dtl_ridx = i;
     local_paca->dtl_curr = dtl;
     return stolen;
 }
 
 /*
  * Accumulate stolen time by scanning the dispatch trace log.
  * Called on entry from user mode.
  */
 void notrace accumulate_stolen_time(void)
 {
     u64 sst, ust;
     struct cpu_accounting_data *acct = &local_paca->accounting;
 
     sst = scan_dispatch_log(acct->starttime_user);
     ust = scan_dispatch_log(acct->starttime);
     acct->stime -= sst;
     acct->utime -= ust;
     acct->steal_time += ust + sst;
 }
 
 static inline u64 calculate_stolen_time(u64 stop_tb)
 {
     if (!firmware_has_feature(FW_FEATURE_SPLPAR))
         return 0;
 
     if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx))
         return scan_dispatch_log(stop_tb);
 
     return 0;
 }
 
 #else /* CONFIG_PPC_SPLPAR */
 static inline u64 calculate_stolen_time(u64 stop_tb)
 {
     return 0;
 }
 
 #endif /* CONFIG_PPC_SPLPAR */
 
 /*
  * Account time for a transition between system, hard irq
  * or soft irq state.
  */
 static unsigned long vtime_delta_scaled(struct cpu_accounting_data *acct,
                     unsigned long now, unsigned long stime)
 {
     unsigned long stime_scaled = 0;
 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
     unsigned long nowscaled, deltascaled;
     unsigned long utime, utime_scaled;
 
     nowscaled = read_spurr(now);
     deltascaled = nowscaled - acct->startspurr;
     acct->startspurr = nowscaled;
     utime = acct->utime - acct->utime_sspurr;
     acct->utime_sspurr = acct->utime;
 
     /*
      * Because we don't read the SPURR on every kernel entry/exit,
      * deltascaled includes both user and system SPURR ticks.
      * Apportion these ticks to system SPURR ticks and user
      * SPURR ticks in the same ratio as the system time (delta)
      * and user time (udelta) values obtained from the timebase
      * over the same interval.  The system ticks get accounted here;
      * the user ticks get saved up in paca->user_time_scaled to be
      * used by account_process_tick.
      */
     stime_scaled = stime;
     utime_scaled = utime;
     if (deltascaled != stime + utime) {
         if (utime) {
             stime_scaled = deltascaled * stime / (stime + utime);
             utime_scaled = deltascaled - stime_scaled;
         } else {
             stime_scaled = deltascaled;
         }
     }
     acct->utime_scaled += utime_scaled;
 #endif
 
     return stime_scaled;
 }
 
 static unsigned long vtime_delta(struct cpu_accounting_data *acct,
                  unsigned long *stime_scaled,
                  unsigned long *steal_time)
 {
     unsigned long now, stime;
 
     WARN_ON_ONCE(!irqs_disabled());
 
     now = mftb();
     stime = now - acct->starttime;
     acct->starttime = now;
 
     *stime_scaled = vtime_delta_scaled(acct, now, stime);
 
     *steal_time = calculate_stolen_time(now);
 
     return stime;
 }
 
 static void vtime_delta_kernel(struct cpu_accounting_data *acct,
                    unsigned long *stime, unsigned long *stime_scaled)
 {
     unsigned long steal_time;
 
     *stime = vtime_delta(acct, stime_scaled, &steal_time);
     *stime -= min(*stime, steal_time);
     acct->steal_time += steal_time;
 }
 
 void vtime_account_kernel(struct task_struct *tsk)
 {
     struct cpu_accounting_data *acct = get_accounting(tsk);
     unsigned long stime, stime_scaled;
 
     vtime_delta_kernel(acct, &stime, &stime_scaled);
 
     if (tsk->flags & PF_VCPU) {
         acct->gtime += stime;
 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
         acct->utime_scaled += stime_scaled;
 #endif
     } else {
         acct->stime += stime;
 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
         acct->stime_scaled += stime_scaled;
 #endif
     }
 }
 EXPORT_SYMBOL_GPL(vtime_account_kernel);
 
 void vtime_account_idle(struct task_struct *tsk)
 {
     unsigned long stime, stime_scaled, steal_time;
     struct cpu_accounting_data *acct = get_accounting(tsk);
 
     stime = vtime_delta(acct, &stime_scaled, &steal_time);
     acct->idle_time += stime + steal_time;
 }
 
 static void vtime_account_irq_field(struct cpu_accounting_data *acct,
                     unsigned long *field)
 {
     unsigned long stime, stime_scaled;
 
     vtime_delta_kernel(acct, &stime, &stime_scaled);
     *field += stime;
 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
     acct->stime_scaled += stime_scaled;
 #endif
 }
 
 void vtime_account_softirq(struct task_struct *tsk)
 {
     struct cpu_accounting_data *acct = get_accounting(tsk);
     vtime_account_irq_field(acct, &acct->softirq_time);
 }
 
 void vtime_account_hardirq(struct task_struct *tsk)
 {
     struct cpu_accounting_data *acct = get_accounting(tsk);
     vtime_account_irq_field(acct, &acct->hardirq_time);
 }
 
 static void vtime_flush_scaled(struct task_struct *tsk,
                    struct cpu_accounting_data *acct)
 {
 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
     if (acct->utime_scaled)
         tsk->utimescaled += cputime_to_nsecs(acct->utime_scaled);
     if (acct->stime_scaled)
         tsk->stimescaled += cputime_to_nsecs(acct->stime_scaled);
 
     acct->utime_scaled = 0;
     acct->utime_sspurr = 0;
     acct->stime_scaled = 0;
 #endif
 }
 
 /*
  * Account the whole cputime accumulated in the paca
  * Must be called with interrupts disabled.
  * Assumes that vtime_account_kernel/idle() has been called
  * recently (i.e. since the last entry from usermode) so that
  * get_paca()->user_time_scaled is up to date.
  */
 void vtime_flush(struct task_struct *tsk)
 {
     struct cpu_accounting_data *acct = get_accounting(tsk);
 
     if (acct->utime)
         account_user_time(tsk, cputime_to_nsecs(acct->utime));
 
     if (acct->gtime)
         account_guest_time(tsk, cputime_to_nsecs(acct->gtime));
 
     if (IS_ENABLED(CONFIG_PPC_SPLPAR) && acct->steal_time) {
         account_steal_time(cputime_to_nsecs(acct->steal_time));
         acct->steal_time = 0;
     }
 
     if (acct->idle_time)
         account_idle_time(cputime_to_nsecs(acct->idle_time));
 
     if (acct->stime)
         account_system_index_time(tsk, cputime_to_nsecs(acct->stime),
                       CPUTIME_SYSTEM);
 
     if (acct->hardirq_time)
         account_system_index_time(tsk, cputime_to_nsecs(acct->hardirq_time),
                       CPUTIME_IRQ);
     if (acct->softirq_time)
         account_system_index_time(tsk, cputime_to_nsecs(acct->softirq_time),
                       CPUTIME_SOFTIRQ);
 
     vtime_flush_scaled(tsk, acct);
 
     acct->utime = 0;
     acct->gtime = 0;
     acct->idle_time = 0;
     acct->stime = 0;
     acct->hardirq_time = 0;
     acct->softirq_time = 0;
 }
 
 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 #define calc_cputime_factors()
 #endif
 
 void __delay(unsigned long loops)
 {
     unsigned long start;
 
     spin_begin();
     if (tb_invalid) {
         /*
          * TB is in error state and isn't ticking anymore.
          * HMI handler was unable to recover from TB error.
          * Return immediately, so that kernel won't get stuck here.
          */
         spin_cpu_relax();
     } else {
         start = mftb();
         while (mftb() - start < loops)
             spin_cpu_relax();
     }
     spin_end();
 }
 EXPORT_SYMBOL(__delay);
 
 void udelay(unsigned long usecs)
 {
     __delay(tb_ticks_per_usec * usecs);
 }
 EXPORT_SYMBOL(udelay);
 
 #ifdef CONFIG_SMP
 unsigned long profile_pc(struct pt_regs *regs)
 {
     unsigned long pc = instruction_pointer(regs);
 
     if (in_lock_functions(pc))
         return regs->link;
 
     return pc;
 }
 EXPORT_SYMBOL(profile_pc);
 #endif
 
 #ifdef CONFIG_IRQ_WORK
 
 /*
  * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
  */
 #ifdef CONFIG_PPC64
 static inline unsigned long test_irq_work_pending(void)
 {
     unsigned long x;
 
     asm volatile("lbz %0,%1(13)"
         : "=r" (x)
         : "i" (offsetof(struct paca_struct, irq_work_pending)));
     return x;
 }
 
 static inline void set_irq_work_pending_flag(void)
 {
     asm volatile("stb %0,%1(13)" : :
         "r" (1),
         "i" (offsetof(struct paca_struct, irq_work_pending)));
 }
 
 static inline void clear_irq_work_pending(void)
 {
     asm volatile("stb %0,%1(13)" : :
         "r" (0),
         "i" (offsetof(struct paca_struct, irq_work_pending)));
 }
 
 #else /* 32-bit */
 
 DEFINE_PER_CPU(u8, irq_work_pending);
 
 #define set_irq_work_pending_flag() __this_cpu_write(irq_work_pending, 1)
 #define test_irq_work_pending()     __this_cpu_read(irq_work_pending)
 #define clear_irq_work_pending()    __this_cpu_write(irq_work_pending, 0)
 
 #endif /* 32 vs 64 bit */
 
 void arch_irq_work_raise(void)
 {
     /*
      * 64-bit code that uses irq soft-mask can just cause an immediate
      * interrupt here that gets soft masked, if this is called under
      * local_irq_disable(). It might be possible to prevent that happening
      * by noticing interrupts are disabled and setting decrementer pending
      * to be replayed when irqs are enabled. The problem there is that
      * tracing can call irq_work_raise, including in code that does low
      * level manipulations of irq soft-mask state (e.g., trace_hardirqs_on)
      * which could get tangled up if we're messing with the same state
      * here.
      */
     preempt_disable();
     set_irq_work_pending_flag();
     set_dec(1);
     preempt_enable();
 }
 
 static void set_dec_or_work(u64 val)
 {
     set_dec(val);
     /* We may have raced with new irq work */
     if (unlikely(test_irq_work_pending()))
         set_dec(1);
 }
 
 #else  /* CONFIG_IRQ_WORK */
 
 #define test_irq_work_pending() 0
 #define clear_irq_work_pending()
 
 static void set_dec_or_work(u64 val)
 {
     set_dec(val);
 }
 #endif /* CONFIG_IRQ_WORK */
 
 #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
 void timer_rearm_host_dec(u64 now)
 {
     u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
 
     WARN_ON_ONCE(!arch_irqs_disabled());
     WARN_ON_ONCE(mfmsr() & MSR_EE);
 
     if (now >= *next_tb) {
         local_paca->irq_happened |= PACA_IRQ_DEC;
     } else {
         now = *next_tb - now;
         if (now > decrementer_max)
             now = decrementer_max;
         set_dec_or_work(now);
     }
 }
 EXPORT_SYMBOL_GPL(timer_rearm_host_dec);
 #endif
 
 /*
  * timer_interrupt - gets called when the decrementer overflows,
  * with interrupts disabled.
  */
 DEFINE_INTERRUPT_HANDLER_ASYNC(timer_interrupt)
 {
     struct clock_event_device *evt = this_cpu_ptr(&decrementers);
     u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
     struct pt_regs *old_regs;
     u64 now;
 
     /*
      * Some implementations of hotplug will get timer interrupts while
      * offline, just ignore these.
      */
     if (unlikely(!cpu_online(smp_processor_id()))) {
         set_dec(decrementer_max);
         return;
     }
 
     /*
      * Ensure a positive value is written to the decrementer, or
      * else some CPUs will continue to take decrementer exceptions.
      * When the PPC_WATCHDOG (decrementer based) is configured,
      * keep this at most 31 bits, which is about 4 seconds on most
      * systems, which gives the watchdog a chance of catching timer
      * interrupt hard lockups.
      */
     if (IS_ENABLED(CONFIG_PPC_WATCHDOG))
         set_dec(0x7fffffff);
     else
         set_dec(decrementer_max);
 
     /* Conditionally hard-enable interrupts. */
     if (should_hard_irq_enable())
         do_hard_irq_enable();
 
 #if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC)
     if (atomic_read(&ppc_n_lost_interrupts) != 0)
         __do_IRQ(regs);
 #endif
 
     old_regs = set_irq_regs(regs);
 
     trace_timer_interrupt_entry(regs);
 
     if (test_irq_work_pending()) {
         clear_irq_work_pending();
         mce_run_irq_context_handlers();
         irq_work_run();
     }
 
     now = get_tb();
     if (now >= *next_tb) {
         evt->event_handler(evt);
         __this_cpu_inc(irq_stat.timer_irqs_event);
     } else {
         now = *next_tb - now;
         if (now > decrementer_max)
             now = decrementer_max;
         set_dec_or_work(now);
         __this_cpu_inc(irq_stat.timer_irqs_others);
     }
 
     trace_timer_interrupt_exit(regs);
 
     set_irq_regs(old_regs);
 }
 EXPORT_SYMBOL(timer_interrupt);
 
 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 void timer_broadcast_interrupt(void)
 {
     tick_receive_broadcast();
     __this_cpu_inc(irq_stat.broadcast_irqs_event);
 }
 #endif
 
 #ifdef CONFIG_SUSPEND
 /* Overrides the weak version in kernel/power/main.c */
 void arch_suspend_disable_irqs(void)
 {
     if (ppc_md.suspend_disable_irqs)
         ppc_md.suspend_disable_irqs();
 
     /* Disable the decrementer, so that it doesn't interfere
      * with suspending.
      */
 
     set_dec(decrementer_max);
     local_irq_disable();
     set_dec(decrementer_max);
 }
 
 /* Overrides the weak version in kernel/power/main.c */
 void arch_suspend_enable_irqs(void)
 {
     local_irq_enable();
 
     if (ppc_md.suspend_enable_irqs)
         ppc_md.suspend_enable_irqs();
 }
 #endif
 
 unsigned long long tb_to_ns(unsigned long long ticks)
 {
     return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
 }
 EXPORT_SYMBOL_GPL(tb_to_ns);
 
 /*
  * Scheduler clock - returns current time in nanosec units.
  *
  * Note: mulhdu(a, b) (multiply high double unsigned) returns
  * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
  * are 64-bit unsigned numbers.
  */
 notrace unsigned long long sched_clock(void)
 {
     return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
 }
 
 
 #ifdef CONFIG_PPC_PSERIES
 
 /*
  * Running clock - attempts to give a view of time passing for a virtualised
  * kernels.
  * Uses the VTB register if available otherwise a next best guess.
  */
 unsigned long long running_clock(void)
 {
     /*
      * Don't read the VTB as a host since KVM does not switch in host
      * timebase into the VTB when it takes a guest off the CPU, reading the
      * VTB would result in reading 'last switched out' guest VTB.
      *
      * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
      * would be unsafe to rely only on the #ifdef above.
      */
     if (firmware_has_feature(FW_FEATURE_LPAR) &&
         cpu_has_feature(CPU_FTR_ARCH_207S))
         return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
 
     /*
      * This is a next best approximation without a VTB.
      * On a host which is running bare metal there should never be any stolen
      * time and on a host which doesn't do any virtualisation TB *should* equal
      * VTB so it makes no difference anyway.
      */
     return local_clock() - kcpustat_this_cpu->cpustat[CPUTIME_STEAL];
 }
 #endif
 
 static int __init get_freq(char *name, int cells, unsigned long *val)
 {
     struct device_node *cpu;
     const __be32 *fp;
     int found = 0;
 
     /* The cpu node should have timebase and clock frequency properties */
     cpu = of_find_node_by_type(NULL, "cpu");
 
     if (cpu) {
         fp = of_get_property(cpu, name, NULL);
         if (fp) {
             found = 1;
             *val = of_read_ulong(fp, cells);
         }
 
         of_node_put(cpu);
     }
 
     return found;
 }
 
 static void start_cpu_decrementer(void)
 {
 #ifdef CONFIG_BOOKE_OR_40x
     unsigned int tcr;
 
     /* Clear any pending timer interrupts */
     mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
 
     tcr = mfspr(SPRN_TCR);
     /*
      * The watchdog may have already been enabled by u-boot. So leave
      * TRC[WP] (Watchdog Period) alone.
      */
     tcr &= TCR_WP_MASK; /* Clear all bits except for TCR[WP] */
     tcr |= TCR_DIE;     /* Enable decrementer */
     mtspr(SPRN_TCR, tcr);
 #endif
 }
 
 void __init generic_calibrate_decr(void)
 {
     ppc_tb_freq = DEFAULT_TB_FREQ;      /* hardcoded default */
 
     if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
         !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
 
         printk(KERN_ERR "WARNING: Estimating decrementer frequency "
                 "(not found)\n");
     }
 
     ppc_proc_freq = DEFAULT_PROC_FREQ;  /* hardcoded default */
 
     if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
         !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
 
         printk(KERN_ERR "WARNING: Estimating processor frequency "
                 "(not found)\n");
     }
 }
 
 int update_persistent_clock64(struct timespec64 now)
 {
     struct rtc_time tm;
 
     if (!ppc_md.set_rtc_time)
         return -ENODEV;
 
     rtc_time64_to_tm(now.tv_sec + 1 + timezone_offset, &tm);
 
     return ppc_md.set_rtc_time(&tm);
 }
 
 static void __read_persistent_clock(struct timespec64 *ts)
 {
     struct rtc_time tm;
     static int first = 1;
 
     ts->tv_nsec = 0;
     /* XXX this is a little fragile but will work okay in the short term */
     if (first) {
         first = 0;
         if (ppc_md.time_init)
             timezone_offset = ppc_md.time_init();
 
         /* get_boot_time() isn't guaranteed to be safe to call late */
         if (ppc_md.get_boot_time) {
             ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
             return;
         }
     }
     if (!ppc_md.get_rtc_time) {
         ts->tv_sec = 0;
         return;
     }
     ppc_md.get_rtc_time(&tm);
 
     ts->tv_sec = rtc_tm_to_time64(&tm);
 }
 
 void read_persistent_clock64(struct timespec64 *ts)
 {
     __read_persistent_clock(ts);
 
     /* Sanitize it in case real time clock is set below EPOCH */
     if (ts->tv_sec < 0) {
         ts->tv_sec = 0;
         ts->tv_nsec = 0;
     }
         
 }
 
 /* clocksource code */
 static notrace u64 timebase_read(struct clocksource *cs)
 {
     return (u64)get_tb();
 }
 
 static void __init clocksource_init(void)
 {
     struct clocksource *clock = &clocksource_timebase;
 
     if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
         printk(KERN_ERR "clocksource: %s is already registered\n",
                clock->name);
         return;
     }
 
     printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
            clock->name, clock->mult, clock->shift);
 }
 
 static int decrementer_set_next_event(unsigned long evt,
                       struct clock_event_device *dev)
 {
     __this_cpu_write(decrementers_next_tb, get_tb() + evt);
     set_dec_or_work(evt);
 
     return 0;
 }
 
 static int decrementer_shutdown(struct clock_event_device *dev)
 {
     __this_cpu_write(decrementers_next_tb, DEC_CLOCKEVENT_STOPPED);
     set_dec_or_work(decrementer_max);
 
     return 0;
 }
 
 static void register_decrementer_clockevent(int cpu)
 {
     struct clock_event_device *dec = &per_cpu(decrementers, cpu);
 
     *dec = decrementer_clockevent;
     dec->cpumask = cpumask_of(cpu);
 
     clockevents_config_and_register(dec, ppc_tb_freq, 2, decrementer_max);
 
     printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
             dec->name, dec->mult, dec->shift, cpu);
 
     /* Set values for KVM, see kvm_emulate_dec() */
     decrementer_clockevent.mult = dec->mult;
     decrementer_clockevent.shift = dec->shift;
 }
 
 static void enable_large_decrementer(void)
 {
     if (!cpu_has_feature(CPU_FTR_ARCH_300))
         return;
 
     if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
         return;
 
     /*
      * If we're running as the hypervisor we need to enable the LD manually
      * otherwise firmware should have done it for us.
      */
     if (cpu_has_feature(CPU_FTR_HVMODE))
         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD);
 }
 
 static void __init set_decrementer_max(void)
 {
     struct device_node *cpu;
     u32 bits = 32;
 
     /* Prior to ISAv3 the decrementer is always 32 bit */
     if (!cpu_has_feature(CPU_FTR_ARCH_300))
         return;
 
     cpu = of_find_node_by_type(NULL, "cpu");
 
     if (of_property_read_u32(cpu, "ibm,dec-bits", &bits) == 0) {
         if (bits > 64 || bits < 32) {
             pr_warn("time_init: firmware supplied invalid ibm,dec-bits");
             bits = 32;
         }
 
         /* calculate the signed maximum given this many bits */
         decrementer_max = (1ul << (bits - 1)) - 1;
     }
 
     of_node_put(cpu);
 
     pr_info("time_init: %u bit decrementer (max: %llx)\n",
         bits, decrementer_max);
 }
 
 static void __init init_decrementer_clockevent(void)
 {
     register_decrementer_clockevent(smp_processor_id());
 }
 
 void secondary_cpu_time_init(void)
 {
     /* Enable and test the large decrementer for this cpu */
     enable_large_decrementer();
 
     /* Start the decrementer on CPUs that have manual control
      * such as BookE
      */
     start_cpu_decrementer();
 
     /* FIME: Should make unrelated change to move snapshot_timebase
      * call here ! */
     register_decrementer_clockevent(smp_processor_id());
 }
 
 /* This function is only called on the boot processor */
 void __init time_init(void)
 {
     struct div_result res;
     u64 scale;
     unsigned shift;
 
     /* Normal PowerPC with timebase register */
     ppc_md.calibrate_decr();
     printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
            ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
     printk(KERN_DEBUG "time_init: processor frequency   = %lu.%.6lu MHz\n",
            ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
 
     tb_ticks_per_jiffy = ppc_tb_freq / HZ;
     tb_ticks_per_sec = ppc_tb_freq;
     tb_ticks_per_usec = ppc_tb_freq / 1000000;
     calc_cputime_factors();
 
     /*
      * Compute scale factor for sched_clock.
      * The calibrate_decr() function has set tb_ticks_per_sec,
      * which is the timebase frequency.
      * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
      * the 128-bit result as a 64.64 fixed-point number.
      * We then shift that number right until it is less than 1.0,
      * giving us the scale factor and shift count to use in
      * sched_clock().
      */
     div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
     scale = res.result_low;
     for (shift = 0; res.result_high != 0; ++shift) {
         scale = (scale >> 1) | (res.result_high << 63);
         res.result_high >>= 1;
     }
     tb_to_ns_scale = scale;
     tb_to_ns_shift = shift;
     /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
     boot_tb = get_tb();
 
     /* If platform provided a timezone (pmac), we correct the time */
     if (timezone_offset) {
         sys_tz.tz_minuteswest = -timezone_offset / 60;
         sys_tz.tz_dsttime = 0;
     }
 
     vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
 
     /* initialise and enable the large decrementer (if we have one) */
     set_decrementer_max();
     enable_large_decrementer();
 
     /* Start the decrementer on CPUs that have manual control
      * such as BookE
      */
     start_cpu_decrementer();
 
     /* Register the clocksource */
     clocksource_init();
 
     init_decrementer_clockevent();
     tick_setup_hrtimer_broadcast();
 
     of_clk_init(NULL);
     enable_sched_clock_irqtime();
 }
 
 /*
  * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
  * result.
  */
 void div128_by_32(u64 dividend_high, u64 dividend_low,
           unsigned divisor, struct div_result *dr)
 {
     unsigned long a, b, c, d;
     unsigned long w, x, y, z;
     u64 ra, rb, rc;
 
     a = dividend_high >> 32;
     b = dividend_high & 0xffffffff;
     c = dividend_low >> 32;
     d = dividend_low & 0xffffffff;
 
     w = a / divisor;
     ra = ((u64)(a - (w * divisor)) << 32) + b;
 
     rb = ((u64) do_div(ra, divisor) << 32) + c;
     x = ra;
 
     rc = ((u64) do_div(rb, divisor) << 32) + d;
     y = rb;
 
     do_div(rc, divisor);
     z = rc;
 
     dr->result_high = ((u64)w << 32) + x;
     dr->result_low  = ((u64)y << 32) + z;
 
 }
 
 /* We don't need to calibrate delay, we use the CPU timebase for that */
 void calibrate_delay(void)
 {
     /* Some generic code (such as spinlock debug) use loops_per_jiffy
      * as the number of __delay(1) in a jiffy, so make it so
      */
     loops_per_jiffy = tb_ticks_per_jiffy;
 }
 
 #if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
 static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
 {
     ppc_md.get_rtc_time(tm);
     return 0;
 }
 
 static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
 {
     if (!ppc_md.set_rtc_time)
         return -EOPNOTSUPP;
 
     if (ppc_md.set_rtc_time(tm) < 0)
         return -EOPNOTSUPP;
 
     return 0;
 }
 
 static const struct rtc_class_ops rtc_generic_ops = {
     .read_time = rtc_generic_get_time,
     .set_time = rtc_generic_set_time,
 };
 
 static int __init rtc_init(void)
 {
     struct platform_device *pdev;
 
     if (!ppc_md.get_rtc_time)
         return -ENODEV;
 
     pdev = platform_device_register_data(NULL, "rtc-generic", -1,
                          &rtc_generic_ops,
                          sizeof(rtc_generic_ops));
 
     return PTR_ERR_OR_ZERO(pdev);
 }
 
 device_initcall(rtc_init);
 #endif

This page was automatically generated by the 2.1.0 LXR engine. The LXR team