v4.19.13 snapshot.
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
new file mode 100644
index 0000000..70f145e
--- /dev/null
+++ b/arch/powerpc/kernel/time.c
@@ -0,0 +1,1221 @@
+/*
+ * 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
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/sched/clock.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/clockchips.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/clk-provider.h>
+#include <linux/suspend.h>
+#include <linux/rtc.h>
+#include <linux/sched/cputime.h>
+#include <linux/processor.h>
+#include <asm/trace.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/prom.h>
+#include <asm/irq.h>
+#include <asm/div64.h>
+#include <asm/smp.h>
+#include <asm/vdso_datapage.h>
+#include <asm/firmware.h>
+#include <asm/asm-prototypes.h>
+
+/* powerpc clocksource/clockevent code */
+
+#include <linux/clockchips.h>
+#include <linux/timekeeper_internal.h>
+
+static u64 rtc_read(struct clocksource *);
+static struct clocksource clocksource_rtc = {
+ .name = "rtc",
+ .rating = 400,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+ .mask = CLOCKSOURCE_MASK(64),
+ .read = rtc_read,
+};
+
+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,
+};
+
+#define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF
+u64 decrementer_max = DECREMENTER_DEFAULT_MAX;
+
+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_shutdown = decrementer_shutdown,
+ .tick_resume = decrementer_shutdown,
+ .features = CLOCK_EVT_FEAT_ONESHOT |
+ CLOCK_EVT_FEAT_C3STOP,
+};
+EXPORT_SYMBOL(decrementer_clockevent);
+
+DEFINE_PER_CPU(u64, 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);
+
+#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);
+
+#ifdef CONFIG_PPC_SPLPAR
+void (*dtl_consumer)(struct dtl_entry *, u64);
+#endif
+
+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 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
+
+/*
+ * 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 accumulate_stolen_time(void)
+{
+ u64 sst, ust;
+ unsigned long save_irq_soft_mask = irq_soft_mask_return();
+ struct cpu_accounting_data *acct = &local_paca->accounting;
+
+ /* We are called early in the exception entry, before
+ * soft/hard_enabled are sync'ed to the expected state
+ * for the exception. We are hard disabled but the PACA
+ * needs to reflect that so various debug stuff doesn't
+ * complain
+ */
+ irq_soft_mask_set(IRQS_DISABLED);
+
+ sst = scan_dispatch_log(acct->starttime_user);
+ ust = scan_dispatch_log(acct->starttime);
+ acct->stime -= sst;
+ acct->utime -= ust;
+ acct->steal_time += ust + sst;
+
+ irq_soft_mask_set(save_irq_soft_mask);
+}
+
+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(struct task_struct *tsk,
+ unsigned long *stime_scaled,
+ unsigned long *steal_time)
+{
+ unsigned long now, nowscaled, deltascaled;
+ unsigned long stime;
+ unsigned long utime, utime_scaled;
+ struct cpu_accounting_data *acct = get_accounting(tsk);
+
+ WARN_ON_ONCE(!irqs_disabled());
+
+ now = mftb();
+ nowscaled = read_spurr(now);
+ stime = now - acct->starttime;
+ acct->starttime = now;
+ deltascaled = nowscaled - acct->startspurr;
+ acct->startspurr = nowscaled;
+
+ *steal_time = calculate_stolen_time(now);
+
+ 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;
+
+ return stime;
+}
+
+void vtime_account_system(struct task_struct *tsk)
+{
+ unsigned long stime, stime_scaled, steal_time;
+ struct cpu_accounting_data *acct = get_accounting(tsk);
+
+ stime = vtime_delta(tsk, &stime_scaled, &steal_time);
+
+ stime -= min(stime, steal_time);
+ acct->steal_time += steal_time;
+
+ if ((tsk->flags & PF_VCPU) && !irq_count()) {
+ acct->gtime += stime;
+ acct->utime_scaled += stime_scaled;
+ } else {
+ if (hardirq_count())
+ acct->hardirq_time += stime;
+ else if (in_serving_softirq())
+ acct->softirq_time += stime;
+ else
+ acct->stime += stime;
+
+ acct->stime_scaled += stime_scaled;
+ }
+}
+EXPORT_SYMBOL_GPL(vtime_account_system);
+
+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(tsk, &stime_scaled, &steal_time);
+ acct->idle_time += stime + steal_time;
+}
+
+/*
+ * Account the whole cputime accumulated in the paca
+ * Must be called with interrupts disabled.
+ * Assumes that vtime_account_system/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->utime_scaled)
+ tsk->utimescaled += cputime_to_nsecs(acct->utime_scaled);
+
+ if (acct->gtime)
+ account_guest_time(tsk, cputime_to_nsecs(acct->gtime));
+
+ if (acct->steal_time)
+ account_steal_time(cputime_to_nsecs(acct->steal_time));
+
+ 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->stime_scaled)
+ tsk->stimescaled += cputime_to_nsecs(acct->stime_scaled);
+
+ 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);
+
+ acct->utime = 0;
+ acct->utime_scaled = 0;
+ acct->utime_sspurr = 0;
+ acct->gtime = 0;
+ acct->steal_time = 0;
+ acct->idle_time = 0;
+ acct->stime = 0;
+ acct->stime_scaled = 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;
+ int diff;
+
+ spin_begin();
+ if (__USE_RTC()) {
+ start = get_rtcl();
+ do {
+ /* the RTCL register wraps at 1000000000 */
+ diff = get_rtcl() - start;
+ if (diff < 0)
+ diff += 1000000000;
+ spin_cpu_relax();
+ } while (diff < loops);
+ } else {
+ start = get_tbl();
+ while (get_tbl() - 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)));
+}
+
+void arch_irq_work_raise(void)
+{
+ preempt_disable();
+ set_irq_work_pending_flag();
+ /*
+ * Non-nmi code running with interrupts disabled will replay
+ * irq_happened before it re-enables interrupts, so setthe
+ * decrementer there instead of causing a hardware exception
+ * which would immediately hit the masked interrupt handler
+ * and have the net effect of setting the decrementer in
+ * irq_happened.
+ *
+ * NMI interrupts can not check this when they return, so the
+ * decrementer hardware exception is raised, which will fire
+ * when interrupts are next enabled.
+ *
+ * BookE does not support this yet, it must audit all NMI
+ * interrupt handlers to ensure they call nmi_enter() so this
+ * check would be correct.
+ */
+ if (IS_ENABLED(CONFIG_BOOKE) || !irqs_disabled() || in_nmi()) {
+ set_dec(1);
+ } else {
+ hard_irq_disable();
+ local_paca->irq_happened |= PACA_IRQ_DEC;
+ }
+ preempt_enable();
+}
+
+#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)
+
+void arch_irq_work_raise(void)
+{
+ preempt_disable();
+ set_irq_work_pending_flag();
+ set_dec(1);
+ preempt_enable();
+}
+
+#endif /* 32 vs 64 bit */
+
+#else /* CONFIG_IRQ_WORK */
+
+#define test_irq_work_pending() 0
+#define clear_irq_work_pending()
+
+#endif /* CONFIG_IRQ_WORK */
+
+/*
+ * timer_interrupt - gets called when the decrementer overflows,
+ * with interrupts disabled.
+ */
+void timer_interrupt(struct pt_regs *regs)
+{
+ 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 and we also need to set
+ * decrementers_next_tb as MAX to make sure __check_irq_replay
+ * don't replay timer interrupt when return, otherwise we'll trap
+ * here infinitely :(
+ */
+ if (unlikely(!cpu_online(smp_processor_id()))) {
+ *next_tb = ~(u64)0;
+ 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 now that the DEC has been
+ * bumped to its maximum value
+ */
+ may_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);
+ irq_enter();
+ trace_timer_interrupt_entry(regs);
+
+ if (test_irq_work_pending()) {
+ clear_irq_work_pending();
+ irq_work_run();
+ }
+
+ now = get_tb_or_rtc();
+ if (now >= *next_tb) {
+ *next_tb = ~(u64)0;
+ if (evt->event_handler)
+ evt->event_handler(evt);
+ __this_cpu_inc(irq_stat.timer_irqs_event);
+ } else {
+ now = *next_tb - now;
+ if (now <= decrementer_max)
+ set_dec(now);
+ /* We may have raced with new irq work */
+ if (test_irq_work_pending())
+ set_dec(1);
+ __this_cpu_inc(irq_stat.timer_irqs_others);
+ }
+
+ trace_timer_interrupt_exit(regs);
+ irq_exit();
+ set_irq_regs(old_regs);
+}
+EXPORT_SYMBOL(timer_interrupt);
+
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+void timer_broadcast_interrupt(void)
+{
+ u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
+
+ *next_tb = ~(u64)0;
+ tick_receive_broadcast();
+ __this_cpu_inc(irq_stat.broadcast_irqs_event);
+}
+#endif
+
+/*
+ * Hypervisor decrementer interrupts shouldn't occur but are sometimes
+ * left pending on exit from a KVM guest. We don't need to do anything
+ * to clear them, as they are edge-triggered.
+ */
+void hdec_interrupt(struct pt_regs *regs)
+{
+}
+
+#ifdef CONFIG_SUSPEND
+static void generic_suspend_disable_irqs(void)
+{
+ /* Disable the decrementer, so that it doesn't interfere
+ * with suspending.
+ */
+
+ set_dec(decrementer_max);
+ local_irq_disable();
+ set_dec(decrementer_max);
+}
+
+static void generic_suspend_enable_irqs(void)
+{
+ local_irq_enable();
+}
+
+/* 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();
+ generic_suspend_disable_irqs();
+}
+
+/* Overrides the weak version in kernel/power/main.c */
+void arch_suspend_enable_irqs(void)
+{
+ generic_suspend_enable_irqs();
+ 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)
+{
+ if (__USE_RTC())
+ return get_rtc();
+ 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)
+{
+#if defined(CONFIG_BOOKE) || defined(CONFIG_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 litle 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 rtc_read(struct clocksource *cs)
+{
+ return (u64)get_rtc();
+}
+
+static notrace u64 timebase_read(struct clocksource *cs)
+{
+ return (u64)get_tb();
+}
+
+
+void update_vsyscall(struct timekeeper *tk)
+{
+ struct timespec xt;
+ struct clocksource *clock = tk->tkr_mono.clock;
+ u32 mult = tk->tkr_mono.mult;
+ u32 shift = tk->tkr_mono.shift;
+ u64 cycle_last = tk->tkr_mono.cycle_last;
+ u64 new_tb_to_xs, new_stamp_xsec;
+ u64 frac_sec;
+
+ if (clock != &clocksource_timebase)
+ return;
+
+ xt.tv_sec = tk->xtime_sec;
+ xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
+
+ /* Make userspace gettimeofday spin until we're done. */
+ ++vdso_data->tb_update_count;
+ smp_mb();
+
+ /*
+ * This computes ((2^20 / 1e9) * mult) >> shift as a
+ * 0.64 fixed-point fraction.
+ * The computation in the else clause below won't overflow
+ * (as long as the timebase frequency is >= 1.049 MHz)
+ * but loses precision because we lose the low bits of the constant
+ * in the shift. Note that 19342813113834067 ~= 2^(20+64) / 1e9.
+ * For a shift of 24 the error is about 0.5e-9, or about 0.5ns
+ * over a second. (Shift values are usually 22, 23 or 24.)
+ * For high frequency clocks such as the 512MHz timebase clock
+ * on POWER[6789], the mult value is small (e.g. 32768000)
+ * and so we can shift the constant by 16 initially
+ * (295147905179 ~= 2^(20+64-16) / 1e9) and then do the
+ * remaining shifts after the multiplication, which gives a
+ * more accurate result (e.g. with mult = 32768000, shift = 24,
+ * the error is only about 1.2e-12, or 0.7ns over 10 minutes).
+ */
+ if (mult <= 62500000 && clock->shift >= 16)
+ new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16);
+ else
+ new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift);
+
+ /*
+ * Compute the fractional second in units of 2^-32 seconds.
+ * The fractional second is tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift
+ * in nanoseconds, so multiplying that by 2^32 / 1e9 gives
+ * it in units of 2^-32 seconds.
+ * We assume shift <= 32 because clocks_calc_mult_shift()
+ * generates shift values in the range 0 - 32.
+ */
+ frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift);
+ do_div(frac_sec, NSEC_PER_SEC);
+
+ /*
+ * Work out new stamp_xsec value for any legacy users of systemcfg.
+ * stamp_xsec is in units of 2^-20 seconds.
+ */
+ new_stamp_xsec = frac_sec >> 12;
+ new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC;
+
+ /*
+ * tb_update_count is used to allow the userspace gettimeofday code
+ * to assure itself that it sees a consistent view of the tb_to_xs and
+ * stamp_xsec variables. It reads the tb_update_count, then reads
+ * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
+ * the two values of tb_update_count match and are even then the
+ * tb_to_xs and stamp_xsec values are consistent. If not, then it
+ * loops back and reads them again until this criteria is met.
+ */
+ vdso_data->tb_orig_stamp = cycle_last;
+ vdso_data->stamp_xsec = new_stamp_xsec;
+ vdso_data->tb_to_xs = new_tb_to_xs;
+ vdso_data->wtom_clock_sec = tk->wall_to_monotonic.tv_sec;
+ vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
+ vdso_data->stamp_xtime = xt;
+ vdso_data->stamp_sec_fraction = frac_sec;
+ smp_wmb();
+ ++(vdso_data->tb_update_count);
+}
+
+void update_vsyscall_tz(void)
+{
+ vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
+ vdso_data->tz_dsttime = sys_tz.tz_dsttime;
+}
+
+static void __init clocksource_init(void)
+{
+ struct clocksource *clock;
+
+ if (__USE_RTC())
+ clock = &clocksource_rtc;
+ else
+ 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_or_rtc() + evt);
+ set_dec(evt);
+
+ /* We may have raced with new irq work */
+ if (test_irq_work_pending())
+ set_dec(1);
+
+ return 0;
+}
+
+static int decrementer_shutdown(struct clock_event_device *dev)
+{
+ decrementer_set_next_event(decrementer_max, dev);
+ 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);
+
+ printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
+ dec->name, dec->mult, dec->shift, cpu);
+
+ clockevents_register_device(dec);
+}
+
+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)
+{
+ int cpu = smp_processor_id();
+
+ clockevents_calc_mult_shift(&decrementer_clockevent, ppc_tb_freq, 4);
+
+ decrementer_clockevent.max_delta_ns =
+ clockevent_delta2ns(decrementer_max, &decrementer_clockevent);
+ decrementer_clockevent.max_delta_ticks = decrementer_max;
+ decrementer_clockevent.min_delta_ns =
+ clockevent_delta2ns(2, &decrementer_clockevent);
+ decrementer_clockevent.min_delta_ticks = 2;
+
+ register_decrementer_clockevent(cpu);
+}
+
+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 unrelatred 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;
+
+ if (__USE_RTC()) {
+ /* 601 processor: dec counts down by 128 every 128ns */
+ ppc_tb_freq = 1000000000;
+ } else {
+ /* 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_or_rtc();
+
+ /* 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_update_count = 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();
+
+#ifdef CONFIG_COMMON_CLK
+ of_clk_init(NULL);
+#endif
+}
+
+/*
+ * 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