--- /dev/null
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ * 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, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for
+ * more details.
+ *
+ * Support the cycle counter clocksource and tile timer clock event device.
+ */
+
+#include <linux/time.h>
+#include <linux/timex.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/hardirq.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/timekeeper_internal.h>
+#include <asm/irq_regs.h>
+#include <asm/traps.h>
+#include <asm/vdso.h>
+#include <hv/hypervisor.h>
+#include <arch/interrupts.h>
+#include <arch/spr_def.h>
+
+
+/*
+ * Define the cycle counter clock source.
+ */
+
+/* How many cycles per second we are running at. */
+static cycles_t cycles_per_sec __write_once;
+
+cycles_t get_clock_rate(void)
+{
+ return cycles_per_sec;
+}
+
+#if CHIP_HAS_SPLIT_CYCLE()
+cycles_t get_cycles(void)
+{
+ unsigned int high = __insn_mfspr(SPR_CYCLE_HIGH);
+ unsigned int low = __insn_mfspr(SPR_CYCLE_LOW);
+ unsigned int high2 = __insn_mfspr(SPR_CYCLE_HIGH);
+
+ while (unlikely(high != high2)) {
+ low = __insn_mfspr(SPR_CYCLE_LOW);
+ high = high2;
+ high2 = __insn_mfspr(SPR_CYCLE_HIGH);
+ }
+
+ return (((cycles_t)high) << 32) | low;
+}
+EXPORT_SYMBOL(get_cycles);
+#endif
+
+/*
+ * We use a relatively small shift value so that sched_clock()
+ * won't wrap around very often.
+ */
+#define SCHED_CLOCK_SHIFT 10
+
+static unsigned long sched_clock_mult __write_once;
+
+static cycles_t clocksource_get_cycles(struct clocksource *cs)
+{
+ return get_cycles();
+}
+
+static struct clocksource cycle_counter_cs = {
+ .name = "cycle counter",
+ .rating = 300,
+ .read = clocksource_get_cycles,
+ .mask = CLOCKSOURCE_MASK(64),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+/*
+ * Called very early from setup_arch() to set cycles_per_sec.
+ * We initialize it early so we can use it to set up loops_per_jiffy.
+ */
+void __init setup_clock(void)
+{
+ cycles_per_sec = hv_sysconf(HV_SYSCONF_CPU_SPEED);
+ sched_clock_mult =
+ clocksource_hz2mult(cycles_per_sec, SCHED_CLOCK_SHIFT);
+}
+
+void __init calibrate_delay(void)
+{
+ loops_per_jiffy = get_clock_rate() / HZ;
+ pr_info("Clock rate yields %lu.%02lu BogoMIPS (lpj=%lu)\n",
+ loops_per_jiffy / (500000 / HZ),
+ (loops_per_jiffy / (5000 / HZ)) % 100, loops_per_jiffy);
+}
+
+/* Called fairly late in init/main.c, but before we go smp. */
+void __init time_init(void)
+{
+ /* Initialize and register the clock source. */
+ clocksource_register_hz(&cycle_counter_cs, cycles_per_sec);
+
+ /* Start up the tile-timer interrupt source on the boot cpu. */
+ setup_tile_timer();
+}
+
+/*
+ * Define the tile timer clock event device. The timer is driven by
+ * the TILE_TIMER_CONTROL register, which consists of a 31-bit down
+ * counter, plus bit 31, which signifies that the counter has wrapped
+ * from zero to (2**31) - 1. The INT_TILE_TIMER interrupt will be
+ * raised as long as bit 31 is set.
+ *
+ * The TILE_MINSEC value represents the largest range of real-time
+ * we can possibly cover with the timer, based on MAX_TICK combined
+ * with the slowest reasonable clock rate we might run at.
+ */
+
+#define MAX_TICK 0x7fffffff /* we have 31 bits of countdown timer */
+#define TILE_MINSEC 5 /* timer covers no more than 5 seconds */
+
+static int tile_timer_set_next_event(unsigned long ticks,
+ struct clock_event_device *evt)
+{
+ BUG_ON(ticks > MAX_TICK);
+ __insn_mtspr(SPR_TILE_TIMER_CONTROL, ticks);
+ arch_local_irq_unmask_now(INT_TILE_TIMER);
+ return 0;
+}
+
+/*
+ * Whenever anyone tries to change modes, we just mask interrupts
+ * and wait for the next event to get set.
+ */
+static void tile_timer_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ arch_local_irq_mask_now(INT_TILE_TIMER);
+}
+
+/*
+ * Set min_delta_ns to 1 microsecond, since it takes about
+ * that long to fire the interrupt.
+ */
+static DEFINE_PER_CPU(struct clock_event_device, tile_timer) = {
+ .name = "tile timer",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .min_delta_ns = 1000,
+ .rating = 100,
+ .irq = -1,
+ .set_next_event = tile_timer_set_next_event,
+ .set_mode = tile_timer_set_mode,
+};
+
+void setup_tile_timer(void)
+{
+ struct clock_event_device *evt = this_cpu_ptr(&tile_timer);
+
+ /* Fill in fields that are speed-specific. */
+ clockevents_calc_mult_shift(evt, cycles_per_sec, TILE_MINSEC);
+ evt->max_delta_ns = clockevent_delta2ns(MAX_TICK, evt);
+
+ /* Mark as being for this cpu only. */
+ evt->cpumask = cpumask_of(smp_processor_id());
+
+ /* Start out with timer not firing. */
+ arch_local_irq_mask_now(INT_TILE_TIMER);
+
+ /* Register tile timer. */
+ clockevents_register_device(evt);
+}
+
+/* Called from the interrupt vector. */
+void do_timer_interrupt(struct pt_regs *regs, int fault_num)
+{
+ struct pt_regs *old_regs = set_irq_regs(regs);
+ struct clock_event_device *evt = this_cpu_ptr(&tile_timer);
+
+ /*
+ * Mask the timer interrupt here, since we are a oneshot timer
+ * and there are now by definition no events pending.
+ */
+ arch_local_irq_mask(INT_TILE_TIMER);
+
+ /* Track time spent here in an interrupt context */
+ irq_enter();
+
+ /* Track interrupt count. */
+ __this_cpu_inc(irq_stat.irq_timer_count);
+
+ /* Call the generic timer handler */
+ evt->event_handler(evt);
+
+ /*
+ * Track time spent against the current process again and
+ * process any softirqs if they are waiting.
+ */
+ irq_exit();
+
+ set_irq_regs(old_regs);
+}
+
+/*
+ * Scheduler clock - returns current time in nanosec units.
+ * Note that with LOCKDEP, this is called during lockdep_init(), and
+ * we will claim that sched_clock() is zero for a little while, until
+ * we run setup_clock(), above.
+ */
+unsigned long long sched_clock(void)
+{
+ return clocksource_cyc2ns(get_cycles(),
+ sched_clock_mult, SCHED_CLOCK_SHIFT);
+}
+
+int setup_profiling_timer(unsigned int multiplier)
+{
+ return -EINVAL;
+}
+
+/*
+ * Use the tile timer to convert nsecs to core clock cycles, relying
+ * on it having the same frequency as SPR_CYCLE.
+ */
+cycles_t ns2cycles(unsigned long nsecs)
+{
+ /*
+ * We do not have to disable preemption here as each core has the same
+ * clock frequency.
+ */
+ struct clock_event_device *dev = raw_cpu_ptr(&tile_timer);
+
+ /*
+ * as in clocksource.h and x86's timer.h, we split the calculation
+ * into 2 parts to avoid unecessary overflow of the intermediate
+ * value. This will not lead to any loss of precision.
+ */
+ u64 quot = (u64)nsecs >> dev->shift;
+ u64 rem = (u64)nsecs & ((1ULL << dev->shift) - 1);
+ return quot * dev->mult + ((rem * dev->mult) >> dev->shift);
+}
+
+void update_vsyscall_tz(void)
+{
+ write_seqcount_begin(&vdso_data->tz_seq);
+ vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
+ vdso_data->tz_dsttime = sys_tz.tz_dsttime;
+ write_seqcount_end(&vdso_data->tz_seq);
+}
+
+void update_vsyscall(struct timekeeper *tk)
+{
+ if (tk->tkr_mono.clock != &cycle_counter_cs)
+ return;
+
+ write_seqcount_begin(&vdso_data->tb_seq);
+
+ vdso_data->cycle_last = tk->tkr_mono.cycle_last;
+ vdso_data->mask = tk->tkr_mono.mask;
+ vdso_data->mult = tk->tkr_mono.mult;
+ vdso_data->shift = tk->tkr_mono.shift;
+
+ vdso_data->wall_time_sec = tk->xtime_sec;
+ vdso_data->wall_time_snsec = tk->tkr_mono.xtime_nsec;
+
+ vdso_data->monotonic_time_sec = tk->xtime_sec
+ + tk->wall_to_monotonic.tv_sec;
+ vdso_data->monotonic_time_snsec = tk->tkr_mono.xtime_nsec
+ + ((u64)tk->wall_to_monotonic.tv_nsec
+ << tk->tkr_mono.shift);
+ while (vdso_data->monotonic_time_snsec >=
+ (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
+ vdso_data->monotonic_time_snsec -=
+ ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
+ vdso_data->monotonic_time_sec++;
+ }
+
+ vdso_data->wall_time_coarse_sec = tk->xtime_sec;
+ vdso_data->wall_time_coarse_nsec = (long)(tk->tkr_mono.xtime_nsec >>
+ tk->tkr_mono.shift);
+
+ vdso_data->monotonic_time_coarse_sec =
+ vdso_data->wall_time_coarse_sec + tk->wall_to_monotonic.tv_sec;
+ vdso_data->monotonic_time_coarse_nsec =
+ vdso_data->wall_time_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
+
+ while (vdso_data->monotonic_time_coarse_nsec >= NSEC_PER_SEC) {
+ vdso_data->monotonic_time_coarse_nsec -= NSEC_PER_SEC;
+ vdso_data->monotonic_time_coarse_sec++;
+ }
+
+ write_seqcount_end(&vdso_data->tb_seq);
+}
Code Review / kvmfornfv.git / blobdiff