2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
14 * Support the cycle counter clocksource and tile timer clock event device.
17 #include <linux/time.h>
18 #include <linux/timex.h>
19 #include <linux/clocksource.h>
20 #include <linux/clockchips.h>
21 #include <linux/hardirq.h>
22 #include <linux/sched.h>
23 #include <linux/smp.h>
24 #include <linux/delay.h>
25 #include <asm/irq_regs.h>
26 #include <hv/hypervisor.h>
27 #include <arch/interrupts.h>
28 #include <arch/spr_def.h>
32 * Define the cycle counter clock source.
35 /* How many cycles per second we are running at. */
36 static cycles_t cycles_per_sec __write_once;
39 * We set up shift and multiply values with a minsec of five seconds,
40 * since our timer counter counts down 31 bits at a frequency of
41 * no less than 500 MHz. See @minsec for clocks_calc_mult_shift().
42 * We could use a different value for the 64-bit free-running
43 * cycle counter, but we use the same one for consistency, and since
44 * we will be reasonably precise with this value anyway.
48 cycles_t get_clock_rate()
50 return cycles_per_sec;
53 #if CHIP_HAS_SPLIT_CYCLE()
56 unsigned int high = __insn_mfspr(SPR_CYCLE_HIGH);
57 unsigned int low = __insn_mfspr(SPR_CYCLE_LOW);
58 unsigned int high2 = __insn_mfspr(SPR_CYCLE_HIGH);
60 while (unlikely(high != high2)) {
61 low = __insn_mfspr(SPR_CYCLE_LOW);
63 high2 = __insn_mfspr(SPR_CYCLE_HIGH);
66 return (((cycles_t)high) << 32) | low;
70 cycles_t clocksource_get_cycles(struct clocksource *cs)
75 static struct clocksource cycle_counter_cs = {
76 .name = "cycle counter",
78 .read = clocksource_get_cycles,
79 .mask = CLOCKSOURCE_MASK(64),
80 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
84 * Called very early from setup_arch() to set cycles_per_sec.
85 * We initialize it early so we can use it to set up loops_per_jiffy.
87 void __init setup_clock(void)
89 cycles_per_sec = hv_sysconf(HV_SYSCONF_CPU_SPEED);
90 clocksource_calc_mult_shift(&cycle_counter_cs, cycles_per_sec,
94 void __init calibrate_delay(void)
96 loops_per_jiffy = get_clock_rate() / HZ;
97 pr_info("Clock rate yields %lu.%02lu BogoMIPS (lpj=%lu)\n",
98 loops_per_jiffy/(500000/HZ),
99 (loops_per_jiffy/(5000/HZ)) % 100, loops_per_jiffy);
102 /* Called fairly late in init/main.c, but before we go smp. */
103 void __init time_init(void)
105 /* Initialize and register the clock source. */
106 clocksource_register(&cycle_counter_cs);
108 /* Start up the tile-timer interrupt source on the boot cpu. */
114 * Define the tile timer clock event device. The timer is driven by
115 * the TILE_TIMER_CONTROL register, which consists of a 31-bit down
116 * counter, plus bit 31, which signifies that the counter has wrapped
117 * from zero to (2**31) - 1. The INT_TILE_TIMER interrupt will be
118 * raised as long as bit 31 is set.
121 #define MAX_TICK 0x7fffffff /* we have 31 bits of countdown timer */
123 static int tile_timer_set_next_event(unsigned long ticks,
124 struct clock_event_device *evt)
126 BUG_ON(ticks > MAX_TICK);
127 __insn_mtspr(SPR_TILE_TIMER_CONTROL, ticks);
128 raw_local_irq_unmask_now(INT_TILE_TIMER);
133 * Whenever anyone tries to change modes, we just mask interrupts
134 * and wait for the next event to get set.
136 static void tile_timer_set_mode(enum clock_event_mode mode,
137 struct clock_event_device *evt)
139 raw_local_irq_mask_now(INT_TILE_TIMER);
143 * Set min_delta_ns to 1 microsecond, since it takes about
144 * that long to fire the interrupt.
146 static DEFINE_PER_CPU(struct clock_event_device, tile_timer) = {
147 .name = "tile timer",
148 .features = CLOCK_EVT_FEAT_ONESHOT,
149 .min_delta_ns = 1000,
152 .set_next_event = tile_timer_set_next_event,
153 .set_mode = tile_timer_set_mode,
156 void __cpuinit setup_tile_timer(void)
158 struct clock_event_device *evt = &__get_cpu_var(tile_timer);
160 /* Fill in fields that are speed-specific. */
161 clockevents_calc_mult_shift(evt, cycles_per_sec, TILE_MINSEC);
162 evt->max_delta_ns = clockevent_delta2ns(MAX_TICK, evt);
164 /* Mark as being for this cpu only. */
165 evt->cpumask = cpumask_of(smp_processor_id());
167 /* Start out with timer not firing. */
168 raw_local_irq_mask_now(INT_TILE_TIMER);
170 /* Register tile timer. */
171 clockevents_register_device(evt);
174 /* Called from the interrupt vector. */
175 void do_timer_interrupt(struct pt_regs *regs, int fault_num)
177 struct pt_regs *old_regs = set_irq_regs(regs);
178 struct clock_event_device *evt = &__get_cpu_var(tile_timer);
181 * Mask the timer interrupt here, since we are a oneshot timer
182 * and there are now by definition no events pending.
184 raw_local_irq_mask(INT_TILE_TIMER);
186 /* Track time spent here in an interrupt context */
189 /* Track interrupt count. */
190 __get_cpu_var(irq_stat).irq_timer_count++;
192 /* Call the generic timer handler */
193 evt->event_handler(evt);
196 * Track time spent against the current process again and
197 * process any softirqs if they are waiting.
201 set_irq_regs(old_regs);
205 * Scheduler clock - returns current time in nanosec units.
206 * Note that with LOCKDEP, this is called during lockdep_init(), and
207 * we will claim that sched_clock() is zero for a little while, until
208 * we run setup_clock(), above.
210 unsigned long long sched_clock(void)
212 return clocksource_cyc2ns(get_cycles(),
213 cycle_counter_cs.mult,
214 cycle_counter_cs.shift);
217 int setup_profiling_timer(unsigned int multiplier)