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 <linux/module.h>
26 #include <linux/timekeeper_internal.h>
27 #include <asm/irq_regs.h>
28 #include <asm/traps.h>
30 #include <hv/hypervisor.h>
31 #include <arch/interrupts.h>
32 #include <arch/spr_def.h>
36 * Define the cycle counter clock source.
39 /* How many cycles per second we are running at. */
40 static cycles_t cycles_per_sec __write_once
;
42 cycles_t
get_clock_rate(void)
44 return cycles_per_sec
;
47 #if CHIP_HAS_SPLIT_CYCLE()
48 cycles_t
get_cycles(void)
50 unsigned int high
= __insn_mfspr(SPR_CYCLE_HIGH
);
51 unsigned int low
= __insn_mfspr(SPR_CYCLE_LOW
);
52 unsigned int high2
= __insn_mfspr(SPR_CYCLE_HIGH
);
54 while (unlikely(high
!= high2
)) {
55 low
= __insn_mfspr(SPR_CYCLE_LOW
);
57 high2
= __insn_mfspr(SPR_CYCLE_HIGH
);
60 return (((cycles_t
)high
) << 32) | low
;
62 EXPORT_SYMBOL(get_cycles
);
66 * We use a relatively small shift value so that sched_clock()
67 * won't wrap around very often.
69 #define SCHED_CLOCK_SHIFT 10
71 static unsigned long sched_clock_mult __write_once
;
73 static cycles_t
clocksource_get_cycles(struct clocksource
*cs
)
78 static struct clocksource cycle_counter_cs
= {
79 .name
= "cycle counter",
81 .read
= clocksource_get_cycles
,
82 .mask
= CLOCKSOURCE_MASK(64),
83 .flags
= CLOCK_SOURCE_IS_CONTINUOUS
,
87 * Called very early from setup_arch() to set cycles_per_sec.
88 * We initialize it early so we can use it to set up loops_per_jiffy.
90 void __init
setup_clock(void)
92 cycles_per_sec
= hv_sysconf(HV_SYSCONF_CPU_SPEED
);
94 clocksource_hz2mult(cycles_per_sec
, SCHED_CLOCK_SHIFT
);
97 void __init
calibrate_delay(void)
99 loops_per_jiffy
= get_clock_rate() / HZ
;
100 pr_info("Clock rate yields %lu.%02lu BogoMIPS (lpj=%lu)\n",
101 loops_per_jiffy
/ (500000 / HZ
),
102 (loops_per_jiffy
/ (5000 / HZ
)) % 100, loops_per_jiffy
);
105 /* Called fairly late in init/main.c, but before we go smp. */
106 void __init
time_init(void)
108 /* Initialize and register the clock source. */
109 clocksource_register_hz(&cycle_counter_cs
, cycles_per_sec
);
111 /* Start up the tile-timer interrupt source on the boot cpu. */
116 * Define the tile timer clock event device. The timer is driven by
117 * the TILE_TIMER_CONTROL register, which consists of a 31-bit down
118 * counter, plus bit 31, which signifies that the counter has wrapped
119 * from zero to (2**31) - 1. The INT_TILE_TIMER interrupt will be
120 * raised as long as bit 31 is set.
122 * The TILE_MINSEC value represents the largest range of real-time
123 * we can possibly cover with the timer, based on MAX_TICK combined
124 * with the slowest reasonable clock rate we might run at.
127 #define MAX_TICK 0x7fffffff /* we have 31 bits of countdown timer */
128 #define TILE_MINSEC 5 /* timer covers no more than 5 seconds */
130 static int tile_timer_set_next_event(unsigned long ticks
,
131 struct clock_event_device
*evt
)
133 BUG_ON(ticks
> MAX_TICK
);
134 __insn_mtspr(SPR_TILE_TIMER_CONTROL
, ticks
);
135 arch_local_irq_unmask_now(INT_TILE_TIMER
);
140 * Whenever anyone tries to change modes, we just mask interrupts
141 * and wait for the next event to get set.
143 static int tile_timer_shutdown(struct clock_event_device
*evt
)
145 arch_local_irq_mask_now(INT_TILE_TIMER
);
150 * Set min_delta_ns to 1 microsecond, since it takes about
151 * that long to fire the interrupt.
153 static DEFINE_PER_CPU(struct clock_event_device
, tile_timer
) = {
154 .name
= "tile timer",
155 .features
= CLOCK_EVT_FEAT_ONESHOT
,
156 .min_delta_ns
= 1000,
159 .set_next_event
= tile_timer_set_next_event
,
160 .set_state_shutdown
= tile_timer_shutdown
,
161 .set_state_oneshot
= tile_timer_shutdown
,
162 .tick_resume
= tile_timer_shutdown
,
165 void setup_tile_timer(void)
167 struct clock_event_device
*evt
= this_cpu_ptr(&tile_timer
);
169 /* Fill in fields that are speed-specific. */
170 clockevents_calc_mult_shift(evt
, cycles_per_sec
, TILE_MINSEC
);
171 evt
->max_delta_ns
= clockevent_delta2ns(MAX_TICK
, evt
);
173 /* Mark as being for this cpu only. */
174 evt
->cpumask
= cpumask_of(smp_processor_id());
176 /* Start out with timer not firing. */
177 arch_local_irq_mask_now(INT_TILE_TIMER
);
179 /* Register tile timer. */
180 clockevents_register_device(evt
);
183 /* Called from the interrupt vector. */
184 void do_timer_interrupt(struct pt_regs
*regs
, int fault_num
)
186 struct pt_regs
*old_regs
= set_irq_regs(regs
);
187 struct clock_event_device
*evt
= this_cpu_ptr(&tile_timer
);
190 * Mask the timer interrupt here, since we are a oneshot timer
191 * and there are now by definition no events pending.
193 arch_local_irq_mask(INT_TILE_TIMER
);
195 /* Track time spent here in an interrupt context */
198 /* Track interrupt count. */
199 __this_cpu_inc(irq_stat
.irq_timer_count
);
201 /* Call the generic timer handler */
202 evt
->event_handler(evt
);
205 * Track time spent against the current process again and
206 * process any softirqs if they are waiting.
210 set_irq_regs(old_regs
);
214 * Scheduler clock - returns current time in nanosec units.
215 * Note that with LOCKDEP, this is called during lockdep_init(), and
216 * we will claim that sched_clock() is zero for a little while, until
217 * we run setup_clock(), above.
219 unsigned long long sched_clock(void)
221 return clocksource_cyc2ns(get_cycles(),
222 sched_clock_mult
, SCHED_CLOCK_SHIFT
);
225 int setup_profiling_timer(unsigned int multiplier
)
231 * Use the tile timer to convert nsecs to core clock cycles, relying
232 * on it having the same frequency as SPR_CYCLE.
234 cycles_t
ns2cycles(unsigned long nsecs
)
237 * We do not have to disable preemption here as each core has the same
240 struct clock_event_device
*dev
= raw_cpu_ptr(&tile_timer
);
243 * as in clocksource.h and x86's timer.h, we split the calculation
244 * into 2 parts to avoid unecessary overflow of the intermediate
245 * value. This will not lead to any loss of precision.
247 u64 quot
= (u64
)nsecs
>> dev
->shift
;
248 u64 rem
= (u64
)nsecs
& ((1ULL << dev
->shift
) - 1);
249 return quot
* dev
->mult
+ ((rem
* dev
->mult
) >> dev
->shift
);
252 void update_vsyscall_tz(void)
254 write_seqcount_begin(&vdso_data
->tz_seq
);
255 vdso_data
->tz_minuteswest
= sys_tz
.tz_minuteswest
;
256 vdso_data
->tz_dsttime
= sys_tz
.tz_dsttime
;
257 write_seqcount_end(&vdso_data
->tz_seq
);
260 void update_vsyscall(struct timekeeper
*tk
)
262 if (tk
->tkr_mono
.clock
!= &cycle_counter_cs
)
265 write_seqcount_begin(&vdso_data
->tb_seq
);
267 vdso_data
->cycle_last
= tk
->tkr_mono
.cycle_last
;
268 vdso_data
->mask
= tk
->tkr_mono
.mask
;
269 vdso_data
->mult
= tk
->tkr_mono
.mult
;
270 vdso_data
->shift
= tk
->tkr_mono
.shift
;
272 vdso_data
->wall_time_sec
= tk
->xtime_sec
;
273 vdso_data
->wall_time_snsec
= tk
->tkr_mono
.xtime_nsec
;
275 vdso_data
->monotonic_time_sec
= tk
->xtime_sec
276 + tk
->wall_to_monotonic
.tv_sec
;
277 vdso_data
->monotonic_time_snsec
= tk
->tkr_mono
.xtime_nsec
278 + ((u64
)tk
->wall_to_monotonic
.tv_nsec
279 << tk
->tkr_mono
.shift
);
280 while (vdso_data
->monotonic_time_snsec
>=
281 (((u64
)NSEC_PER_SEC
) << tk
->tkr_mono
.shift
)) {
282 vdso_data
->monotonic_time_snsec
-=
283 ((u64
)NSEC_PER_SEC
) << tk
->tkr_mono
.shift
;
284 vdso_data
->monotonic_time_sec
++;
287 vdso_data
->wall_time_coarse_sec
= tk
->xtime_sec
;
288 vdso_data
->wall_time_coarse_nsec
= (long)(tk
->tkr_mono
.xtime_nsec
>>
291 vdso_data
->monotonic_time_coarse_sec
=
292 vdso_data
->wall_time_coarse_sec
+ tk
->wall_to_monotonic
.tv_sec
;
293 vdso_data
->monotonic_time_coarse_nsec
=
294 vdso_data
->wall_time_coarse_nsec
+ tk
->wall_to_monotonic
.tv_nsec
;
296 while (vdso_data
->monotonic_time_coarse_nsec
>= NSEC_PER_SEC
) {
297 vdso_data
->monotonic_time_coarse_nsec
-= NSEC_PER_SEC
;
298 vdso_data
->monotonic_time_coarse_sec
++;
301 write_seqcount_end(&vdso_data
->tb_seq
);