linux/arch/tile/kernel/time.c
Linus Torvalds 4de9ad9bc0 Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile
Pull Tile arch updates from Chris Metcalf:
 "These changes bring in a bunch of new functionality that has been
  maintained internally at Tilera over the last year, plus other stray
  bits of work that I've taken into the tile tree from other folks.

  The changes include some PCI root complex work, interrupt-driven
  console support, support for performing fast-path unaligned data
  fixups by kernel-based JIT code generation, CONFIG_PREEMPT support,
  vDSO support for gettimeofday(), a serial driver for the tilegx
  on-chip UART, KGDB support, more optimized string routines, support
  for ftrace and kprobes, improved ASLR, and many bug fixes.

  We also remove support for the old TILE64 chip, which is no longer
  buildable"

* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile: (85 commits)
  tile: refresh tile defconfig files
  tile: rework <asm/cmpxchg.h>
  tile PCI RC: make default consistent DMA mask 32-bit
  tile: add null check for kzalloc in tile/kernel/setup.c
  tile: make __write_once a synonym for __read_mostly
  tile: remove support for TILE64
  tile: use asm-generic/bitops/builtin-*.h
  tile: eliminate no-op "noatomichash" boot argument
  tile: use standard tile_bundle_bits type in traps.c
  tile: simplify code referencing hypervisor API addresses
  tile: change <asm/system.h> to <asm/switch_to.h> in comments
  tile: mark pcibios_init() as __init
  tile: check for correct compiler earlier in asm-offsets.c
  tile: use standard 'generic-y' model for <asm/hw_irq.h>
  tile: use asm-generic version of <asm/local64.h>
  tile PCI RC: add comment about "PCI hole" problem
  tile: remove DEBUG_EXTRA_FLAGS kernel config option
  tile: add virt_to_kpte() API and clean up and document behavior
  tile: support FRAME_POINTER
  tile: support reporting Tilera hypervisor statistics
  ...
2013-09-06 11:14:33 -07:00

275 lines
7.3 KiB
C

/*
* 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 = &__get_cpu_var(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 = &__get_cpu_var(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. */
__get_cpu_var(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_get_cpu_var(tile_timer);
return ((u64)nsecs * dev->mult) >> dev->shift;
}
void update_vsyscall_tz(void)
{
/* Userspace gettimeofday will spin while this value is odd. */
++vdso_data->tz_update_count;
smp_wmb();
vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
vdso_data->tz_dsttime = sys_tz.tz_dsttime;
smp_wmb();
++vdso_data->tz_update_count;
}
void update_vsyscall(struct timekeeper *tk)
{
struct timespec wall_time = tk_xtime(tk);
struct timespec *wtm = &tk->wall_to_monotonic;
struct clocksource *clock = tk->clock;
if (clock != &cycle_counter_cs)
return;
/* Userspace gettimeofday will spin while this value is odd. */
++vdso_data->tb_update_count;
smp_wmb();
vdso_data->xtime_tod_stamp = clock->cycle_last;
vdso_data->xtime_clock_sec = wall_time.tv_sec;
vdso_data->xtime_clock_nsec = wall_time.tv_nsec;
vdso_data->wtom_clock_sec = wtm->tv_sec;
vdso_data->wtom_clock_nsec = wtm->tv_nsec;
vdso_data->mult = clock->mult;
vdso_data->shift = clock->shift;
smp_wmb();
++vdso_data->tb_update_count;
}