fasttimer.c

linux内核源码

/*
 * linux/arch/cris/kernel/fasttimer.c
 *
 * Fast timers for ETRAX100/ETRAX100LX
 *
 * Copyright (C) 2000-2007 Axis Communications AB, Lund, Sweden
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/delay.h>

#include <asm/segment.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/delay.h>
#include <asm/rtc.h>


#include <asm/arch/svinto.h>
#include <asm/fasttimer.h>
#include <linux/proc_fs.h>


#define DEBUG_LOG_INCLUDED
#define FAST_TIMER_LOG
//#define FAST_TIMER_TEST

#define FAST_TIMER_SANITY_CHECKS

#ifdef FAST_TIMER_SANITY_CHECKS
#define SANITYCHECK(x) x
static int sanity_failed;
#else
#define SANITYCHECK(x)
#endif

#define D1(x)
#define D2(x)
#define DP(x)

static unsigned int fast_timer_running;
static unsigned int fast_timers_added;
static unsigned int fast_timers_started;
static unsigned int fast_timers_expired;
static unsigned int fast_timers_deleted;
static unsigned int fast_timer_is_init;
static unsigned int fast_timer_ints;

struct fast_timer *fast_timer_list = NULL;

#ifdef DEBUG_LOG_INCLUDED
#define DEBUG_LOG_MAX 128
static const char * debug_log_string[DEBUG_LOG_MAX];
static unsigned long debug_log_value[DEBUG_LOG_MAX];
static unsigned int debug_log_cnt;
static unsigned int debug_log_cnt_wrapped;

#define DEBUG_LOG(string, value) \
{ \
  unsigned long log_flags; \
  local_irq_save(log_flags); \
  debug_log_string[debug_log_cnt] = (string); \
  debug_log_value[debug_log_cnt] = (unsigned long)(value); \
  if (++debug_log_cnt >= DEBUG_LOG_MAX) \
  { \
    debug_log_cnt = debug_log_cnt % DEBUG_LOG_MAX; \
    debug_log_cnt_wrapped = 1; \
  } \
  local_irq_restore(log_flags); \
}
#else
#define DEBUG_LOG(string, value)
#endif


/* The frequencies for index = clkselx number in R_TIMER_CTRL */
#define NUM_TIMER_FREQ 15
#define MAX_USABLE_TIMER_FREQ 7
#define MAX_DELAY_US  853333L
const unsigned long timer_freq_100[NUM_TIMER_FREQ] =
{
  3,   /* 0 3333 - 853333 us */
  6,   /* 1 1666 - 426666 us */
  12,  /* 2  833 - 213333 us */
  24,  /* 3  416 - 106666 us */
  48,  /* 4  208 -  53333 us */
  96,  /* 5  104 -  26666 us */
  192, /* 6   52 -  13333 us */
  384, /* 7   26 -   6666 us */
  576,
  1152,
  2304,
  4608,
  9216,
  18432,
  62500,
  /* 15 = cascade */
};
#define NUM_TIMER_STATS 16
#ifdef FAST_TIMER_LOG
struct fast_timer timer_added_log[NUM_TIMER_STATS];
struct fast_timer timer_started_log[NUM_TIMER_STATS];
struct fast_timer timer_expired_log[NUM_TIMER_STATS];
#endif

int timer_div_settings[NUM_TIMER_STATS];
int timer_freq_settings[NUM_TIMER_STATS];
int timer_delay_settings[NUM_TIMER_STATS];

/* Not true gettimeofday, only checks the jiffies (uptime) + useconds */
inline void do_gettimeofday_fast(struct fasttime_t *tv)
{
	tv->tv_jiff = jiffies;
	tv->tv_usec = GET_JIFFIES_USEC();
}

inline int fasttime_cmp(struct fasttime_t *t0, struct fasttime_t *t1)
{
	/* Compare jiffies. Takes care of wrapping */
	if (time_before(t0->tv_jiff, t1->tv_jiff))
		return -1;
	else if (time_after(t0->tv_jiff, t1->tv_jiff))
		return 1;

	/* Compare us */
	if (t0->tv_usec < t1->tv_usec)
		return -1;
	else if (t0->tv_usec > t1->tv_usec)
		return 1;
	return 0;
}

inline void start_timer1(unsigned long delay_us)
{
  int freq_index = 0; /* This is the lowest resolution */
  unsigned long upper_limit = MAX_DELAY_US;

  unsigned long div;
  /* Start/Restart the timer to the new shorter value */
  /* t = 1/freq = 1/19200 = 53us
   * T=div*t,  div = T/t = delay_us*freq/1000000
   */
#if 1 /* Adaptive timer settings */
  while (delay_us < upper_limit && freq_index < MAX_USABLE_TIMER_FREQ)
  {
    freq_index++;
    upper_limit >>= 1; /* Divide by 2 using shift */
  }
  if (freq_index > 0)
  {
    freq_index--;
  }
#else
  freq_index = 6;
#endif
  div = delay_us * timer_freq_100[freq_index]/10000;
  if (div < 2)
  {
    /* Maybe increase timer freq? */
    div = 2;
  }
  if (div > 255)
  {
    div = 0; /* This means 256, the max the timer takes */
    /* If a longer timeout than the timer can handle is used,
     * then we must restart it when it goes off.
     */
  }

  timer_div_settings[fast_timers_started % NUM_TIMER_STATS] = div;
  timer_freq_settings[fast_timers_started % NUM_TIMER_STATS] = freq_index;
  timer_delay_settings[fast_timers_started % NUM_TIMER_STATS] = delay_us;

	D1(printk(KERN_DEBUG "start_timer1 : %d us freq: %i div: %i\n",
            delay_us, freq_index, div));
  /* Clear timer1 irq */
  *R_IRQ_MASK0_CLR = IO_STATE(R_IRQ_MASK0_CLR, timer1, clr);

  /* Set timer values */
  *R_TIMER_CTRL = r_timer_ctrl_shadow =
    (r_timer_ctrl_shadow &
     ~IO_MASK(R_TIMER_CTRL, timerdiv1) &
     ~IO_MASK(R_TIMER_CTRL, tm1) &
     ~IO_MASK(R_TIMER_CTRL, clksel1)) |
    IO_FIELD(R_TIMER_CTRL, timerdiv1, div) |
    IO_STATE(R_TIMER_CTRL, tm1, stop_ld) |
    IO_FIELD(R_TIMER_CTRL, clksel1, freq_index ); /* 6=c19k2Hz */

  /* Ack interrupt */
  *R_TIMER_CTRL =  r_timer_ctrl_shadow |
    IO_STATE(R_TIMER_CTRL, i1, clr);

  /* Start timer */
  *R_TIMER_CTRL = r_timer_ctrl_shadow =
    (r_timer_ctrl_shadow & ~IO_MASK(R_TIMER_CTRL, tm1)) |
    IO_STATE(R_TIMER_CTRL, tm1, run);

  /* Enable timer1 irq */
  *R_IRQ_MASK0_SET = IO_STATE(R_IRQ_MASK0_SET, timer1, set);
  fast_timers_started++;
  fast_timer_running = 1;
}

/* In version 1.4 this function takes 27 - 50 us */
void start_one_shot_timer(struct fast_timer *t,
                          fast_timer_function_type *function,
                          unsigned long data,
                          unsigned long delay_us,
                          const char *name)
{
  unsigned long flags;
  struct fast_timer *tmp;

  D1(printk("sft %s %d us\n", name, delay_us));

  local_irq_save(flags);

  do_gettimeofday_fast(&t->tv_set);
  tmp = fast_timer_list;

  SANITYCHECK({ /* Check so this is not in the list already... */
    while (tmp != NULL)
    {
      if (tmp == t)
      {
        printk(KERN_WARNING
               "timer name: %s data: 0x%08lX already in list!\n", name, data);
        sanity_failed++;
				goto done;
      }
      else
      {
        tmp = tmp->next;
      }
    }
    tmp = fast_timer_list;
  });

  t->delay_us = delay_us;
  t->function = function;
  t->data = data;
  t->name = name;

  t->tv_expires.tv_usec = t->tv_set.tv_usec + delay_us % 1000000;
	t->tv_expires.tv_jiff = t->tv_set.tv_jiff + delay_us / 1000000 / HZ;
  if (t->tv_expires.tv_usec > 1000000)
  {
    t->tv_expires.tv_usec -= 1000000;
		t->tv_expires.tv_jiff += HZ;
  }
#ifdef FAST_TIMER_LOG
  timer_added_log[fast_timers_added % NUM_TIMER_STATS] = *t;
#endif
  fast_timers_added++;

  /* Check if this should timeout before anything else */
	if (tmp == NULL || fasttime_cmp(&t->tv_expires, &tmp->tv_expires) < 0)
  {
    /* Put first in list and modify the timer value */
    t->prev = NULL;
    t->next = fast_timer_list;
    if (fast_timer_list)
    {
      fast_timer_list->prev = t;
    }
    fast_timer_list = t;
#ifdef FAST_TIMER_LOG
    timer_started_log[fast_timers_started % NUM_TIMER_STATS] = *t;
#endif
    start_timer1(delay_us);
  } else {
    /* Put in correct place in list */
		while (tmp->next && fasttime_cmp(&t->tv_expires,
				&tmp->next->tv_expires) > 0)
    {
      tmp = tmp->next;
    }
    /* Insert t after tmp */
    t->prev = tmp;
    t->next = tmp->next;
    if (tmp->next)
    {
      tmp->next->prev = t;
    }
    tmp->next = t;
  }

  D2(printk("start_one_shot_timer: %d us done\n", delay_us));

done:
  local_irq_restore(flags);
} /* start_one_shot_timer */

static inline int fast_timer_pending (const struct fast_timer * t)
{
  return (t->next != NULL) || (t->prev != NULL) || (t == fast_timer_list);
}

static inline int detach_fast_timer (struct fast_timer *t)
{
  struct fast_timer *next, *prev;
  if (!fast_timer_pending(t))
    return 0;
  next = t->next;
  prev = t->prev;
  if (next)
    next->prev = prev;
  if (prev)
    prev->next = next;
  else
    fast_timer_list = next;
  fast_timers_deleted++;
  return 1;
}

int del_fast_timer(struct fast_timer * t)
{
  unsigned long flags;
  int ret;
  
  local_irq_save(flags);
  ret = detach_fast_timer(t);
  t->next = t->prev = NULL;
  local_irq_restore(flags);
  return ret;
} /* del_fast_timer */


/* Interrupt routines or functions called in interrupt context */

/* Timer 1 interrupt handler */

static irqreturn_t
timer1_handler(int irq, void *dev_id)
{
  struct fast_timer *t;
  unsigned long flags;

	/* We keep interrupts disabled not only when we modify the
	 * fast timer list, but any time we hold a reference to a
	 * timer in the list, since del_fast_timer may be called
	 * from (another) interrupt context.  Thus, the only time
	 * when interrupts are enabled is when calling the timer
	 * callback function.
	 */
  local_irq_save(flags);

  /* Clear timer1 irq */
  *R_IRQ_MASK0_CLR = IO_STATE(R_IRQ_MASK0_CLR, timer1, clr);

  /* First stop timer, then ack interrupt */
  /* Stop timer */
  *R_TIMER_CTRL = r_timer_ctrl_shadow =
    (r_timer_ctrl_shadow & ~IO_MASK(R_TIMER_CTRL, tm1)) |
    IO_STATE(R_TIMER_CTRL, tm1, stop_ld);

  /* Ack interrupt */
  *R_TIMER_CTRL =  r_timer_ctrl_shadow | IO_STATE(R_TIMER_CTRL, i1, clr);

  fast_timer_running = 0;
  fast_timer_ints++;

  t = fast_timer_list;
  while (t)
  {
		struct fasttime_t tv;
		fast_timer_function_type *f;
		unsigned long d;

    /* Has it really expired? */
    do_gettimeofday_fast(&tv);
		D1(printk(KERN_DEBUG "t: %is %06ius\n",
			tv.tv_jiff, tv.tv_usec));

		if (fasttime_cmp(&t->tv_expires, &tv) <= 0)
    {
      /* Yes it has expired */
#ifdef FAST_TIMER_LOG
      timer_expired_log[fast_timers_expired % NUM_TIMER_STATS] = *t;
#endif
      fast_timers_expired++;

      /* Remove this timer before call, since it may reuse the timer */
      if (t->prev)
      {
        t->prev->next = t->next;
      }
      else
      {
        fast_timer_list = t->next;
      }
      if (t->next)
      {
        t->next->prev = t->prev;
      }
      t->prev = NULL;
      t->next = NULL;

			/* Save function callback data before enabling
			 * interrupts, since the timer may be removed and
			 * we don't know how it was allocated
			 * (e.g. ->function and ->data may become overwritten
			 * after deletion if the timer was stack-allocated).
			 */
			f = t->function;
			d = t->data;

			if (f != NULL) {
				/* Run callback with interrupts enabled. */
				local_irq_restore(flags);
				f(d);
				local_irq_save(flags);
			} else
        DEBUG_LOG("!timer1 %i function==NULL!\n", fast_timer_ints);
    }
    else
    {
      /* Timer is to early, let's set it again using the normal routines */
      D1(printk(".\n"));
    }

    if ((t = fast_timer_list) != NULL)
    {
      /* Start next timer.. */
			long us = 0;
			struct fasttime_t tv;

      do_gettimeofday_fast(&tv);

			/* time_after_eq takes care of wrapping */
			if (time_after_eq(t->tv_expires.tv_jiff, tv.tv_jiff))
				us = ((t->tv_expires.tv_jiff - tv.tv_jiff) *
					1000000 / HZ + t->tv_expires.tv_usec -
					tv.tv_usec);

      if (us > 0)
      {