LXR qemu/include/hw/ptimer.h

   1/*
   2 * General purpose implementation of a simple periodic countdown timer.
   3 *
   4 * Copyright (c) 2007 CodeSourcery.
   5 *
   6 * This code is licensed under the GNU LGPL.
   7 */
   8#ifndef PTIMER_H
   9#define PTIMER_H
  10
  11#include "qemu-common.h"
  12#include "qemu/timer.h"
  13#include "migration/vmstate.h"
  14
  15/* The default ptimer policy retains backward compatibility with the legacy
  16 * timers. Custom policies are adjusting the default one. Consider providing
  17 * a correct policy for your timer.
  18 *
  19 * The rough edges of the default policy:
  20 *  - Starting to run with a period = 0 emits error message and stops the
  21 *    timer without a trigger.
  22 *
  23 *  - Setting period to 0 of the running timer emits error message and
  24 *    stops the timer without a trigger.
  25 *
  26 *  - Starting to run with counter = 0 or setting it to "0" while timer
  27 *    is running causes a trigger and reloads counter with a limit value.
  28 *    If limit = 0, ptimer emits error message and stops the timer.
  29 *
  30 *  - Counter value of the running timer is one less than the actual value.
  31 *
  32 *  - Changing period/frequency of the running timer loses time elapsed
  33 *    since the last period, effectively restarting the timer with a
  34 *    counter = counter value at the moment of change (.i.e. one less).
  35 */
  36#define PTIMER_POLICY_DEFAULT               0
  37
  38/* Periodic timer counter stays with "0" for a one period before wrapping
  39 * around.  */
  40#define PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD (1 << 0)
  41
  42/* Running periodic timer that has counter = limit = 0 would continuously
  43 * re-trigger every period.  */
  44#define PTIMER_POLICY_CONTINUOUS_TRIGGER    (1 << 1)
  45
  46/* Starting to run with/setting counter to "0" won't trigger immediately,
  47 * but after a one period for both oneshot and periodic modes.  */
  48#define PTIMER_POLICY_NO_IMMEDIATE_TRIGGER  (1 << 2)
  49
  50/* Starting to run with/setting counter to "0" won't re-load counter
  51 * immediately, but after a one period.  */
  52#define PTIMER_POLICY_NO_IMMEDIATE_RELOAD   (1 << 3)
  53
  54/* Make counter value of the running timer represent the actual value and
  55 * not the one less.  */
  56#define PTIMER_POLICY_NO_COUNTER_ROUND_DOWN (1 << 4)
  57
  58/* ptimer.c */
  59typedef struct ptimer_state ptimer_state;
  60typedef void (*ptimer_cb)(void *opaque);
  61
  62ptimer_state *ptimer_init(QEMUBH *bh, uint8_t policy_mask);
  63void ptimer_set_period(ptimer_state *s, int64_t period);
  64void ptimer_set_freq(ptimer_state *s, uint32_t freq);
  65uint64_t ptimer_get_limit(ptimer_state *s);
  66void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload);
  67uint64_t ptimer_get_count(ptimer_state *s);
  68void ptimer_set_count(ptimer_state *s, uint64_t count);
  69void ptimer_run(ptimer_state *s, int oneshot);
  70void ptimer_stop(ptimer_state *s);
  71
  72extern const VMStateDescription vmstate_ptimer;
  73
  74#define VMSTATE_PTIMER(_field, _state) \
  75    VMSTATE_STRUCT_POINTER_V(_field, _state, 1, vmstate_ptimer, ptimer_state)
  76
  77#define VMSTATE_PTIMER_ARRAY(_f, _s, _n)                                \
  78    VMSTATE_ARRAY_OF_POINTER_TO_STRUCT(_f, _s, _n, 0,                   \
  79                                       vmstate_ptimer, ptimer_state)
  80
  81#endif
  82