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 */
  59 typedef struct ptimer_state ptimer_state;
  60 typedef void (*ptimer_cb)(void *opaque);
  61
  62 ptimer_state *ptimer_init(QEMUBH *bh, uint8_t policy_mask);
  63 void ptimer_set_period(ptimer_state *s, int64_t period);
  64 void ptimer_set_freq(ptimer_state *s, uint32_t freq);
  65 uint64_t ptimer_get_limit(ptimer_state *s);
  66 void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload);
  67 uint64_t ptimer_get_count(ptimer_state *s);
  68 void ptimer_set_count(ptimer_state *s, uint64_t count);
  69 void ptimer_run(ptimer_state *s, int oneshot);
  70 void ptimer_stop(ptimer_state *s);
  71
  72 extern 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