include/hw/ptimer.h - qemu - Git at Google

 /*
  * General purpose implementation of a simple periodic countdown timer.
  *
  * Copyright (c) 2007 CodeSourcery.
  *
  * This code is licensed under the GNU LGPL.
  */
 #ifndef PTIMER_H
 #define PTIMER_H

 #include "qemu-common.h"
 #include "qemu/timer.h"
 #include "migration/vmstate.h"

 /* The ptimer API implements a simple periodic countdown timer.
  * The countdown timer has a value (which can be read and written via
  * ptimer_get_count() and ptimer_set_count()). When it is enabled
  * using ptimer_run(), the value will count downwards at the frequency
  * which has been configured using ptimer_set_period() or ptimer_set_freq().
  * When it reaches zero it will trigger a QEMU bottom half handler, and
  * can be set to either reload itself from a specified limit value
  * and keep counting down, or to stop (as a one-shot timer).
  *
  * Forgetting to set the period/frequency (or setting it to zero) is a
  * bug in the QEMU device and will cause warning messages to be printed
  * to stderr when the guest attempts to enable the timer.
  */

 /* The default ptimer policy retains backward compatibility with the legacy
  * timers. Custom policies are adjusting the default one. Consider providing
  * a correct policy for your timer.
  *
  * The rough edges of the default policy:
  *  - Starting to run with a period = 0 emits error message and stops the
  *    timer without a trigger.
  *
  *  - Setting period to 0 of the running timer emits error message and
  *    stops the timer without a trigger.
  *
  *  - Starting to run with counter = 0 or setting it to "0" while timer
  *    is running causes a trigger and reloads counter with a limit value.
  *    If limit = 0, ptimer emits error message and stops the timer.
  *
  *  - Counter value of the running timer is one less than the actual value.
  *
  *  - Changing period/frequency of the running timer loses time elapsed
  *    since the last period, effectively restarting the timer with a
  *    counter = counter value at the moment of change (.i.e. one less).
  */
 #define PTIMER_POLICY_DEFAULT               0

 /* Periodic timer counter stays with "0" for a one period before wrapping
  * around.  */
 #define PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD (1 << 0)

 /* Running periodic timer that has counter = limit = 0 would continuously
  * re-trigger every period.  */
 #define PTIMER_POLICY_CONTINUOUS_TRIGGER    (1 << 1)

 /* Starting to run with/setting counter to "0" won't trigger immediately,
  * but after a one period for both oneshot and periodic modes.  */
 #define PTIMER_POLICY_NO_IMMEDIATE_TRIGGER  (1 << 2)

 /* Starting to run with/setting counter to "0" won't re-load counter
  * immediately, but after a one period.  */
 #define PTIMER_POLICY_NO_IMMEDIATE_RELOAD   (1 << 3)

 /* Make counter value of the running timer represent the actual value and
  * not the one less.  */
 #define PTIMER_POLICY_NO_COUNTER_ROUND_DOWN (1 << 4)

 /*
  * Starting to run with a zero counter, or setting the counter to "0" via
  * ptimer_set_count() or ptimer_set_limit() will not trigger the timer
  * (though it will cause a reload). Only a counter decrement to "0"
  * will cause a trigger. Not compatible with NO_IMMEDIATE_TRIGGER;
  * ptimer_init() will assert() that you don't set both.
  */
 #define PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT (1 << 5)

 /* ptimer.c */
 typedef struct ptimer_state ptimer_state;
 typedef void (*ptimer_cb)(void *opaque);

 /**
  * ptimer_init - Allocate and return a new ptimer
  * @bh: QEMU bottom half which is run on timer expiry
  * @policy: PTIMER_POLICY_* bits specifying behaviour
  *
  * The ptimer returned must be freed using ptimer_free().
  * The ptimer takes ownership of @bh and will delete it
  * when the ptimer is eventually freed.
  */
 ptimer_state *ptimer_init(QEMUBH *bh, uint8_t policy_mask);

 /**
  * ptimer_free - Free a ptimer
  * @s: timer to free
  *
  * Free a ptimer created using ptimer_init() (including
  * deleting the bottom half which it is using).
  */
 void ptimer_free(ptimer_state *s);

 /**
  * ptimer_set_period - Set counter increment interval in nanoseconds
  * @s: ptimer to configure
  * @period: period of the counter in nanoseconds
  *
  * Note that if your counter behaviour is specified as having a
  * particular frequency rather than a period then ptimer_set_freq()
  * may be more appropriate.
  */
 void ptimer_set_period(ptimer_state *s, int64_t period);

 /**
  * ptimer_set_freq - Set counter frequency in Hz
  * @s: ptimer to configure
  * @freq: counter frequency in Hz
  *
  * This does the same thing as ptimer_set_period(), so you only
  * need to call one of them. If the counter behaviour is specified
  * as setting the frequency then this function is more appropriate,
  * because it allows specifying an effective period which is
  * precise to fractions of a nanosecond, avoiding rounding errors.
  */
 void ptimer_set_freq(ptimer_state *s, uint32_t freq);

 /**
  * ptimer_get_limit - Get the configured limit of the ptimer
  * @s: ptimer to query
  *
  * This function returns the current limit (reload) value
  * of the down-counter; that is, the value which it will be
  * reset to when it hits zero.
  *
  * Generally timer devices using ptimers should be able to keep
  * their reload register state inside the ptimer using the get
  * and set limit functions rather than needing to also track it
  * in their own state structure.
  */
 uint64_t ptimer_get_limit(ptimer_state *s);

 /**
  * ptimer_set_limit - Set the limit of the ptimer
  * @s: ptimer
  * @limit: initial countdown value
  * @reload: if nonzero, then reset the counter to the new limit
  *
  * Set the limit value of the down-counter. The @reload flag can
  * be used to emulate the behaviour of timers which immediately
  * reload the counter when their reload register is written to.
  */
 void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload);

 /**
  * ptimer_get_count - Get the current value of the ptimer
  * @s: ptimer
  *
  * Return the current value of the down-counter. This will
  * return the correct value whether the counter is enabled or
  * disabled.
  */
 uint64_t ptimer_get_count(ptimer_state *s);

 /**
  * ptimer_set_count - Set the current value of the ptimer
  * @s: ptimer
  * @count: count value to set
  *
  * Set the value of the down-counter. If the counter is currently
  * enabled this will arrange for a timer callback at the appropriate
  * point in the future.
  */
 void ptimer_set_count(ptimer_state *s, uint64_t count);

 /**
  * ptimer_run - Start a ptimer counting
  * @s: ptimer
  * @oneshot: non-zero if this timer should only count down once
  *
  * Start a ptimer counting down; when it reaches zero the bottom half
  * passed to ptimer_init() will be invoked. If the @oneshot argument is zero,
  * the counter value will then be reloaded from the limit and it will
  * start counting down again. If @oneshot is non-zero, then the counter
  * will disable itself when it reaches zero.
  */
 void ptimer_run(ptimer_state *s, int oneshot);

 /**
  * ptimer_stop - Stop a ptimer counting
  * @s: ptimer
  *
  * Pause a timer (the count stays at its current value until ptimer_run()
  * is called to start it counting again).
  *
  * Note that this can cause it to "lose" time, even if it is immediately
  * restarted.
  */
 void ptimer_stop(ptimer_state *s);

 extern const VMStateDescription vmstate_ptimer;

 #define VMSTATE_PTIMER(_field, _state) \
     VMSTATE_STRUCT_POINTER_V(_field, _state, 1, vmstate_ptimer, ptimer_state)

 #define VMSTATE_PTIMER_ARRAY(_f, _s, _n)                                \
     VMSTATE_ARRAY_OF_POINTER_TO_STRUCT(_f, _s, _n, 0,                   \
                                        vmstate_ptimer, ptimer_state)

 #endif
	/*
	* General purpose implementation of a simple periodic countdown timer.
	*
	* Copyright (c) 2007 CodeSourcery.
	*
	* This code is licensed under the GNU LGPL.
	*/
	#ifndef PTIMER_H
	#define PTIMER_H

	#include "qemu-common.h"
	#include "qemu/timer.h"
	#include "migration/vmstate.h"

	/* The ptimer API implements a simple periodic countdown timer.
	* The countdown timer has a value (which can be read and written via
	* ptimer_get_count() and ptimer_set_count()). When it is enabled
	* using ptimer_run(), the value will count downwards at the frequency
	* which has been configured using ptimer_set_period() or ptimer_set_freq().
	* When it reaches zero it will trigger a QEMU bottom half handler, and
	* can be set to either reload itself from a specified limit value
	* and keep counting down, or to stop (as a one-shot timer).
	*
	* Forgetting to set the period/frequency (or setting it to zero) is a
	* bug in the QEMU device and will cause warning messages to be printed
	* to stderr when the guest attempts to enable the timer.
	*/

	/* The default ptimer policy retains backward compatibility with the legacy
	* timers. Custom policies are adjusting the default one. Consider providing
	* a correct policy for your timer.
	*
	* The rough edges of the default policy:
	* - Starting to run with a period = 0 emits error message and stops the
	* timer without a trigger.
	*
	* - Setting period to 0 of the running timer emits error message and
	* stops the timer without a trigger.
	*
	* - Starting to run with counter = 0 or setting it to "0" while timer
	* is running causes a trigger and reloads counter with a limit value.
	* If limit = 0, ptimer emits error message and stops the timer.
	*
	* - Counter value of the running timer is one less than the actual value.
	*
	* - Changing period/frequency of the running timer loses time elapsed
	* since the last period, effectively restarting the timer with a
	* counter = counter value at the moment of change (.i.e. one less).
	*/
	#define PTIMER_POLICY_DEFAULT 0

	/* Periodic timer counter stays with "0" for a one period before wrapping
	* around. */
	#define PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD (1 << 0)

	/* Running periodic timer that has counter = limit = 0 would continuously
	* re-trigger every period. */
	#define PTIMER_POLICY_CONTINUOUS_TRIGGER (1 << 1)

	/* Starting to run with/setting counter to "0" won't trigger immediately,
	* but after a one period for both oneshot and periodic modes. */
	#define PTIMER_POLICY_NO_IMMEDIATE_TRIGGER (1 << 2)

	/* Starting to run with/setting counter to "0" won't re-load counter
	* immediately, but after a one period. */
	#define PTIMER_POLICY_NO_IMMEDIATE_RELOAD (1 << 3)

	/* Make counter value of the running timer represent the actual value and
	* not the one less. */
	#define PTIMER_POLICY_NO_COUNTER_ROUND_DOWN (1 << 4)

	/*
	* Starting to run with a zero counter, or setting the counter to "0" via
	* ptimer_set_count() or ptimer_set_limit() will not trigger the timer
	* (though it will cause a reload). Only a counter decrement to "0"
	* will cause a trigger. Not compatible with NO_IMMEDIATE_TRIGGER;
	* ptimer_init() will assert() that you don't set both.
	*/
	#define PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT (1 << 5)

	/* ptimer.c */
	typedef struct ptimer_state ptimer_state;
	typedef void (ptimer_cb)(void opaque);

	/**
	* ptimer_init - Allocate and return a new ptimer
	* @bh: QEMU bottom half which is run on timer expiry
	* @policy: PTIMER_POLICY_* bits specifying behaviour
	*
	* The ptimer returned must be freed using ptimer_free().
	* The ptimer takes ownership of @bh and will delete it
	* when the ptimer is eventually freed.
	*/
	ptimer_state ptimer_init(QEMUBH bh, uint8_t policy_mask);

	/**
	* ptimer_free - Free a ptimer
	* @s: timer to free
	*
	* Free a ptimer created using ptimer_init() (including
	* deleting the bottom half which it is using).
	*/
	void ptimer_free(ptimer_state *s);

	/**
	* ptimer_set_period - Set counter increment interval in nanoseconds
	* @s: ptimer to configure
	* @period: period of the counter in nanoseconds
	*
	* Note that if your counter behaviour is specified as having a
	* particular frequency rather than a period then ptimer_set_freq()
	* may be more appropriate.
	*/
	void ptimer_set_period(ptimer_state *s, int64_t period);

	/**
	* ptimer_set_freq - Set counter frequency in Hz
	* @s: ptimer to configure
	* @freq: counter frequency in Hz
	*
	* This does the same thing as ptimer_set_period(), so you only
	* need to call one of them. If the counter behaviour is specified
	* as setting the frequency then this function is more appropriate,
	* because it allows specifying an effective period which is
	* precise to fractions of a nanosecond, avoiding rounding errors.
	*/
	void ptimer_set_freq(ptimer_state *s, uint32_t freq);

	/**
	* ptimer_get_limit - Get the configured limit of the ptimer
	* @s: ptimer to query
	*
	* This function returns the current limit (reload) value
	* of the down-counter; that is, the value which it will be
	* reset to when it hits zero.
	*
	* Generally timer devices using ptimers should be able to keep
	* their reload register state inside the ptimer using the get
	* and set limit functions rather than needing to also track it
	* in their own state structure.
	*/
	uint64_t ptimer_get_limit(ptimer_state *s);

	/**
	* ptimer_set_limit - Set the limit of the ptimer
	* @s: ptimer
	* @limit: initial countdown value
	* @reload: if nonzero, then reset the counter to the new limit
	*
	* Set the limit value of the down-counter. The @reload flag can
	* be used to emulate the behaviour of timers which immediately
	* reload the counter when their reload register is written to.
	*/
	void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload);

	/**
	* ptimer_get_count - Get the current value of the ptimer
	* @s: ptimer
	*
	* Return the current value of the down-counter. This will
	* return the correct value whether the counter is enabled or
	* disabled.
	*/
	uint64_t ptimer_get_count(ptimer_state *s);

	/**
	* ptimer_set_count - Set the current value of the ptimer
	* @s: ptimer
	* @count: count value to set
	*
	* Set the value of the down-counter. If the counter is currently
	* enabled this will arrange for a timer callback at the appropriate
	* point in the future.
	*/
	void ptimer_set_count(ptimer_state *s, uint64_t count);

	/**
	* ptimer_run - Start a ptimer counting
	* @s: ptimer
	* @oneshot: non-zero if this timer should only count down once
	*
	* Start a ptimer counting down; when it reaches zero the bottom half
	* passed to ptimer_init() will be invoked. If the @oneshot argument is zero,
	* the counter value will then be reloaded from the limit and it will
	* start counting down again. If @oneshot is non-zero, then the counter
	* will disable itself when it reaches zero.
	*/
	void ptimer_run(ptimer_state *s, int oneshot);

	/**
	* ptimer_stop - Stop a ptimer counting
	* @s: ptimer
	*
	* Pause a timer (the count stays at its current value until ptimer_run()
	* is called to start it counting again).
	*
	* Note that this can cause it to "lose" time, even if it is immediately
	* restarted.
	*/
	void ptimer_stop(ptimer_state *s);

	extern const VMStateDescription vmstate_ptimer;

	#define VMSTATE_PTIMER(_field, _state) \
	VMSTATE_STRUCT_POINTER_V(_field, _state, 1, vmstate_ptimer, ptimer_state)

	#define VMSTATE_PTIMER_ARRAY(_f, _s, _n) \
	VMSTATE_ARRAY_OF_POINTER_TO_STRUCT(_f, _s, _n, 0, \
	vmstate_ptimer, ptimer_state)

	#endif