Timer implementation. More...

Classes
struct	sleep_data
	Contains the entry of a wait queue and timespec which keeps trakc of the remaining time. More...

Macros
#define	__DEBUG_HEADER__ "[TIMER ]"
	Change header.

#define	__DEBUG_LEVEL__ LOGLEVEL_NOTICE
	Set log level.

#define	PIT_DATAREG0 0x40u
	Channel 0 data port (read/write).

#define	PIT_DATAREG1 0x41u
	Channel 1 data port (read/write).

#define	PIT_DATAREG2 0x42u
	Channel 2 data port (read/write).

#define	PIT_COMREG 0x43u
	Mode/Command register (write only, a read is ignored).

#define	PIT_DIVISOR 1193182
	Frequency divider value (1.193182 MHz).

#define	PIT_CONFIGURATION 0x34u
	Command used to configure the PIT. More...

#define	PIT_MASK 0xFFu
	Mask used to set the divisor.

Typedefs
typedef struct sleep_data	sleep_data_t
	Contains the entry of a wait queue and timespec which keeps trakc of the remaining time.

Functions
void	timer_phase (const uint32_t hz)
	Allows to set the timer phase to the given frequency. More...

void	timer_handler (pt_regs *reg)
	Handles the timer. More...

void	timer_install (void)
	Sets up the system clock by installing the timer handler into IRQ0.

uint64_t	timer_get_seconds (void)
	Returns the number of seconds since the system started its execution. More...

unsigned long	timer_get_ticks (void)
	Returns the number of ticks since the system started its execution. More...

static void	__print_vector (list_head *vector)
	Prints the addresses of all the timers inside a vector. More...

static void	__print_vector_base (tvec_base_t *base)
	Prints the addresses of all the timers inside a vector base. More...

static void	__tvec_base_init (tvec_base_t *base)
	Initializes the tvec_base. More...

static list_head *	__timer_get_target_vector (tvec_base_t base, struct timer_list timer)
	Select correct timer vector and position inside of it for the input timer index contains the position inside of the tv_index timer vector. More...

static void	__timer_cascate_vector (tvec_base_t base, list_head current_vector)
	Move all timers from tv up one level. More...

static void	__timer_cascate_base (tvec_base_t *base)
	Move all timers from tv up one level. More...

static struct timer_list *	__timer_list_alloc (void)
	Allocates the memory for timer. More...

static void	__timer_list_dealloc (struct timer_list *timer)
	Frees the memory of a timer. More...

void	init_timer (struct timer_list *timer)
	Initializes a new timer struct. More...

void	add_timer (struct timer_list *timer)
	Add a new timer to the current CPU. More...

void	remove_timer (struct timer_list *timer)
	Removes a timer from the current CPU. More...

static sleep_data_t *	__sleep_data_alloc (void)
	Allocates the memory for sleep_data. More...

static void	__sleep_data_dealloc (sleep_data_t *sleep_data)
	Frees the memory of a sleep_data. More...

static void	__values_to_itimerval (time_t interval, time_t value, struct itimerval *timer)
	Transforms interval and value to the timer. More...

static void	__itimerval_to_values (time_t interval, time_t value, const struct itimerval *timer)
	Transforms an interval timer to values. More...

static void	__update_task_itimerval (int which, const struct itimerval *timer)
	Updates the timer for the given task. More...

void	dynamic_timers_install (void)
	Initialize dynamic timer system.

void	run_timer_softirq (void)
	Updates the timer data structures.

static void	debug_timeout (unsigned long data)
	Standard debugging function callback. More...

static void	sleep_timeout (unsigned long data)
	Callback for when a sleep timer expires. More...

static void	alarm_timeout (unsigned long task_ptr)
	Function executed when the real_timer of a process expires, sends SIGALRM to process. More...

static void	real_timer_timeout (unsigned long task_ptr)
	Function executed when the real_timer of a process expires, sends SIGALRM to process. More...

int	sys_nanosleep (const struct timespec req, struct timespec rem)
	Suspends the execution of the calling thread. More...

unsigned	sys_alarm (int seconds)
	Send signal to calling thread after desired seconds. More...

int	sys_getitimer (int which, struct itimerval *curr_value)
	Fills the structure pointed to by curr_value with the current setting for the timer specified by which. More...

int	sys_setitimer (int which, const struct itimerval new_value, struct itimerval old_value)
	Arms or disarms the timer specified by which, by setting the timer to the value specified by new_value. More...

void	update_process_profiling_timer (task_struct *proc)
	Update the profiling timer and generate SIGPROF if it has expired. More...

Variables
static __volatile__ unsigned long	timer_ticks = 0
	The number of ticks since the system started its execution.

static tvec_base_t	cpu_base = { 0 }
	Contains timer for each CPU (for now only one)

static wait_queue_head_t	sleep_queue
	Contains all process waiting for a sleep.

Detailed Description

Timer implementation.

Copyright: (c) 2014-2024 This file is distributed under the MIT License. See LICENSE.md for details.

Macro Definition Documentation

◆ PIT_CONFIGURATION

#define PIT_CONFIGURATION 0x34u

Command used to configure the PIT.

Bits Usage 6 and 7 [Select channel] 0 0 = Channel 0 0 1 = Channel 1 1 0 = Channel 2 1 1 = Read-back command (8254 only) 4 and 5 [Access mode] 0 0 = Latch count value command 0 1 = Access mode: lobyte only 1 0 = Access mode: hibyte only 1 1 = Access mode: lobyte/hibyte 1 to 3 [Operating mode] 0 0 0 = Mode 0 (interrupt on terminal count) 0 0 1 = Mode 1 (hardware re-triggerable one-shot) 0 1 0 = Mode 2 (rate generator) 0 1 1 = Mode 3 (square wave generator) 1 0 0 = Mode 4 (software triggered strobe) 1 0 1 = Mode 5 (hardware triggered strobe) 1 1 0 = Mode 2 (rate generator, same as 010b) 1 1 1 = Mode 3 (square wave generator, same as 011b) 0 [BCD/Binary mode] 0 = 16-bit binary 1 = four-digit BCD

Examples: 0x36 = 00|11|011|0 0x34 = 00|11|010|0

Function Documentation

◆ __itimerval_to_values()

static void __itimerval_to_values	(	time_t *	interval,
		time_t *	value,
		const struct itimerval *	timer
	)

inlinestatic

Transforms an interval timer to values.

Parameters

interval	the output variable where to store the interval for periodic timer.
value	the output variable where to store the time until next expiration.
timer	the timer used to initialize the values.

◆ __print_vector()

static void __print_vector ( list_head * vector )

inlinestatic

Prints the addresses of all the timers inside a vector.

Parameters

vector the vector for which we print the details.

◆ __print_vector_base()

static void __print_vector_base ( tvec_base_t * base )

inlinestatic

Prints the addresses of all the timers inside a vector base.

Parameters

base	the base for which we print the details.

◆ __sleep_data_alloc()

static sleep_data_t* __sleep_data_alloc ( void )

inlinestatic

Allocates the memory for sleep_data.

Returns: a pointer to the allocated sleep_data.

◆ __sleep_data_dealloc()

static void __sleep_data_dealloc ( sleep_data_t * sleep_data )

inlinestatic

Frees the memory of a sleep_data.

Parameters

sleep_data pointer to the sleep_data.

◆ __timer_cascate_base()

static void __timer_cascate_base ( tvec_base_t * base )

inlinestatic

Move all timers from tv up one level.

Parameters

base	the base for which we move the timers.

Cascading means moving all dynamic timers in the base->tvn list into the proper lists of base->tvr; then, it returns a positive value, unless all base->tvn lists are now empty. If so, cascade() is invoked once more to replenish base->tvn with the timers included in a list of base->tvn, and so on.

◆ __timer_cascate_vector()

static void __timer_cascate_vector	(	tvec_base_t *	base,
		list_head *	current_vector
	)

inlinestatic

Move all timers from tv up one level.

Parameters

base	the base that contains the vector we want to cascate.
current_vector	the vector we want to cascate.

◆ __timer_get_target_vector()

static list_head* __timer_get_target_vector	(	tvec_base_t *	base,
		struct timer_list *	timer
	)

inlinestatic

Select correct timer vector and position inside of it for the input timer index contains the position inside of the tv_index timer vector.

Parameters

base	the vector base we use to search the vector.
timer	the timer we use to determine the target vector.

Returns: a pointer to the target vector.

◆ __timer_list_alloc()

static struct timer_list* __timer_list_alloc ( void )

inlinestatic

Allocates the memory for timer.

Returns: a pointer to the allocated timer.

◆ __timer_list_dealloc()

static void __timer_list_dealloc ( struct timer_list * timer )

inlinestatic

Frees the memory of a timer.

Parameters

timer pointer to the timer.

◆ __tvec_base_init()

static void __tvec_base_init ( tvec_base_t * base )

inlinestatic

Initializes the tvec_base.

Parameters

base	the base to initialize.

◆ __update_task_itimerval()

static void __update_task_itimerval	(	int	which,
		const struct itimerval *	timer
	)

static

Updates the timer for the given task.

Parameters

which	the type of operation to execute.
timer	the timer to update.

◆ __values_to_itimerval()

static void __values_to_itimerval	(	time_t	interval,
		time_t	value,
		struct itimerval *	timer
	)

inlinestatic

Transforms interval and value to the timer.

Parameters

interval	the interval for periodic timer.
value	the time until next expiration.
timer	where the final values should be stored.

◆ add_timer()

void add_timer ( struct timer_list * timer )

Add a new timer to the current CPU.

Parameters

timer The timer to add.

◆ alarm_timeout()

static void alarm_timeout ( unsigned long task_ptr )

inlinestatic

Function executed when the real_timer of a process expires, sends SIGALRM to process.

Parameters

task_ptr pointer to the process whos associated timer has expired.

◆ debug_timeout()

static void debug_timeout ( unsigned long data )

inlinestatic

Standard debugging function callback.

Parameters

data The data.

◆ init_timer()

void init_timer ( struct timer_list * timer )

Initializes a new timer struct.

Parameters

timer The timer to initialize.

◆ real_timer_timeout()

static void real_timer_timeout ( unsigned long task_ptr )

inlinestatic

Function executed when the real_timer of a process expires, sends SIGALRM to process.

Parameters

task_ptr pointer to the process whos associated timer has expired.

◆ remove_timer()

void remove_timer ( struct timer_list * timer )

Removes a timer from the current CPU.

Parameters

timer The timer to remove.

◆ sleep_timeout()

static void sleep_timeout ( unsigned long data )

inlinestatic

Callback for when a sleep timer expires.

Parameters

data	Custom data stored in the timer.

◆ sys_alarm()

unsigned sys_alarm ( int seconds )

Send signal to calling thread after desired seconds.

Parameters

seconds The number of seconds in the interval

Returns: the number of seconds remaining until any previously scheduled alarm was due to be delivered, or zero if there was no previously scheduled alarm.

◆ sys_getitimer()

int sys_getitimer	(	int	which,
		struct itimerval *	curr_value
	)

Fills the structure pointed to by curr_value with the current setting for the timer specified by which.

Parameters

which	The time domain (i.e., ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF)
curr_value	There the values must be stored.

Returns: Zero on success, or a negative value indicating the error.

◆ sys_nanosleep()

int sys_nanosleep	(	const struct timespec *	req,
		struct timespec *	rem
	)

Suspends the execution of the calling thread.

Parameters

req	The amount of time we want to sleep.
rem	The remaining time we did not sleep.

Returns: If the call is interrupted by a signal handler, nanosleep() returns -1, sets errno to EINTR, and writes the remaining time into the structure pointed to by rem unless rem is NULL.

The execution is suspended until either at least the time specified in *req has elapsed, or the delivery of a signal that triggers the invocation of a handler in the calling thread or that terminates the process.

◆ sys_setitimer()

int sys_setitimer	(	int	which,
		const struct itimerval *	new_value,
		struct itimerval *	old_value
	)

Arms or disarms the timer specified by which, by setting the timer to the value specified by new_value.

The system provides each process with three interval timers, each decrementing in a distinct time domain. When any timer expires, a signal is sent to the process, and the timer (potentially) restarts.

Parameters

which	The time domain (i.e., ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF)
new_value	The new value to set.
old_value	Where the old value must be stored.

Returns: Zero on success, or a negative value indicating the error.

◆ timer_get_seconds()

uint64_t timer_get_seconds ( void )

Returns the number of seconds since the system started its execution.

Returns: Value in seconds.

◆ timer_get_ticks()

unsigned long timer_get_ticks ( void )

Returns the number of ticks since the system started its execution.

Returns: Value in ticks.

◆ timer_handler()

void timer_handler ( pt_regs * f )

Handles the timer.

Parameters

f	The interrupt stack frame.

In this case, it's very simple: We increment the 'timer_ticks' variable every time the timer fires. By default, the timer fires 18.222 times per second. Why 18.222Hz? Some engineer at IBM must've been smoking something funky.

◆ timer_phase()

void timer_phase ( const uint32_t hz )

Allows to set the timer phase to the given frequency.

Parameters

hz	The frequency to set.

◆ update_process_profiling_timer()

void update_process_profiling_timer ( task_struct * proc )

Update the profiling timer and generate SIGPROF if it has expired.

Parameters

proc	The process for which we must update the profiling.

Classes

Macros

Typedefs

Functions

Variables

Detailed Description

Macro Definition Documentation

◆ PIT_CONFIGURATION

Function Documentation

◆ __itimerval_to_values()

◆ __print_vector()

◆ __print_vector_base()

◆ __sleep_data_alloc()

◆ __sleep_data_dealloc()

◆ __timer_cascate_base()

◆ __timer_cascate_vector()

◆ __timer_get_target_vector()

◆ __timer_list_alloc()

◆ __timer_list_dealloc()

◆ __tvec_base_init()

◆ __update_task_itimerval()

◆ __values_to_itimerval()

◆ add_timer()

◆ alarm_timeout()

◆ debug_timeout()

◆ init_timer()

◆ real_timer_timeout()

◆ remove_timer()

◆ sleep_timeout()

◆ sys_alarm()

◆ sys_getitimer()

◆ sys_nanosleep()

◆ sys_setitimer()

◆ timer_get_seconds()

◆ timer_get_ticks()

◆ timer_handler()

◆ timer_phase()

◆ update_process_profiling_timer()