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[Timers] Initialise timers on first use

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Timers are sometimes required before the call to initialise(), so we
cannot rely on initialise() to set up the timers before use.

Also fix a potential integer overflow issue in generic_currticks_udelay()
This commit is contained in:
Michael Brown 2008-03-18 15:23:10 +00:00
parent 2652abdc5f
commit 070cbebc26
2 changed files with 26 additions and 27 deletions
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52
src/core/timer.c
View File

@ -20,7 +20,6 @@
#include <stddef.h>
#include <assert.h>
#include <gpxe/init.h>
#include <gpxe/timer.h>
static struct timer ts_table[0]
@ -28,34 +27,39 @@ static struct timer ts_table[0]
static struct timer ts_table_end[0]
__table_end ( struct timer, timers );
static struct timer *used_ts = NULL;
/*
* This function may be used in custom timer driver.
*
* This udelay implementation works well if you've got a
* fast currticks().
*/
void generic_currticks_udelay(unsigned int usecs)
{
tick_t t;
t = currticks();
while (t + usecs > currticks())
; /* xxx: Relax the cpu some way. */
void generic_currticks_udelay ( unsigned int usecs ) {
tick_t start;
tick_t elapsed;
start = currticks();
do {
/* xxx: Relax the cpu some way. */
elapsed = ( currticks() - start );
} while ( elapsed < usecs );
}
/**
* Identify timer source
*
* @ret timer Timer source
*/
static struct timer * timer ( void ) {
static struct timer *ts = NULL;
static void timer_init(void)
{
struct timer *ts;
/* If we have a timer, use it */
if ( ts )
return ts;
for (ts = ts_table; ts < ts_table_end; ts++) {
if ( ts->init() == 0 ) {
used_ts = ts;
return;
}
/* Scan for a usable timer */
for ( ts = ts_table ; ts < ts_table_end ; ts++ ) {
if ( ts->init() == 0 )
return ts;
}
/* No timer found; we cannot continue */
@ -63,10 +67,6 @@ static void timer_init(void)
while ( 1 ) {};
}
struct init_fn ts_init_fn __init_fn ( INIT_NORMAL ) = {
.initialise = timer_init,
};
/**
* Read current time
*
@ -74,9 +74,8 @@ struct init_fn ts_init_fn __init_fn ( INIT_NORMAL ) = {
*/
tick_t currticks ( void ) {
tick_t ct;
assert(used_ts);
ct = used_ts->currticks();
ct = timer()->currticks();
DBG ( "currticks: %ld.%06ld seconds\n",
ct / USECS_IN_SEC, ct % USECS_IN_SEC );
@ -89,8 +88,7 @@ tick_t currticks ( void ) {
* @v usecs Time to delay, in microseconds
*/
void udelay ( unsigned int usecs ) {
assert(used_ts);
used_ts->udelay ( usecs );
timer()->udelay ( usecs );
}
/**

1
src/include/gpxe/timer.h
View File

@ -2,6 +2,7 @@
#define GPXE_TIMER_H
#include <stddef.h>
#include <gpxe/tables.h>
typedef unsigned long tick_t;