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Added tick and interrupt level functions

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@449 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Linus Nielsen Feltzing 2002-05-05 18:34:06 +00:00
parent 011f1d30f6
commit 9e142daa83
2 changed files with 131 additions and 0 deletions
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129
firmware/kernel.c
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@ -16,11 +16,25 @@
* KIND, either express or implied.
*
****************************************************************************/
#include <stdlib.h>
#include "kernel.h"
#include "thread.h"
#include "sh7034.h"
#include "system.h"
#include "panic.h"
long current_tick = 0;
static void tick_start(unsigned int interval_in_ms);
/****************************************************************************
* Standard kernel stuff
****************************************************************************/
void kernel_init(void)
{
tick_start(1);
}
void sleep(int ticks)
{
int timeout = current_tick + ticks;
@ -36,6 +50,24 @@ void yield(void)
switch_thread();
}
/****************************************************************************
* Interrupt level setting
* NOTE!!!!!!
* This one is not entirely safe. If an interrupt uses this function it
* MUST restore the old level before returning. Otherwise there is a small
* risk that set_irq_level returns the wrong level if interrupted after
* the stc instruction.
****************************************************************************/
int set_irq_level(int level)
{
int i;
/* Read the old level and set the new one */
asm volatile ("stc sr, %0" : "=r" (i));
asm volatile ("ldc %0, sr" : : "r" (level<<4));
return (i >> 4) & 0x0f;
}
/****************************************************************************
* Queue handling stuff
****************************************************************************/
@ -62,3 +94,100 @@ void queue_post(struct event_queue *q, int id, void *data)
q->events[wr].id = id;
q->events[wr].data = data;
}
/****************************************************************************
* Timer tick
****************************************************************************/
#define NUM_TICK_TASKS 4
void (*tick_funcs[NUM_TICK_TASKS])(void) = {NULL, NULL, NULL, NULL};
static void tick_start(unsigned int interval_in_ms)
{
unsigned int count;
count = FREQ / 1000 / 8 * interval_in_ms;
if(count > 0xffff)
{
panicf("Error! The tick interval is too long (%d ms)\n",
interval_in_ms);
return;
}
/* We are using timer 0 */
TSTR &= ~0x01; /* Stop the timer */
TSNC &= ~0x01; /* No synchronization */
TMDR &= ~0x01; /* Operate normally */
TCNT0 = 0; /* Start counting at 0 */
GRA0 = count;
TCR0 = 0x23; /* Clear at GRA match, sysclock/8 */
/* Enable interrupt on level 1 */
IPRC = (IPRC & ~0x00f0) | 0x0010;
TSR0 &= ~0x01;
TIER0 = 0xf9; /* Enable GRA match interrupt */
TSTR |= 0x01; /* Start timer 1 */
}
#pragma interrupt
void IMIA0(void)
{
int i;
/* Run through the list of tick tasks */
for(i = 0;i < NUM_TICK_TASKS;i++)
{
if(tick_funcs[i])
{
tick_funcs[i]();
}
}
current_tick++;
TSR0 &= ~0x01;
}
int tick_add_task(void (*f)(void))
{
int i;
int oldlevel = set_irq_level(15);
/* Add a task if there is room */
for(i = 0;i < NUM_TICK_TASKS;i++)
{
if(tick_funcs[i] == NULL)
{
tick_funcs[i] = f;
set_irq_level(oldlevel);
return 0;
}
}
set_irq_level(oldlevel);
return -1;
}
int tick_remove_task(void (*f)(void))
{
int i;
int oldlevel = set_irq_level(15);
/* Remove a task if it is there */
for(i = 0;i < NUM_TICK_TASKS;i++)
{
if(tick_funcs[i] == f)
{
tick_funcs[i] = NULL;
set_irq_level(oldlevel);
return 0;
}
}
set_irq_level(oldlevel);
return -1;
}