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AS3525: implement tick_start() with TIMER2

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19027 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Rafaël Carré 2008-11-06 14:34:37 +00:00
parent baecdb632c
commit 94c06c7e95
2 changed files with 38 additions and 1 deletions
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31
firmware/target/arm/as3525/kernel-as3525.c
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@ -21,8 +21,37 @@
#include "config.h"
#include "system.h"
#include "kernel.h"
#include "panic.h"
void INT_TIMER2(void)
{
call_tick_tasks(); /* Run through the list of tick tasks */
TIMER2_INTCLR = 0; /* clear interrupt */
}
void tick_start(unsigned int interval_in_ms)
{
(void)interval_in_ms;
int phi = 0; /* prescaler bits */
int prescale = 1;
int cycles = 64000 * interval_in_ms; /* pclk is clocked at 64MHz */
while(cycles > 0x10000)
{
phi++;
prescale <<= 4;
cycles >>= 4;
}
if(prescale > 256)
panicf("%s : interval too big", __func__);
CGU_PERI |= CGU_TIMER2_CLOCK_ENABLE; /* enable peripheral */
VIC_INT_ENABLE = INTERRUPT_TIMER2; /* enable interrupt */
TIMER2_LOAD = TIMER2_BGLOAD = cycles; /* timer period */
/* /!\ bit 4 (reserved) must not be modified
* periodic mode, interrupt enabled, 16 bits counter */
TIMER2_CONTROL = (TIMER2_CONTROL & (1<<4)) | 0xe0 | (phi<<2);
}