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/* Periodic Interval Timer Implementation for OpenPCD
* (C) 2006 by Harald Welte <hwelte@hmw-consulting.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
* TODO: handle jiffies wrap correctly!
*/
#include <errno.h>
#include <sys/types.h>
#include <asm/system.h>
#include <lib_AT91SAM7.h>
#include <AT91SAM7.h>
#include <os/pit.h>
#include <os/dbgu.h>
#include <os/system_irq.h>
#include "../openpcd.h"
/* PIT runs at MCK/16 (= 3MHz) */
#define PIV_MS(x) (x * 3000)
static struct timer_list *timers;
volatile unsigned long jiffies;
static void __timer_insert(struct timer_list *new)
{
struct timer_list *tl, *tl_prev = NULL;
if (!timers) {
/* optimize for the common, fast case */
new->next = NULL;
timers = new;
return;
}
for (tl = timers; tl != NULL; tl = tl->next) {
if (tl->expires < new->expires) {
/* we need ot add just before this one */
if (!tl_prev) {
new->next = timers;
timers = new;
} else {
new->next = tl;
tl_prev->next = new;
}
}
tl_prev = tl;
}
}
static int __timer_remove(struct timer_list *old)
{
struct timer_list *tl, *tl_prev = NULL;
for (tl = timers; tl != NULL; tl = tl->next) {
if (tl == old) {
if (tl == timers)
timers = tl->next;
else
tl_prev->next = tl->next;
return 1;
}
tl_prev = tl;
}
return 0;
}
int timer_del(struct timer_list *tl)
{
unsigned long flags;
int ret;
local_irq_save(flags);
ret = __timer_remove(tl);
local_irq_restore(flags);
return ret;
}
void timer_add(struct timer_list *tl)
{
unsigned long flags;
local_irq_save(flags);
__timer_insert(tl);
local_irq_restore(flags);
}
static void pit_irq(u_int32_t sr)
{
struct timer_list *tl, *next;
unsigned long flags;
if (!(sr & 0x1))
return;
jiffies += *AT91C_PITC_PIVR >> 20;
/* this is the most simple/stupid algorithm one can come up with, but
* hey, we're on a small embedded platform with only a hand ful
* of timers, at all */
for (tl = timers; tl != NULL; tl = next) {
next = tl->next;
if (tl->expires <= jiffies) {
/* delete timer from list */
timer_del(tl);
tl->function(tl->data);
}
}
}
void pit_mdelay(u_int32_t ms)
{
u_int32_t end;
end = (AT91F_PITGetPIIR(AT91C_BASE_PITC) + ms) % 20;
while (end < AT91F_PITGetPIIR(AT91C_BASE_PITC)) { }
}
void pit_init(void)
{
AT91F_PITC_CfgPMC();
AT91F_PITInit(AT91C_BASE_PITC, 1000000/HZ /* uS */, 48 /* MHz */);
sysirq_register(AT91SAM7_SYSIRQ_PIT, &pit_irq);
AT91F_PITEnableInt(AT91C_BASE_PITC);
}
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