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ep93xx timer: refactoring

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ep93xx timer: Simplified the timer code by eliminating clk_to_systicks() and
performing (almost) all manipulation of the timer structure in read_timer()

Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
This commit is contained in:
Matthias Kaehlcke 2010-03-09 22:13:56 +01:00 committed by trix
parent 33eef04bf8
commit b032698ff6
1 changed files with 24 additions and 28 deletions
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52
cpu/arm920t/ep93xx/timer.c
View file

@ -1,8 +1,7 @@
/*
* Cirrus Logic EP93xx timer support.
*
* Copyright (C) 2009, 2010
* Matthias Kaehlcke <matthias@kaehlcke.net>
* Copyright (C) 2009, 2010 Matthias Kaehlcke <matthias@kaehlcke.net>
*
* Copyright (C) 2004, 2005
* Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com>
@ -42,17 +41,9 @@
static struct ep93xx_timer
{
unsigned long long ticks;
unsigned long last_update;
unsigned long last_read;
} timer;
static inline unsigned long clk_to_systicks(unsigned long long clk_ticks)
{
unsigned long long sys_ticks = (clk_ticks * CONFIG_SYS_HZ);
do_div(sys_ticks, TIMER_FREQ);
return (unsigned long)sys_ticks;
}
static inline unsigned long long usecs_to_ticks(unsigned long usecs)
{
unsigned long long ticks = (unsigned long long)usecs * TIMER_FREQ;
@ -61,11 +52,18 @@ static inline unsigned long long usecs_to_ticks(unsigned long usecs)
return ticks;
}
static inline unsigned long read_timer(void)
static inline void read_timer(void)
{
struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE;
const unsigned long now = TIMER_MAX_VAL - readl(&timer_regs->timer3.value);
return TIMER_MAX_VAL - readl(&timer_regs->timer3.value);
if (now >= timer.last_read)
timer.ticks += now - timer.last_read;
else
/* an overflow occurred */
timer.ticks += TIMER_MAX_VAL - timer.last_read + now;
timer.last_read = now;
}
/*
@ -73,17 +71,14 @@ static inline unsigned long read_timer(void)
*/
unsigned long long get_ticks(void)
{
const unsigned long now = read_timer();
unsigned long long sys_ticks;
if (now >= timer.last_update)
timer.ticks += now - timer.last_update;
else
/* an overflow occurred */
timer.ticks += TIMER_MAX_VAL - timer.last_update + now;
read_timer();
timer.last_update = now;
sys_ticks = timer.ticks * CONFIG_SYS_HZ;
do_div(sys_ticks, TIMER_FREQ);
return clk_to_systicks(timer.ticks);
return sys_ticks;
}
unsigned long get_timer_masked(void)
@ -98,7 +93,7 @@ unsigned long get_timer(unsigned long base)
void reset_timer_masked(void)
{
timer.last_update = read_timer();
read_timer();
timer.ticks = 0;
}
@ -109,23 +104,24 @@ void reset_timer(void)
void __udelay(unsigned long usec)
{
/* read the timer and update timer.ticks */
get_ticks();
unsigned long long target;
const unsigned long long target = timer.ticks + usecs_to_ticks(usec);
read_timer();
target = timer.ticks + usecs_to_ticks(usec);
while (timer.ticks < target)
get_ticks();
read_timer();
}
int timer_init(void)
{
struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE;
/* use timer 3 with 508KHz and free running */
/* use timer 3 with 508KHz and free running, not enabled now */
writel(TIMER_CLKSEL, &timer_regs->timer3.control);
/* set initial timer value 3 */
/* set initial timer value */
writel(TIMER_MAX_VAL, &timer_regs->timer3.load);
/* Enable the timer */