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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 5962bffcb5
commit 44de3e8ff7
1 changed files with 24 additions and 28 deletions
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52
cpu/arm920t/ep93xx/timer.c
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@ -1,8 +1,7 @@
/* /*
* Cirrus Logic EP93xx timer support. * Cirrus Logic EP93xx timer support.
* *
* Copyright (C) 2009, 2010 * Copyright (C) 2009, 2010 Matthias Kaehlcke <matthias@kaehlcke.net>
* Matthias Kaehlcke <matthias@kaehlcke.net>
* *
* Copyright (C) 2004, 2005 * Copyright (C) 2004, 2005
* Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com> * Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com>
@ -42,17 +41,9 @@
static struct ep93xx_timer static struct ep93xx_timer
{ {
unsigned long long ticks; unsigned long long ticks;
unsigned long last_update; unsigned long last_read;
} timer; } 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) static inline unsigned long long usecs_to_ticks(unsigned long usecs)
{ {
unsigned long long ticks = (unsigned long long)usecs * TIMER_FREQ; 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; 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; 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) unsigned long long get_ticks(void)
{ {
const unsigned long now = read_timer(); unsigned long long sys_ticks;
if (now >= timer.last_update) read_timer();
timer.ticks += now - timer.last_update;
else
/* an overflow occurred */
timer.ticks += TIMER_MAX_VAL - timer.last_update + now;
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) unsigned long get_timer_masked(void)
@ -98,7 +93,7 @@ unsigned long get_timer(unsigned long base)
void reset_timer_masked(void) void reset_timer_masked(void)
{ {
timer.last_update = read_timer(); read_timer();
timer.ticks = 0; timer.ticks = 0;
} }
@ -109,23 +104,24 @@ void reset_timer(void)
void __udelay(unsigned long usec) void __udelay(unsigned long usec)
{ {
/* read the timer and update timer.ticks */ unsigned long long target;
get_ticks();
const unsigned long long target = timer.ticks + usecs_to_ticks(usec); read_timer();
target = timer.ticks + usecs_to_ticks(usec);
while (timer.ticks < target) while (timer.ticks < target)
get_ticks(); read_timer();
} }
int timer_init(void) int timer_init(void)
{ {
struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE; 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); writel(TIMER_CLKSEL, &timer_regs->timer3.control);
/* set initial timer value 3 */ /* set initial timer value */
writel(TIMER_MAX_VAL, &timer_regs->timer3.load); writel(TIMER_MAX_VAL, &timer_regs->timer3.load);
/* Enable the timer */ /* Enable the timer */