ep93xx timer: Make get_ticks() consistent with get_tbclk(), returning a value with CONFIG_SYS_HZ resolution. This fix obsoletes the function clk_to_systicks(), leading to a simplification of the timer code. Further a variable in usecs_to_ticks() is promoted to a 64-bit value, to avoid overflows of intermediate values.
Signed-off-by: Matthias Kaehlcke matthias@kaehlcke.net Tested-by: Alessandro Rubini rubini-list@gnudd.com
--- cpu/arm920t/ep93xx/timer.c | 83 +++++++++++++++++++------------------------ 1 files changed, 37 insertions(+), 46 deletions(-)
diff --git a/cpu/arm920t/ep93xx/timer.c b/cpu/arm920t/ep93xx/timer.c index b1a01a0..c4c1fb0 100644 --- a/cpu/arm920t/ep93xx/timer.c +++ b/cpu/arm920t/ep93xx/timer.c @@ -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 @@ -36,67 +35,55 @@ #define TIMER_CLKSEL (1 << 3) #define TIMER_ENABLE (1 << 7)
-#define TIMER_FREQ 508469 +#define TIMER_FREQ 508469 /* ticks / second */ #define TIMER_MAX_VAL 0xFFFFFFFF
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) +static inline unsigned long long usecs_to_ticks(unsigned long usecs) { - 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 usecs_to_ticks(unsigned long usecs) -{ - unsigned long ticks; - - if (usecs >= 1000) { - ticks = usecs / 1000; - ticks *= TIMER_FREQ; - ticks /= 1000; - } else { - ticks = usecs * TIMER_FREQ; - ticks /= (1000 * 1000); - } + unsigned long long ticks = usecs * TIMER_FREQ; + do_div(ticks, 1000 * 1000);
return ticks; }
-static inline unsigned long read_timer(void) +static inline void read_timer(void) { - struct timer_regs *timer = (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); + + if (now >= timer.last_read) + timer.ticks += now - timer.last_read; + else + /* an overflow occurred */ + timer.ticks += TIMER_MAX_VAL - timer.last_read + now;
- return TIMER_MAX_VAL - readl(&timer->timer3.value); + timer.last_read = now; }
/* - * timer without interrupts + * Get the number of ticks (in CONFIG_SYS_HZ resolution) */ 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 timer.ticks; + return sys_ticks; }
unsigned long get_timer_masked(void) { - return clk_to_systicks(get_ticks()); + return get_ticks(); }
unsigned long get_timer(unsigned long base) @@ -106,7 +93,7 @@ unsigned long get_timer(unsigned long base)
void reset_timer_masked(void) { - timer.last_update = read_timer(); + read_timer(); timer.ticks = 0; }
@@ -117,25 +104,29 @@ void reset_timer(void)
void __udelay(unsigned long usec) { - const unsigned long target = get_ticks() + usecs_to_ticks(usec); + unsigned long long target; + + read_timer(); + + target = timer.ticks + usecs_to_ticks(usec);
- while (get_ticks() < target) - /* noop */; + while (timer.ticks < target) + read_timer(); }
int timer_init(void) { - struct timer_regs *timer = (struct timer_regs *)TIMER_BASE; + struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE;
- /* use timer 3 with 508KHz and free running */ - writel(TIMER_CLKSEL, &timer->timer3.control); + /* use timer 3 with 508KHz and free running, not enabled now */ + writel(TIMER_CLKSEL, &timer_regs->timer3.control);
- /* set initial timer value 3 */ - writel(TIMER_MAX_VAL, &timer->timer3.load); + /* set initial timer value */ + writel(TIMER_MAX_VAL, &timer_regs->timer3.load);
/* Enable the timer */ writel(TIMER_ENABLE | TIMER_CLKSEL, - &timer->timer3.control); + &timer_regs->timer3.control);
reset_timer_masked();