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Diffstat (limited to 'cpu/arm920t/ep93xx/timer.c')
-rw-r--r-- | cpu/arm920t/ep93xx/timer.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/cpu/arm920t/ep93xx/timer.c b/cpu/arm920t/ep93xx/timer.c new file mode 100644 index 00000000000..6d969d9302d --- /dev/null +++ b/cpu/arm920t/ep93xx/timer.c @@ -0,0 +1,168 @@ +/* + * Cirrus Logic EP93xx timer support. + * + * Copyright (C) 2009, 2010 + * Matthias Kaehlcke <matthias@kaehlcke.net> + * + * Copyright (C) 2004, 2005 + * Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com> + * + * Based on the original intr.c Cirrus Logic EP93xx Rev D. interrupt support, + * author unknown. + * + * See file CREDITS for list of people who contributed to this project. + * + * 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., + * 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <common.h> +#include <linux/types.h> +#include <asm/arch/ep93xx.h> +#include <asm/io.h> + +#define TIMER_CLKSEL (1 << 3) +#define TIMER_MODE (1 << 6) +#define TIMER_ENABLE (1 << 7) + +#define TIMER_FREQ 508469 +#define TIMER_LOAD_VAL (TIMER_FREQ / CONFIG_SYS_HZ) + +static ulong timestamp; +static ulong lastdec; + +static inline unsigned long clk_to_systicks(unsigned long clk_ticks) +{ + unsigned long sys_ticks = (clk_ticks * CONFIG_SYS_HZ) / TIMER_FREQ; + + return sys_ticks; +} + +static inline unsigned long usecs_to_ticks(unsigned long usecs) +{ + unsigned long ticks; + + if (usecs >= 1000) { + ticks = usecs / 1000; + ticks *= (TIMER_LOAD_VAL * CONFIG_SYS_HZ); + ticks /= 1000; + } else { + ticks = usecs * TIMER_LOAD_VAL * CONFIG_SYS_HZ; + ticks /= (1000 * 1000); + } + + return ticks; +} + +static inline unsigned long read_timer(void) +{ + struct timer_regs *timer = (struct timer_regs *)TIMER_BASE; + + return readl(&timer->timer3.value); +} + +/* + * timer without interrupts + */ +unsigned long long get_ticks(void) +{ + const unsigned long now = read_timer(); + + if (lastdec >= now) { + /* normal mode */ + timestamp += lastdec - now; + } else { + /* we have an overflow ... */ + timestamp += lastdec + TIMER_LOAD_VAL - now; + } + + lastdec = now; + + return timestamp; +} + +unsigned long get_timer_masked(void) +{ + return clk_to_systicks(get_ticks()); +} + +unsigned long get_timer(unsigned long base) +{ + return get_timer_masked() - base; +} + +void reset_timer_masked(void) +{ + lastdec = read_timer(); + timestamp = 0; +} + +void reset_timer(void) +{ + reset_timer_masked(); +} + +void set_timer(unsigned long t) +{ + timestamp = t; +} + +void __udelay(unsigned long usec) +{ + const unsigned long ticks = usecs_to_ticks(usec); + const unsigned long target = clk_to_systicks(ticks) + get_timer(0); + + while (get_timer_masked() < target) + /* noop */; +} + +void udelay_masked(unsigned long usec) +{ + const unsigned long ticks = usecs_to_ticks(usec); + const unsigned long target = clk_to_systicks(ticks) + get_timer(0); + + reset_timer_masked(); + + while (get_timer_masked() < target) + /* noop */; +} + +int timer_init(void) +{ + struct timer_regs *timer = (struct timer_regs *)TIMER_BASE; + + /* use timer 3 with 508KHz and free running */ + writel(TIMER_CLKSEL, &timer->timer3.control); + + /* auto load, manual update of Timer 3 */ + lastdec = TIMER_LOAD_VAL; + writel(TIMER_LOAD_VAL, &timer->timer3.load); + + /* Enable the timer and periodic mode */ + writel(TIMER_ENABLE | TIMER_MODE | TIMER_CLKSEL, + &timer->timer3.control); + + reset_timer_masked(); + + return 0; +} + +/* + * This function is derived from PowerPC code (timebase clock frequency). + * On ARM it returns the number of timer ticks per second. + */ +unsigned long get_tbclk(void) +{ + return CONFIG_SYS_HZ; +} |