diff options
Diffstat (limited to 'arch/arm/cpu/armv7/at91/timer.c')
-rw-r--r-- | arch/arm/cpu/armv7/at91/timer.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/arch/arm/cpu/armv7/at91/timer.c b/arch/arm/cpu/armv7/at91/timer.c new file mode 100644 index 0000000000..f70ce83f08 --- /dev/null +++ b/arch/arm/cpu/armv7/at91/timer.c @@ -0,0 +1,136 @@ +/* + * (C) Copyright 2007-2008 + * Stelian Pop <stelian@popies.net> + * Lead Tech Design <www.leadtechdesign.com> + * + * 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., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +#include <common.h> +#include <asm/io.h> +#include <asm/arch/hardware.h> +#include <asm/arch/at91_pit.h> +#include <asm/arch/at91_pmc.h> +#include <asm/arch/clk.h> +#include <div64.h> + +#if !defined(CONFIG_AT91FAMILY) +# error You need to define CONFIG_AT91FAMILY in your board config! +#endif + +DECLARE_GLOBAL_DATA_PTR; + +/* + * We're using the AT91CAP9/SAM9 PITC in 32 bit mode, by + * setting the 20 bit counter period to its maximum (0xfffff). + * (See the relevant data sheets to understand that this really works) + * + * We do also mimic the typical powerpc way of incrementing + * two 32 bit registers called tbl and tbu. + * + * Those registers increment at 1/16 the main clock rate. + */ + +#define TIMER_LOAD_VAL 0xfffff + +static inline unsigned long long tick_to_time(unsigned long long tick) +{ + tick *= CONFIG_SYS_HZ; + do_div(tick, gd->timer_rate_hz); + + return tick; +} + +static inline unsigned long long usec_to_tick(unsigned long long usec) +{ + usec *= gd->timer_rate_hz; + do_div(usec, 1000000); + + return usec; +} + +/* + * Use the PITC in full 32 bit incrementing mode + */ +int timer_init(void) +{ + at91_pmc_t *pmc = (at91_pmc_t *) ATMEL_BASE_PMC; + at91_pit_t *pit = (at91_pit_t *) ATMEL_BASE_PIT; + + /* Enable PITC Clock */ + writel(1 << ATMEL_ID_SYS, &pmc->pcer); + + /* Enable PITC */ + writel(TIMER_LOAD_VAL | AT91_PIT_MR_EN , &pit->mr); + + gd->timer_rate_hz = gd->mck_rate_hz / 16; + gd->tbu = gd->tbl = 0; + + return 0; +} + +/* + * Get the current 64 bit timer tick count + */ +unsigned long long get_ticks(void) +{ + at91_pit_t *pit = (at91_pit_t *) ATMEL_BASE_PIT; + + ulong now = readl(&pit->piir); + + /* increment tbu if tbl has rolled over */ + if (now < gd->tbl) + gd->tbu++; + gd->tbl = now; + return (((unsigned long long)gd->tbu) << 32) | gd->tbl; +} + +void __udelay(unsigned long usec) +{ + unsigned long long start; + ulong tmo; + + start = get_ticks(); /* get current timestamp */ + tmo = usec_to_tick(usec); /* convert usecs to ticks */ + while ((get_ticks() - start) < tmo) + ; /* loop till time has passed */ +} + +/* + * get_timer(base) can be used to check for timeouts or + * to measure elasped time relative to an event: + * + * ulong start_time = get_timer(0) sets start_time to the current + * time value. + * get_timer(start_time) returns the time elapsed since then. + * + * The time is used in CONFIG_SYS_HZ units! + */ +ulong get_timer(ulong base) +{ + return tick_to_time(get_ticks()) - base; +} + +/* + * Return the number of timer ticks per second. + */ +ulong get_tbclk(void) +{ + return gd->timer_rate_hz; +} |