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Diffstat (limited to 'board/armltd/integratorcp/timer.c')
| -rw-r--r-- | board/armltd/integratorcp/timer.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/board/armltd/integratorcp/timer.c b/board/armltd/integratorcp/timer.c new file mode 100644 index 000000000..741035cc6 --- /dev/null +++ b/board/armltd/integratorcp/timer.c @@ -0,0 +1,176 @@ +/* + * (C) Copyright 2002 + * Sysgo Real-Time Solutions, GmbH <www.elinos.com> + * Marius Groeger <mgroeger@sysgo.de> + * + * (C) Copyright 2002 + * David Mueller, ELSOFT AG, <d.mueller@elsoft.ch> + * + * (C) Copyright 2003 + * Texas Instruments, <www.ti.com> + * Kshitij Gupta <Kshitij@ti.com> + * + * (C) Copyright 2004 + * ARM Ltd. + * Philippe Robin, <philippe.robin@arm.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 <div64.h> + +/* The Integrator/CP timer1 is clocked at 1MHz + * can be divided by 16 or 256 + * and can be set up as a 32-bit timer + */ +/* U-Boot expects a 32 bit timer, running at CONFIG_SYS_HZ */ +/* Keep total timer count to avoid losing decrements < div_timer */ +static unsigned long long total_count = 0; +static unsigned long long lastdec; /* Timer reading at last call */ +static unsigned long long div_clock = 1; /* Divisor applied to timer clock */ +static unsigned long long div_timer = 1; /* Divisor to convert timer reading + * change to U-Boot ticks + */ +/* CONFIG_SYS_HZ = CONFIG_SYS_HZ_CLOCK/(div_clock * div_timer) */ +static ulong timestamp; /* U-Boot ticks since startup */ + +#define TIMER_LOAD_VAL ((ulong)0xFFFFFFFF) +#define READ_TIMER (*(volatile ulong *)(CONFIG_SYS_TIMERBASE+4)) + +/* all function return values in U-Boot ticks i.e. (1/CONFIG_SYS_HZ) sec + * - unless otherwise stated + */ + +/* starts up a counter + * - the Integrator/CP timer can be set up to issue an interrupt */ +int timer_init (void) +{ + /* Load timer with initial value */ + *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 0) = TIMER_LOAD_VAL; + /* Set timer to be + * enabled 1 + * periodic 1 + * no interrupts 0 + * X 0 + * divider 1 00 == less rounding error + * 32 bit 1 + * wrapping 0 + */ + *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8) = 0x000000C2; + /* init the timestamp */ + total_count = 0ULL; + reset_timer_masked(); + + div_timer = (unsigned long long)(CONFIG_SYS_HZ_CLOCK / CONFIG_SYS_HZ); + div_timer /= div_clock; + + return (0); +} + +/* + * timer without interrupts + */ +void reset_timer (void) +{ + reset_timer_masked (); +} + +ulong get_timer (ulong base_ticks) +{ + return get_timer_masked () - base_ticks; +} + +void set_timer (ulong ticks) +{ + timestamp = ticks; + total_count = (unsigned long long)ticks * div_timer; +} + +/* delay usec useconds */ +void udelay (unsigned long usec) +{ + ulong tmo, tmp; + + /* Convert to U-Boot ticks */ + tmo = usec * CONFIG_SYS_HZ; + tmo /= (1000000L); + + tmp = get_timer_masked(); /* get current timestamp */ + tmo += tmp; /* form target timestamp */ + + while (get_timer_masked () < tmo) {/* loop till event */ + /*NOP*/; + } +} + +void reset_timer_masked (void) +{ + /* capure current decrementer value */ + lastdec = (unsigned long long)READ_TIMER; + /* start "advancing" time stamp from 0 */ + timestamp = 0L; +} + +/* converts the timer reading to U-Boot ticks */ +/* the timestamp is the number of ticks since reset */ +ulong get_timer_masked (void) +{ + /* get current count */ + unsigned long long now = (unsigned long long)READ_TIMER; + + if(now > lastdec) { + /* Must have wrapped */ + total_count += lastdec + TIMER_LOAD_VAL + 1 - now; + } else { + total_count += lastdec - now; + } + lastdec = now; + + /* Reuse "now" */ + now = total_count; + do_div(now, div_timer); + timestamp = now; + + return timestamp; +} + +/* waits specified delay value and resets timestamp */ +void udelay_masked (unsigned long usec) +{ + udelay(usec); +} + +/* + * This function is derived from PowerPC code (read timebase as long long). + * On ARM it just returns the timer value. + */ +unsigned long long get_ticks(void) +{ + return (unsigned long long)get_timer(0); +} + +/* + * Return the timebase clock frequency + * i.e. how often the timer decrements + */ +ulong get_tbclk (void) +{ + return (ulong)(((unsigned long long)CONFIG_SYS_HZ_CLOCK)/div_clock); +} |