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git.ipfire.org Git - people/ms/u-boot.git/blob - cpu/arm926ejs/nomadik/timer.c
2 * (C) Copyright 2009 Alessandro Rubini
4 * See file CREDITS for list of people who contributed to this
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2 of
10 * the License, or (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
25 #include <asm/arch/mtu.h>
28 * The timer is a decrementer, we'll left it free running at 2.4MHz.
29 * We have 2.4 ticks per microsecond and an overflow in almost 30min
31 #define TIMER_CLOCK (24 * 100 * 1000)
32 #define COUNT_TO_USEC(x) ((x) * 5 / 12) /* overflows at 6min */
33 #define USEC_TO_COUNT(x) ((x) * 12 / 5) /* overflows at 6min */
34 #define TICKS_PER_HZ (TIMER_CLOCK / CONFIG_SYS_HZ)
35 #define TICKS_TO_HZ(x) ((x) / TICKS_PER_HZ)
37 /* macro to read the 32 bit timer: since it decrements, we invert read value */
38 #define READ_TIMER() (~readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0)))
40 /* Configure a free-running, auto-wrap counter with no prescaler */
43 writel(MTU_CRn_ENA
| MTU_CRn_PRESCALE_1
| MTU_CRn_32BITS
,
44 CONFIG_SYS_TIMERBASE
+ MTU_CR(0));
49 /* Restart counting from 0 */
50 void reset_timer(void)
52 writel(0, CONFIG_SYS_TIMERBASE
+ MTU_LR(0)); /* Immediate effect */
55 /* Return how many HZ passed since "base" */
56 ulong
get_timer(ulong base
)
58 return TICKS_TO_HZ(READ_TIMER()) - base
;
61 /* Delay x useconds */
62 void udelay(unsigned long usec
)
67 end
= ini
+ USEC_TO_COUNT(usec
);
68 while ((signed)(end
- READ_TIMER()) > 0)