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git.ipfire.org Git - people/ms/u-boot.git/blob - cpu/arm920t/ep93xx/timer.c
2 * Cirrus Logic EP93xx timer support.
4 * Copyright (C) 2009, 2010
5 * Matthias Kaehlcke <matthias@kaehlcke.net>
7 * Copyright (C) 2004, 2005
8 * Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com>
10 * Based on the original intr.c Cirrus Logic EP93xx Rev D. interrupt support,
13 * See file CREDITS for list of people who contributed to this project.
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2 of the License, or
18 * (at your option) any later version.
20 * This program is distributed in the hope that it will be useful, but
21 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
22 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
25 * You should have received a copy of the GNU General Public License along
26 * with this program; if not, write to the Free Software Foundation, Inc.,
27 * 675 Mass Ave, Cambridge, MA 02139, USA.
31 #include <linux/types.h>
32 #include <asm/arch/ep93xx.h>
35 #define TIMER_CLKSEL (1 << 3)
36 #define TIMER_MODE (1 << 6)
37 #define TIMER_ENABLE (1 << 7)
39 #define TIMER_FREQ 508469
40 #define TIMER_LOAD_VAL (TIMER_FREQ / CONFIG_SYS_HZ)
42 static ulong timestamp
;
45 static inline unsigned long clk_to_systicks(unsigned long clk_ticks
)
47 unsigned long sys_ticks
= (clk_ticks
* CONFIG_SYS_HZ
) / TIMER_FREQ
;
52 static inline unsigned long usecs_to_ticks(unsigned long usecs
)
58 ticks
*= (TIMER_LOAD_VAL
* CONFIG_SYS_HZ
);
61 ticks
= usecs
* TIMER_LOAD_VAL
* CONFIG_SYS_HZ
;
62 ticks
/= (1000 * 1000);
68 static inline unsigned long read_timer(void)
70 struct timer_regs
*timer
= (struct timer_regs
*)TIMER_BASE
;
72 return readl(&timer
->timer3
.value
);
76 * timer without interrupts
78 unsigned long long get_ticks(void)
80 const unsigned long now
= read_timer();
84 timestamp
+= lastdec
- now
;
86 /* we have an overflow ... */
87 timestamp
+= lastdec
+ TIMER_LOAD_VAL
- now
;
95 unsigned long get_timer_masked(void)
97 return clk_to_systicks(get_ticks());
100 unsigned long get_timer(unsigned long base
)
102 return get_timer_masked() - base
;
105 void reset_timer_masked(void)
107 lastdec
= read_timer();
111 void reset_timer(void)
113 reset_timer_masked();
116 void set_timer(unsigned long t
)
121 void __udelay(unsigned long usec
)
123 const unsigned long ticks
= usecs_to_ticks(usec
);
124 const unsigned long target
= clk_to_systicks(ticks
) + get_timer(0);
126 while (get_timer_masked() < target
)
130 void udelay_masked(unsigned long usec
)
132 const unsigned long ticks
= usecs_to_ticks(usec
);
133 const unsigned long target
= clk_to_systicks(ticks
) + get_timer(0);
135 reset_timer_masked();
137 while (get_timer_masked() < target
)
143 struct timer_regs
*timer
= (struct timer_regs
*)TIMER_BASE
;
145 /* use timer 3 with 508KHz and free running */
146 writel(TIMER_CLKSEL
, &timer
->timer3
.control
);
148 /* auto load, manual update of Timer 3 */
149 lastdec
= TIMER_LOAD_VAL
;
150 writel(TIMER_LOAD_VAL
, &timer
->timer3
.load
);
152 /* Enable the timer and periodic mode */
153 writel(TIMER_ENABLE
| TIMER_MODE
| TIMER_CLKSEL
,
154 &timer
->timer3
.control
);
156 reset_timer_masked();
162 * This function is derived from PowerPC code (timebase clock frequency).
163 * On ARM it returns the number of timer ticks per second.
165 unsigned long get_tbclk(void)
167 return CONFIG_SYS_HZ
;