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;