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>
36 #define TIMER_CLKSEL (1 << 3)
37 #define TIMER_MODE (1 << 6)
38 #define TIMER_ENABLE (1 << 7)
40 #define TIMER_FREQ 508469
41 #define TIMER_LOAD_VAL (TIMER_FREQ / CONFIG_SYS_HZ)
43 static ulong timestamp;
46 static inline unsigned long clk_to_systicks(unsigned long clk_ticks)
48 unsigned long long sys_ticks = (clk_ticks * CONFIG_SYS_HZ);
49 do_div(sys_ticks, TIMER_FREQ);
51 return (unsigned long)sys_ticks;
54 static inline unsigned long usecs_to_ticks(unsigned long usecs)
60 ticks *= (TIMER_LOAD_VAL * CONFIG_SYS_HZ);
63 ticks = usecs * TIMER_LOAD_VAL * CONFIG_SYS_HZ;
64 ticks /= (1000 * 1000);
70 static inline unsigned long read_timer(void)
72 struct timer_regs *timer = (struct timer_regs *)TIMER_BASE;
74 return readl(&timer->timer3.value);
78 * timer without interrupts
80 unsigned long long get_ticks(void)
82 const unsigned long now = read_timer();
86 timestamp += lastdec - now;
88 /* we have an overflow ... */
89 timestamp += lastdec + TIMER_LOAD_VAL - now;
97 unsigned long get_timer_masked(void)
99 return clk_to_systicks(get_ticks());
102 unsigned long get_timer(unsigned long base)
104 return get_timer_masked() - base;
107 void reset_timer_masked(void)
109 lastdec = read_timer();
113 void reset_timer(void)
115 reset_timer_masked();
118 void set_timer(unsigned long t)
123 void __udelay(unsigned long usec)
125 const unsigned long ticks = usecs_to_ticks(usec);
126 const unsigned long target = clk_to_systicks(ticks) + get_timer(0);
128 while (get_timer_masked() < target)
132 void udelay_masked(unsigned long usec)
134 const unsigned long ticks = usecs_to_ticks(usec);
135 const unsigned long target = clk_to_systicks(ticks) + get_timer(0);
137 reset_timer_masked();
139 while (get_timer_masked() < target)
145 struct timer_regs *timer = (struct timer_regs *)TIMER_BASE;
147 /* use timer 3 with 508KHz and free running */
148 writel(TIMER_CLKSEL, &timer->timer3.control);
150 /* auto load, manual update of Timer 3 */
151 lastdec = TIMER_LOAD_VAL;
152 writel(TIMER_LOAD_VAL, &timer->timer3.load);
154 /* Enable the timer and periodic mode */
155 writel(TIMER_ENABLE | TIMER_MODE | TIMER_CLKSEL,
156 &timer->timer3.control);
158 reset_timer_masked();
164 * This function is derived from PowerPC code (timebase clock frequency).
165 * On ARM it returns the number of timer ticks per second.
167 unsigned long get_tbclk(void)
169 return CONFIG_SYS_HZ;