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fcfb632bd1
Add support for the Cirrus EP93xx platform Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net> Acked-by: Tom <Tom.Rix@windriver.com>
168 lines
3.7 KiB
C
168 lines
3.7 KiB
C
/*
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* Cirrus Logic EP93xx timer support.
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*
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* Copyright (C) 2009, 2010
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* Matthias Kaehlcke <matthias@kaehlcke.net>
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*
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* Copyright (C) 2004, 2005
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* Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com>
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*
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* Based on the original intr.c Cirrus Logic EP93xx Rev D. interrupt support,
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* author unknown.
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*
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* See file CREDITS for list of people who contributed to this project.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <common.h>
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#include <linux/types.h>
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#include <asm/arch/ep93xx.h>
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#include <asm/io.h>
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#define TIMER_CLKSEL (1 << 3)
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#define TIMER_MODE (1 << 6)
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#define TIMER_ENABLE (1 << 7)
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#define TIMER_FREQ 508469
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#define TIMER_LOAD_VAL (TIMER_FREQ / CONFIG_SYS_HZ)
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static ulong timestamp;
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static ulong lastdec;
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static inline unsigned long clk_to_systicks(unsigned long clk_ticks)
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{
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unsigned long sys_ticks = (clk_ticks * CONFIG_SYS_HZ) / TIMER_FREQ;
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return sys_ticks;
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}
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static inline unsigned long usecs_to_ticks(unsigned long usecs)
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{
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unsigned long ticks;
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if (usecs >= 1000) {
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ticks = usecs / 1000;
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ticks *= (TIMER_LOAD_VAL * CONFIG_SYS_HZ);
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ticks /= 1000;
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} else {
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ticks = usecs * TIMER_LOAD_VAL * CONFIG_SYS_HZ;
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ticks /= (1000 * 1000);
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}
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return ticks;
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}
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static inline unsigned long read_timer(void)
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{
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struct timer_regs *timer = (struct timer_regs *)TIMER_BASE;
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return readl(&timer->timer3.value);
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}
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/*
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* timer without interrupts
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*/
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unsigned long long get_ticks(void)
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{
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const unsigned long now = read_timer();
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if (lastdec >= now) {
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/* normal mode */
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timestamp += lastdec - now;
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} else {
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/* we have an overflow ... */
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timestamp += lastdec + TIMER_LOAD_VAL - now;
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}
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lastdec = now;
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return timestamp;
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}
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unsigned long get_timer_masked(void)
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{
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return clk_to_systicks(get_ticks());
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}
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unsigned long get_timer(unsigned long base)
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{
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return get_timer_masked() - base;
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}
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void reset_timer_masked(void)
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{
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lastdec = read_timer();
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timestamp = 0;
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}
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void reset_timer(void)
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{
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reset_timer_masked();
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}
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void set_timer(unsigned long t)
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{
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timestamp = t;
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}
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void __udelay(unsigned long usec)
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{
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const unsigned long ticks = usecs_to_ticks(usec);
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const unsigned long target = clk_to_systicks(ticks) + get_timer(0);
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while (get_timer_masked() < target)
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/* noop */;
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}
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void udelay_masked(unsigned long usec)
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{
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const unsigned long ticks = usecs_to_ticks(usec);
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const unsigned long target = clk_to_systicks(ticks) + get_timer(0);
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reset_timer_masked();
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while (get_timer_masked() < target)
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/* noop */;
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}
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int timer_init(void)
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{
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struct timer_regs *timer = (struct timer_regs *)TIMER_BASE;
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/* use timer 3 with 508KHz and free running */
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writel(TIMER_CLKSEL, &timer->timer3.control);
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/* auto load, manual update of Timer 3 */
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lastdec = TIMER_LOAD_VAL;
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writel(TIMER_LOAD_VAL, &timer->timer3.load);
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/* Enable the timer and periodic mode */
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writel(TIMER_ENABLE | TIMER_MODE | TIMER_CLKSEL,
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&timer->timer3.control);
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reset_timer_masked();
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return 0;
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}
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/*
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* This function is derived from PowerPC code (timebase clock frequency).
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* On ARM it returns the number of timer ticks per second.
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*/
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unsigned long get_tbclk(void)
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{
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return CONFIG_SYS_HZ;
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}
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