/*
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* Cirrus Logic EP93xx timer support.
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*
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* Copyright (C) 2009, 2010 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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* SPDX-License-Identifier: GPL-2.0+
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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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#include <div64.h>
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#define TIMER_CLKSEL (1 << 3)
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#define TIMER_ENABLE (1 << 7)
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#define TIMER_FREQ 508469 /* ticks / second */
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#define TIMER_MAX_VAL 0xFFFFFFFF
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static struct ep93xx_timer
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{
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unsigned long long ticks;
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unsigned long last_read;
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} timer;
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static inline unsigned long long usecs_to_ticks(unsigned long usecs)
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{
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unsigned long long ticks = (unsigned long long)usecs * TIMER_FREQ;
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do_div(ticks, 1000 * 1000);
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return ticks;
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}
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static inline void read_timer(void)
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{
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struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE;
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const unsigned long now = TIMER_MAX_VAL - readl(&timer_regs->timer3.value);
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if (now >= timer.last_read)
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timer.ticks += now - timer.last_read;
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else
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/* an overflow occurred */
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timer.ticks += TIMER_MAX_VAL - timer.last_read + now;
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timer.last_read = now;
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}
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/*
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* Get the number of ticks (in CONFIG_SYS_HZ resolution)
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*/
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unsigned long long get_ticks(void)
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{
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unsigned long long sys_ticks;
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read_timer();
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sys_ticks = timer.ticks * CONFIG_SYS_HZ;
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do_div(sys_ticks, TIMER_FREQ);
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return sys_ticks;
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}
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unsigned long get_timer_masked(void)
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{
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return 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 __udelay(unsigned long usec)
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{
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unsigned long long target;
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read_timer();
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target = timer.ticks + usecs_to_ticks(usec);
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while (timer.ticks < target)
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read_timer();
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}
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int timer_init(void)
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{
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struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE;
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/* use timer 3 with 508KHz and free running, not enabled now */
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writel(TIMER_CLKSEL, &timer_regs->timer3.control);
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/* set initial timer value */
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writel(TIMER_MAX_VAL, &timer_regs->timer3.load);
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/* Enable the timer */
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writel(TIMER_ENABLE | TIMER_CLKSEL,
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&timer_regs->timer3.control);
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/* Reset the timer */
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read_timer();
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timer.ticks = 0;
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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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