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/*
* linux/arch/arm/mach-nomadik/timer.c
*
* Copyright (C) 2008 STMicroelectronics
* Copyright (C) 2009 Alessandro Rubini, somewhat based on at91sam926x
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2, as
* published by the Free Software Foundation.
*/
#include <common.h>
#include <init.h>
#include <clock.h>
#include <io.h>
#include <mach/hardware.h>
#include <mach/mtu.h>
#include <mach/timex.h>
/* Initial value for SRC control register: all timers use MXTAL/8 source */
#define SRC_CR_INIT_MASK 0x00007fff
#define SRC_CR_INIT_VAL 0x2aaa8000
static u32 nmdk_cycle; /* write-once */
static __iomem void *mtu_base;
/*
* clocksource: the MTU device is a decrementing counters, so we negate
* the value being read.
*/
static uint64_t nmdk_read_timer(void)
{
return nmdk_cycle - readl(mtu_base + MTU_VAL(0));
}
static struct clocksource nmdk_clksrc = {
.read = nmdk_read_timer,
.shift = 20,
.mask = CLOCKSOURCE_MASK(32),
};
static void nmdk_timer_reset(void)
{
u32 cr;
writel(0, mtu_base + MTU_CR(0)); /* off */
/* configure load and background-load, and fire it up */
writel(nmdk_cycle, mtu_base + MTU_LR(0));
writel(nmdk_cycle, mtu_base + MTU_BGLR(0));
cr = MTU_CRn_PRESCALE_1 | MTU_CRn_32BITS;
writel(cr, mtu_base + MTU_CR(0));
writel(cr | MTU_CRn_ENA, mtu_base + MTU_CR(0));
}
static int nmdk_timer_init(void)
{
u32 src_cr;
unsigned long rate;
rate = CLOCK_TICK_RATE; /* 2.4MHz */
nmdk_cycle = (rate + 1000 / 2) / 1000;
/* Configure timer sources in "system reset controller" ctrl reg */
src_cr = readl(NOMADIK_SRC_BASE);
src_cr &= SRC_CR_INIT_MASK;
src_cr |= SRC_CR_INIT_VAL;
writel(src_cr, NOMADIK_SRC_BASE);
/* Save global pointer to mtu, used by functions above */
mtu_base = (void *)NOMADIK_MTU0_BASE;
/* Init the timer and register clocksource */
nmdk_timer_reset();
nmdk_clksrc.mult = clocksource_hz2mult(rate, nmdk_clksrc.shift);
init_clock(&nmdk_clksrc);
return 0;
}
core_initcall(nmdk_timer_init);
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