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/*
* dma_timer.c -- Freescale ColdFire DMA Timer.
*
* Copyright (C) 2007, Benedikt Spranger <b.spranger@linutronix.de>
* Copyright (C) 2008. Sebastian Siewior, Linutronix
*
*/
#include <linux/clocksource.h>
#include <linux/io.h>
#include <asm/machdep.h>
#include <asm/coldfire.h>
#include <asm/mcfpit.h>
#include <asm/mcfsim.h>
#define DMA_TIMER_0 (0x00)
#define DMA_TIMER_1 (0x40)
#define DMA_TIMER_2 (0x80)
#define DMA_TIMER_3 (0xc0)
#define DTMR0 (MCF_IPSBAR + DMA_TIMER_0 + 0x400)
#define DTXMR0 (MCF_IPSBAR + DMA_TIMER_0 + 0x402)
#define DTER0 (MCF_IPSBAR + DMA_TIMER_0 + 0x403)
#define DTRR0 (MCF_IPSBAR + DMA_TIMER_0 + 0x404)
#define DTCR0 (MCF_IPSBAR + DMA_TIMER_0 + 0x408)
#define DTCN0 (MCF_IPSBAR + DMA_TIMER_0 + 0x40c)
#define DMA_FREQ ((MCF_CLK / 2) / 16)
/* DTMR */
#define DMA_DTMR_RESTART (1 << 3)
#define DMA_DTMR_CLK_DIV_1 (1 << 1)
#define DMA_DTMR_CLK_DIV_16 (2 << 1)
#define DMA_DTMR_ENABLE (1 << 0)
static cycle_t cf_dt_get_cycles(void)
{
return __raw_readl(DTCN0);
}
static struct clocksource clocksource_cf_dt = {
.name = "coldfire_dma_timer",
.rating = 200,
.read = cf_dt_get_cycles,
.mask = CLOCKSOURCE_MASK(32),
.shift = 20,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static int __init init_cf_dt_clocksource(void)
{
/*
* We setup DMA timer 0 in free run mode. This incrementing counter is
* used as a highly precious clock source. With MCF_CLOCK = 150 MHz we
* get a ~213 ns resolution and the 32bit register will overflow almost
* every 15 minutes.
*/
__raw_writeb(0x00, DTXMR0);
__raw_writeb(0x00, DTER0);
__raw_writel(0x00000000, DTRR0);
__raw_writew(DMA_DTMR_CLK_DIV_16 | DMA_DTMR_ENABLE, DTMR0);
clocksource_cf_dt.mult = clocksource_hz2mult(DMA_FREQ,
clocksource_cf_dt.shift);
return clocksource_register(&clocksource_cf_dt);
}
arch_initcall(init_cf_dt_clocksource);
#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
#define CYC2NS_SCALE ((1000000 << CYC2NS_SCALE_FACTOR) / (DMA_FREQ / 1000))
static unsigned long long cycles2ns(unsigned long cycl)
{
return (unsigned long long) ((unsigned long long)cycl *
CYC2NS_SCALE) >> CYC2NS_SCALE_FACTOR;
}
unsigned long long sched_clock(void)
{
unsigned long cycl = __raw_readl(DTCN0);
return cycles2ns(cycl);
}
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