85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
/*
|
|
* 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(struct clocksource *cs)
|
|
{
|
|
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);
|
|
}
|