/* * 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), .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); return clocksource_register_hz(&clocksource_cf_dt, DMA_FREQ); } 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); }