mirror of https://gitee.com/openkylin/linux.git
179 lines
4.5 KiB
C
179 lines
4.5 KiB
C
/***************************************************************************/
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/*
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* pit.c -- Freescale ColdFire PIT timer. Currently this type of
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* hardware timer only exists in the Freescale ColdFire
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* 5270/5271, 5282 and 5208 CPUs. No doubt newer ColdFire
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* family members will probably use it too.
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*
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* Copyright (C) 1999-2008, Greg Ungerer (gerg@snapgear.com)
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* Copyright (C) 2001-2004, SnapGear Inc. (www.snapgear.com)
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*/
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/***************************************************************************/
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/param.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/clockchips.h>
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#include <asm/machdep.h>
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#include <asm/io.h>
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#include <asm/coldfire.h>
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#include <asm/mcfpit.h>
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#include <asm/mcfsim.h>
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/***************************************************************************/
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/*
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* By default use timer1 as the system clock timer.
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*/
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#define FREQ ((MCF_CLK / 2) / 64)
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#define TA(a) (MCF_IPSBAR + MCFPIT_BASE1 + (a))
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#define INTC0 (MCF_IPSBAR + MCFICM_INTC0)
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#define PIT_CYCLES_PER_JIFFY (FREQ / HZ)
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static u32 pit_cnt;
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/*
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* Initialize the PIT timer.
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*
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* This is also called after resume to bring the PIT into operation again.
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*/
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static void init_cf_pit_timer(enum clock_event_mode mode,
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struct clock_event_device *evt)
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{
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switch (mode) {
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case CLOCK_EVT_MODE_PERIODIC:
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__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
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__raw_writew(PIT_CYCLES_PER_JIFFY, TA(MCFPIT_PMR));
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__raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | \
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MCFPIT_PCSR_OVW | MCFPIT_PCSR_RLD | \
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MCFPIT_PCSR_CLK64, TA(MCFPIT_PCSR));
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break;
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case CLOCK_EVT_MODE_SHUTDOWN:
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case CLOCK_EVT_MODE_UNUSED:
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__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
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break;
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case CLOCK_EVT_MODE_ONESHOT:
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__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
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__raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | \
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MCFPIT_PCSR_OVW | MCFPIT_PCSR_CLK64, \
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TA(MCFPIT_PCSR));
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break;
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case CLOCK_EVT_MODE_RESUME:
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/* Nothing to do here */
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break;
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}
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}
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/*
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* Program the next event in oneshot mode
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*
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* Delta is given in PIT ticks
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*/
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static int cf_pit_next_event(unsigned long delta,
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struct clock_event_device *evt)
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{
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__raw_writew(delta, TA(MCFPIT_PMR));
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return 0;
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}
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struct clock_event_device cf_pit_clockevent = {
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.name = "pit",
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.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
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.set_mode = init_cf_pit_timer,
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.set_next_event = cf_pit_next_event,
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.shift = 32,
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.irq = MCFINT_VECBASE + MCFINT_PIT1,
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};
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/***************************************************************************/
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static irqreturn_t pit_tick(int irq, void *dummy)
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{
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struct clock_event_device *evt = &cf_pit_clockevent;
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u16 pcsr;
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/* Reset the ColdFire timer */
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pcsr = __raw_readw(TA(MCFPIT_PCSR));
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__raw_writew(pcsr | MCFPIT_PCSR_PIF, TA(MCFPIT_PCSR));
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pit_cnt += PIT_CYCLES_PER_JIFFY;
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evt->event_handler(evt);
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return IRQ_HANDLED;
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}
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/***************************************************************************/
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static struct irqaction pit_irq = {
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.name = "timer",
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.flags = IRQF_DISABLED | IRQF_TIMER,
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.handler = pit_tick,
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};
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/***************************************************************************/
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static cycle_t pit_read_clk(void)
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{
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unsigned long flags;
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u32 cycles;
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u16 pcntr;
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local_irq_save(flags);
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pcntr = __raw_readw(TA(MCFPIT_PCNTR));
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cycles = pit_cnt;
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local_irq_restore(flags);
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return cycles + PIT_CYCLES_PER_JIFFY - pcntr;
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}
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/***************************************************************************/
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static struct clocksource pit_clk = {
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.name = "pit",
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.rating = 100,
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.read = pit_read_clk,
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.shift = 20,
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.mask = CLOCKSOURCE_MASK(32),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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};
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/***************************************************************************/
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void hw_timer_init(void)
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{
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u32 imr;
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cf_pit_clockevent.cpumask = cpumask_of(smp_processor_id());
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cf_pit_clockevent.mult = div_sc(FREQ, NSEC_PER_SEC, 32);
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cf_pit_clockevent.max_delta_ns =
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clockevent_delta2ns(0xFFFF, &cf_pit_clockevent);
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cf_pit_clockevent.min_delta_ns =
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clockevent_delta2ns(0x3f, &cf_pit_clockevent);
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clockevents_register_device(&cf_pit_clockevent);
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setup_irq(MCFINT_VECBASE + MCFINT_PIT1, &pit_irq);
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__raw_writeb(ICR_INTRCONF, INTC0 + MCFINTC_ICR0 + MCFINT_PIT1);
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imr = __raw_readl(INTC0 + MCFPIT_IMR);
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imr &= ~MCFPIT_IMR_IBIT;
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__raw_writel(imr, INTC0 + MCFPIT_IMR);
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pit_clk.mult = clocksource_hz2mult(FREQ, pit_clk.shift);
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clocksource_register(&pit_clk);
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}
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/***************************************************************************/
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