163 lines
4.2 KiB
C
163 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/***************************************************************************/
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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) (MCFPIT_BASE1 + (a))
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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 int cf_pit_set_periodic(struct clock_event_device *evt)
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{
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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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return 0;
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}
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static int cf_pit_set_oneshot(struct clock_event_device *evt)
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{
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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, TA(MCFPIT_PCSR));
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return 0;
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}
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static int cf_pit_shutdown(struct clock_event_device *evt)
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{
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__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
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return 0;
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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 |
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CLOCK_EVT_FEAT_ONESHOT,
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.set_state_shutdown = cf_pit_shutdown,
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.set_state_periodic = cf_pit_set_periodic,
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.set_state_oneshot = cf_pit_set_oneshot,
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.set_next_event = cf_pit_next_event,
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.shift = 32,
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.irq = MCF_IRQ_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 u64 pit_read_clk(struct clocksource *cs)
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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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.mask = CLOCKSOURCE_MASK(32),
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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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int ret;
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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.max_delta_ticks = 0xFFFF;
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cf_pit_clockevent.min_delta_ns =
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clockevent_delta2ns(0x3f, &cf_pit_clockevent);
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cf_pit_clockevent.min_delta_ticks = 0x3f;
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clockevents_register_device(&cf_pit_clockevent);
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ret = request_irq(MCF_IRQ_PIT1, pit_tick, IRQF_TIMER, "timer", NULL);
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if (ret) {
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pr_err("Failed to request irq %d (timer): %pe\n", MCF_IRQ_PIT1,
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ERR_PTR(ret));
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}
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clocksource_register_hz(&pit_clk, FREQ);
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}
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/***************************************************************************/
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