0c093a7055
- Disable interrupt when updating compare value in order to
make this operation atomical
- Increase minimum period for event timer. Systimer on BCM2835
is compare timer, so if minimum period is too small it might
be less then fraction of time between "read current value" and
"set compare timer" operations. It means that when timer is armed
actual counter value is more then compare value and it will take
whole cycle (~32sec for 1MHz timer) to fire interrupt.
Submitted by: Daisuke Aoyama <aoyama at peach.ne.jp>
313 lines
8.2 KiB
C
313 lines
8.2 KiB
C
/*
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* Copyright (c) 2012 Oleksandr Tymoshenko <gonzo@freebsd.org>
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* Copyright (c) 2012 Damjan Marion <dmarion@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bus.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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#include <sys/malloc.h>
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#include <sys/rman.h>
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#include <sys/timeet.h>
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#include <sys/timetc.h>
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#include <sys/watchdog.h>
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#include <machine/bus.h>
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#include <machine/cpu.h>
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#include <machine/frame.h>
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#include <machine/intr.h>
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#include <dev/fdt/fdt_common.h>
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#include <dev/ofw/openfirm.h>
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#include <dev/ofw/ofw_bus.h>
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#include <dev/ofw/ofw_bus_subr.h>
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#include <machine/bus.h>
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#include <machine/fdt.h>
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#define BCM2835_NUM_TIMERS 4
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#define DEFAULT_TIMER 3
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#define DEFAULT_FREQUENCY 1000000
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#define MIN_PERIOD 100LLU
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#define SYSTIMER_CS 0x00
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#define SYSTIMER_CLO 0x04
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#define SYSTIMER_CHI 0x08
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#define SYSTIMER_C0 0x0C
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#define SYSTIMER_C1 0x10
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#define SYSTIMER_C2 0x14
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#define SYSTIMER_C3 0x18
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struct systimer {
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int index;
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bool enabled;
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struct eventtimer et;
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};
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struct bcm_systimer_softc {
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struct resource* mem_res;
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struct resource* irq_res[BCM2835_NUM_TIMERS];
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void* intr_hl[BCM2835_NUM_TIMERS];
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uint32_t sysclk_freq;
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bus_space_tag_t bst;
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bus_space_handle_t bsh;
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struct systimer st[BCM2835_NUM_TIMERS];
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};
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static struct resource_spec bcm_systimer_irq_spec[] = {
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{ SYS_RES_IRQ, 0, RF_ACTIVE },
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{ SYS_RES_IRQ, 1, RF_ACTIVE },
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{ SYS_RES_IRQ, 2, RF_ACTIVE },
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{ SYS_RES_IRQ, 3, RF_ACTIVE },
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{ -1, 0, 0 }
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};
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static struct bcm_systimer_softc *bcm_systimer_sc = NULL;
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/* Read/Write macros for Timer used as timecounter */
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#define bcm_systimer_tc_read_4(reg) \
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bus_space_read_4(bcm_systimer_sc->bst, \
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bcm_systimer_sc->bsh, reg)
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#define bcm_systimer_tc_write_4(reg, val) \
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bus_space_write_4(bcm_systimer_sc->bst, \
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bcm_systimer_sc->bsh, reg, val)
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static unsigned bcm_systimer_tc_get_timecount(struct timecounter *);
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static struct timecounter bcm_systimer_tc = {
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.tc_name = "BCM2835 Timecounter",
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.tc_get_timecount = bcm_systimer_tc_get_timecount,
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.tc_poll_pps = NULL,
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.tc_counter_mask = ~0u,
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.tc_frequency = 0,
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.tc_quality = 1000,
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};
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static unsigned
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bcm_systimer_tc_get_timecount(struct timecounter *tc)
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{
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return bcm_systimer_tc_read_4(SYSTIMER_CLO);
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}
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static int
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bcm_systimer_start(struct eventtimer *et, struct bintime *first,
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struct bintime *period)
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{
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struct systimer *st = et->et_priv;
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uint32_t clo;
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uint32_t count;
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register_t s;
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if (first != NULL) {
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count = (st->et.et_frequency * (first->frac >> 32)) >> 32;
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if (first->sec != 0)
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count += st->et.et_frequency * first->sec;
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s = intr_disable();
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clo = bcm_systimer_tc_read_4(SYSTIMER_CLO);
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clo += count;
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/*
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* Clear pending interrupts
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*/
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bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
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bcm_systimer_tc_write_4(SYSTIMER_C0 + st->index*4, clo);
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st->enabled = 1;
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intr_restore(s);
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return (0);
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}
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return (EINVAL);
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}
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static int
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bcm_systimer_stop(struct eventtimer *et)
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{
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struct systimer *st = et->et_priv;
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st->enabled = 0;
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return (0);
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}
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static int
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bcm_systimer_intr(void *arg)
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{
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struct systimer *st = (struct systimer *)arg;
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uint32_t cs;
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cs = bcm_systimer_tc_read_4(SYSTIMER_CS);
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if ((cs & (1 << st->index)) == 0)
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return (FILTER_STRAY);
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/* ACK interrupt */
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bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
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if (st->enabled) {
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if (st->et.et_active) {
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st->et.et_event_cb(&st->et, st->et.et_arg);
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}
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}
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return (FILTER_HANDLED);
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}
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static int
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bcm_systimer_probe(device_t dev)
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{
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if (ofw_bus_is_compatible(dev, "broadcom,bcm2835-system-timer")) {
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device_set_desc(dev, "BCM2835 System Timer");
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return (BUS_PROBE_DEFAULT);
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}
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return (ENXIO);
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}
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static int
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bcm_systimer_attach(device_t dev)
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{
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struct bcm_systimer_softc *sc = device_get_softc(dev);
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int err;
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int rid = 0;
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if (bcm_systimer_sc != NULL)
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return (EINVAL);
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sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
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if (sc->mem_res == NULL) {
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device_printf(dev, "could not allocate memory resource\n");
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return (ENXIO);
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}
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sc->bst = rman_get_bustag(sc->mem_res);
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sc->bsh = rman_get_bushandle(sc->mem_res);
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/* Request the IRQ resources */
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err = bus_alloc_resources(dev, bcm_systimer_irq_spec,
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sc->irq_res);
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if (err) {
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device_printf(dev, "Error: could not allocate irq resources\n");
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return (ENXIO);
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}
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/* TODO: get frequency from FDT */
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sc->sysclk_freq = DEFAULT_FREQUENCY;
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/* Setup and enable the timer */
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if (bus_setup_intr(dev, sc->irq_res[DEFAULT_TIMER], INTR_TYPE_CLK,
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bcm_systimer_intr, NULL, &sc->st[DEFAULT_TIMER],
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&sc->intr_hl[DEFAULT_TIMER]) != 0) {
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bus_release_resources(dev, bcm_systimer_irq_spec,
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sc->irq_res);
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device_printf(dev, "Unable to setup the clock irq handler.\n");
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return (ENXIO);
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}
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sc->st[DEFAULT_TIMER].index = DEFAULT_TIMER;
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sc->st[DEFAULT_TIMER].enabled = 0;
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sc->st[DEFAULT_TIMER].et.et_name = malloc(64, M_DEVBUF, M_NOWAIT | M_ZERO);
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sprintf(sc->st[DEFAULT_TIMER].et.et_name, "BCM2835 Event Timer %d", DEFAULT_TIMER);
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sc->st[DEFAULT_TIMER].et.et_flags = ET_FLAGS_ONESHOT;
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sc->st[DEFAULT_TIMER].et.et_quality = 1000;
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sc->st[DEFAULT_TIMER].et.et_frequency = sc->sysclk_freq;
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sc->st[DEFAULT_TIMER].et.et_min_period.sec = 0;
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sc->st[DEFAULT_TIMER].et.et_min_period.frac =
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((MIN_PERIOD << 32) / sc->st[DEFAULT_TIMER].et.et_frequency) << 32;
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sc->st[DEFAULT_TIMER].et.et_max_period.sec = 0xfffffff0U / sc->st[DEFAULT_TIMER].et.et_frequency;
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sc->st[DEFAULT_TIMER].et.et_max_period.frac =
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((0xfffffffeLLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency) << 32;
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sc->st[DEFAULT_TIMER].et.et_start = bcm_systimer_start;
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sc->st[DEFAULT_TIMER].et.et_stop = bcm_systimer_stop;
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sc->st[DEFAULT_TIMER].et.et_priv = &sc->st[DEFAULT_TIMER];
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et_register(&sc->st[DEFAULT_TIMER].et);
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bcm_systimer_sc = sc;
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bcm_systimer_tc.tc_frequency = DEFAULT_FREQUENCY;
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tc_init(&bcm_systimer_tc);
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return (0);
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}
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static device_method_t bcm_systimer_methods[] = {
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DEVMETHOD(device_probe, bcm_systimer_probe),
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DEVMETHOD(device_attach, bcm_systimer_attach),
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{ 0, 0 }
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};
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static driver_t bcm_systimer_driver = {
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"systimer",
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bcm_systimer_methods,
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sizeof(struct bcm_systimer_softc),
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};
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static devclass_t bcm_systimer_devclass;
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DRIVER_MODULE(bcm_systimer, simplebus, bcm_systimer_driver, bcm_systimer_devclass, 0, 0);
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void
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cpu_initclocks(void)
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{
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cpu_initclocks_bsp();
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}
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void
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DELAY(int usec)
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{
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int32_t counts;
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uint32_t first, last;
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if (bcm_systimer_sc == NULL) {
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for (; usec > 0; usec--)
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for (counts = 200; counts > 0; counts--)
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/* Prevent gcc from optimizing out the loop */
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cpufunc_nullop();
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return;
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}
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/* Get the number of times to count */
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counts = usec * ((bcm_systimer_tc.tc_frequency / 1000000) + 1);
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first = bcm_systimer_tc_read_4(SYSTIMER_CLO);
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while (counts > 0) {
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last = bcm_systimer_tc_read_4(SYSTIMER_CLO);
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if (last == first)
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continue;
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if (last>first) {
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counts -= (int32_t)(last - first);
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} else {
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counts -= (int32_t)((0xFFFFFFFF - first) + last);
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}
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first = last;
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}
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}
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