arm/at91/at91_st.c

/*-
 * Copyright (c) 2005 Olivier Houchard.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: stable/11/sys/arm/at91/at91_st.c 308325 2016-11-05 04:30:44Z mmel $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/time.h>
#include <sys/bus.h>
#include <sys/resource.h>
#include <sys/rman.h>
#include <sys/timetc.h>
#include <sys/watchdog.h>

#include <machine/bus.h>
#include <machine/cpu.h>
#include <machine/resource.h>
#include <machine/frame.h>
#include <machine/intr.h>
#include <arm/at91/at91var.h>
#include <arm/at91/at91_streg.h>
#include <arm/at91/at91rm92reg.h>

static struct at91_st_softc {
	struct resource *	sc_irq_res;
	struct resource	*	sc_mem_res;
	void *			sc_intrhand;
	eventhandler_tag	sc_wet;	/* watchdog event handler tag */
} *timer_softc;

static inline uint32_t
RD4(bus_size_t off)
{

	if (timer_softc == NULL) {
		uint32_t *p = (uint32_t *)(AT91_BASE + AT91RM92_ST_BASE + off);

		return *p;
	}

	return (bus_read_4(timer_softc->sc_mem_res, off));
}

static inline void
WR4(bus_size_t off, uint32_t val)
{

	if (timer_softc == NULL) {
		uint32_t *p = (uint32_t *)(AT91_BASE + AT91RM92_ST_BASE + off);

		*p = val;
	}
	else
		bus_write_4(timer_softc->sc_mem_res, off, val);
}

static void at91_st_watchdog(void *, u_int, int *);
static void at91_st_initclocks(device_t , struct at91_st_softc *);

static inline int
st_crtr(void)
{
	int cur1, cur2;
	do {
		cur1 = RD4(ST_CRTR);
		cur2 = RD4(ST_CRTR);
	} while (cur1 != cur2);
	return (cur1);
}

static unsigned at91_st_get_timecount(struct timecounter *tc);

static struct timecounter at91_st_timecounter = {
	at91_st_get_timecount, /* get_timecount */
	NULL, /* no poll_pps */
	0xfffffu, /* counter_mask */
	32768, /* frequency */
	"AT91RM9200 timer", /* name */
	1000 /* quality */
};

static int
clock_intr(void *arg)
{
	struct trapframe *fp = arg;

	/* The interrupt is shared, so we have to make sure it's for us. */
	if (RD4(ST_SR) & ST_SR_PITS) {
		hardclock(TRAPF_USERMODE(fp), TRAPF_PC(fp));
		return (FILTER_HANDLED);
	}
	return (FILTER_STRAY);
}

void
at91_st_delay(int n)
{
	uint32_t start, end, cur;

	start = st_crtr();
	n = (n * 1000) / 32768;
	if (n <= 0)
		n = 1;
	end = (start + n) & ST_CRTR_MASK;
	cur = start;
	if (start > end) {
		while (cur >= start || cur < end)
			cur = st_crtr();
	} else {
		while (cur < end)
			cur = st_crtr();
	}
}

void
at91_st_cpu_reset(void)
{
	/*
	 * Reset the CPU by programmig the watchdog timer to reset the
	 * CPU after 128 'slow' clocks, or about ~4ms.  Loop until
	 * the reset happens for safety.
	 */
	WR4(ST_WDMR, ST_WDMR_RSTEN | 2);
	WR4(ST_CR, ST_CR_WDRST);
	while (1)
		continue;
}

static int
at91_st_probe(device_t dev)
{

	device_set_desc(dev, "ST");
	return (0);
}

static void
at91_st_deactivate(device_t dev)
{
	struct at91_st_softc *sc = timer_softc;

	if (sc->sc_intrhand)
		bus_teardown_intr(dev, sc->sc_irq_res, sc->sc_intrhand);
	sc->sc_intrhand = NULL;

	if (sc->sc_irq_res)
		bus_release_resource(dev, SYS_RES_IRQ,
		    rman_get_rid(sc->sc_irq_res), sc->sc_irq_res);
	sc->sc_irq_res = NULL;

	if (sc->sc_mem_res)
		bus_release_resource(dev, SYS_RES_MEMORY,
		    rman_get_rid(sc->sc_mem_res), sc->sc_mem_res);
	sc->sc_mem_res = NULL;
}

static int
at91_st_activate(device_t dev)
{
	int rid;
	int err;
	struct at91_st_softc *sc = timer_softc;

	rid = 0;
	sc->sc_mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
	    RF_ACTIVE);
	err = ENOMEM;
	if (sc->sc_mem_res == NULL)
		goto out;
	/* Disable all interrupts */
	WR4(ST_IDR, 0xffffffff);

	/* The system timer shares the system irq (1) */
	rid = 0;
	sc->sc_irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
	    RF_ACTIVE | RF_SHAREABLE);
	if (sc->sc_irq_res == NULL) {
		printf("Unable to allocate irq for the system timer");
		goto out;
	}
	err = bus_setup_intr(dev, sc->sc_irq_res, INTR_TYPE_CLK, clock_intr,
	    NULL, NULL, &sc->sc_intrhand);
out:
	if (err != 0)
		at91_st_deactivate(dev);
	return (err);
}

static int
at91_st_attach(device_t dev)
{
	int err;

	timer_softc = device_get_softc(dev);
	err = at91_st_activate(dev);
	if (err)
		return err;

	timer_softc->sc_wet = EVENTHANDLER_REGISTER(watchdog_list,
	  at91_st_watchdog, dev, 0);

	device_printf(dev,
	  "watchdog registered, timeout intervall max. 64 sec\n");

	at91_st_initclocks(dev, timer_softc);
	return (0);
}

static device_method_t at91_st_methods[] = {
	DEVMETHOD(device_probe, at91_st_probe),
	DEVMETHOD(device_attach, at91_st_attach),
	{0, 0},
};

static driver_t at91_st_driver = {
	"at91_st",
	at91_st_methods,
	sizeof(struct at91_st_softc),
};
static devclass_t at91_st_devclass;

DRIVER_MODULE(at91_st, atmelarm, at91_st_driver, at91_st_devclass, 0, 0);

static unsigned
at91_st_get_timecount(struct timecounter *tc)
{
	return (st_crtr());
}

/*
 * t below is in a weird unit.  The watchdog is set to 2^t
 * nanoseconds.  Since our watchdog timer can't really do that too
 * well, we approximate it by assuming that the timeout interval for
 * the lsb is 2^22 ns, which is 4.194ms.  This is an overestimation of
 * the actual time (3.906ms), but close enough for watchdogging.
 * These approximations, though a violation of the spec, improve the
 * performance of the application which typically specifies things as
 * WD_TO_32SEC.  In that last case, we'd wait 32s before the wdog
 * reset.  The spec says we should wait closer to 34s, but given how
 * it is likely to be used, and the extremely coarse nature time
 * interval, I think this is the best solution.
 */
static void
at91_st_watchdog(void *argp, u_int cmd, int *error)
{
	uint32_t wdog;
	int t;

	t = cmd & WD_INTERVAL;
	if (t >= 22 && t <= 37) {
		wdog = (1 << (t - 22)) | ST_WDMR_RSTEN;
		*error = 0;
	} else {
		wdog = 0;
	}
	WR4(ST_WDMR, wdog);
	WR4(ST_CR, ST_CR_WDRST);
}

static void
at91_st_initclocks(device_t dev, struct at91_st_softc *sc)
{
	int rel_value;

	/*
	 * Real time counter increments every clock cycle, need to set before
	 * initializing clocks so that DELAY works.
	 */
	WR4(ST_RTMR, 1);
	/* disable watchdog timer */
	WR4(ST_WDMR, 0);

	rel_value = 32768 / hz;
	if (rel_value < 1)
		rel_value = 1;
	if (32768 % hz) {
		device_printf(dev, "Cannot get %d Hz clock; using %dHz\n", hz,
		    32768 / rel_value);
		hz = 32768 / rel_value;
		tick = 1000000 / hz;
	}
	WR4(ST_PIMR, rel_value);

	/* Enable PITS interrupts. */
	WR4(ST_IER, ST_SR_PITS);
	tc_init(&at91_st_timecounter);
}