imx_machdep.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2013 Ian Lepore <[email protected]>
 * 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 THE 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 THE 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 "opt_platform.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/reboot.h>

#include <vm/vm.h>
#include <vm/pmap.h>

#include <machine/armreg.h>
#include <machine/bus.h>
#include <machine/cpu.h>
#include <machine/machdep.h>

#include <arm/freescale/imx/imx_machdep.h>
#include <arm/freescale/imx/imx_wdogreg.h>

SYSCTL_NODE(_hw, OID_AUTO, imx, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
    "i.MX container");

static int last_reset_status;
SYSCTL_UINT(_hw_imx, OID_AUTO, last_reset_status, CTLFLAG_RD, 
    &last_reset_status, 0, "Last reset status register");

SYSCTL_STRING(_hw_imx, OID_AUTO, last_reset_reason, CTLFLAG_RD, 
    "unknown", 0, "Last reset reason");

/*
 * This code which manipulates the watchdog hardware is here to implement
 * cpu_reset() because the watchdog is the only way for software to reset the
 * chip.  Why here and not in imx_wdog.c?  Because there's no requirement that
 * the watchdog driver be compiled in, but it's nice to be able to reboot even
 * if it's not.
 */
void
imx_wdog_cpu_reset(vm_offset_t wdcr_physaddr)
{
	volatile uint16_t cr, *pcr;

	if ((pcr = pmap_mapdev(wdcr_physaddr, sizeof(*pcr))) == NULL) {
		printf("imx_wdog_cpu_reset(): "
		    "cannot find control register... locking up now.");
		for (;;)
			cpu_spinwait();
	}
	cr = *pcr;

	/*
	 * If the watchdog hardware has been set up to trigger an external reset
	 * signal on watchdog timeout, then we do software-requested rebooting
	 * the same way, by asserting the external reset signal.
	 *
	 * Asserting external reset is supposed to result in some external
	 * component asserting the POR pin on the SoC, possibly after adjusting
	 * and stabilizing system voltages, or taking other system-wide reset
	 * actions.  Just in case there is some kind of misconfiguration, we
	 * hang out and do nothing for a full second, then continue on into
	 * the code to assert a software reset as well.
	 */
	if (cr & WDOG_CR_WDT) {
		cr &= ~WDOG_CR_WDA; /* Assert active-low ext reset bit. */
		*pcr = cr;
		DELAY(1000000);
		printf("imx_wdog_cpu_reset(): "
		    "External reset failed, trying internal cpu-reset\n");
		DELAY(10000); /* Time for printf to appear */
	}

	/*
	 * Imx6 erratum ERR004346 says the SRS bit has to be cleared twice
	 * within the same cycle of the 32khz clock to reliably trigger the
	 * reset.  Writing it 3 times in a row ensures at least 2 of the writes
	 * happen in the same 32k clock cycle.
	 */
	cr &= ~WDOG_CR_SRS; /* Assert active-low software reset bit. */
	*pcr = cr;
	*pcr = cr;
	*pcr = cr;

	/* Reset happens on the next tick of the 32khz clock, wait for it. */
	for (;;)
		cpu_spinwait();
}

void
imx_wdog_init_last_reset(vm_offset_t wdsr_phys)
{
	volatile uint16_t * psr;

	if ((psr = pmap_mapdev(wdsr_phys, sizeof(*psr))) == NULL)
		return;
	last_reset_status = *psr;
	if (last_reset_status & WDOG_RSR_SFTW) {
		sysctl___hw_imx_last_reset_reason.oid_arg1 = "SoftwareReset";
	} else if (last_reset_status & WDOG_RSR_TOUT) {
		sysctl___hw_imx_last_reset_reason.oid_arg1 = "WatchdogTimeout";
	} else if (last_reset_status & WDOG_RSR_POR) {
		sysctl___hw_imx_last_reset_reason.oid_arg1 = "PowerOnReset";
	}
	pmap_unmapdev((void *)(uintptr_t)psr, sizeof(*psr));
}