FreeBSD/Linux Kernel Cross Reference
sys/arm/freescale/imx/imx_machdep.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2013 Ian Lepore <ian@freebsd.org>
      * 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/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/reboot.h>
    #include <sys/devmap.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, 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 = devmap_ptov(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 = devmap_ptov(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";
           }
   }
   

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