common/cpr/cpr_driver.c

	cpr_driver.c revision 2df1fe9ca32bb227b9158c67f5c00b54c20b10fd
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * CPR driver support routines
 */

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <sys/sunddi.h>
#include <sys/ddi_impldefs.h>
#include <sys/epm.h>
#include <sys/cpr.h>

#define CPR_BUFSIZE 128

extern int devi_detach(dev_info_t *, int);
extern int devi_attach(dev_info_t *, int);

static char     *devi_string(dev_info_t *, char *);
static int  cpr_is_real_device(dev_info_t *);
/*
 * Xen uses this code to suspend _all_ drivers quickly and easily.
 * Suspend and Resume uses it for the same reason, but also has
 * to contend with some platform specific code that Xen does not.
 * it is also used as a test entry point for developers/testers to
 * execute code without going through a complete suspend.  So additions
 * that have platform implications shall need #if[n]def's.
 */
#ifndef __xpv
extern void i_cpr_save_configuration(dev_info_t *);
extern void i_cpr_restore_configuration(dev_info_t *);
#endif

/*
 * Traverse the dev info tree:
 *  Call each device driver in the system via a special case
 *  of the detach() entry point to quiesce itself.
 *  Suspend children first.
 *
 * We only suspend/resume real devices.
 */

int
cpr_suspend_devices(dev_info_t *dip)
{
    int     error;
    char        buf[CPR_BUFSIZE];

    for (; dip != NULL; dip = ddi_get_next_sibling(dip)) {
        if (cpr_suspend_devices(ddi_get_child(dip)))
            return (ENXIO);
        if (!cpr_is_real_device(dip))
            continue;
        CPR_DEBUG(CPR_DEBUG2, "Suspending device %s\n",
            devi_string(dip, buf));
        ASSERT((DEVI(dip)->devi_cpr_flags & DCF_CPR_SUSPENDED) == 0);

#ifndef __xpv
        i_cpr_save_configuration(dip);
#endif


        if (!i_ddi_devi_attached(dip)) {
            error = DDI_FAILURE;
        } else {
#ifndef __xpv
            if (cpr_test_point != DEVICE_SUSPEND_TO_RAM ||
                (cpr_test_point == DEVICE_SUSPEND_TO_RAM &&
                cpr_device == ddi_driver_major(dip))) {
#endif
                error = devi_detach(dip, DDI_SUSPEND);
#ifndef __xpv
            } else {
                error = DDI_SUCCESS;
            }
#endif
        }

        if (error == DDI_SUCCESS) {
            DEVI(dip)->devi_cpr_flags |= DCF_CPR_SUSPENDED;
        }

        else {
            CPR_DEBUG(CPR_DEBUG2,
                "WARNING: Unable to suspend device %s\n",
                devi_string(dip, buf));
            cpr_err(CE_WARN, "Unable to suspend device %s.",
                devi_string(dip, buf));
            cpr_err(CE_WARN, "Device is busy or does not "
                "support suspend/resume.");
#ifndef __xpv
            /*
             * the device has failed to suspend however,
             * if cpr_test_point == FORCE_SUSPEND_TO_RAM
             * after putting out the warning message above,
             * we carry on as if suspending the device had
             * been successful
             */
            if (cpr_test_point == FORCE_SUSPEND_TO_RAM)
                DEVI(dip)->devi_cpr_flags |= DCF_CPR_SUSPENDED;
            else
#endif
                return (ENXIO);
        }
    }
    return (0);
}

/*
 * Traverse the dev info tree:
 *  Call each device driver in the system via a special case
 *  of the attach() entry point to restore itself.
 *  This is a little tricky because it has to reverse the traversal
 *  order of cpr_suspend_devices().
 */
int
cpr_resume_devices(dev_info_t *start, int resume_failed)
{
    dev_info_t  *dip, *next, *last = NULL;
    int     did_suspend;
    int     error = resume_failed;
    char        buf[CPR_BUFSIZE];

    while (last != start) {
        dip = start;
        next = ddi_get_next_sibling(dip);
        while (next != last) {
            dip = next;
            next = ddi_get_next_sibling(dip);
        }

        /*
         * cpr is the only one that uses this field and the device
         * itself hasn't resumed yet, there is no need to use a
         * lock, even though kernel threads are active by now.
         */
        did_suspend = DEVI(dip)->devi_cpr_flags & DCF_CPR_SUSPENDED;
        if (did_suspend)
            DEVI(dip)->devi_cpr_flags &= ~DCF_CPR_SUSPENDED;

        /*
         * Always attempt to restore device configuration before
         * attempting resume
         */
#ifndef __xpv
        i_cpr_restore_configuration(dip);
#endif

        /*
         * There may be background attaches happening on devices
         * that were not originally suspended by cpr, so resume
         * only devices that were suspended by cpr. Also, stop
         * resuming after the first resume failure, but traverse
         * the entire tree to clear the suspend flag unless the
         * FORCE_SUSPEND_TO_RAM test point is set.
         */
#ifndef __xpv
        if (did_suspend && (!error ||
            cpr_test_point == FORCE_SUSPEND_TO_RAM)) {
#else
        if (did_suspend && !error) {
#endif
            CPR_DEBUG(CPR_DEBUG2, "Resuming device %s\n",
                devi_string(dip, buf));
            /*
             * If a device suspended by cpr gets detached during
             * the resume process (for example, due to hotplugging)
             * before cpr gets around to issuing it a DDI_RESUME,
             * we'll have problems.
             */
            if (!i_ddi_devi_attached(dip)) {
                CPR_DEBUG(CPR_DEBUG2, "WARNING: Skipping "
                    "%s, device not ready for resume\n",
                    devi_string(dip, buf));
                cpr_err(CE_WARN, "Skipping %s, device "
                    "not ready for resume",
                    devi_string(dip, buf));
#ifndef __xpv
            } else if (cpr_test_point != DEVICE_SUSPEND_TO_RAM ||
                (cpr_test_point == DEVICE_SUSPEND_TO_RAM &&
                cpr_device == ddi_driver_major(dip))) {
#else
            } else {
#endif
                if (devi_attach(dip, DDI_RESUME) !=
                    DDI_SUCCESS) {
                    error = ENXIO;
                }
            }
        }

        if (error == ENXIO) {
            CPR_DEBUG(CPR_DEBUG2,
                "WARNING: Unable to resume device %s\n",
                devi_string(dip, buf));
            cpr_err(CE_WARN, "Unable to resume device %s",
                devi_string(dip, buf));
        }

        error = cpr_resume_devices(ddi_get_child(dip), error);
        last = dip;
    }

    return (error);
}

/*
 * Returns a string which contains device name and address.
 */
static char *
devi_string(dev_info_t *devi, char *buf)
{
    char *name;
    char *address;
    int size;

    name = ddi_node_name(devi);
    address = ddi_get_name_addr(devi);
    size = (name == NULL) ? strlen("<null name>") : strlen(name);
    size += (address == NULL) ? strlen("<null>") : strlen(address);

    /*
     * Make sure that we don't over-run the buffer.
     * There are 2 additional characters in the string.
     */
    ASSERT((size + 2) <= CPR_BUFSIZE);

    if (name == NULL)
        (void) strcpy(buf, "<null name>");
    else
        (void) strcpy(buf, name);

    (void) strcat(buf, "@");
    if (address == NULL)
        (void) strcat(buf, "<null>");
    else
        (void) strcat(buf, address);

    return (buf);
}

/*
 * This function determines whether the given device is real (and should
 * be suspended) or not (pseudo like).  If the device has a "reg" property
 * then it is presumed to have register state to save/restore.
 */
static int
cpr_is_real_device(dev_info_t *dip)
{
    struct regspec *regbuf;
    int length;
    int rc;

    if (ddi_get_driver(dip) == NULL)
        return (0);

    /*
     * First those devices for which special arrangements have been made
     */
    if (DEVI(dip)->devi_pm_flags & (PMC_NEEDS_SR|PMC_PARENTAL_SR))
        return (1);
    if (DEVI(dip)->devi_pm_flags & PMC_NO_SR)
        return (0);

    /*
     * now the general case
     */
    rc = ddi_getlongprop(DDI_DEV_T_ANY, dip, DDI_PROP_DONTPASS, "reg",
        (caddr_t)&regbuf, &length);
    ASSERT(rc != DDI_PROP_NO_MEMORY);
    if (rc != DDI_PROP_SUCCESS) {
        return (0);
    } else {
        kmem_free((caddr_t)regbuf, length);
        return (1);
    }
}