powerpc/eeh: Avoid I/O access during PE reset

[linux-beck.git] / arch / powerpc / kernel / eeh.c

/*
 * Copyright IBM Corporation 2001, 2005, 2006
 * Copyright Dave Engebretsen & Todd Inglett 2001
 * Copyright Linas Vepstas 2005, 2006
 * Copyright 2001-2012 IBM Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 * Please address comments and feedback to Linas Vepstas <linas@austin.ibm.com>
 */

#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/proc_fs.h>
#include <linux/rbtree.h>
#include <linux/reboot.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/export.h>
#include <linux/of.h>

#include <linux/atomic.h>
#include <asm/eeh.h>
#include <asm/eeh_event.h>
#include <asm/io.h>
#include <asm/machdep.h>
#include <asm/ppc-pci.h>
#include <asm/rtas.h>


/** Overview:
 *  EEH, or "Extended Error Handling" is a PCI bridge technology for
 *  dealing with PCI bus errors that can't be dealt with within the
 *  usual PCI framework, except by check-stopping the CPU.  Systems
 *  that are designed for high-availability/reliability cannot afford
 *  to crash due to a "mere" PCI error, thus the need for EEH.
 *  An EEH-capable bridge operates by converting a detected error
 *  into a "slot freeze", taking the PCI adapter off-line, making
 *  the slot behave, from the OS'es point of view, as if the slot
 *  were "empty": all reads return 0xff's and all writes are silently
 *  ignored.  EEH slot isolation events can be triggered by parity
 *  errors on the address or data busses (e.g. during posted writes),
 *  which in turn might be caused by low voltage on the bus, dust,
 *  vibration, humidity, radioactivity or plain-old failed hardware.
 *
 *  Note, however, that one of the leading causes of EEH slot
 *  freeze events are buggy device drivers, buggy device microcode,
 *  or buggy device hardware.  This is because any attempt by the
 *  device to bus-master data to a memory address that is not
 *  assigned to the device will trigger a slot freeze.   (The idea
 *  is to prevent devices-gone-wild from corrupting system memory).
 *  Buggy hardware/drivers will have a miserable time co-existing
 *  with EEH.
 *
 *  Ideally, a PCI device driver, when suspecting that an isolation
 *  event has occurred (e.g. by reading 0xff's), will then ask EEH
 *  whether this is the case, and then take appropriate steps to
 *  reset the PCI slot, the PCI device, and then resume operations.
 *  However, until that day,  the checking is done here, with the
 *  eeh_check_failure() routine embedded in the MMIO macros.  If
 *  the slot is found to be isolated, an "EEH Event" is synthesized
 *  and sent out for processing.
 */

/* If a device driver keeps reading an MMIO register in an interrupt
 * handler after a slot isolation event, it might be broken.
 * This sets the threshold for how many read attempts we allow
 * before printing an error message.
 */
#define EEH_MAX_FAILS   2100000

/* Time to wait for a PCI slot to report status, in milliseconds */
#define PCI_BUS_RESET_WAIT_MSEC (5*60*1000)

/* Platform dependent EEH operations */
struct eeh_ops *eeh_ops = NULL;

bool eeh_subsystem_enabled = false;
EXPORT_SYMBOL(eeh_subsystem_enabled);

/*
 * EEH probe mode support. The intention is to support multiple
 * platforms for EEH. Some platforms like pSeries do PCI emunation
 * based on device tree. However, other platforms like powernv probe
 * PCI devices from hardware. The flag is used to distinguish that.
 * In addition, struct eeh_ops::probe would be invoked for particular
 * OF node or PCI device so that the corresponding PE would be created
 * there.
 */
int eeh_probe_mode;

/* Lock to avoid races due to multiple reports of an error */
DEFINE_RAW_SPINLOCK(confirm_error_lock);

/* Buffer for reporting pci register dumps. Its here in BSS, and
 * not dynamically alloced, so that it ends up in RMO where RTAS
 * can access it.
 */
#define EEH_PCI_REGS_LOG_LEN 4096
static unsigned char pci_regs_buf[EEH_PCI_REGS_LOG_LEN];

/*
 * The struct is used to maintain the EEH global statistic
 * information. Besides, the EEH global statistics will be
 * exported to user space through procfs
 */
struct eeh_stats {
        u64 no_device;          /* PCI device not found         */
        u64 no_dn;              /* OF node not found            */
        u64 no_cfg_addr;        /* Config address not found     */
        u64 ignored_check;      /* EEH check skipped            */
        u64 total_mmio_ffs;     /* Total EEH checks             */
        u64 false_positives;    /* Unnecessary EEH checks       */
        u64 slot_resets;        /* PE reset                     */
};

static struct eeh_stats eeh_stats;

#define IS_BRIDGE(class_code) (((class_code)<<16) == PCI_BASE_CLASS_BRIDGE)

/**
 * eeh_gather_pci_data - Copy assorted PCI config space registers to buff
 * @edev: device to report data for
 * @buf: point to buffer in which to log
 * @len: amount of room in buffer
 *
 * This routine captures assorted PCI configuration space data,
 * and puts them into a buffer for RTAS error logging.
 */
static size_t eeh_gather_pci_data(struct eeh_dev *edev, char * buf, size_t len)
{
        struct device_node *dn = eeh_dev_to_of_node(edev);
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
        u32 cfg;
        int cap, i;
        int n = 0;

        n += scnprintf(buf+n, len-n, "%s\n", dn->full_name);
        printk(KERN_WARNING "EEH: of node=%s\n", dn->full_name);

        eeh_ops->read_config(dn, PCI_VENDOR_ID, 4, &cfg);
        n += scnprintf(buf+n, len-n, "dev/vend:%08x\n", cfg);
        printk(KERN_WARNING "EEH: PCI device/vendor: %08x\n", cfg);

        eeh_ops->read_config(dn, PCI_COMMAND, 4, &cfg);
        n += scnprintf(buf+n, len-n, "cmd/stat:%x\n", cfg);
        printk(KERN_WARNING "EEH: PCI cmd/status register: %08x\n", cfg);

        if (!dev) {
                printk(KERN_WARNING "EEH: no PCI device for this of node\n");
                return n;
        }

        /* Gather bridge-specific registers */
        if (dev->class >> 16 == PCI_BASE_CLASS_BRIDGE) {
                eeh_ops->read_config(dn, PCI_SEC_STATUS, 2, &cfg);
                n += scnprintf(buf+n, len-n, "sec stat:%x\n", cfg);
                printk(KERN_WARNING "EEH: Bridge secondary status: %04x\n", cfg);

                eeh_ops->read_config(dn, PCI_BRIDGE_CONTROL, 2, &cfg);
                n += scnprintf(buf+n, len-n, "brdg ctl:%x\n", cfg);
                printk(KERN_WARNING "EEH: Bridge control: %04x\n", cfg);
        }

        /* Dump out the PCI-X command and status regs */
        cap = pci_find_capability(dev, PCI_CAP_ID_PCIX);
        if (cap) {
                eeh_ops->read_config(dn, cap, 4, &cfg);
                n += scnprintf(buf+n, len-n, "pcix-cmd:%x\n", cfg);
                printk(KERN_WARNING "EEH: PCI-X cmd: %08x\n", cfg);

                eeh_ops->read_config(dn, cap+4, 4, &cfg);
                n += scnprintf(buf+n, len-n, "pcix-stat:%x\n", cfg);
                printk(KERN_WARNING "EEH: PCI-X status: %08x\n", cfg);
        }

        /* If PCI-E capable, dump PCI-E cap 10, and the AER */
        if (pci_is_pcie(dev)) {
                n += scnprintf(buf+n, len-n, "pci-e cap10:\n");
                printk(KERN_WARNING
                       "EEH: PCI-E capabilities and status follow:\n");

                for (i=0; i<=8; i++) {
                        eeh_ops->read_config(dn, dev->pcie_cap+4*i, 4, &cfg);
                        n += scnprintf(buf+n, len-n, "%02x:%x\n", 4*i, cfg);
                        printk(KERN_WARNING "EEH: PCI-E %02x: %08x\n", i, cfg);
                }

                cap = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
                if (cap) {
                        n += scnprintf(buf+n, len-n, "pci-e AER:\n");
                        printk(KERN_WARNING
                               "EEH: PCI-E AER capability register set follows:\n");

                        for (i=0; i<14; i++) {
                                eeh_ops->read_config(dn, cap+4*i, 4, &cfg);
                                n += scnprintf(buf+n, len-n, "%02x:%x\n", 4*i, cfg);
                                printk(KERN_WARNING "EEH: PCI-E AER %02x: %08x\n", i, cfg);
                        }
                }
        }

        return n;
}

/**
 * eeh_slot_error_detail - Generate combined log including driver log and error log
 * @pe: EEH PE
 * @severity: temporary or permanent error log
 *
 * This routine should be called to generate the combined log, which
 * is comprised of driver log and error log. The driver log is figured
 * out from the config space of the corresponding PCI device, while
 * the error log is fetched through platform dependent function call.
 */
void eeh_slot_error_detail(struct eeh_pe *pe, int severity)
{
        size_t loglen = 0;
        struct eeh_dev *edev, *tmp;

        /*
         * When the PHB is fenced or dead, it's pointless to collect
         * the data from PCI config space because it should return
         * 0xFF's. For ER, we still retrieve the data from the PCI
         * config space.
         *
         * For pHyp, we have to enable IO for log retrieval. Otherwise,
         * 0xFF's is always returned from PCI config space.
         */
        if (!(pe->type & EEH_PE_PHB)) {
                if (eeh_probe_mode_devtree())
                        eeh_pci_enable(pe, EEH_OPT_THAW_MMIO);
                eeh_ops->configure_bridge(pe);
                eeh_pe_restore_bars(pe);

                pci_regs_buf[0] = 0;
                eeh_pe_for_each_dev(pe, edev, tmp) {
                        loglen += eeh_gather_pci_data(edev, pci_regs_buf + loglen,
                                                      EEH_PCI_REGS_LOG_LEN - loglen);
                }
        }

        eeh_ops->get_log(pe, severity, pci_regs_buf, loglen);
}

/**
 * eeh_token_to_phys - Convert EEH address token to phys address
 * @token: I/O token, should be address in the form 0xA....
 *
 * This routine should be called to convert virtual I/O address
 * to physical one.
 */
static inline unsigned long eeh_token_to_phys(unsigned long token)
{
        pte_t *ptep;
        unsigned long pa;
        int hugepage_shift;

        /*
         * We won't find hugepages here, iomem
         */
        ptep = find_linux_pte_or_hugepte(init_mm.pgd, token, &hugepage_shift);
        if (!ptep)
                return token;
        WARN_ON(hugepage_shift);
        pa = pte_pfn(*ptep) << PAGE_SHIFT;

        return pa | (token & (PAGE_SIZE-1));
}

/*
 * On PowerNV platform, we might already have fenced PHB there.
 * For that case, it's meaningless to recover frozen PE. Intead,
 * We have to handle fenced PHB firstly.
 */
static int eeh_phb_check_failure(struct eeh_pe *pe)
{
        struct eeh_pe *phb_pe;
        unsigned long flags;
        int ret;

        if (!eeh_probe_mode_dev())
                return -EPERM;

        /* Find the PHB PE */
        phb_pe = eeh_phb_pe_get(pe->phb);
        if (!phb_pe) {
                pr_warning("%s Can't find PE for PHB#%d\n",
                           __func__, pe->phb->global_number);
                return -EEXIST;
        }

        /* If the PHB has been in problematic state */
        eeh_serialize_lock(&flags);
        if (phb_pe->state & EEH_PE_ISOLATED) {
                ret = 0;
                goto out;
        }

        /* Check PHB state */
        ret = eeh_ops->get_state(phb_pe, NULL);
        if ((ret < 0) ||
            (ret == EEH_STATE_NOT_SUPPORT) ||
            (ret & (EEH_STATE_MMIO_ACTIVE | EEH_STATE_DMA_ACTIVE)) ==
            (EEH_STATE_MMIO_ACTIVE | EEH_STATE_DMA_ACTIVE)) {
                ret = 0;
                goto out;
        }

        /* Isolate the PHB and send event */
        eeh_pe_state_mark(phb_pe, EEH_PE_ISOLATED);
        eeh_serialize_unlock(flags);

        pr_err("EEH: PHB#%x failure detected\n",
                phb_pe->phb->global_number);
        dump_stack();
        eeh_send_failure_event(phb_pe);

        return 1;
out:
        eeh_serialize_unlock(flags);
        return ret;
}

/**
 * eeh_dev_check_failure - Check if all 1's data is due to EEH slot freeze
 * @edev: eeh device
 *
 * Check for an EEH failure for the given device node.  Call this
 * routine if the result of a read was all 0xff's and you want to
 * find out if this is due to an EEH slot freeze.  This routine
 * will query firmware for the EEH status.
 *
 * Returns 0 if there has not been an EEH error; otherwise returns
 * a non-zero value and queues up a slot isolation event notification.
 *
 * It is safe to call this routine in an interrupt context.
 */
int eeh_dev_check_failure(struct eeh_dev *edev)
{
        int ret;
        unsigned long flags;
        struct device_node *dn;
        struct pci_dev *dev;
        struct eeh_pe *pe;
        int rc = 0;
        const char *location;

        eeh_stats.total_mmio_ffs++;

        if (!eeh_enabled())
                return 0;

        if (!edev) {
                eeh_stats.no_dn++;
                return 0;
        }
        dn = eeh_dev_to_of_node(edev);
        dev = eeh_dev_to_pci_dev(edev);
        pe = edev->pe;

        /* Access to IO BARs might get this far and still not want checking. */
        if (!pe) {
                eeh_stats.ignored_check++;
                pr_debug("EEH: Ignored check for %s %s\n",
                        eeh_pci_name(dev), dn->full_name);
                return 0;
        }

        if (!pe->addr && !pe->config_addr) {
                eeh_stats.no_cfg_addr++;
                return 0;
        }

        /*
         * On PowerNV platform, we might already have fenced PHB
         * there and we need take care of that firstly.
         */
        ret = eeh_phb_check_failure(pe);
        if (ret > 0)
                return ret;

        /* If we already have a pending isolation event for this
         * slot, we know it's bad already, we don't need to check.
         * Do this checking under a lock; as multiple PCI devices
         * in one slot might report errors simultaneously, and we
         * only want one error recovery routine running.
         */
        eeh_serialize_lock(&flags);
        rc = 1;
        if (pe->state & EEH_PE_ISOLATED) {
                pe->check_count++;
                if (pe->check_count % EEH_MAX_FAILS == 0) {
                        location = of_get_property(dn, "ibm,loc-code", NULL);
                        printk(KERN_ERR "EEH: %d reads ignored for recovering device at "
                                "location=%s driver=%s pci addr=%s\n",
                                pe->check_count, location,
                                eeh_driver_name(dev), eeh_pci_name(dev));
                        printk(KERN_ERR "EEH: Might be infinite loop in %s driver\n",
                                eeh_driver_name(dev));
                        dump_stack();
                }
                goto dn_unlock;
        }

        /*
         * Now test for an EEH failure.  This is VERY expensive.
         * Note that the eeh_config_addr may be a parent device
         * in the case of a device behind a bridge, or it may be
         * function zero of a multi-function device.
         * In any case they must share a common PHB.
         */
        ret = eeh_ops->get_state(pe, NULL);

        /* Note that config-io to empty slots may fail;
         * they are empty when they don't have children.
         * We will punt with the following conditions: Failure to get
         * PE's state, EEH not support and Permanently unavailable
         * state, PE is in good state.
         */
        if ((ret < 0) ||
            (ret == EEH_STATE_NOT_SUPPORT) ||
            (ret & (EEH_STATE_MMIO_ACTIVE | EEH_STATE_DMA_ACTIVE)) ==
            (EEH_STATE_MMIO_ACTIVE | EEH_STATE_DMA_ACTIVE)) {
                eeh_stats.false_positives++;
                pe->false_positives++;
                rc = 0;
                goto dn_unlock;
        }

        eeh_stats.slot_resets++;

        /* Avoid repeated reports of this failure, including problems
         * with other functions on this device, and functions under
         * bridges.
         */
        eeh_pe_state_mark(pe, EEH_PE_ISOLATED);
        eeh_serialize_unlock(flags);

        /* Most EEH events are due to device driver bugs.  Having
         * a stack trace will help the device-driver authors figure
         * out what happened.  So print that out.
         */
        pr_err("EEH: Frozen PE#%x detected on PHB#%x\n",
                pe->addr, pe->phb->global_number);
        dump_stack();

        eeh_send_failure_event(pe);

        return 1;

dn_unlock:
        eeh_serialize_unlock(flags);
        return rc;
}

EXPORT_SYMBOL_GPL(eeh_dev_check_failure);

/**
 * eeh_check_failure - Check if all 1's data is due to EEH slot freeze
 * @token: I/O token, should be address in the form 0xA....
 * @val: value, should be all 1's (XXX why do we need this arg??)
 *
 * Check for an EEH failure at the given token address.  Call this
 * routine if the result of a read was all 0xff's and you want to
 * find out if this is due to an EEH slot freeze event.  This routine
 * will query firmware for the EEH status.
 *
 * Note this routine is safe to call in an interrupt context.
 */
unsigned long eeh_check_failure(const volatile void __iomem *token, unsigned long val)
{
        unsigned long addr;
        struct eeh_dev *edev;

        /* Finding the phys addr + pci device; this is pretty quick. */
        addr = eeh_token_to_phys((unsigned long __force) token);
        edev = eeh_addr_cache_get_dev(addr);
        if (!edev) {
                eeh_stats.no_device++;
                return val;
        }

        eeh_dev_check_failure(edev);
        return val;
}

EXPORT_SYMBOL(eeh_check_failure);


/**
 * eeh_pci_enable - Enable MMIO or DMA transfers for this slot
 * @pe: EEH PE
 *
 * This routine should be called to reenable frozen MMIO or DMA
 * so that it would work correctly again. It's useful while doing
 * recovery or log collection on the indicated device.
 */
int eeh_pci_enable(struct eeh_pe *pe, int function)
{
        int rc, flags = (EEH_STATE_MMIO_ACTIVE | EEH_STATE_DMA_ACTIVE);

        /*
         * pHyp doesn't allow to enable IO or DMA on unfrozen PE.
         * Also, it's pointless to enable them on unfrozen PE. So
         * we have the check here.
         */
        if (function == EEH_OPT_THAW_MMIO ||
            function == EEH_OPT_THAW_DMA) {
                rc = eeh_ops->get_state(pe, NULL);
                if (rc < 0)
                        return rc;

                /* Needn't to enable or already enabled */
                if ((rc == EEH_STATE_NOT_SUPPORT) ||
                    ((rc & flags) == flags))
                        return 0;
        }

        rc = eeh_ops->set_option(pe, function);
        if (rc)
                pr_warn("%s: Unexpected state change %d on "
                        "PHB#%d-PE#%x, err=%d\n",
                        __func__, function, pe->phb->global_number,
                        pe->addr, rc);

        rc = eeh_ops->wait_state(pe, PCI_BUS_RESET_WAIT_MSEC);
        if (rc <= 0)
                return rc;

        if ((function == EEH_OPT_THAW_MMIO) &&
            (rc & EEH_STATE_MMIO_ENABLED))
                return 0;

        if ((function == EEH_OPT_THAW_DMA) &&
            (rc & EEH_STATE_DMA_ENABLED))
                return 0;

        return rc;
}

/**
 * pcibios_set_pcie_slot_reset - Set PCI-E reset state
 * @dev: pci device struct
 * @state: reset state to enter
 *
 * Return value:
 *      0 if success
 */
int pcibios_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state)
{
        struct eeh_dev *edev = pci_dev_to_eeh_dev(dev);
        struct eeh_pe *pe = edev->pe;

        if (!pe) {
                pr_err("%s: No PE found on PCI device %s\n",
                        __func__, pci_name(dev));
                return -EINVAL;
        }

        switch (state) {
        case pcie_deassert_reset:
                eeh_ops->reset(pe, EEH_RESET_DEACTIVATE);
                break;
        case pcie_hot_reset:
                eeh_ops->reset(pe, EEH_RESET_HOT);
                break;
        case pcie_warm_reset:
                eeh_ops->reset(pe, EEH_RESET_FUNDAMENTAL);
                break;
        default:
                return -EINVAL;
        };

        return 0;
}

/**
 * eeh_set_pe_freset - Check the required reset for the indicated device
 * @data: EEH device
 * @flag: return value
 *
 * Each device might have its preferred reset type: fundamental or
 * hot reset. The routine is used to collected the information for
 * the indicated device and its children so that the bunch of the
 * devices could be reset properly.
 */
static void *eeh_set_dev_freset(void *data, void *flag)
{
        struct pci_dev *dev;
        unsigned int *freset = (unsigned int *)flag;
        struct eeh_dev *edev = (struct eeh_dev *)data;

        dev = eeh_dev_to_pci_dev(edev);
        if (dev)
                *freset |= dev->needs_freset;

        return NULL;
}

/**
 * eeh_reset_pe_once - Assert the pci #RST line for 1/4 second
 * @pe: EEH PE
 *
 * Assert the PCI #RST line for 1/4 second.
 */
static void eeh_reset_pe_once(struct eeh_pe *pe)
{
        unsigned int freset = 0;

        /* Determine type of EEH reset required for
         * Partitionable Endpoint, a hot-reset (1)
         * or a fundamental reset (3).
         * A fundamental reset required by any device under
         * Partitionable Endpoint trumps hot-reset.
         */
        eeh_pe_dev_traverse(pe, eeh_set_dev_freset, &freset);

        if (freset)
                eeh_ops->reset(pe, EEH_RESET_FUNDAMENTAL);
        else
                eeh_ops->reset(pe, EEH_RESET_HOT);

        /* The PCI bus requires that the reset be held high for at least
         * a 100 milliseconds. We wait a bit longer 'just in case'.
         */
#define PCI_BUS_RST_HOLD_TIME_MSEC 250
        msleep(PCI_BUS_RST_HOLD_TIME_MSEC);

        eeh_ops->reset(pe, EEH_RESET_DEACTIVATE);

        /* After a PCI slot has been reset, the PCI Express spec requires
         * a 1.5 second idle time for the bus to stabilize, before starting
         * up traffic.
         */
#define PCI_BUS_SETTLE_TIME_MSEC 1800
        msleep(PCI_BUS_SETTLE_TIME_MSEC);
}

/**
 * eeh_reset_pe - Reset the indicated PE
 * @pe: EEH PE
 *
 * This routine should be called to reset indicated device, including
 * PE. A PE might include multiple PCI devices and sometimes PCI bridges
 * might be involved as well.
 */
int eeh_reset_pe(struct eeh_pe *pe)
{
        int flags = (EEH_STATE_MMIO_ACTIVE | EEH_STATE_DMA_ACTIVE);
        int i, rc;

        /* Take three shots at resetting the bus */
        for (i=0; i<3; i++) {
                eeh_reset_pe_once(pe);

                /*
                 * EEH_PE_ISOLATED is expected to be removed after
                 * BAR restore.
                 */
                rc = eeh_ops->wait_state(pe, PCI_BUS_RESET_WAIT_MSEC);
                if ((rc & flags) == flags)
                        return 0;

                if (rc < 0) {
                        pr_err("%s: Unrecoverable slot failure on PHB#%d-PE#%x",
                                __func__, pe->phb->global_number, pe->addr);
                        return -1;
                }
                pr_err("EEH: bus reset %d failed on PHB#%d-PE#%x, rc=%d\n",
                        i+1, pe->phb->global_number, pe->addr, rc);
        }

        return -1;
}

/**
 * eeh_save_bars - Save device bars
 * @edev: PCI device associated EEH device
 *
 * Save the values of the device bars. Unlike the restore
 * routine, this routine is *not* recursive. This is because
 * PCI devices are added individually; but, for the restore,
 * an entire slot is reset at a time.
 */
void eeh_save_bars(struct eeh_dev *edev)
{
        int i;
        struct device_node *dn;

        if (!edev)
                return;
        dn = eeh_dev_to_of_node(edev);

        for (i = 0; i < 16; i++)
                eeh_ops->read_config(dn, i * 4, 4, &edev->config_space[i]);

        /*
         * For PCI bridges including root port, we need enable bus
         * master explicitly. Otherwise, it can't fetch IODA table
         * entries correctly. So we cache the bit in advance so that
         * we can restore it after reset, either PHB range or PE range.
         */
        if (edev->mode & EEH_DEV_BRIDGE)
                edev->config_space[1] |= PCI_COMMAND_MASTER;
}

/**
 * eeh_ops_register - Register platform dependent EEH operations
 * @ops: platform dependent EEH operations
 *
 * Register the platform dependent EEH operation callback
 * functions. The platform should call this function before
 * any other EEH operations.
 */
int __init eeh_ops_register(struct eeh_ops *ops)
{
        if (!ops->name) {
                pr_warning("%s: Invalid EEH ops name for %p\n",
                        __func__, ops);
                return -EINVAL;
        }

        if (eeh_ops && eeh_ops != ops) {
                pr_warning("%s: EEH ops of platform %s already existing (%s)\n",
                        __func__, eeh_ops->name, ops->name);
                return -EEXIST;
        }

        eeh_ops = ops;

        return 0;
}

/**
 * eeh_ops_unregister - Unreigster platform dependent EEH operations
 * @name: name of EEH platform operations
 *
 * Unregister the platform dependent EEH operation callback
 * functions.
 */
int __exit eeh_ops_unregister(const char *name)
{
        if (!name || !strlen(name)) {
                pr_warning("%s: Invalid EEH ops name\n",
                        __func__);
                return -EINVAL;
        }

        if (eeh_ops && !strcmp(eeh_ops->name, name)) {
                eeh_ops = NULL;
                return 0;
        }

        return -EEXIST;
}

static int eeh_reboot_notifier(struct notifier_block *nb,
                               unsigned long action, void *unused)
{
        eeh_set_enable(false);
        return NOTIFY_DONE;
}

static struct notifier_block eeh_reboot_nb = {
        .notifier_call = eeh_reboot_notifier,
};

/**
 * eeh_init - EEH initialization
 *
 * Initialize EEH by trying to enable it for all of the adapters in the system.
 * As a side effect we can determine here if eeh is supported at all.
 * Note that we leave EEH on so failed config cycles won't cause a machine
 * check.  If a user turns off EEH for a particular adapter they are really
 * telling Linux to ignore errors.  Some hardware (e.g. POWER5) won't
 * grant access to a slot if EEH isn't enabled, and so we always enable
 * EEH for all slots/all devices.
 *
 * The eeh-force-off option disables EEH checking globally, for all slots.
 * Even if force-off is set, the EEH hardware is still enabled, so that
 * newer systems can boot.
 */
int eeh_init(void)
{
        struct pci_controller *hose, *tmp;
        struct device_node *phb;
        static int cnt = 0;
        int ret = 0;

        /*
         * We have to delay the initialization on PowerNV after
         * the PCI hierarchy tree has been built because the PEs
         * are figured out based on PCI devices instead of device
         * tree nodes
         */
        if (machine_is(powernv) && cnt++ <= 0)
                return ret;

        /* Register reboot notifier */
        ret = register_reboot_notifier(&eeh_reboot_nb);
        if (ret) {
                pr_warn("%s: Failed to register notifier (%d)\n",
                        __func__, ret);
                return ret;
        }

        /* call platform initialization function */
        if (!eeh_ops) {
                pr_warning("%s: Platform EEH operation not found\n",
                        __func__);
                return -EEXIST;
        } else if ((ret = eeh_ops->init())) {
                pr_warning("%s: Failed to call platform init function (%d)\n",
                        __func__, ret);
                return ret;
        }

        /* Initialize EEH event */
        ret = eeh_event_init();
        if (ret)
                return ret;

        /* Enable EEH for all adapters */
        if (eeh_probe_mode_devtree()) {
                list_for_each_entry_safe(hose, tmp,
                        &hose_list, list_node) {
                        phb = hose->dn;
                        traverse_pci_devices(phb, eeh_ops->of_probe, NULL);
                }
        } else if (eeh_probe_mode_dev()) {
                list_for_each_entry_safe(hose, tmp,
                        &hose_list, list_node)
                        pci_walk_bus(hose->bus, eeh_ops->dev_probe, NULL);
        } else {
                pr_warning("%s: Invalid probe mode %d\n",
                           __func__, eeh_probe_mode);
                return -EINVAL;
        }

        /*
         * Call platform post-initialization. Actually, It's good chance
         * to inform platform that EEH is ready to supply service if the
         * I/O cache stuff has been built up.
         */
        if (eeh_ops->post_init) {
                ret = eeh_ops->post_init();
                if (ret)
                        return ret;
        }

        if (eeh_enabled())
                pr_info("EEH: PCI Enhanced I/O Error Handling Enabled\n");
        else
                pr_warning("EEH: No capable adapters found\n");

        return ret;
}

core_initcall_sync(eeh_init);

/**
 * eeh_add_device_early - Enable EEH for the indicated device_node
 * @dn: device node for which to set up EEH
 *
 * This routine must be used to perform EEH initialization for PCI
 * devices that were added after system boot (e.g. hotplug, dlpar).
 * This routine must be called before any i/o is performed to the
 * adapter (inluding any config-space i/o).
 * Whether this actually enables EEH or not for this device depends
 * on the CEC architecture, type of the device, on earlier boot
 * command-line arguments & etc.
 */
void eeh_add_device_early(struct device_node *dn)
{
        struct pci_controller *phb;

        /*
         * If we're doing EEH probe based on PCI device, we
         * would delay the probe until late stage because
         * the PCI device isn't available this moment.
         */
        if (!eeh_probe_mode_devtree())
                return;

        if (!of_node_to_eeh_dev(dn))
                return;
        phb = of_node_to_eeh_dev(dn)->phb;

        /* USB Bus children of PCI devices will not have BUID's */
        if (NULL == phb || 0 == phb->buid)
                return;

        eeh_ops->of_probe(dn, NULL);
}

/**
 * eeh_add_device_tree_early - Enable EEH for the indicated device
 * @dn: device node
 *
 * This routine must be used to perform EEH initialization for the
 * indicated PCI device that was added after system boot (e.g.
 * hotplug, dlpar).
 */
void eeh_add_device_tree_early(struct device_node *dn)
{
        struct device_node *sib;

        for_each_child_of_node(dn, sib)
                eeh_add_device_tree_early(sib);
        eeh_add_device_early(dn);
}
EXPORT_SYMBOL_GPL(eeh_add_device_tree_early);

/**
 * eeh_add_device_late - Perform EEH initialization for the indicated pci device
 * @dev: pci device for which to set up EEH
 *
 * This routine must be used to complete EEH initialization for PCI
 * devices that were added after system boot (e.g. hotplug, dlpar).
 */
void eeh_add_device_late(struct pci_dev *dev)
{
        struct device_node *dn;
        struct eeh_dev *edev;

        if (!dev || !eeh_enabled())
                return;

        pr_debug("EEH: Adding device %s\n", pci_name(dev));

        dn = pci_device_to_OF_node(dev);
        edev = of_node_to_eeh_dev(dn);
        if (edev->pdev == dev) {
                pr_debug("EEH: Already referenced !\n");
                return;
        }

        /*
         * The EEH cache might not be removed correctly because of
         * unbalanced kref to the device during unplug time, which
         * relies on pcibios_release_device(). So we have to remove
         * that here explicitly.
         */
        if (edev->pdev) {
                eeh_rmv_from_parent_pe(edev);
                eeh_addr_cache_rmv_dev(edev->pdev);
                eeh_sysfs_remove_device(edev->pdev);
                edev->mode &= ~EEH_DEV_SYSFS;

                /*
                 * We definitely should have the PCI device removed
                 * though it wasn't correctly. So we needn't call
                 * into error handler afterwards.
                 */
                edev->mode |= EEH_DEV_NO_HANDLER;

                edev->pdev = NULL;
                dev->dev.archdata.edev = NULL;
        }

        edev->pdev = dev;
        dev->dev.archdata.edev = edev;

        /*
         * We have to do the EEH probe here because the PCI device
         * hasn't been created yet in the early stage.
         */
        if (eeh_probe_mode_dev())
                eeh_ops->dev_probe(dev, NULL);

        eeh_addr_cache_insert_dev(dev);
}

/**
 * eeh_add_device_tree_late - Perform EEH initialization for the indicated PCI bus
 * @bus: PCI bus
 *
 * This routine must be used to perform EEH initialization for PCI
 * devices which are attached to the indicated PCI bus. The PCI bus
 * is added after system boot through hotplug or dlpar.
 */
void eeh_add_device_tree_late(struct pci_bus *bus)
{
        struct pci_dev *dev;

        list_for_each_entry(dev, &bus->devices, bus_list) {
                eeh_add_device_late(dev);
                if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
                        struct pci_bus *subbus = dev->subordinate;
                        if (subbus)
                                eeh_add_device_tree_late(subbus);
                }
        }
}
EXPORT_SYMBOL_GPL(eeh_add_device_tree_late);

/**
 * eeh_add_sysfs_files - Add EEH sysfs files for the indicated PCI bus
 * @bus: PCI bus
 *
 * This routine must be used to add EEH sysfs files for PCI
 * devices which are attached to the indicated PCI bus. The PCI bus
 * is added after system boot through hotplug or dlpar.
 */
void eeh_add_sysfs_files(struct pci_bus *bus)
{
        struct pci_dev *dev;

        list_for_each_entry(dev, &bus->devices, bus_list) {
                eeh_sysfs_add_device(dev);
                if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
                        struct pci_bus *subbus = dev->subordinate;
                        if (subbus)
                                eeh_add_sysfs_files(subbus);
                }
        }
}
EXPORT_SYMBOL_GPL(eeh_add_sysfs_files);

/**
 * eeh_remove_device - Undo EEH setup for the indicated pci device
 * @dev: pci device to be removed
 *
 * This routine should be called when a device is removed from
 * a running system (e.g. by hotplug or dlpar).  It unregisters
 * the PCI device from the EEH subsystem.  I/O errors affecting
 * this device will no longer be detected after this call; thus,
 * i/o errors affecting this slot may leave this device unusable.
 */
void eeh_remove_device(struct pci_dev *dev)
{
        struct eeh_dev *edev;

        if (!dev || !eeh_enabled())
                return;
        edev = pci_dev_to_eeh_dev(dev);

        /* Unregister the device with the EEH/PCI address search system */
        pr_debug("EEH: Removing device %s\n", pci_name(dev));

        if (!edev || !edev->pdev || !edev->pe) {
                pr_debug("EEH: Not referenced !\n");
                return;
        }

        /*
         * During the hotplug for EEH error recovery, we need the EEH
         * device attached to the parent PE in order for BAR restore
         * a bit later. So we keep it for BAR restore and remove it
         * from the parent PE during the BAR resotre.
         */
        edev->pdev = NULL;
        dev->dev.archdata.edev = NULL;
        if (!(edev->pe->state & EEH_PE_KEEP))
                eeh_rmv_from_parent_pe(edev);
        else
                edev->mode |= EEH_DEV_DISCONNECTED;

        /*
         * We're removing from the PCI subsystem, that means
         * the PCI device driver can't support EEH or not
         * well. So we rely on hotplug completely to do recovery
         * for the specific PCI device.
         */
        edev->mode |= EEH_DEV_NO_HANDLER;

        eeh_addr_cache_rmv_dev(dev);
        eeh_sysfs_remove_device(dev);
        edev->mode &= ~EEH_DEV_SYSFS;
}

static int proc_eeh_show(struct seq_file *m, void *v)
{
        if (!eeh_enabled()) {
                seq_printf(m, "EEH Subsystem is globally disabled\n");
                seq_printf(m, "eeh_total_mmio_ffs=%llu\n", eeh_stats.total_mmio_ffs);
        } else {
                seq_printf(m, "EEH Subsystem is enabled\n");
                seq_printf(m,
                                "no device=%llu\n"
                                "no device node=%llu\n"
                                "no config address=%llu\n"
                                "check not wanted=%llu\n"
                                "eeh_total_mmio_ffs=%llu\n"
                                "eeh_false_positives=%llu\n"
                                "eeh_slot_resets=%llu\n",
                                eeh_stats.no_device,
                                eeh_stats.no_dn,
                                eeh_stats.no_cfg_addr,
                                eeh_stats.ignored_check,
                                eeh_stats.total_mmio_ffs,
                                eeh_stats.false_positives,
                                eeh_stats.slot_resets);
        }

        return 0;
}

static int proc_eeh_open(struct inode *inode, struct file *file)
{
        return single_open(file, proc_eeh_show, NULL);
}

static const struct file_operations proc_eeh_operations = {
        .open      = proc_eeh_open,
        .read      = seq_read,
        .llseek    = seq_lseek,
        .release   = single_release,
};

static int __init eeh_init_proc(void)
{
        if (machine_is(pseries) || machine_is(powernv))
                proc_create("powerpc/eeh", 0, NULL, &proc_eeh_operations);
        return 0;
}
__initcall(eeh_init_proc);