arch/powerpc/kernel/eeh.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright IBM Corporation 2001, 2005, 2006
 * Copyright Dave Engebretsen & Todd Inglett 2001
 * Copyright Linas Vepstas 2005, 2006
 * Copyright 2001-2012 IBM Corporation.
 *
 * 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/iommu.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/debugfs.h>

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


/** Overview:
 *  EEH, or "Enhanced 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)

/*
 * EEH probe mode support, which is part of the flags,
 * 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_subsystem_flags;
EXPORT_SYMBOL(eeh_subsystem_flags);

/*
 * EEH allowed maximal frozen times. If one particular PE's
 * frozen count in last hour exceeds this limit, the PE will
 * be forced to be offline permanently.
 */
u32 eeh_max_freezes = 5;

/*
 * Controls whether a recovery event should be scheduled when an
 * isolated device is discovered. This is only really useful for
 * debugging problems with the EEH core.
 */
bool eeh_debugfs_no_recover;

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

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

/* Lock to protect passed flags */
static DEFINE_MUTEX(eeh_dev_mutex);

/* 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 8192
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;

static int __init eeh_setup(char *str)
{
	if (!strcmp(str, "off"))
		eeh_add_flag(EEH_FORCE_DISABLED);
	else if (!strcmp(str, "early_log"))
		eeh_add_flag(EEH_EARLY_DUMP_LOG);

	return 1;
}
__setup("eeh=", eeh_setup);

void eeh_show_enabled(void)
{
	if (eeh_has_flag(EEH_FORCE_DISABLED))
		pr_info("EEH: Recovery disabled by kernel parameter.\n");
	else if (eeh_has_flag(EEH_ENABLED))
		pr_info("EEH: Capable adapter found: recovery enabled.\n");
	else
		pr_info("EEH: No capable adapters found: recovery disabled.\n");
}

/*
 * This routine captures assorted PCI configuration space data
 * for the indicated PCI device, and puts them into a buffer
 * for RTAS error logging.
 */
static size_t eeh_dump_dev_log(struct eeh_dev *edev, char *buf, size_t len)
{
	u32 cfg;
	int cap, i;
	int n = 0, l = 0;
	char buffer[128];

	n += scnprintf(buf+n, len-n, "%04x:%02x:%02x.%01x\n",
			edev->pe->phb->global_number, edev->bdfn >> 8,
			PCI_SLOT(edev->bdfn), PCI_FUNC(edev->bdfn));
	pr_warn("EEH: of node=%04x:%02x:%02x.%01x\n",
		edev->pe->phb->global_number, edev->bdfn >> 8,
		PCI_SLOT(edev->bdfn), PCI_FUNC(edev->bdfn));

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

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

	/* Gather bridge-specific registers */
	if (edev->mode & EEH_DEV_BRIDGE) {
		eeh_ops->read_config(edev, PCI_SEC_STATUS, 2, &cfg);
		n += scnprintf(buf+n, len-n, "sec stat:%x\n", cfg);
		pr_warn("EEH: Bridge secondary status: %04x\n", cfg);

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

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

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

	/* If PCI-E capable, dump PCI-E cap 10 */
	cap = edev->pcie_cap;
	if (cap) {
		n += scnprintf(buf+n, len-n, "pci-e cap10:\n");
		pr_warn("EEH: PCI-E capabilities and status follow:\n");

		for (i=0; i<=8; i++) {
			eeh_ops->read_config(edev, cap+4*i, 4, &cfg);
			n += scnprintf(buf+n, len-n, "%02x:%x\n", 4*i, cfg);

			if ((i % 4) == 0) {
				if (i != 0)
					pr_warn("%s\n", buffer);

				l = scnprintf(buffer, sizeof(buffer),
					      "EEH: PCI-E %02x: %08x ",
					      4*i, cfg);
			} else {
				l += scnprintf(buffer+l, sizeof(buffer)-l,
					       "%08x ", cfg);
			}

		}

		pr_warn("%s\n", buffer);
	}

	/* If AER capable, dump it */
	cap = edev->aer_cap;
	if (cap) {
		n += scnprintf(buf+n, len-n, "pci-e AER:\n");
		pr_warn("EEH: PCI-E AER capability register set follows:\n");

		for (i=0; i<=13; i++) {
			eeh_ops->read_config(edev, cap+4*i, 4, &cfg);
			n += scnprintf(buf+n, len-n, "%02x:%x\n", 4*i, cfg);

			if ((i % 4) == 0) {
				if (i != 0)
					pr_warn("%s\n", buffer);

				l = scnprintf(buffer, sizeof(buffer),
					      "EEH: PCI-E AER %02x: %08x ",
					      4*i, cfg);
			} else {
				l += scnprintf(buffer+l, sizeof(buffer)-l,
					       "%08x ", cfg);
			}
		}

		pr_warn("%s\n", buffer);
	}

	return n;
}

static void *eeh_dump_pe_log(struct eeh_pe *pe, void *flag)
{
	struct eeh_dev *edev, *tmp;
	size_t *plen = flag;

	eeh_pe_for_each_dev(pe, edev, tmp)
		*plen += eeh_dump_dev_log(edev, pci_regs_buf + *plen,
					  EEH_PCI_REGS_LOG_LEN - *plen);

	return NULL;
}

/**
 * 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;

	/*
	 * 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.
	 *
	 * When the @severity is EEH_LOG_PERM, the PE is going to be
	 * removed. Prior to that, the drivers for devices included in
	 * the PE will be closed. The drivers rely on working IO path
	 * to bring the devices to quiet state. Otherwise, PCI traffic
	 * from those devices after they are removed is like to cause
	 * another unexpected EEH error.
	 */
	if (!(pe->type & EEH_PE_PHB)) {
		if (eeh_has_flag(EEH_ENABLE_IO_FOR_LOG) ||
		    severity == EEH_LOG_PERM)
			eeh_pci_enable(pe, EEH_OPT_THAW_MMIO);

		/*
		 * The config space of some PCI devices can't be accessed
		 * when their PEs are in frozen state. Otherwise, fenced
		 * PHB might be seen. Those PEs are identified with flag
		 * EEH_PE_CFG_RESTRICTED, indicating EEH_PE_CFG_BLOCKED
		 * is set automatically when the PE is put to EEH_PE_ISOLATED.
		 *
		 * Restoring BARs possibly triggers PCI config access in
		 * (OPAL) firmware and then causes fenced PHB. If the
		 * PCI config is blocked with flag EEH_PE_CFG_BLOCKED, it's
		 * pointless to restore BARs and dump config space.
		 */
		eeh_ops->configure_bridge(pe);
		if (!(pe->state & EEH_PE_CFG_BLOCKED)) {
			eeh_pe_restore_bars(pe);

			pci_regs_buf[0] = 0;
			eeh_pe_traverse(pe, eeh_dump_pe_log, &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)
{
	return ppc_find_vmap_phys(token);
}

/*
 * 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_has_flag(EEH_PROBE_MODE_DEV))
		return -EPERM;

	/* Find the PHB PE */
	phb_pe = eeh_phb_pe_get(pe->phb);
	if (!phb_pe) {
		pr_warn("%s Can't find PE for PHB#%x\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) || eeh_state_active(ret)) {
		ret = 0;
		goto out;
	}

	/* Isolate the PHB and send event */
	eeh_pe_mark_isolated(phb_pe);
	eeh_serialize_unlock(flags);

	pr_debug("EEH: PHB#%x failure detected, location: %s\n",
		phb_pe->phb->global_number, eeh_pe_loc_get(phb_pe));
	eeh_send_failure_event(phb_pe);
	return 1;
out:
	eeh_serialize_unlock(flags);
	return ret;
}

static inline const char *eeh_driver_name(struct pci_dev *pdev)
{
	if (pdev)
		return dev_driver_string(&pdev->dev);

	return "<null>";
}

/**
 * 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, *parent_pe;
	int rc = 0;
	const char *location = NULL;

	eeh_stats.total_mmio_ffs++;

	if (!eeh_enabled())
		return 0;

	if (!edev) {
		eeh_stats.no_dn++;
		return 0;
	}
	dev = eeh_dev_to_pci_dev(edev);
	pe = eeh_dev_to_pe(edev);

	/* Access to IO BARs might get this far and still not want checking. */
	if (!pe) {
		eeh_stats.ignored_check++;
		eeh_edev_dbg(edev, "Ignored check\n");
		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 the PE isn't owned by us, we shouldn't check the
	 * state. Instead, let the owner handle it if the PE has
	 * been frozen.
	 */
	if (eeh_pe_passed(pe))
		return 0;

	/* 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) {
			dn = pci_device_to_OF_node(dev);
			if (dn)
				location = of_get_property(dn, "ibm,loc-code",
						NULL);
			eeh_edev_err(edev, "%d reads ignored for recovering device at location=%s driver=%s\n",
				pe->check_count,
				location ? location : "unknown",
				eeh_driver_name(dev));
			eeh_edev_err(edev, "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.
	 *
	 * On the pSeries, after reaching the threshold, get_state might
	 * return EEH_STATE_NOT_SUPPORT. However, it's possible that the
	 * device state remains uncleared if the device is not marked
	 * pci_channel_io_perm_failure. Therefore, consider logging the
	 * event to let device removal happen.
	 *
	 */
	if ((ret < 0) ||
	    (ret == EEH_STATE_NOT_SUPPORT &&
	     dev->error_state == pci_channel_io_perm_failure) ||
	    eeh_state_active(ret)) {
		eeh_stats.false_positives++;
		pe->false_positives++;
		rc = 0;
		goto dn_unlock;
	}

	/*
	 * It should be corner case that the parent PE has been
	 * put into frozen state as well. We should take care
	 * that at first.
	 */
	parent_pe = pe->parent;
	while (parent_pe) {
		/* Hit the ceiling ? */
		if (parent_pe->type & EEH_PE_PHB)
			break;

		/* Frozen parent PE ? */
		ret = eeh_ops->get_state(parent_pe, NULL);
		if (ret > 0 && !eeh_state_active(ret)) {
			pe = parent_pe;
			pr_err("EEH: Failure of PHB#%x-PE#%x will be handled at parent PHB#%x-PE#%x.\n",
			       pe->phb->global_number, pe->addr,
			       pe->phb->global_number, parent_pe->addr);
		}

		/* Next parent level */
		parent_pe = parent_pe->parent;
	}

	eeh_stats.slot_resets++;

	/* Avoid repeated reports of this failure, including problems
	 * with other functions on this device, and functions under
	 * bridges.
	 */
	eeh_pe_mark_isolated(pe);
	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_debug("EEH: %s: Frozen PHB#%x-PE#%x detected\n",
		__func__, pe->phb->global_number, pe->addr);
	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 address
 *
 * Check for an EEH failure at the given I/O 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.
 */
int eeh_check_failure(const volatile void __iomem *token)
{
	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 0;
	}

	return eeh_dev_check_failure(edev);
}
EXPORT_SYMBOL(eeh_check_failure);


/**
 * eeh_pci_enable - Enable MMIO or DMA transfers for this slot
 * @pe: EEH PE
 * @function: EEH option
 *
 * 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 active_flag, rc;

	/*
	 * 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 to check before enabling IO or DMA.
	 */
	switch (function) {
	case EEH_OPT_THAW_MMIO:
		active_flag = EEH_STATE_MMIO_ACTIVE | EEH_STATE_MMIO_ENABLED;
		break;
	case EEH_OPT_THAW_DMA:
		active_flag = EEH_STATE_DMA_ACTIVE;
		break;
	case EEH_OPT_DISABLE:
	case EEH_OPT_ENABLE:
	case EEH_OPT_FREEZE_PE:
		active_flag = 0;
		break;
	default:
		pr_warn("%s: Invalid function %d\n",
			__func__, function);
		return -EINVAL;
	}

	/*
	 * Check if IO or DMA has been enabled before
	 * enabling them.
	 */
	if (active_flag) {
		rc = eeh_ops->get_state(pe, NULL);
		if (rc < 0)
			return rc;

		/* Needn't enable it at all */
		if (rc == EEH_STATE_NOT_SUPPORT)
			return 0;

		/* It's already enabled */
		if (rc & active_flag)
			return 0;
	}


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

	/* Check if the request is finished successfully */
	if (active_flag) {
		rc = eeh_wait_state(pe, PCI_BUS_RESET_WAIT_MSEC);
		if (rc < 0)
			return rc;

		if (rc & active_flag)
			return 0;

		return -EIO;
	}

	return rc;
}

static void eeh_disable_and_save_dev_state(struct eeh_dev *edev,
					    void *userdata)
{
	struct pci_dev *pdev = eeh_dev_to_pci_dev(edev);
	struct pci_dev *dev = userdata;

	/*
	 * The caller should have disabled and saved the
	 * state for the specified device
	 */
	if (!pdev || pdev == dev)
		return;

	/* Ensure we have D0 power state */
	pci_set_power_state(pdev, PCI_D0);

	/* Save device state */
	pci_save_state(pdev);

	/*
	 * Disable device to avoid any DMA traffic and
	 * interrupt from the device
	 */
	pci_write_config_word(pdev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);
}

static void eeh_restore_dev_state(struct eeh_dev *edev, void *userdata)
{
	struct pci_dev *pdev = eeh_dev_to_pci_dev(edev);
	struct pci_dev *dev = userdata;

	if (!pdev)
		return;

	/* Apply customization from firmware */
	if (eeh_ops->restore_config)
		eeh_ops->restore_config(edev);

	/* The caller should restore state for the specified device */
	if (pdev != dev)
		pci_restore_state(pdev);
}

/**
 * pcibios_set_pcie_reset_state - 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 = eeh_dev_to_pe(edev);

	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);
		eeh_unfreeze_pe(pe);
		if (!(pe->type & EEH_PE_VF))
			eeh_pe_state_clear(pe, EEH_PE_CFG_BLOCKED, true);
		eeh_pe_dev_traverse(pe, eeh_restore_dev_state, dev);
		eeh_pe_state_clear(pe, EEH_PE_ISOLATED, true);
		break;
	case pcie_hot_reset:
		eeh_pe_mark_isolated(pe);
		eeh_pe_state_clear(pe, EEH_PE_CFG_BLOCKED, true);
		eeh_ops->set_option(pe, EEH_OPT_FREEZE_PE);
		eeh_pe_dev_traverse(pe, eeh_disable_and_save_dev_state, dev);
		if (!(pe->type & EEH_PE_VF))
			eeh_pe_state_mark(pe, EEH_PE_CFG_BLOCKED);
		eeh_ops->reset(pe, EEH_RESET_HOT);
		break;
	case pcie_warm_reset:
		eeh_pe_mark_isolated(pe);
		eeh_pe_state_clear(pe, EEH_PE_CFG_BLOCKED, true);
		eeh_ops->set_option(pe, EEH_OPT_FREEZE_PE);
		eeh_pe_dev_traverse(pe, eeh_disable_and_save_dev_state, dev);
		if (!(pe->type & EEH_PE_VF))
			eeh_pe_state_mark(pe, EEH_PE_CFG_BLOCKED);
		eeh_ops->reset(pe, EEH_RESET_FUNDAMENTAL);
		break;
	default:
		eeh_pe_state_clear(pe, EEH_PE_ISOLATED | EEH_PE_CFG_BLOCKED, true);
		return -EINVAL;
	}

	return 0;
}

/**
 * eeh_set_dev_freset - Check the required reset for the indicated device
 * @edev: 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(struct eeh_dev *edev, void *flag)
{
	struct pci_dev *dev;
	unsigned int *freset = (unsigned int *)flag;

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

static void eeh_pe_refreeze_passed(struct eeh_pe *root)
{
	struct eeh_pe *pe;
	int state;

	eeh_for_each_pe(root, pe) {
		if (eeh_pe_passed(pe)) {
			state = eeh_ops->get_state(pe, NULL);
			if (state &
			   (EEH_STATE_MMIO_ACTIVE | EEH_STATE_MMIO_ENABLED)) {
				pr_info("EEH: Passed-through PE PHB#%x-PE#%x was thawed by reset, re-freezing for safety.\n",
					pe->phb->global_number, pe->addr);
				eeh_pe_set_option(pe, EEH_OPT_FREEZE_PE);
			}
		}
	}
}

/**
 * eeh_pe_reset_full - Complete a full reset process on the indicated PE
 * @pe: EEH PE
 * @include_passed: include passed-through devices?
 *
 * This function executes a full reset procedure on a PE, including setting
 * the appropriate flags, performing a fundamental or hot reset, and then
 * deactivating the reset status.  It is designed to be used within the EEH
 * subsystem, as opposed to eeh_pe_reset which is exported to drivers and
 * only performs a single operation at a time.
 *
 * This function will attempt to reset a PE three times before failing.
 */
int eeh_pe_reset_full(struct eeh_pe *pe, bool include_passed)
{
	int reset_state = (EEH_PE_RESET | EEH_PE_CFG_BLOCKED);
	int type = EEH_RESET_HOT;
	unsigned int freset = 0;
	int i, state = 0, ret;

	/*
	 * Determine the type of reset to perform - hot or fundamental.
	 * Hot reset is the default operation, unless any device under the
	 * PE requires a fundamental reset.
	 */
	eeh_pe_dev_traverse(pe, eeh_set_dev_freset, &freset);

	if (freset)
		type = EEH_RESET_FUNDAMENTAL;

	/* Mark the PE as in reset state and block config space accesses */
	eeh_pe_state_mark(pe, reset_state);

	/* Make three attempts at resetting the bus */
	for (i = 0; i < 3; i++) {
		ret = eeh_pe_reset(pe, type, include_passed);
		if (!ret)
			ret = eeh_pe_reset(pe, EEH_RESET_DEACTIVATE,
					   include_passed);
		if (ret) {
			ret = -EIO;
			pr_warn("EEH: Failure %d resetting PHB#%x-PE#%x (attempt %d)\n\n",
				state, pe->phb->global_number, pe->addr, i + 1);
			continue;
		}
		if (i)
			pr_warn("EEH: PHB#%x-PE#%x: Successful reset (attempt %d)\n",
				pe->phb->global_number, pe->addr, i + 1);

		/* Wait until the PE is in a functioning state */
		state = eeh_wait_state(pe, PCI_BUS_RESET_WAIT_MSEC);
		if (state < 0) {
			pr_warn("EEH: Unrecoverable slot failure on PHB#%x-PE#%x",
				pe->phb->global_number, pe->addr);
			ret = -ENOTRECOVERABLE;
			break;
		}
		if (eeh_state_active(state))
			break;
		else
			pr_warn("EEH: PHB#%x-PE#%x: Slot inactive after reset: 0x%x (attempt %d)\n",
				pe->phb->global_number, pe->addr, state, i + 1);
	}

	/* Resetting the PE may have unfrozen child PEs. If those PEs have been
	 * (potentially) passed through to a guest, re-freeze them:
	 */
	if (!include_passed)
		eeh_pe_refreeze_passed(pe);

	eeh_pe_state_clear(pe, reset_state, true);
	return ret;
}

/**
 * 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;

	if (!edev)
		return;

	for (i = 0; i < 16; i++)
		eeh_ops->read_config(edev, 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;
}

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

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

static int eeh_device_notifier(struct notifier_block *nb,
			       unsigned long action, void *data)
{
	struct device *dev = data;

	switch (action) {
	/*
	 * Note: It's not possible to perform EEH device addition (i.e.
	 * {pseries,pnv}_pcibios_bus_add_device()) here because it depends on
	 * the device's resources, which have not yet been set up.
	 */
	case BUS_NOTIFY_DEL_DEVICE:
		eeh_remove_device(to_pci_dev(dev));
		break;
	default:
		break;
	}
	return NOTIFY_DONE;
}

static struct notifier_block eeh_device_nb = {
	.notifier_call = eeh_device_notifier,
};

/**
 * eeh_init - System wide EEH initialization
 * @ops: struct to trace EEH operation callback functions
 *
 * It's the platform's job to call this from an arch_initcall().
 */
int eeh_init(struct eeh_ops *ops)
{
	struct pci_controller *hose, *tmp;
	int ret = 0;

	/* the platform should only initialise EEH once */
	if (WARN_ON(eeh_ops))
		return -EEXIST;
	if (WARN_ON(!ops))
		return -ENOENT;
	eeh_ops = ops;

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

	ret = bus_register_notifier(&pci_bus_type, &eeh_device_nb);
	if (ret) {
		pr_warn("%s: Failed to register bus notifier (%d)\n",
			__func__, ret);
		return ret;
	}

	/* Initialize PHB PEs */
	list_for_each_entry_safe(hose, tmp, &hose_list, list_node)
		eeh_phb_pe_create(hose);

	eeh_addr_cache_init();

	/* Initialize EEH event */
	return eeh_event_init();
}

/**
 * eeh_probe_device() - 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_probe_device(struct pci_dev *dev)
{
	struct eeh_dev *edev;

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

	/*
	 * pci_dev_to_eeh_dev() can only work if eeh_probe_dev() was
	 * already called for this device.
	 */
	if (WARN_ON_ONCE(pci_dev_to_eeh_dev(dev))) {
		pci_dbg(dev, "Already bound to an eeh_dev!\n");
		return;
	}

	edev = eeh_ops->probe(dev);
	if (!edev) {
		pr_debug("EEH: Adding device failed\n");
		return;
	}

	/*
	 * FIXME: We rely on pcibios_release_device() to remove the
	 * existing EEH state. The release function is only called if
	 * the pci_dev's refcount drops to zero so if something is
	 * keeping a ref to a device (e.g. a filesystem) we need to
	 * remove the old EEH state.
	 *
	 * FIXME: HEY MA, LOOK AT ME, NO LOCKING!
	 */
	if (edev->pdev && edev->pdev != dev) {
		eeh_pe_tree_remove(edev);
		eeh_addr_cache_rmv_dev(edev->pdev);
		eeh_sysfs_remove_device(edev->pdev);

		/*
		 * 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;
	}

	/* bind the pdev and the edev together */
	edev->pdev = dev;
	dev->dev.archdata.edev = edev;
	eeh_addr_cache_insert_dev(dev);
	eeh_sysfs_add_device(dev);
}

/**
 * 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 */
	dev_dbg(&dev->dev, "EEH: Removing device\n");

	if (!edev || !edev->pdev || !edev->pe) {
		dev_dbg(&dev->dev, "EEH: Device 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;

	/*
	 * eeh_sysfs_remove_device() uses pci_dev_to_eeh_dev() so we need to
	 * remove the sysfs files before clearing dev.archdata.edev
	 */
	if (edev->mode & EEH_DEV_SYSFS)
		eeh_sysfs_remove_device(dev);

	/*
	 * 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);

	/*
	 * The flag "in_error" is used to trace EEH devices for VFs
	 * in error state or not. It's set in eeh_report_error(). If
	 * it's not set, eeh_report_{reset,resume}() won't be called
	 * for the VF EEH device.
	 */
	edev->in_error = false;
	dev->dev.archdata.edev = NULL;
	if (!(edev->pe->state & EEH_PE_KEEP))
		eeh_pe_tree_remove(edev);
	else
		edev->mode |= EEH_DEV_DISCONNECTED;
}

int eeh_unfreeze_pe(struct eeh_pe *pe)
{
	int ret;

	ret = eeh_pci_enable(pe, EEH_OPT_THAW_MMIO);
	if (ret) {
		pr_warn("%s: Failure %d enabling IO on PHB#%x-PE#%x\n",
			__func__, ret, pe->phb->global_number, pe->addr);
		return ret;
	}

	ret = eeh_pci_enable(pe, EEH_OPT_THAW_DMA);
	if (ret) {
		pr_warn("%s: Failure %d enabling DMA on PHB#%x-PE#%x\n",
			__func__, ret, pe->phb->global_number, pe->addr);
		return ret;
	}

	return ret;
}
EXPORT_SYMBOL_GPL(eeh_unfreeze_pe);


static struct pci_device_id eeh_reset_ids[] = {
	{ PCI_DEVICE(0x19a2, 0x0710) },	/* Emulex, BE     */
	{ PCI_DEVICE(0x10df, 0xe220) },	/* Emulex, Lancer */
	{ PCI_DEVICE(0x14e4, 0x1657) }, /* Broadcom BCM5719 */
	{ 0 }
};

static int eeh_pe_change_owner(struct eeh_pe *pe)
{
	struct eeh_dev *edev, *tmp;
	struct pci_dev *pdev;
	struct pci_device_id *id;
	int ret;

	/* Check PE state */
	ret = eeh_ops->get_state(pe, NULL);
	if (ret < 0 || ret == EEH_STATE_NOT_SUPPORT)
		return 0;

	/* Unfrozen PE, nothing to do */
	if (eeh_state_active(ret))
		return 0;

	/* Frozen PE, check if it needs PE level reset */
	eeh_pe_for_each_dev(pe, edev, tmp) {
		pdev = eeh_dev_to_pci_dev(edev);
		if (!pdev)
			continue;

		for (id = &eeh_reset_ids[0]; id->vendor != 0; id++) {
			if (id->vendor != PCI_ANY_ID &&
			    id->vendor != pdev->vendor)
				continue;
			if (id->device != PCI_ANY_ID &&
			    id->device != pdev->device)
				continue;
			if (id->subvendor != PCI_ANY_ID &&
			    id->subvendor != pdev->subsystem_vendor)
				continue;
			if (id->subdevice != PCI_ANY_ID &&
			    id->subdevice != pdev->subsystem_device)
				continue;

			return eeh_pe_reset_and_recover(pe);
		}
	}

	ret = eeh_unfreeze_pe(pe);
	if (!ret)
		eeh_pe_state_clear(pe, EEH_PE_ISOLATED, true);
	return ret;
}

/**
 * eeh_dev_open - Increase count of pass through devices for PE
 * @pdev: PCI device
 *
 * Increase count of passed through devices for the indicated
 * PE. In the result, the EEH errors detected on the PE won't be
 * reported. The PE owner will be responsible for detection
 * and recovery.
 */
int eeh_dev_open(struct pci_dev *pdev)
{
	struct eeh_dev *edev;
	int ret = -ENODEV;

	guard(mutex)(&eeh_dev_mutex);

	/* No PCI device ? */
	if (!pdev)
		return ret;

	/* No EEH device or PE ? */
	edev = pci_dev_to_eeh_dev(pdev);
	if (!edev || !edev->pe)
		return ret;

	/*
	 * The PE might have been put into frozen state, but we
	 * didn't detect that yet. The passed through PCI devices
	 * in frozen PE won't work properly. Clear the frozen state
	 * in advance.
	 */
	ret = eeh_pe_change_owner(edev->pe);
	if (ret)
		return ret;

	/* Increase PE's pass through count */
	atomic_inc(&edev->pe->pass_dev_cnt);

	return 0;
}
EXPORT_SYMBOL_GPL(eeh_dev_open);

/**
 * eeh_dev_release - Decrease count of pass through devices for PE
 * @pdev: PCI device
 *
 * Decrease count of pass through devices for the indicated PE. If
 * there is no passed through device in PE, the EEH errors detected
 * on the PE will be reported and handled as usual.
 */
void eeh_dev_release(struct pci_dev *pdev)
{
	struct eeh_dev *edev;

	guard(mutex)(&eeh_dev_mutex);

	/* No PCI device ? */
	if (!pdev)
		return;

	/* No EEH device ? */
	edev = pci_dev_to_eeh_dev(pdev);
	if (!edev || !edev->pe || !eeh_pe_passed(edev->pe))
		return;

	/* Decrease PE's pass through count */
	WARN_ON(atomic_dec_if_positive(&edev->pe->pass_dev_cnt) < 0);
	eeh_pe_change_owner(edev->pe);
}
EXPORT_SYMBOL(eeh_dev_release);

#ifdef CONFIG_IOMMU_API

/**
 * eeh_iommu_group_to_pe - Convert IOMMU group to EEH PE
 * @group: IOMMU group
 *
 * The routine is called to convert IOMMU group to EEH PE.
 */
struct eeh_pe *eeh_iommu_group_to_pe(struct iommu_group *group)
{
	struct pci_dev *pdev = NULL;
	struct eeh_dev *edev;
	int ret;

	/* No IOMMU group ? */
	if (!group)
		return NULL;

	ret = iommu_group_for_each_dev(group, &pdev, dev_has_iommu_table);
	if (!ret || !pdev)
		return NULL;

	/* No EEH device or PE ? */
	edev = pci_dev_to_eeh_dev(pdev);
	if (!edev || !edev->pe)
		return NULL;

	return edev->pe;
}
EXPORT_SYMBOL_GPL(eeh_iommu_group_to_pe);

#endif /* CONFIG_IOMMU_API */

/**
 * eeh_pe_set_option - Set options for the indicated PE
 * @pe: EEH PE
 * @option: requested option
 *
 * The routine is called to enable or disable EEH functionality
 * on the indicated PE, to enable IO or DMA for the frozen PE.
 */
int eeh_pe_set_option(struct eeh_pe *pe, int option)
{
	int ret = 0;

	/* Invalid PE ? */
	if (!pe)
		return -ENODEV;

	/*
	 * EEH functionality could possibly be disabled, just
	 * return error for the case. And the EEH functionality
	 * isn't expected to be disabled on one specific PE.
	 */
	switch (option) {
	case EEH_OPT_ENABLE:
		if (eeh_enabled()) {
			ret = eeh_pe_change_owner(pe);
			break;
		}
		ret = -EIO;
		break;
	case EEH_OPT_DISABLE:
		break;
	case EEH_OPT_THAW_MMIO:
	case EEH_OPT_THAW_DMA:
	case EEH_OPT_FREEZE_PE:
		if (!eeh_ops || !eeh_ops->set_option) {
			ret = -ENOENT;
			break;
		}

		ret = eeh_pci_enable(pe, option);
		break;
	default:
		pr_debug("%s: Option %d out of range (%d, %d)\n",
			__func__, option, EEH_OPT_DISABLE, EEH_OPT_THAW_DMA);
		ret = -EINVAL;
	}

	return ret;
}
EXPORT_SYMBOL_GPL(eeh_pe_set_option);

/**
 * eeh_pe_get_state - Retrieve PE's state
 * @pe: EEH PE
 *
 * Retrieve the PE's state, which includes 3 aspects: enabled
 * DMA, enabled IO and asserted reset.
 */
int eeh_pe_get_state(struct eeh_pe *pe)
{
	int result, ret = 0;
	bool rst_active, dma_en, mmio_en;

	/* Existing PE ? */
	if (!pe)
		return -ENODEV;

	if (!eeh_ops || !eeh_ops->get_state)
		return -ENOENT;

	/*
	 * If the parent PE is owned by the host kernel and is undergoing
	 * error recovery, we should return the PE state as temporarily
	 * unavailable so that the error recovery on the guest is suspended
	 * until the recovery completes on the host.
	 */
	if (pe->parent &&
	    !(pe->state & EEH_PE_REMOVED) &&
	    (pe->parent->state & (EEH_PE_ISOLATED | EEH_PE_RECOVERING)))
		return EEH_PE_STATE_UNAVAIL;

	result = eeh_ops->get_state(pe, NULL);
	rst_active = !!(result & EEH_STATE_RESET_ACTIVE);
	dma_en = !!(result & EEH_STATE_DMA_ENABLED);
	mmio_en = !!(result & EEH_STATE_MMIO_ENABLED);

	if (rst_active)
		ret = EEH_PE_STATE_RESET;
	else if (dma_en && mmio_en)
		ret = EEH_PE_STATE_NORMAL;
	else if (!dma_en && !mmio_en)
		ret = EEH_PE_STATE_STOPPED_IO_DMA;
	else if (!dma_en && mmio_en)
		ret = EEH_PE_STATE_STOPPED_DMA;
	else
		ret = EEH_PE_STATE_UNAVAIL;

	return ret;
}
EXPORT_SYMBOL_GPL(eeh_pe_get_state);

static int eeh_pe_reenable_devices(struct eeh_pe *pe, bool include_passed)
{
	struct eeh_dev *edev, *tmp;
	struct pci_dev *pdev;
	int ret = 0;

	eeh_pe_restore_bars(pe);

	/*
	 * Reenable PCI devices as the devices passed
	 * through are always enabled before the reset.
	 */
	eeh_pe_for_each_dev(pe, edev, tmp) {
		pdev = eeh_dev_to_pci_dev(edev);
		if (!pdev)
			continue;

		ret = pci_reenable_device(pdev);
		if (ret) {
			pr_warn("%s: Failure %d reenabling %s\n",
				__func__, ret, pci_name(pdev));
			return ret;
		}
	}

	/* The PE is still in frozen state */
	if (include_passed || !eeh_pe_passed(pe)) {
		ret = eeh_unfreeze_pe(pe);
	} else
		pr_info("EEH: Note: Leaving passthrough PHB#%x-PE#%x frozen.\n",
			pe->phb->global_number, pe->addr);
	if (!ret)
		eeh_pe_state_clear(pe, EEH_PE_ISOLATED, include_passed);
	return ret;
}


/**
 * eeh_pe_reset - Issue PE reset according to specified type
 * @pe: EEH PE
 * @option: reset type
 * @include_passed: include passed-through devices?
 *
 * The routine is called to reset the specified PE with the
 * indicated type, either fundamental reset or hot reset.
 * PE reset is the most important part for error recovery.
 */
int eeh_pe_reset(struct eeh_pe *pe, int option, bool include_passed)
{
	int ret = 0;

	/* Invalid PE ? */
	if (!pe)
		return -ENODEV;

	if (!eeh_ops || !eeh_ops->set_option || !eeh_ops->reset)
		return -ENOENT;

	switch (option) {
	case EEH_RESET_DEACTIVATE:
		ret = eeh_ops->reset(pe, option);
		eeh_pe_state_clear(pe, EEH_PE_CFG_BLOCKED, include_passed);
		if (ret)
			break;

		ret = eeh_pe_reenable_devices(pe, include_passed);
		break;
	case EEH_RESET_HOT:
	case EEH_RESET_FUNDAMENTAL:
		/*
		 * Proactively freeze the PE to drop all MMIO access
		 * during reset, which should be banned as it's always
		 * cause recursive EEH error.
		 */
		eeh_ops->set_option(pe, EEH_OPT_FREEZE_PE);

		eeh_pe_state_mark(pe, EEH_PE_CFG_BLOCKED);
		ret = eeh_ops->reset(pe, option);
		break;
	default:
		pr_debug("%s: Unsupported option %d\n",
			__func__, option);
		ret = -EINVAL;
	}

	return ret;
}
EXPORT_SYMBOL_GPL(eeh_pe_reset);

/**
 * eeh_pe_configure - Configure PCI bridges after PE reset
 * @pe: EEH PE
 *
 * The routine is called to restore the PCI config space for
 * those PCI devices, especially PCI bridges affected by PE
 * reset issued previously.
 */
int eeh_pe_configure(struct eeh_pe *pe)
{
	int ret = 0;

	/* Invalid PE ? */
	if (!pe)
		return -ENODEV;
	else
		ret = eeh_ops->configure_bridge(pe);

	return ret;
}
EXPORT_SYMBOL_GPL(eeh_pe_configure);

/**
 * eeh_pe_inject_err - Injecting the specified PCI error to the indicated PE
 * @pe: the indicated PE
 * @type: error type
 * @func: error function
 * @addr: address
 * @mask: address mask
 *
 * The routine is called to inject the specified PCI error, which
 * is determined by @type and @func, to the indicated PE for
 * testing purpose.
 */
int eeh_pe_inject_err(struct eeh_pe *pe, int type, int func,
		      unsigned long addr, unsigned long mask)
{
	/* Invalid PE ? */
	if (!pe)
		return -ENODEV;

	/* Unsupported operation ? */
	if (!eeh_ops || !eeh_ops->err_inject)
		return -ENOENT;

	/* Check on PCI error function */
	if (func < EEH_ERR_FUNC_MIN || func > EEH_ERR_FUNC_MAX)
		return -EINVAL;

	return eeh_ops->err_inject(pe, type, func, addr, mask);
}
EXPORT_SYMBOL_GPL(eeh_pe_inject_err);

#ifdef CONFIG_PROC_FS
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;
}
#endif /* CONFIG_PROC_FS */

static int eeh_break_device(struct pci_dev *pdev)
{
	struct resource *bar = NULL;
	void __iomem *mapped;
	u16 old, bit;
	int i, pos;

	/* Do we have an MMIO BAR to disable? */
	for (i = 0; i <= PCI_STD_RESOURCE_END; i++) {
		struct resource *r = &pdev->resource[i];

		if (!r->flags || !r->start)
			continue;
		if (r->flags & IORESOURCE_IO)
			continue;
		if (r->flags & IORESOURCE_UNSET)
			continue;

		bar = r;
		break;
	}

	if (!bar) {
		pci_err(pdev, "Unable to find Memory BAR to cause EEH with\n");
		return -ENXIO;
	}

	pci_err(pdev, "Going to break: %pR\n", bar);

	if (pdev->is_virtfn) {
#ifndef CONFIG_PCI_IOV
		return -ENXIO;
#else
		/*
		 * VFs don't have a per-function COMMAND register, so the best
		 * we can do is clear the Memory Space Enable bit in the PF's
		 * SRIOV control reg.
		 *
		 * Unfortunately, this requires that we have a PF (i.e doesn't
		 * work for a passed-through VF) and it has the potential side
		 * effect of also causing an EEH on every other VF under the
		 * PF. Oh well.
		 */
		pdev = pdev->physfn;
		if (!pdev)
			return -ENXIO; /* passed through VFs have no PF */

		pos  = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_SRIOV);
		pos += PCI_SRIOV_CTRL;
		bit  = PCI_SRIOV_CTRL_MSE;
#endif /* !CONFIG_PCI_IOV */
	} else {
		bit = PCI_COMMAND_MEMORY;
		pos = PCI_COMMAND;
	}

	/*
	 * Process here is:
	 *
	 * 1. Disable Memory space.
	 *
	 * 2. Perform an MMIO to the device. This should result in an error
	 *    (CA  / UR) being raised by the device which results in an EEH
	 *    PE freeze. Using the in_8() accessor skips the eeh detection hook
	 *    so the freeze hook so the EEH Detection machinery won't be
	 *    triggered here. This is to match the usual behaviour of EEH
	 *    where the HW will asynchronously freeze a PE and it's up to
	 *    the kernel to notice and deal with it.
	 *
	 * 3. Turn Memory space back on. This is more important for VFs
	 *    since recovery will probably fail if we don't. For normal
	 *    the COMMAND register is reset as a part of re-initialising
	 *    the device.
	 *
	 * Breaking stuff is the point so who cares if it's racy ;)
	 */
	pci_read_config_word(pdev, pos, &old);

	mapped = ioremap(bar->start, PAGE_SIZE);
	if (!mapped) {
		pci_err(pdev, "Unable to map MMIO BAR %pR\n", bar);
		return -ENXIO;
	}

	pci_write_config_word(pdev, pos, old & ~bit);
	in_8(mapped);
	pci_write_config_word(pdev, pos, old);

	iounmap(mapped);

	return 0;
}

int eeh_pe_inject_mmio_error(struct pci_dev *pdev)
{
	return eeh_break_device(pdev);
}

#ifdef CONFIG_DEBUG_FS


static struct pci_dev *eeh_debug_lookup_pdev(struct file *filp,
					     const char __user *user_buf,
					     size_t count, loff_t *ppos)
{
	uint32_t domain, bus, dev, fn;
	struct pci_dev *pdev;
	char buf[20];
	int ret;

	memset(buf, 0, sizeof(buf));
	ret = simple_write_to_buffer(buf, sizeof(buf)-1, ppos, user_buf, count);
	if (!ret)
		return ERR_PTR(-EFAULT);

	ret = sscanf(buf, "%x:%x:%x.%x", &domain, &bus, &dev, &fn);
	if (ret != 4) {
		pr_err("%s: expected 4 args, got %d\n", __func__, ret);
		return ERR_PTR(-EINVAL);
	}

	pdev = pci_get_domain_bus_and_slot(domain, bus, (dev << 3) | fn);
	if (!pdev)
		return ERR_PTR(-ENODEV);

	return pdev;
}

static int eeh_enable_dbgfs_set(void *data, u64 val)
{
	if (val)
		eeh_clear_flag(EEH_FORCE_DISABLED);
	else
		eeh_add_flag(EEH_FORCE_DISABLED);

	return 0;
}

static int eeh_enable_dbgfs_get(void *data, u64 *val)
{
	if (eeh_enabled())
		*val = 0x1ul;
	else
		*val = 0x0ul;
	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(eeh_enable_dbgfs_ops, eeh_enable_dbgfs_get,
			 eeh_enable_dbgfs_set, "0x%llx\n");

static ssize_t eeh_force_recover_write(struct file *filp,
				const char __user *user_buf,
				size_t count, loff_t *ppos)
{
	struct pci_controller *hose;
	uint32_t phbid, pe_no;
	struct eeh_pe *pe;
	char buf[20];
	int ret;

	ret = simple_write_to_buffer(buf, sizeof(buf), ppos, user_buf, count);
	if (!ret)
		return -EFAULT;

	/*
	 * When PE is NULL the event is a "special" event. Rather than
	 * recovering a specific PE it forces the EEH core to scan for failed
	 * PHBs and recovers each. This needs to be done before any device
	 * recoveries can occur.
	 */
	if (!strncmp(buf, "hwcheck", 7)) {
		__eeh_send_failure_event(NULL);
		return count;
	}

	ret = sscanf(buf, "%x:%x", &phbid, &pe_no);
	if (ret != 2)
		return -EINVAL;

	hose = pci_find_controller_for_domain(phbid);
	if (!hose)
		return -ENODEV;

	/* Retrieve PE */
	pe = eeh_pe_get(hose, pe_no);
	if (!pe)
		return -ENODEV;

	/*
	 * We don't do any state checking here since the detection
	 * process is async to the recovery process. The recovery
	 * thread *should* not break even if we schedule a recovery
	 * from an odd state (e.g. PE removed, or recovery of a
	 * non-isolated PE)
	 */
	__eeh_send_failure_event(pe);

	return ret < 0 ? ret : count;
}

static const struct file_operations eeh_force_recover_fops = {
	.open	= simple_open,
	.write	= eeh_force_recover_write,
};

static ssize_t eeh_debugfs_dev_usage(struct file *filp,
				char __user *user_buf,
				size_t count, loff_t *ppos)
{
	static const char usage[] = "input format: <domain>:<bus>:<dev>.<fn>\n";

	return simple_read_from_buffer(user_buf, count, ppos,
				       usage, sizeof(usage) - 1);
}

static ssize_t eeh_dev_check_write(struct file *filp,
				const char __user *user_buf,
				size_t count, loff_t *ppos)
{
	struct pci_dev *pdev;
	struct eeh_dev *edev;
	int ret;

	pdev = eeh_debug_lookup_pdev(filp, user_buf, count, ppos);
	if (IS_ERR(pdev))
		return PTR_ERR(pdev);

	edev = pci_dev_to_eeh_dev(pdev);
	if (!edev) {
		pci_err(pdev, "No eeh_dev for this device!\n");
		pci_dev_put(pdev);
		return -ENODEV;
	}

	ret = eeh_dev_check_failure(edev);
	pci_info(pdev, "eeh_dev_check_failure(%s) = %d\n",
			pci_name(pdev), ret);

	pci_dev_put(pdev);

	return count;
}

static const struct file_operations eeh_dev_check_fops = {
	.open	= simple_open,
	.write	= eeh_dev_check_write,
	.read   = eeh_debugfs_dev_usage,
};

static ssize_t eeh_dev_break_write(struct file *filp,
				const char __user *user_buf,
				size_t count, loff_t *ppos)
{
	struct pci_dev *pdev;
	int ret;

	pdev = eeh_debug_lookup_pdev(filp, user_buf, count, ppos);
	if (IS_ERR(pdev))
		return PTR_ERR(pdev);

	ret = eeh_break_device(pdev);
	pci_dev_put(pdev);

	if (ret < 0)
		return ret;

	return count;
}

static const struct file_operations eeh_dev_break_fops = {
	.open	= simple_open,
	.write	= eeh_dev_break_write,
	.read   = eeh_debugfs_dev_usage,
};

static ssize_t eeh_dev_can_recover(struct file *filp,
				   const char __user *user_buf,
				   size_t count, loff_t *ppos)
{
	struct pci_driver *drv;
	struct pci_dev *pdev;
	size_t ret;

	pdev = eeh_debug_lookup_pdev(filp, user_buf, count, ppos);
	if (IS_ERR(pdev))
		return PTR_ERR(pdev);

	/*
	 * In order for error recovery to work the driver needs to implement
	 * .error_detected(), so it can quiesce IO to the device, and
	 * .slot_reset() so it can re-initialise the device after a reset.
	 *
	 * Ideally they'd implement .resume() too, but some drivers which
	 * we need to support (notably IPR) don't so I guess we can tolerate
	 * that.
	 *
	 * .mmio_enabled() is mostly there as a work-around for devices which
	 * take forever to re-init after a hot reset. Implementing that is
	 * strictly optional.
	 */
	drv = pci_dev_driver(pdev);
	if (drv &&
	    drv->err_handler &&
	    drv->err_handler->error_detected &&
	    drv->err_handler->slot_reset) {
		ret = count;
	} else {
		ret = -EOPNOTSUPP;
	}

	pci_dev_put(pdev);

	return ret;
}

static const struct file_operations eeh_dev_can_recover_fops = {
	.open	= simple_open,
	.write	= eeh_dev_can_recover,
	.read   = eeh_debugfs_dev_usage,
};

#endif

static int __init eeh_init_proc(void)
{
	if (machine_is(pseries) || machine_is(powernv)) {
		proc_create_single("powerpc/eeh", 0, NULL, proc_eeh_show);
#ifdef CONFIG_DEBUG_FS
		debugfs_create_file_unsafe("eeh_enable", 0600,
					   arch_debugfs_dir, NULL,
					   &eeh_enable_dbgfs_ops);
		debugfs_create_u32("eeh_max_freezes", 0600,
				arch_debugfs_dir, &eeh_max_freezes);
		debugfs_create_bool("eeh_disable_recovery", 0600,
				arch_debugfs_dir,
				&eeh_debugfs_no_recover);
		debugfs_create_file_unsafe("eeh_dev_check", 0600,
				arch_debugfs_dir, NULL,
				&eeh_dev_check_fops);
		debugfs_create_file_unsafe("eeh_dev_break", 0600,
				arch_debugfs_dir, NULL,
				&eeh_dev_break_fops);
		debugfs_create_file_unsafe("eeh_force_recover", 0600,
				arch_debugfs_dir, NULL,
				&eeh_force_recover_fops);
		debugfs_create_file_unsafe("eeh_dev_can_recover", 0600,
				arch_debugfs_dir, NULL,
				&eeh_dev_can_recover_fops);
		eeh_cache_debugfs_init();
#endif
	}

	return 0;
}
__initcall(eeh_init_proc);