arch/powerpc/platforms/pseries/eeh_driver.c - kernel/msm - Gitiles

 /*
  * PCI Error Recovery Driver for RPA-compliant PPC64 platform.
  * Copyright IBM Corp. 2004 2005
  * Copyright Linas Vepstas <linas@linas.org> 2004, 2005
  *
  * All rights reserved.
  *
  * 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, GOOD TITLE or
  * NON INFRINGEMENT.  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., 675 Mass Ave, Cambridge, MA 02139, USA.
  *
  * Send comments and feedback to Linas Vepstas <linas@austin.ibm.com>
  */
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/pci.h>
 #include <asm/eeh.h>
 #include <asm/eeh_event.h>
 #include <asm/ppc-pci.h>
 #include <asm/pci-bridge.h>
 #include <asm/prom.h>
 #include <asm/rtas.h>


 static inline const char * pcid_name (struct pci_dev *pdev)
 {
 	if (pdev && pdev->dev.driver)
 		return pdev->dev.driver->name;
 	return "";
 }

 #if 0
 static void print_device_node_tree(struct pci_dn *pdn, int dent)
 {
 	int i;
 	struct device_node *pc;

 	if (!pdn)
 		return;
 	for (i = 0; i < dent; i++)
 		printk(" ");
 	printk("dn=%s mode=%x \tcfg_addr=%x pe_addr=%x \tfull=%s\n",
 		pdn->node->name, pdn->eeh_mode, pdn->eeh_config_addr,
 		pdn->eeh_pe_config_addr, pdn->node->full_name);
 	dent += 3;
 	pc = pdn->node->child;
 	while (pc) {
 		print_device_node_tree(PCI_DN(pc), dent);
 		pc = pc->sibling;
 	}
 }
 #endif

 /**
  * eeh_disable_irq - disable interrupt for the recovering device
  */
 static void eeh_disable_irq(struct pci_dev *dev)
 {
 	struct device_node *dn = pci_device_to_OF_node(dev);

 	/* Don't disable MSI and MSI-X interrupts. They are
 	 * effectively disabled by the DMA Stopped state
 	 * when an EEH error occurs.
 	*/
 	if (dev->msi_enabled || dev->msix_enabled)
 		return;

 	if (!irq_has_action(dev->irq))
 		return;

 	PCI_DN(dn)->eeh_mode |= EEH_MODE_IRQ_DISABLED;
 	disable_irq_nosync(dev->irq);
 }

 /**
  * eeh_enable_irq - enable interrupt for the recovering device
  */
 static void eeh_enable_irq(struct pci_dev *dev)
 {
 	struct device_node *dn = pci_device_to_OF_node(dev);

 	if ((PCI_DN(dn)->eeh_mode) & EEH_MODE_IRQ_DISABLED) {
 		PCI_DN(dn)->eeh_mode &= ~EEH_MODE_IRQ_DISABLED;
 		enable_irq(dev->irq);
 	}
 }

 /* ------------------------------------------------------- */
 /**
  * eeh_report_error - report pci error to each device driver
  *
  * Report an EEH error to each device driver, collect up and
  * merge the device driver responses. Cumulative response
  * passed back in "userdata".
  */

 static int eeh_report_error(struct pci_dev *dev, void *userdata)
 {
 	enum pci_ers_result rc, *res = userdata;
 	struct pci_driver *driver = dev->driver;

 	dev->error_state = pci_channel_io_frozen;

 	if (!driver)
 		return 0;

 	eeh_disable_irq(dev);

 	if (!driver->err_handler ||
 	    !driver->err_handler->error_detected)
 		return 0;

 	rc = driver->err_handler->error_detected (dev, pci_channel_io_frozen);

 	/* A driver that needs a reset trumps all others */
 	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
 	if (*res == PCI_ERS_RESULT_NONE) *res = rc;

 	return 0;
 }

 /**
  * eeh_report_mmio_enabled - tell drivers that MMIO has been enabled
  *
  * Tells each device driver that IO ports, MMIO and config space I/O
  * are now enabled. Collects up and merges the device driver responses.
  * Cumulative response passed back in "userdata".
  */

 static int eeh_report_mmio_enabled(struct pci_dev *dev, void *userdata)
 {
 	enum pci_ers_result rc, *res = userdata;
 	struct pci_driver *driver = dev->driver;

 	if (!driver ||
 	    !driver->err_handler ||
 	    !driver->err_handler->mmio_enabled)
 		return 0;

 	rc = driver->err_handler->mmio_enabled (dev);

 	/* A driver that needs a reset trumps all others */
 	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
 	if (*res == PCI_ERS_RESULT_NONE) *res = rc;

 	return 0;
 }

 /**
  * eeh_report_reset - tell device that slot has been reset
  */

 static int eeh_report_reset(struct pci_dev *dev, void *userdata)
 {
 	enum pci_ers_result rc, *res = userdata;
 	struct pci_driver *driver = dev->driver;

 	if (!driver)
 		return 0;

 	dev->error_state = pci_channel_io_normal;

 	eeh_enable_irq(dev);

 	if (!driver->err_handler ||
 	    !driver->err_handler->slot_reset)
 		return 0;

 	rc = driver->err_handler->slot_reset(dev);
 	if ((*res == PCI_ERS_RESULT_NONE) ||
 	    (*res == PCI_ERS_RESULT_RECOVERED)) *res = rc;
 	if (*res == PCI_ERS_RESULT_DISCONNECT &&
 	     rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;

 	return 0;
 }

 /**
  * eeh_report_resume - tell device to resume normal operations
  */

 static int eeh_report_resume(struct pci_dev *dev, void *userdata)
 {
 	struct pci_driver *driver = dev->driver;

 	dev->error_state = pci_channel_io_normal;

 	if (!driver)
 		return 0;

 	eeh_enable_irq(dev);

 	if (!driver->err_handler ||
 	    !driver->err_handler->resume)
 		return 0;

 	driver->err_handler->resume(dev);

 	return 0;
 }

 /**
  * eeh_report_failure - tell device driver that device is dead.
  *
  * This informs the device driver that the device is permanently
  * dead, and that no further recovery attempts will be made on it.
  */

 static int eeh_report_failure(struct pci_dev *dev, void *userdata)
 {
 	struct pci_driver *driver = dev->driver;

 	dev->error_state = pci_channel_io_perm_failure;

 	if (!driver)
 		return 0;

 	eeh_disable_irq(dev);

 	if (!driver->err_handler ||
 	    !driver->err_handler->error_detected)
 		return 0;

 	driver->err_handler->error_detected(dev, pci_channel_io_perm_failure);

 	return 0;
 }

 /* ------------------------------------------------------- */
 /**
  * handle_eeh_events -- reset a PCI device after hard lockup.
  *
  * pSeries systems will isolate a PCI slot if the PCI-Host
  * bridge detects address or data parity errors, DMA's
  * occurring to wild addresses (which usually happen due to
  * bugs in device drivers or in PCI adapter firmware).
  * Slot isolations also occur if #SERR, #PERR or other misc
  * PCI-related errors are detected.
  *
  * Recovery process consists of unplugging the device driver
  * (which generated hotplug events to userspace), then issuing
  * a PCI #RST to the device, then reconfiguring the PCI config
  * space for all bridges & devices under this slot, and then
  * finally restarting the device drivers (which cause a second
  * set of hotplug events to go out to userspace).
  */

 /**
  * eeh_reset_device() -- perform actual reset of a pci slot
  * @bus: pointer to the pci bus structure corresponding
  *            to the isolated slot. A non-null value will
  *            cause all devices under the bus to be removed
  *            and then re-added.
  * @pe_dn: pointer to a "Partionable Endpoint" device node.
  *            This is the top-level structure on which pci
  *            bus resets can be performed.
  */

 static int eeh_reset_device (struct pci_dn *pe_dn, struct pci_bus *bus)
 {
 	struct device_node *dn;
 	int cnt, rc;

 	/* pcibios will clear the counter; save the value */
 	cnt = pe_dn->eeh_freeze_count;

 	if (bus)
 		pcibios_remove_pci_devices(bus);

 	/* Reset the pci controller. (Asserts RST#; resets config space).
 	 * Reconfigure bridges and devices. Don't try to bring the system
 	 * up if the reset failed for some reason. */
 	rc = rtas_set_slot_reset(pe_dn);
 	if (rc)
 		return rc;

 	/* Walk over all functions on this device.  */
 	dn = pe_dn->node;
 	if (!pcibios_find_pci_bus(dn) && PCI_DN(dn->parent))
 		dn = dn->parent->child;

 	while (dn) {
 		struct pci_dn *ppe = PCI_DN(dn);
 		/* On Power4, always true because eeh_pe_config_addr=0 */
 		if (pe_dn->eeh_pe_config_addr == ppe->eeh_pe_config_addr) {
 			rtas_configure_bridge(ppe);
 			eeh_restore_bars(ppe);
  		}
 		dn = dn->sibling;
 	}

 	/* Give the system 5 seconds to finish running the user-space
 	 * hotplug shutdown scripts, e.g. ifdown for ethernet.  Yes,
 	 * this is a hack, but if we don't do this, and try to bring
 	 * the device up before the scripts have taken it down,
 	 * potentially weird things happen.
 	 */
 	if (bus) {
 		ssleep (5);
 		pcibios_add_pci_devices(bus);
 	}
 	pe_dn->eeh_freeze_count = cnt;

 	return 0;
 }

 /* The longest amount of time to wait for a pci device
  * to come back on line, in seconds.
  */
 #define MAX_WAIT_FOR_RECOVERY 150

 struct pci_dn * handle_eeh_events (struct eeh_event *event)
 {
 	struct device_node *frozen_dn;
 	struct pci_dn *frozen_pdn;
 	struct pci_bus *frozen_bus;
 	int rc = 0;
 	enum pci_ers_result result = PCI_ERS_RESULT_NONE;
 	const char *location, *pci_str, *drv_str;

 	frozen_dn = find_device_pe(event->dn);
 	if (!frozen_dn) {

 		location = of_get_property(event->dn, "ibm,loc-code", NULL);
 		location = location ? location : "unknown";
 		printk(KERN_ERR "EEH: Error: Cannot find partition endpoint "
 		                "for location=%s pci addr=%s\n",
 		        location, pci_name(event->dev));
 		return NULL;
 	}

 	frozen_bus = pcibios_find_pci_bus(frozen_dn);
 	location = of_get_property(frozen_dn, "ibm,loc-code", NULL);
 	location = location ? location : "unknown";

 	/* There are two different styles for coming up with the PE.
 	 * In the old style, it was the highest EEH-capable device
 	 * which was always an EADS pci bridge.  In the new style,
 	 * there might not be any EADS bridges, and even when there are,
 	 * the firmware marks them as "EEH incapable". So another
 	 * two-step is needed to find the pci bus.. */
 	if (!frozen_bus)
 		frozen_bus = pcibios_find_pci_bus (frozen_dn->parent);

 	if (!frozen_bus) {
 		printk(KERN_ERR "EEH: Cannot find PCI bus "
 		        "for location=%s dn=%s\n",
 		        location, frozen_dn->full_name);
 		return NULL;
 	}

 	frozen_pdn = PCI_DN(frozen_dn);
 	frozen_pdn->eeh_freeze_count++;

 	if (frozen_pdn->pcidev) {
 		pci_str = pci_name (frozen_pdn->pcidev);
 		drv_str = pcid_name (frozen_pdn->pcidev);
 	} else {
 		pci_str = pci_name (event->dev);
 		drv_str = pcid_name (event->dev);
 	}

 	if (frozen_pdn->eeh_freeze_count > EEH_MAX_ALLOWED_FREEZES)
 		goto excess_failures;

 	printk(KERN_WARNING
 	   "EEH: This PCI device has failed %d times in the last hour:\n",
 		frozen_pdn->eeh_freeze_count);
 	printk(KERN_WARNING
 		"EEH: location=%s driver=%s pci addr=%s\n",
 		location, drv_str, pci_str);

 	/* Walk the various device drivers attached to this slot through
 	 * a reset sequence, giving each an opportunity to do what it needs
 	 * to accomplish the reset.  Each child gets a report of the
 	 * status ... if any child can't handle the reset, then the entire
 	 * slot is dlpar removed and added.
 	 */
 	pci_walk_bus(frozen_bus, eeh_report_error, &result);

 	/* Get the current PCI slot state. This can take a long time,
 	 * sometimes over 3 seconds for certain systems. */
 	rc = eeh_wait_for_slot_status (frozen_pdn, MAX_WAIT_FOR_RECOVERY*1000);
 	if (rc < 0) {
 		printk(KERN_WARNING "EEH: Permanent failure\n");
 		goto hard_fail;
 	}

 	/* Since rtas may enable MMIO when posting the error log,
 	 * don't post the error log until after all dev drivers
 	 * have been informed.
 	 */
 	eeh_slot_error_detail(frozen_pdn, EEH_LOG_TEMP_FAILURE);

 	/* If all device drivers were EEH-unaware, then shut
 	 * down all of the device drivers, and hope they
 	 * go down willingly, without panicing the system.
 	 */
 	if (result == PCI_ERS_RESULT_NONE) {
 		rc = eeh_reset_device(frozen_pdn, frozen_bus);
 		if (rc) {
 			printk(KERN_WARNING "EEH: Unable to reset, rc=%d\n", rc);
 			goto hard_fail;
 		}
 	}

 	/* If all devices reported they can proceed, then re-enable MMIO */
 	if (result == PCI_ERS_RESULT_CAN_RECOVER) {
 		rc = rtas_pci_enable(frozen_pdn, EEH_THAW_MMIO);

 		if (rc < 0)
 			goto hard_fail;
 		if (rc) {
 			result = PCI_ERS_RESULT_NEED_RESET;
 		} else {
 			result = PCI_ERS_RESULT_NONE;
 			pci_walk_bus(frozen_bus, eeh_report_mmio_enabled, &result);
 		}
 	}

 	/* If all devices reported they can proceed, then re-enable DMA */
 	if (result == PCI_ERS_RESULT_CAN_RECOVER) {
 		rc = rtas_pci_enable(frozen_pdn, EEH_THAW_DMA);

 		if (rc < 0)
 			goto hard_fail;
 		if (rc)
 			result = PCI_ERS_RESULT_NEED_RESET;
 		else
 			result = PCI_ERS_RESULT_RECOVERED;
 	}

 	/* If any device has a hard failure, then shut off everything. */
 	if (result == PCI_ERS_RESULT_DISCONNECT) {
 		printk(KERN_WARNING "EEH: Device driver gave up\n");
 		goto hard_fail;
 	}

 	/* If any device called out for a reset, then reset the slot */
 	if (result == PCI_ERS_RESULT_NEED_RESET) {
 		rc = eeh_reset_device(frozen_pdn, NULL);
 		if (rc) {
 			printk(KERN_WARNING "EEH: Cannot reset, rc=%d\n", rc);
 			goto hard_fail;
 		}
 		result = PCI_ERS_RESULT_NONE;
 		pci_walk_bus(frozen_bus, eeh_report_reset, &result);
 	}

 	/* All devices should claim they have recovered by now. */
 	if ((result != PCI_ERS_RESULT_RECOVERED) &&
 	    (result != PCI_ERS_RESULT_NONE)) {
 		printk(KERN_WARNING "EEH: Not recovered\n");
 		goto hard_fail;
 	}

 	/* Tell all device drivers that they can resume operations */
 	pci_walk_bus(frozen_bus, eeh_report_resume, NULL);

 	return frozen_pdn;

 excess_failures:
 	/*
 	 * About 90% of all real-life EEH failures in the field
 	 * are due to poorly seated PCI cards. Only 10% or so are
 	 * due to actual, failed cards.
 	 */
 	printk(KERN_ERR
 	   "EEH: PCI device at location=%s driver=%s pci addr=%s \n"
 		"has failed %d times in the last hour "
 		"and has been permanently disabled. \n"
 		"Please try reseating this device or replacing it.\n",
 		location, drv_str, pci_str, frozen_pdn->eeh_freeze_count);
 	goto perm_error;

 hard_fail:
 	printk(KERN_ERR
 	   "EEH: Unable to recover from failure of PCI device "
 	   "at location=%s driver=%s pci addr=%s \n"
 	   "Please try reseating this device or replacing it.\n",
 		location, drv_str, pci_str);

 perm_error:
 	eeh_slot_error_detail(frozen_pdn, EEH_LOG_PERM_FAILURE);

 	/* Notify all devices that they're about to go down. */
 	pci_walk_bus(frozen_bus, eeh_report_failure, NULL);

 	/* Shut down the device drivers for good. */
 	pcibios_remove_pci_devices(frozen_bus);

 	return NULL;
 }

 /* ---------- end of file ---------- */
	/*
	* PCI Error Recovery Driver for RPA-compliant PPC64 platform.
	* Copyright IBM Corp. 2004 2005
	* Copyright Linas Vepstas <linas@linas.org> 2004, 2005
	*
	* All rights reserved.
	*
	* 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, GOOD TITLE or
	* NON INFRINGEMENT. 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., 675 Mass Ave, Cambridge, MA 02139, USA.
	*
	* Send comments and feedback to Linas Vepstas <linas@austin.ibm.com>
	*/
	#include <linux/delay.h>
	#include <linux/interrupt.h>
	#include <linux/irq.h>
	#include <linux/pci.h>
	#include <asm/eeh.h>
	#include <asm/eeh_event.h>
	#include <asm/ppc-pci.h>
	#include <asm/pci-bridge.h>
	#include <asm/prom.h>
	#include <asm/rtas.h>


	static inline const char * pcid_name (struct pci_dev *pdev)
	{
	if (pdev && pdev->dev.driver)
	return pdev->dev.driver->name;
	return "";
	}

	#if 0
	static void print_device_node_tree(struct pci_dn *pdn, int dent)
	{
	int i;
	struct device_node *pc;

	if (!pdn)
	return;
	for (i = 0; i < dent; i++)
	printk(" ");
	printk("dn=%s mode=%x \tcfg_addr=%x pe_addr=%x \tfull=%s\n",
	pdn->node->name, pdn->eeh_mode, pdn->eeh_config_addr,
	pdn->eeh_pe_config_addr, pdn->node->full_name);
	dent += 3;
	pc = pdn->node->child;
	while (pc) {
	print_device_node_tree(PCI_DN(pc), dent);
	pc = pc->sibling;
	}
	}
	#endif

	/**
	* eeh_disable_irq - disable interrupt for the recovering device
	*/
	static void eeh_disable_irq(struct pci_dev *dev)
	{
	struct device_node *dn = pci_device_to_OF_node(dev);

	/* Don't disable MSI and MSI-X interrupts. They are
	* effectively disabled by the DMA Stopped state
	* when an EEH error occurs.
	*/
	if (dev->msi_enabled \|\| dev->msix_enabled)
	return;

	if (!irq_has_action(dev->irq))
	return;

	PCI_DN(dn)->eeh_mode \|= EEH_MODE_IRQ_DISABLED;
	disable_irq_nosync(dev->irq);
	}

	/**
	* eeh_enable_irq - enable interrupt for the recovering device
	*/
	static void eeh_enable_irq(struct pci_dev *dev)
	{
	struct device_node *dn = pci_device_to_OF_node(dev);

	if ((PCI_DN(dn)->eeh_mode) & EEH_MODE_IRQ_DISABLED) {
	PCI_DN(dn)->eeh_mode &= ~EEH_MODE_IRQ_DISABLED;
	enable_irq(dev->irq);
	}
	}

	/* ------------------------------------------------------- */
	/**
	* eeh_report_error - report pci error to each device driver
	*
	* Report an EEH error to each device driver, collect up and
	* merge the device driver responses. Cumulative response
	* passed back in "userdata".
	*/

	static int eeh_report_error(struct pci_dev dev, void userdata)
	{
	enum pci_ers_result rc, *res = userdata;
	struct pci_driver *driver = dev->driver;

	dev->error_state = pci_channel_io_frozen;

	if (!driver)
	return 0;

	eeh_disable_irq(dev);

	if (!driver->err_handler \|\|
	!driver->err_handler->error_detected)
	return 0;

	rc = driver->err_handler->error_detected (dev, pci_channel_io_frozen);

	/* A driver that needs a reset trumps all others */
	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
	if (res == PCI_ERS_RESULT_NONE) res = rc;

	return 0;
	}

	/**
	* eeh_report_mmio_enabled - tell drivers that MMIO has been enabled
	*
	* Tells each device driver that IO ports, MMIO and config space I/O
	* are now enabled. Collects up and merges the device driver responses.
	* Cumulative response passed back in "userdata".
	*/

	static int eeh_report_mmio_enabled(struct pci_dev dev, void userdata)
	{
	enum pci_ers_result rc, *res = userdata;
	struct pci_driver *driver = dev->driver;

	if (!driver \|\|
	!driver->err_handler \|\|
	!driver->err_handler->mmio_enabled)
	return 0;

	rc = driver->err_handler->mmio_enabled (dev);

	/* A driver that needs a reset trumps all others */
	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
	if (res == PCI_ERS_RESULT_NONE) res = rc;

	return 0;
	}

	/**
	* eeh_report_reset - tell device that slot has been reset
	*/

	static int eeh_report_reset(struct pci_dev dev, void userdata)
	{
	enum pci_ers_result rc, *res = userdata;
	struct pci_driver *driver = dev->driver;

	if (!driver)
	return 0;

	dev->error_state = pci_channel_io_normal;

	eeh_enable_irq(dev);

	if (!driver->err_handler \|\|
	!driver->err_handler->slot_reset)
	return 0;

	rc = driver->err_handler->slot_reset(dev);
	if ((*res == PCI_ERS_RESULT_NONE) \|\|
	(res == PCI_ERS_RESULT_RECOVERED)) res = rc;
	if (*res == PCI_ERS_RESULT_DISCONNECT &&
	rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;

	return 0;
	}

	/**
	* eeh_report_resume - tell device to resume normal operations
	*/

	static int eeh_report_resume(struct pci_dev dev, void userdata)
	{
	struct pci_driver *driver = dev->driver;

	dev->error_state = pci_channel_io_normal;

	if (!driver)
	return 0;

	eeh_enable_irq(dev);

	if (!driver->err_handler \|\|
	!driver->err_handler->resume)
	return 0;

	driver->err_handler->resume(dev);

	return 0;
	}

	/**
	* eeh_report_failure - tell device driver that device is dead.
	*
	* This informs the device driver that the device is permanently
	* dead, and that no further recovery attempts will be made on it.
	*/

	static int eeh_report_failure(struct pci_dev dev, void userdata)
	{
	struct pci_driver *driver = dev->driver;

	dev->error_state = pci_channel_io_perm_failure;

	if (!driver)
	return 0;

	eeh_disable_irq(dev);

	if (!driver->err_handler \|\|
	!driver->err_handler->error_detected)
	return 0;

	driver->err_handler->error_detected(dev, pci_channel_io_perm_failure);

	return 0;
	}

	/* ------------------------------------------------------- */
	/**
	* handle_eeh_events -- reset a PCI device after hard lockup.
	*
	* pSeries systems will isolate a PCI slot if the PCI-Host
	* bridge detects address or data parity errors, DMA's
	* occurring to wild addresses (which usually happen due to
	* bugs in device drivers or in PCI adapter firmware).
	* Slot isolations also occur if #SERR, #PERR or other misc
	* PCI-related errors are detected.
	*
	* Recovery process consists of unplugging the device driver
	* (which generated hotplug events to userspace), then issuing
	* a PCI #RST to the device, then reconfiguring the PCI config
	* space for all bridges & devices under this slot, and then
	* finally restarting the device drivers (which cause a second
	* set of hotplug events to go out to userspace).
	*/

	/**
	* eeh_reset_device() -- perform actual reset of a pci slot
	* @bus: pointer to the pci bus structure corresponding
	* to the isolated slot. A non-null value will
	* cause all devices under the bus to be removed
	* and then re-added.
	* @pe_dn: pointer to a "Partionable Endpoint" device node.
	* This is the top-level structure on which pci
	* bus resets can be performed.
	*/

	static int eeh_reset_device (struct pci_dn pe_dn, struct pci_bus bus)
	{
	struct device_node *dn;
	int cnt, rc;

	/* pcibios will clear the counter; save the value */
	cnt = pe_dn->eeh_freeze_count;

	if (bus)
	pcibios_remove_pci_devices(bus);

	/* Reset the pci controller. (Asserts RST#; resets config space).
	* Reconfigure bridges and devices. Don't try to bring the system
	* up if the reset failed for some reason. */
	rc = rtas_set_slot_reset(pe_dn);
	if (rc)
	return rc;

	/* Walk over all functions on this device. */
	dn = pe_dn->node;
	if (!pcibios_find_pci_bus(dn) && PCI_DN(dn->parent))
	dn = dn->parent->child;

	while (dn) {
	struct pci_dn *ppe = PCI_DN(dn);
	/* On Power4, always true because eeh_pe_config_addr=0 */
	if (pe_dn->eeh_pe_config_addr == ppe->eeh_pe_config_addr) {
	rtas_configure_bridge(ppe);
	eeh_restore_bars(ppe);
	}
	dn = dn->sibling;
	}

	/* Give the system 5 seconds to finish running the user-space
	* hotplug shutdown scripts, e.g. ifdown for ethernet. Yes,
	* this is a hack, but if we don't do this, and try to bring
	* the device up before the scripts have taken it down,
	* potentially weird things happen.
	*/
	if (bus) {
	ssleep (5);
	pcibios_add_pci_devices(bus);
	}
	pe_dn->eeh_freeze_count = cnt;

	return 0;
	}

	/* The longest amount of time to wait for a pci device
	* to come back on line, in seconds.
	*/
	#define MAX_WAIT_FOR_RECOVERY 150

	struct pci_dn * handle_eeh_events (struct eeh_event *event)
	{
	struct device_node *frozen_dn;
	struct pci_dn *frozen_pdn;
	struct pci_bus *frozen_bus;
	int rc = 0;
	enum pci_ers_result result = PCI_ERS_RESULT_NONE;
	const char location, pci_str, *drv_str;

	frozen_dn = find_device_pe(event->dn);
	if (!frozen_dn) {

	location = of_get_property(event->dn, "ibm,loc-code", NULL);
	location = location ? location : "unknown";
	printk(KERN_ERR "EEH: Error: Cannot find partition endpoint "
	"for location=%s pci addr=%s\n",
	location, pci_name(event->dev));
	return NULL;
	}

	frozen_bus = pcibios_find_pci_bus(frozen_dn);
	location = of_get_property(frozen_dn, "ibm,loc-code", NULL);
	location = location ? location : "unknown";

	/* There are two different styles for coming up with the PE.
	* In the old style, it was the highest EEH-capable device
	* which was always an EADS pci bridge. In the new style,
	* there might not be any EADS bridges, and even when there are,
	* the firmware marks them as "EEH incapable". So another
	* two-step is needed to find the pci bus.. */
	if (!frozen_bus)
	frozen_bus = pcibios_find_pci_bus (frozen_dn->parent);

	if (!frozen_bus) {
	printk(KERN_ERR "EEH: Cannot find PCI bus "
	"for location=%s dn=%s\n",
	location, frozen_dn->full_name);
	return NULL;
	}

	frozen_pdn = PCI_DN(frozen_dn);
	frozen_pdn->eeh_freeze_count++;

	if (frozen_pdn->pcidev) {
	pci_str = pci_name (frozen_pdn->pcidev);
	drv_str = pcid_name (frozen_pdn->pcidev);
	} else {
	pci_str = pci_name (event->dev);
	drv_str = pcid_name (event->dev);
	}

	if (frozen_pdn->eeh_freeze_count > EEH_MAX_ALLOWED_FREEZES)
	goto excess_failures;

	printk(KERN_WARNING
	"EEH: This PCI device has failed %d times in the last hour:\n",
	frozen_pdn->eeh_freeze_count);
	printk(KERN_WARNING
	"EEH: location=%s driver=%s pci addr=%s\n",
	location, drv_str, pci_str);

	/* Walk the various device drivers attached to this slot through
	* a reset sequence, giving each an opportunity to do what it needs
	* to accomplish the reset. Each child gets a report of the
	* status ... if any child can't handle the reset, then the entire
	* slot is dlpar removed and added.
	*/
	pci_walk_bus(frozen_bus, eeh_report_error, &result);

	/* Get the current PCI slot state. This can take a long time,
	* sometimes over 3 seconds for certain systems. */
	rc = eeh_wait_for_slot_status (frozen_pdn, MAX_WAIT_FOR_RECOVERY*1000);
	if (rc < 0) {
	printk(KERN_WARNING "EEH: Permanent failure\n");
	goto hard_fail;
	}

	/* Since rtas may enable MMIO when posting the error log,
	* don't post the error log until after all dev drivers
	* have been informed.
	*/
	eeh_slot_error_detail(frozen_pdn, EEH_LOG_TEMP_FAILURE);

	/* If all device drivers were EEH-unaware, then shut
	* down all of the device drivers, and hope they
	* go down willingly, without panicing the system.
	*/
	if (result == PCI_ERS_RESULT_NONE) {
	rc = eeh_reset_device(frozen_pdn, frozen_bus);
	if (rc) {
	printk(KERN_WARNING "EEH: Unable to reset, rc=%d\n", rc);
	goto hard_fail;
	}
	}

	/* If all devices reported they can proceed, then re-enable MMIO */
	if (result == PCI_ERS_RESULT_CAN_RECOVER) {
	rc = rtas_pci_enable(frozen_pdn, EEH_THAW_MMIO);

	if (rc < 0)
	goto hard_fail;
	if (rc) {
	result = PCI_ERS_RESULT_NEED_RESET;
	} else {
	result = PCI_ERS_RESULT_NONE;
	pci_walk_bus(frozen_bus, eeh_report_mmio_enabled, &result);
	}
	}

	/* If all devices reported they can proceed, then re-enable DMA */
	if (result == PCI_ERS_RESULT_CAN_RECOVER) {
	rc = rtas_pci_enable(frozen_pdn, EEH_THAW_DMA);

	if (rc < 0)
	goto hard_fail;
	if (rc)
	result = PCI_ERS_RESULT_NEED_RESET;
	else
	result = PCI_ERS_RESULT_RECOVERED;
	}

	/* If any device has a hard failure, then shut off everything. */
	if (result == PCI_ERS_RESULT_DISCONNECT) {
	printk(KERN_WARNING "EEH: Device driver gave up\n");
	goto hard_fail;
	}

	/* If any device called out for a reset, then reset the slot */
	if (result == PCI_ERS_RESULT_NEED_RESET) {
	rc = eeh_reset_device(frozen_pdn, NULL);
	if (rc) {
	printk(KERN_WARNING "EEH: Cannot reset, rc=%d\n", rc);
	goto hard_fail;
	}
	result = PCI_ERS_RESULT_NONE;
	pci_walk_bus(frozen_bus, eeh_report_reset, &result);
	}

	/* All devices should claim they have recovered by now. */
	if ((result != PCI_ERS_RESULT_RECOVERED) &&
	(result != PCI_ERS_RESULT_NONE)) {
	printk(KERN_WARNING "EEH: Not recovered\n");
	goto hard_fail;
	}

	/* Tell all device drivers that they can resume operations */
	pci_walk_bus(frozen_bus, eeh_report_resume, NULL);

	return frozen_pdn;

	excess_failures:
	/*
	* About 90% of all real-life EEH failures in the field
	* are due to poorly seated PCI cards. Only 10% or so are
	* due to actual, failed cards.
	*/
	printk(KERN_ERR
	"EEH: PCI device at location=%s driver=%s pci addr=%s \n"
	"has failed %d times in the last hour "
	"and has been permanently disabled. \n"
	"Please try reseating this device or replacing it.\n",
	location, drv_str, pci_str, frozen_pdn->eeh_freeze_count);
	goto perm_error;

	hard_fail:
	printk(KERN_ERR
	"EEH: Unable to recover from failure of PCI device "
	"at location=%s driver=%s pci addr=%s \n"
	"Please try reseating this device or replacing it.\n",
	location, drv_str, pci_str);

	perm_error:
	eeh_slot_error_detail(frozen_pdn, EEH_LOG_PERM_FAILURE);

	/* Notify all devices that they're about to go down. */
	pci_walk_bus(frozen_bus, eeh_report_failure, NULL);

	/* Shut down the device drivers for good. */
	pcibios_remove_pci_devices(frozen_bus);

	return NULL;
	}

	/* ---------- end of file ---------- */