drm: merge in Linus mainline

1 files changed, 1213 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/eeh.c b/arch/powerpc/platforms/pseries/eeh.c
new file mode 100644
index 00000000000..c8d2a40dc5b
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/eeh.c
@@ -0,0 +1,1213 @@
+/*
+ * eeh.c
+ * Copyright (C) 2001 Dave Engebretsen & Todd Inglett 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
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/pci.h>
+#include <linux/proc_fs.h>
+#include <linux/rbtree.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <asm/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>
+
+#undef DEBUG
+
+/** 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 occured (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 has occurred, we assume it
+ * is broken and panic.  This sets the threshold for how many read
+ * attempts we allow before panicking.
+ */
+#define EEH_MAX_FAILS	100000
+
+/* Misc forward declaraions */
+static void eeh_save_bars(struct pci_dev * pdev, struct pci_dn *pdn);
+
+/* RTAS tokens */
+static int ibm_set_eeh_option;
+static int ibm_set_slot_reset;
+static int ibm_read_slot_reset_state;
+static int ibm_read_slot_reset_state2;
+static int ibm_slot_error_detail;
+
+int eeh_subsystem_enabled;
+EXPORT_SYMBOL(eeh_subsystem_enabled);
+
+/* Lock to avoid races due to multiple reports of an error */
+static DEFINE_SPINLOCK(confirm_error_lock);
+
+/* Buffer for reporting slot-error-detail rtas calls */
+static unsigned char slot_errbuf[RTAS_ERROR_LOG_MAX];
+static DEFINE_SPINLOCK(slot_errbuf_lock);
+static int eeh_error_buf_size;
+
+/* System monitoring statistics */
+static DEFINE_PER_CPU(unsigned long, no_device);
+static DEFINE_PER_CPU(unsigned long, no_dn);
+static DEFINE_PER_CPU(unsigned long, no_cfg_addr);
+static DEFINE_PER_CPU(unsigned long, ignored_check);
+static DEFINE_PER_CPU(unsigned long, total_mmio_ffs);
+static DEFINE_PER_CPU(unsigned long, false_positives);
+static DEFINE_PER_CPU(unsigned long, ignored_failures);
+static DEFINE_PER_CPU(unsigned long, slot_resets);
+
+/**
+ * The pci address cache subsystem.  This subsystem places
+ * PCI device address resources into a red-black tree, sorted
+ * according to the address range, so that given only an i/o
+ * address, the corresponding PCI device can be **quickly**
+ * found. It is safe to perform an address lookup in an interrupt
+ * context; this ability is an important feature.
+ *
+ * Currently, the only customer of this code is the EEH subsystem;
+ * thus, this code has been somewhat tailored to suit EEH better.
+ * In particular, the cache does *not* hold the addresses of devices
+ * for which EEH is not enabled.
+ *
+ * (Implementation Note: The RB tree seems to be better/faster
+ * than any hash algo I could think of for this problem, even
+ * with the penalty of slow pointer chases for d-cache misses).
+ */
+struct pci_io_addr_range
+{
+	struct rb_node rb_node;
+	unsigned long addr_lo;
+	unsigned long addr_hi;
+	struct pci_dev *pcidev;
+	unsigned int flags;
+};
+
+static struct pci_io_addr_cache
+{
+	struct rb_root rb_root;
+	spinlock_t piar_lock;
+} pci_io_addr_cache_root;
+
+static inline struct pci_dev *__pci_get_device_by_addr(unsigned long addr)
+{
+	struct rb_node *n = pci_io_addr_cache_root.rb_root.rb_node;
+
+	while (n) {
+		struct pci_io_addr_range *piar;
+		piar = rb_entry(n, struct pci_io_addr_range, rb_node);
+
+		if (addr < piar->addr_lo) {
+			n = n->rb_left;
+		} else {
+			if (addr > piar->addr_hi) {
+				n = n->rb_right;
+			} else {
+				pci_dev_get(piar->pcidev);
+				return piar->pcidev;
+			}
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * pci_get_device_by_addr - Get device, given only address
+ * @addr: mmio (PIO) phys address or i/o port number
+ *
+ * Given an mmio phys address, or a port number, find a pci device
+ * that implements this address.  Be sure to pci_dev_put the device
+ * when finished.  I/O port numbers are assumed to be offset
+ * from zero (that is, they do *not* have pci_io_addr added in).
+ * It is safe to call this function within an interrupt.
+ */
+static struct pci_dev *pci_get_device_by_addr(unsigned long addr)
+{
+	struct pci_dev *dev;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
+	dev = __pci_get_device_by_addr(addr);
+	spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
+	return dev;
+}
+
+#ifdef DEBUG
+/*
+ * Handy-dandy debug print routine, does nothing more
+ * than print out the contents of our addr cache.
+ */
+static void pci_addr_cache_print(struct pci_io_addr_cache *cache)
+{
+	struct rb_node *n;
+	int cnt = 0;
+
+	n = rb_first(&cache->rb_root);
+	while (n) {
+		struct pci_io_addr_range *piar;
+		piar = rb_entry(n, struct pci_io_addr_range, rb_node);
+		printk(KERN_DEBUG "PCI: %s addr range %d [%lx-%lx]: %s\n",
+		       (piar->flags & IORESOURCE_IO) ? "i/o" : "mem", cnt,
+		       piar->addr_lo, piar->addr_hi, pci_name(piar->pcidev));
+		cnt++;
+		n = rb_next(n);
+	}
+}
+#endif
+
+/* Insert address range into the rb tree. */
+static struct pci_io_addr_range *
+pci_addr_cache_insert(struct pci_dev *dev, unsigned long alo,
+		      unsigned long ahi, unsigned int flags)
+{
+	struct rb_node **p = &pci_io_addr_cache_root.rb_root.rb_node;
+	struct rb_node *parent = NULL;
+	struct pci_io_addr_range *piar;
+
+	/* Walk tree, find a place to insert into tree */
+	while (*p) {
+		parent = *p;
+		piar = rb_entry(parent, struct pci_io_addr_range, rb_node);
+		if (ahi < piar->addr_lo) {
+			p = &parent->rb_left;
+		} else if (alo > piar->addr_hi) {
+			p = &parent->rb_right;
+		} else {
+			if (dev != piar->pcidev ||
+			    alo != piar->addr_lo || ahi != piar->addr_hi) {
+				printk(KERN_WARNING "PIAR: overlapping address range\n");
+			}
+			return piar;
+		}
+	}
+	piar = (struct pci_io_addr_range *)kmalloc(sizeof(struct pci_io_addr_range), GFP_ATOMIC);
+	if (!piar)
+		return NULL;
+
+	piar->addr_lo = alo;
+	piar->addr_hi = ahi;
+	piar->pcidev = dev;
+	piar->flags = flags;
+
+#ifdef DEBUG
+	printk(KERN_DEBUG "PIAR: insert range=[%lx:%lx] dev=%s\n",
+	                  alo, ahi, pci_name (dev));
+#endif
+
+	rb_link_node(&piar->rb_node, parent, p);
+	rb_insert_color(&piar->rb_node, &pci_io_addr_cache_root.rb_root);
+
+	return piar;
+}
+
+static void __pci_addr_cache_insert_device(struct pci_dev *dev)
+{
+	struct device_node *dn;
+	struct pci_dn *pdn;
+	int i;
+	int inserted = 0;
+
+	dn = pci_device_to_OF_node(dev);
+	if (!dn) {
+		printk(KERN_WARNING "PCI: no pci dn found for dev=%s\n", pci_name(dev));
+		return;
+	}
+
+	/* Skip any devices for which EEH is not enabled. */
+	pdn = PCI_DN(dn);
+	if (!(pdn->eeh_mode & EEH_MODE_SUPPORTED) ||
+	    pdn->eeh_mode & EEH_MODE_NOCHECK) {
+#ifdef DEBUG
+		printk(KERN_INFO "PCI: skip building address cache for=%s - %s\n",
+		       pci_name(dev), pdn->node->full_name);
+#endif
+		return;
+	}
+
+	/* The cache holds a reference to the device... */
+	pci_dev_get(dev);
+
+	/* Walk resources on this device, poke them into the tree */
+	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
+		unsigned long start = pci_resource_start(dev,i);
+		unsigned long end = pci_resource_end(dev,i);
+		unsigned int flags = pci_resource_flags(dev,i);
+
+		/* We are interested only bus addresses, not dma or other stuff */
+		if (0 == (flags & (IORESOURCE_IO | IORESOURCE_MEM)))
+			continue;
+		if (start == 0 || ~start == 0 || end == 0 || ~end == 0)
+			 continue;
+		pci_addr_cache_insert(dev, start, end, flags);
+		inserted = 1;
+	}
+
+	/* If there was nothing to add, the cache has no reference... */
+	if (!inserted)
+		pci_dev_put(dev);
+}
+
+/**
+ * pci_addr_cache_insert_device - Add a device to the address cache
+ * @dev: PCI device whose I/O addresses we are interested in.
+ *
+ * In order to support the fast lookup of devices based on addresses,
+ * we maintain a cache of devices that can be quickly searched.
+ * This routine adds a device to that cache.
+ */
+static void pci_addr_cache_insert_device(struct pci_dev *dev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
+	__pci_addr_cache_insert_device(dev);
+	spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
+}
+
+static inline void __pci_addr_cache_remove_device(struct pci_dev *dev)
+{
+	struct rb_node *n;
+	int removed = 0;
+
+restart:
+	n = rb_first(&pci_io_addr_cache_root.rb_root);
+	while (n) {
+		struct pci_io_addr_range *piar;
+		piar = rb_entry(n, struct pci_io_addr_range, rb_node);
+
+		if (piar->pcidev == dev) {
+			rb_erase(n, &pci_io_addr_cache_root.rb_root);
+			removed = 1;
+			kfree(piar);
+			goto restart;
+		}
+		n = rb_next(n);
+	}
+
+	/* The cache no longer holds its reference to this device... */
+	if (removed)
+		pci_dev_put(dev);
+}
+
+/**
+ * pci_addr_cache_remove_device - remove pci device from addr cache
+ * @dev: device to remove
+ *
+ * Remove a device from the addr-cache tree.
+ * This is potentially expensive, since it will walk
+ * the tree multiple times (once per resource).
+ * But so what; device removal doesn't need to be that fast.
+ */
+static void pci_addr_cache_remove_device(struct pci_dev *dev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
+	__pci_addr_cache_remove_device(dev);
+	spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
+}
+
+/**
+ * pci_addr_cache_build - Build a cache of I/O addresses
+ *
+ * Build a cache of pci i/o addresses.  This cache will be used to
+ * find the pci device that corresponds to a given address.
+ * This routine scans all pci busses to build the cache.
+ * Must be run late in boot process, after the pci controllers
+ * have been scaned for devices (after all device resources are known).
+ */
+void __init pci_addr_cache_build(void)
+{
+	struct device_node *dn;
+	struct pci_dev *dev = NULL;
+
+	if (!eeh_subsystem_enabled)
+		return;
+
+	spin_lock_init(&pci_io_addr_cache_root.piar_lock);
+
+	while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
+		/* Ignore PCI bridges ( XXX why ??) */
+		if ((dev->class >> 16) == PCI_BASE_CLASS_BRIDGE) {
+			continue;
+		}
+		pci_addr_cache_insert_device(dev);
+
+		/* Save the BAR's; firmware doesn't restore these after EEH reset */
+		dn = pci_device_to_OF_node(dev);
+		eeh_save_bars(dev, PCI_DN(dn));
+	}
+
+#ifdef DEBUG
+	/* Verify tree built up above, echo back the list of addrs. */
+	pci_addr_cache_print(&pci_io_addr_cache_root);
+#endif
+}
+
+/* --------------------------------------------------------------- */
+/* Above lies the PCI Address Cache. Below lies the EEH event infrastructure */
+
+void eeh_slot_error_detail (struct pci_dn *pdn, int severity)
+{
+	unsigned long flags;
+	int rc;
+
+	/* Log the error with the rtas logger */
+	spin_lock_irqsave(&slot_errbuf_lock, flags);
+	memset(slot_errbuf, 0, eeh_error_buf_size);
+
+	rc = rtas_call(ibm_slot_error_detail,
+	               8, 1, NULL, pdn->eeh_config_addr,
+	               BUID_HI(pdn->phb->buid),
+	               BUID_LO(pdn->phb->buid), NULL, 0,
+	               virt_to_phys(slot_errbuf),
+	               eeh_error_buf_size,
+	               severity);
+
+	if (rc == 0)
+		log_error(slot_errbuf, ERR_TYPE_RTAS_LOG, 0);
+	spin_unlock_irqrestore(&slot_errbuf_lock, flags);
+}
+
+/**
+ * read_slot_reset_state - Read the reset state of a device node's slot
+ * @dn: device node to read
+ * @rets: array to return results in
+ */
+static int read_slot_reset_state(struct pci_dn *pdn, int rets[])
+{
+	int token, outputs;
+
+	if (ibm_read_slot_reset_state2 != RTAS_UNKNOWN_SERVICE) {
+		token = ibm_read_slot_reset_state2;
+		outputs = 4;
+	} else {
+		token = ibm_read_slot_reset_state;
+		rets[2] = 0; /* fake PE Unavailable info */
+		outputs = 3;
+	}
+
+	return rtas_call(token, 3, outputs, rets, pdn->eeh_config_addr,
+			 BUID_HI(pdn->phb->buid), BUID_LO(pdn->phb->buid));
+}
+
+/**
+ * eeh_token_to_phys - convert EEH address token to phys address
+ * @token i/o token, should be address in the form 0xA....
+ */
+static inline unsigned long eeh_token_to_phys(unsigned long token)
+{
+	pte_t *ptep;
+	unsigned long pa;
+
+	ptep = find_linux_pte(init_mm.pgd, token);
+	if (!ptep)
+		return token;
+	pa = pte_pfn(*ptep) << PAGE_SHIFT;
+
+	return pa | (token & (PAGE_SIZE-1));
+}
+
+/** 
+ * Return the "partitionable endpoint" (pe) under which this device lies
+ */
+static struct device_node * find_device_pe(struct device_node *dn)
+{
+	while ((dn->parent) && PCI_DN(dn->parent) &&
+	      (PCI_DN(dn->parent)->eeh_mode & EEH_MODE_SUPPORTED)) {
+		dn = dn->parent;
+	}
+	return dn;
+}
+
+/** Mark all devices that are peers of this device as failed.
+ *  Mark the device driver too, so that it can see the failure
+ *  immediately; this is critical, since some drivers poll
+ *  status registers in interrupts ... If a driver is polling,
+ *  and the slot is frozen, then the driver can deadlock in
+ *  an interrupt context, which is bad.
+ */
+
+static void __eeh_mark_slot (struct device_node *dn, int mode_flag)
+{
+	while (dn) {
+		if (PCI_DN(dn)) {
+			PCI_DN(dn)->eeh_mode |= mode_flag;
+
+			if (dn->child)
+				__eeh_mark_slot (dn->child, mode_flag);
+		}
+		dn = dn->sibling;
+	}
+}
+
+void eeh_mark_slot (struct device_node *dn, int mode_flag)
+{
+	dn = find_device_pe (dn);
+	PCI_DN(dn)->eeh_mode |= mode_flag;
+	__eeh_mark_slot (dn->child, mode_flag);
+}
+
+static void __eeh_clear_slot (struct device_node *dn, int mode_flag)
+{
+	while (dn) {
+		if (PCI_DN(dn)) {
+			PCI_DN(dn)->eeh_mode &= ~mode_flag;
+			PCI_DN(dn)->eeh_check_count = 0;
+			if (dn->child)
+				__eeh_clear_slot (dn->child, mode_flag);
+		}
+		dn = dn->sibling;
+	}
+}
+
+void eeh_clear_slot (struct device_node *dn, int mode_flag)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&confirm_error_lock, flags);
+	dn = find_device_pe (dn);
+	PCI_DN(dn)->eeh_mode &= ~mode_flag;
+	PCI_DN(dn)->eeh_check_count = 0;
+	__eeh_clear_slot (dn->child, mode_flag);
+	spin_unlock_irqrestore(&confirm_error_lock, flags);
+}
+
+/**
+ * eeh_dn_check_failure - check if all 1's data is due to EEH slot freeze
+ * @dn device node
+ * @dev pci device, if known
+ *
+ * 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_dn_check_failure(struct device_node *dn, struct pci_dev *dev)
+{
+	int ret;
+	int rets[3];
+	unsigned long flags;
+	struct pci_dn *pdn;
+	int rc = 0;
+
+	__get_cpu_var(total_mmio_ffs)++;
+
+	if (!eeh_subsystem_enabled)
+		return 0;
+
+	if (!dn) {
+		__get_cpu_var(no_dn)++;
+		return 0;
+	}
+	pdn = PCI_DN(dn);
+
+	/* Access to IO BARs might get this far and still not want checking. */
+	if (!(pdn->eeh_mode & EEH_MODE_SUPPORTED) ||
+	    pdn->eeh_mode & EEH_MODE_NOCHECK) {
+		__get_cpu_var(ignored_check)++;
+#ifdef DEBUG
+		printk ("EEH:ignored check (%x) for %s %s\n", 
+		        pdn->eeh_mode, pci_name (dev), dn->full_name);
+#endif
+		return 0;
+	}
+
+	if (!pdn->eeh_config_addr) {
+		__get_cpu_var(no_cfg_addr)++;
+		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.
+	 */
+	spin_lock_irqsave(&confirm_error_lock, flags);
+	rc = 1;
+	if (pdn->eeh_mode & EEH_MODE_ISOLATED) {
+		pdn->eeh_check_count ++;
+		if (pdn->eeh_check_count >= EEH_MAX_FAILS) {
+			printk (KERN_ERR "EEH: Device driver ignored %d bad reads, panicing\n",
+			        pdn->eeh_check_count);
+			dump_stack();
+			
+			/* re-read the slot reset state */
+			if (read_slot_reset_state(pdn, rets) != 0)
+				rets[0] = -1;	/* reset state unknown */
+
+			/* If we are here, then we hit an infinite loop. Stop. */
+			panic("EEH: MMIO halt (%d) on device:%s\n", rets[0], pci_name(dev));
+		}
+		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 = read_slot_reset_state(pdn, rets);
+
+	/* If the call to firmware failed, punt */
+	if (ret != 0) {
+		printk(KERN_WARNING "EEH: read_slot_reset_state() failed; rc=%d dn=%s\n",
+		       ret, dn->full_name);
+		__get_cpu_var(false_positives)++;
+		rc = 0;
+		goto dn_unlock;
+	}
+
+	/* If EEH is not supported on this device, punt. */
+	if (rets[1] != 1) {
+		printk(KERN_WARNING "EEH: event on unsupported device, rc=%d dn=%s\n",
+		       ret, dn->full_name);
+		__get_cpu_var(false_positives)++;
+		rc = 0;
+		goto dn_unlock;
+	}
+
+	/* If not the kind of error we know about, punt. */
+	if (rets[0] != 2 && rets[0] != 4 && rets[0] != 5) {
+		__get_cpu_var(false_positives)++;
+		rc = 0;
+		goto dn_unlock;
+	}
+
+	/* Note that config-io to empty slots may fail;
+	 * we recognize empty because they don't have children. */
+	if ((rets[0] == 5) && (dn->child == NULL)) {
+		__get_cpu_var(false_positives)++;
+		rc = 0;
+		goto dn_unlock;
+	}
+
+	__get_cpu_var(slot_resets)++;
+ 
+	/* Avoid repeated reports of this failure, including problems
+	 * with other functions on this device, and functions under
+	 * bridges. */
+	eeh_mark_slot (dn, EEH_MODE_ISOLATED);
+	spin_unlock_irqrestore(&confirm_error_lock, flags);
+
+	eeh_send_failure_event (dn, dev, rets[0], rets[2]);
+	
+	/* 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. */
+	if (rets[0] != 5) dump_stack();
+	return 1;
+
+dn_unlock:
+	spin_unlock_irqrestore(&confirm_error_lock, flags);
+	return rc;
+}
+
+EXPORT_SYMBOL_GPL(eeh_dn_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 pci_dev *dev;
+	struct device_node *dn;
+
+	/* Finding the phys addr + pci device; this is pretty quick. */
+	addr = eeh_token_to_phys((unsigned long __force) token);
+	dev = pci_get_device_by_addr(addr);
+	if (!dev) {
+		__get_cpu_var(no_device)++;
+		return val;
+	}
+
+	dn = pci_device_to_OF_node(dev);
+	eeh_dn_check_failure (dn, dev);
+
+	pci_dev_put(dev);
+	return val;
+}
+
+EXPORT_SYMBOL(eeh_check_failure);
+
+/* ------------------------------------------------------------- */
+/* The code below deals with error recovery */
+
+/** Return negative value if a permanent error, else return
+ * a number of milliseconds to wait until the PCI slot is
+ * ready to be used.
+ */
+static int
+eeh_slot_availability(struct pci_dn *pdn)
+{
+	int rc;
+	int rets[3];
+
+	rc = read_slot_reset_state(pdn, rets);
+
+	if (rc) return rc;
+
+	if (rets[1] == 0) return -1;  /* EEH is not supported */
+	if (rets[0] == 0)  return 0;  /* Oll Korrect */
+	if (rets[0] == 5) {
+		if (rets[2] == 0) return -1; /* permanently unavailable */
+		return rets[2]; /* number of millisecs to wait */
+	}
+	return -1;
+}
+
+/** rtas_pci_slot_reset raises/lowers the pci #RST line
+ *  state: 1/0 to raise/lower the #RST
+ *
+ * Clear the EEH-frozen condition on a slot.  This routine
+ * asserts the PCI #RST line if the 'state' argument is '1',
+ * and drops the #RST line if 'state is '0'.  This routine is
+ * safe to call in an interrupt context.
+ *
+ */
+
+static void
+rtas_pci_slot_reset(struct pci_dn *pdn, int state)
+{
+	int rc;
+
+	BUG_ON (pdn==NULL); 
+
+	if (!pdn->phb) {
+		printk (KERN_WARNING "EEH: in slot reset, device node %s has no phb\n",
+		        pdn->node->full_name);
+		return;
+	}
+
+	rc = rtas_call(ibm_set_slot_reset,4,1, NULL,
+	               pdn->eeh_config_addr,
+	               BUID_HI(pdn->phb->buid),
+	               BUID_LO(pdn->phb->buid),
+	               state);
+	if (rc) {
+		printk (KERN_WARNING "EEH: Unable to reset the failed slot, (%d) #RST=%d dn=%s\n", 
+		        rc, state, pdn->node->full_name);
+		return;
+	}
+}
+
+/** rtas_set_slot_reset -- assert the pci #RST line for 1/4 second
+ *  dn -- device node to be reset.
+ */
+
+void
+rtas_set_slot_reset(struct pci_dn *pdn)
+{
+	int i, rc;
+
+	rtas_pci_slot_reset (pdn, 1);
+
+	/* 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);
+	
+	/* We might get hit with another EEH freeze as soon as the 
+	 * pci slot reset line is dropped. Make sure we don't miss
+	 * these, and clear the flag now. */
+	eeh_clear_slot (pdn->node, EEH_MODE_ISOLATED);
+
+	rtas_pci_slot_reset (pdn, 0);
+
+	/* 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);
+
+	/* Now double check with the firmware to make sure the device is
+	 * ready to be used; if not, wait for recovery. */
+	for (i=0; i<10; i++) {
+		rc = eeh_slot_availability (pdn);
+		if (rc <= 0) break;
+
+		msleep (rc+100);
+	}
+}
+
+/* ------------------------------------------------------- */
+/** Save and restore of PCI BARs
+ *
+ * Although firmware will set up BARs during boot, it doesn't
+ * set up device BAR's after a device reset, although it will,
+ * if requested, set up bridge configuration. Thus, we need to
+ * configure the PCI devices ourselves.  
+ */
+
+/**
+ * __restore_bars - Restore the Base Address Registers
+ * Loads the PCI configuration space base address registers,
+ * the expansion ROM base address, the latency timer, and etc.
+ * from the saved values in the device node.
+ */
+static inline void __restore_bars (struct pci_dn *pdn)
+{
+	int i;
+
+	if (NULL==pdn->phb) return;
+	for (i=4; i<10; i++) {
+		rtas_write_config(pdn, i*4, 4, pdn->config_space[i]);
+	}
+
+	/* 12 == Expansion ROM Address */
+	rtas_write_config(pdn, 12*4, 4, pdn->config_space[12]);
+
+#define BYTE_SWAP(OFF) (8*((OFF)/4)+3-(OFF))
+#define SAVED_BYTE(OFF) (((u8 *)(pdn->config_space))[BYTE_SWAP(OFF)])
+
+	rtas_write_config (pdn, PCI_CACHE_LINE_SIZE, 1,
+	            SAVED_BYTE(PCI_CACHE_LINE_SIZE));
+
+	rtas_write_config (pdn, PCI_LATENCY_TIMER, 1,
+	            SAVED_BYTE(PCI_LATENCY_TIMER));
+
+	/* max latency, min grant, interrupt pin and line */
+	rtas_write_config(pdn, 15*4, 4, pdn->config_space[15]);
+}
+
+/**
+ * eeh_restore_bars - restore the PCI config space info
+ *
+ * This routine performs a recursive walk to the children
+ * of this device as well.
+ */
+void eeh_restore_bars(struct pci_dn *pdn)
+{
+	struct device_node *dn;
+	if (!pdn) 
+		return;
+	
+	if (! pdn->eeh_is_bridge)
+		__restore_bars (pdn);
+
+	dn = pdn->node->child;
+	while (dn) {
+		eeh_restore_bars (PCI_DN(dn));
+		dn = dn->sibling;
+	}
+}
+
+/**
+ * eeh_save_bars - save device bars
+ *
+ * Save the values of the device bars. Unlike the restore
+ * routine, this routine is *not* recursive. This is because
+ * PCI devices are added individuallly; but, for the restore,
+ * an entire slot is reset at a time.
+ */
+static void eeh_save_bars(struct pci_dev * pdev, struct pci_dn *pdn)
+{
+	int i;
+
+	if (!pdev || !pdn )
+		return;
+	
+	for (i = 0; i < 16; i++)
+		pci_read_config_dword(pdev, i * 4, &pdn->config_space[i]);
+
+	if (pdev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
+		pdn->eeh_is_bridge = 1;
+}
+
+void
+rtas_configure_bridge(struct pci_dn *pdn)
+{
+	int token = rtas_token ("ibm,configure-bridge");
+	int rc;
+
+	if (token == RTAS_UNKNOWN_SERVICE)
+		return;
+	rc = rtas_call(token,3,1, NULL,
+	               pdn->eeh_config_addr,
+	               BUID_HI(pdn->phb->buid),
+	               BUID_LO(pdn->phb->buid));
+	if (rc) {
+		printk (KERN_WARNING "EEH: Unable to configure device bridge (%d) for %s\n",
+		        rc, pdn->node->full_name);
+	}
+}
+
+/* ------------------------------------------------------------- */
+/* The code below deals with enabling EEH for devices during  the
+ * early boot sequence.  EEH must be enabled before any PCI probing
+ * can be done.
+ */
+
+#define EEH_ENABLE 1
+
+struct eeh_early_enable_info {
+	unsigned int buid_hi;
+	unsigned int buid_lo;
+};
+
+/* Enable eeh for the given device node. */
+static void *early_enable_eeh(struct device_node *dn, void *data)
+{
+	struct eeh_early_enable_info *info = data;
+	int ret;
+	char *status = get_property(dn, "status", NULL);
+	u32 *class_code = (u32 *)get_property(dn, "class-code", NULL);
+	u32 *vendor_id = (u32 *)get_property(dn, "vendor-id", NULL);
+	u32 *device_id = (u32 *)get_property(dn, "device-id", NULL);
+	u32 *regs;
+	int enable;
+	struct pci_dn *pdn = PCI_DN(dn);
+
+	pdn->eeh_mode = 0;
+	pdn->eeh_check_count = 0;
+	pdn->eeh_freeze_count = 0;
+
+	if (status && strcmp(status, "ok") != 0)
+		return NULL;	/* ignore devices with bad status */
+
+	/* Ignore bad nodes. */
+	if (!class_code || !vendor_id || !device_id)
+		return NULL;
+
+	/* There is nothing to check on PCI to ISA bridges */
+	if (dn->type && !strcmp(dn->type, "isa")) {
+		pdn->eeh_mode |= EEH_MODE_NOCHECK;
+		return NULL;
+	}
+
+	/*
+	 * Now decide if we are going to "Disable" EEH checking
+	 * for this device.  We still run with the EEH hardware active,
+	 * but we won't be checking for ff's.  This means a driver
+	 * could return bad data (very bad!), an interrupt handler could
+	 * hang waiting on status bits that won't change, etc.
+	 * But there are a few cases like display devices that make sense.
+	 */
+	enable = 1;	/* i.e. we will do checking */
+	if ((*class_code >> 16) == PCI_BASE_CLASS_DISPLAY)
+		enable = 0;
+
+	if (!enable)
+		pdn->eeh_mode |= EEH_MODE_NOCHECK;
+
+	/* Ok... see if this device supports EEH.  Some do, some don't,
+	 * and the only way to find out is to check each and every one. */
+	regs = (u32 *)get_property(dn, "reg", NULL);
+	if (regs) {
+		/* First register entry is addr (00BBSS00)  */
+		/* Try to enable eeh */
+		ret = rtas_call(ibm_set_eeh_option, 4, 1, NULL,
+		                regs[0], info->buid_hi, info->buid_lo,
+		                EEH_ENABLE);
+
+		if (ret == 0) {
+			eeh_subsystem_enabled = 1;
+			pdn->eeh_mode |= EEH_MODE_SUPPORTED;
+			pdn->eeh_config_addr = regs[0];
+#ifdef DEBUG
+			printk(KERN_DEBUG "EEH: %s: eeh enabled\n", dn->full_name);
+#endif
+		} else {
+
+			/* This device doesn't support EEH, but it may have an
+			 * EEH parent, in which case we mark it as supported. */
+			if (dn->parent && PCI_DN(dn->parent)
+			    && (PCI_DN(dn->parent)->eeh_mode & EEH_MODE_SUPPORTED)) {
+				/* Parent supports EEH. */
+				pdn->eeh_mode |= EEH_MODE_SUPPORTED;
+				pdn->eeh_config_addr = PCI_DN(dn->parent)->eeh_config_addr;
+				return NULL;
+			}
+		}
+	} else {
+		printk(KERN_WARNING "EEH: %s: unable to get reg property.\n",
+		       dn->full_name);
+	}
+
+	return NULL;
+}
+
+/*
+ * 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.
+ */
+void __init eeh_init(void)
+{
+	struct device_node *phb, *np;
+	struct eeh_early_enable_info info;
+
+	spin_lock_init(&confirm_error_lock);
+	spin_lock_init(&slot_errbuf_lock);
+
+	np = of_find_node_by_path("/rtas");
+	if (np == NULL)
+		return;
+
+	ibm_set_eeh_option = rtas_token("ibm,set-eeh-option");
+	ibm_set_slot_reset = rtas_token("ibm,set-slot-reset");
+	ibm_read_slot_reset_state2 = rtas_token("ibm,read-slot-reset-state2");
+	ibm_read_slot_reset_state = rtas_token("ibm,read-slot-reset-state");
+	ibm_slot_error_detail = rtas_token("ibm,slot-error-detail");
+
+	if (ibm_set_eeh_option == RTAS_UNKNOWN_SERVICE)
+		return;
+
+	eeh_error_buf_size = rtas_token("rtas-error-log-max");
+	if (eeh_error_buf_size == RTAS_UNKNOWN_SERVICE) {
+		eeh_error_buf_size = 1024;
+	}
+	if (eeh_error_buf_size > RTAS_ERROR_LOG_MAX) {
+		printk(KERN_WARNING "EEH: rtas-error-log-max is bigger than allocated "
+		      "buffer ! (%d vs %d)", eeh_error_buf_size, RTAS_ERROR_LOG_MAX);
+		eeh_error_buf_size = RTAS_ERROR_LOG_MAX;
+	}
+
+	/* Enable EEH for all adapters.  Note that eeh requires buid's */
+	for (phb = of_find_node_by_name(NULL, "pci"); phb;
+	     phb = of_find_node_by_name(phb, "pci")) {
+		unsigned long buid;
+
+		buid = get_phb_buid(phb);
+		if (buid == 0 || PCI_DN(phb) == NULL)
+			continue;
+
+		info.buid_lo = BUID_LO(buid);
+		info.buid_hi = BUID_HI(buid);
+		traverse_pci_devices(phb, early_enable_eeh, &info);
+	}
+
+	if (eeh_subsystem_enabled)
+		printk(KERN_INFO "EEH: PCI Enhanced I/O Error Handling Enabled\n");
+	else
+		printk(KERN_WARNING "EEH: No capable adapters found\n");
+}
+
+/**
+ * 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;
+	struct eeh_early_enable_info info;
+
+	if (!dn || !PCI_DN(dn))
+		return;
+	phb = PCI_DN(dn)->phb;
+	if (NULL == phb || 0 == phb->buid) {
+		printk(KERN_WARNING "EEH: Expected buid but found none for %s\n",
+		       dn->full_name);
+		dump_stack();
+		return;
+	}
+
+	info.buid_hi = BUID_HI(phb->buid);
+	info.buid_lo = BUID_LO(phb->buid);
+	early_enable_eeh(dn, &info);
+}
+EXPORT_SYMBOL_GPL(eeh_add_device_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 pci_dn *pdn;
+
+	if (!dev || !eeh_subsystem_enabled)
+		return;
+
+#ifdef DEBUG
+	printk(KERN_DEBUG "EEH: adding device %s\n", pci_name(dev));
+#endif
+
+	pci_dev_get (dev);
+	dn = pci_device_to_OF_node(dev);
+	pdn = PCI_DN(dn);
+	pdn->pcidev = dev;
+
+	pci_addr_cache_insert_device (dev);
+	eeh_save_bars(dev, pdn);
+}
+EXPORT_SYMBOL_GPL(eeh_add_device_late);
+
+/**
+ * eeh_remove_device - undo EEH setup for the indicated pci device
+ * @dev: pci device to be removed
+ *
+ * This routine should be when a device is removed from a running
+ * system (e.g. by hotplug or dlpar).
+ */
+void eeh_remove_device(struct pci_dev *dev)
+{
+	struct device_node *dn;
+	if (!dev || !eeh_subsystem_enabled)
+		return;
+
+	/* Unregister the device with the EEH/PCI address search system */
+#ifdef DEBUG
+	printk(KERN_DEBUG "EEH: remove device %s\n", pci_name(dev));
+#endif
+	pci_addr_cache_remove_device(dev);
+
+	dn = pci_device_to_OF_node(dev);
+	PCI_DN(dn)->pcidev = NULL;
+	pci_dev_put (dev);
+}
+EXPORT_SYMBOL_GPL(eeh_remove_device);
+
+static int proc_eeh_show(struct seq_file *m, void *v)
+{
+	unsigned int cpu;
+	unsigned long ffs = 0, positives = 0, failures = 0;
+	unsigned long resets = 0;
+	unsigned long no_dev = 0, no_dn = 0, no_cfg = 0, no_check = 0;
+
+	for_each_cpu(cpu) {
+		ffs += per_cpu(total_mmio_ffs, cpu);
+		positives += per_cpu(false_positives, cpu);
+		failures += per_cpu(ignored_failures, cpu);
+		resets += per_cpu(slot_resets, cpu);
+		no_dev += per_cpu(no_device, cpu);
+		no_dn += per_cpu(no_dn, cpu);
+		no_cfg += per_cpu(no_cfg_addr, cpu);
+		no_check += per_cpu(ignored_check, cpu);
+	}
+
+	if (0 == eeh_subsystem_enabled) {
+		seq_printf(m, "EEH Subsystem is globally disabled\n");
+		seq_printf(m, "eeh_total_mmio_ffs=%ld\n", ffs);
+	} else {
+		seq_printf(m, "EEH Subsystem is enabled\n");
+		seq_printf(m,
+				"no device=%ld\n"
+				"no device node=%ld\n"
+				"no config address=%ld\n"
+				"check not wanted=%ld\n"
+				"eeh_total_mmio_ffs=%ld\n"
+				"eeh_false_positives=%ld\n"
+				"eeh_ignored_failures=%ld\n"
+				"eeh_slot_resets=%ld\n",
+				no_dev, no_dn, no_cfg, no_check,
+				ffs, positives, failures, resets);
+	}
+
+	return 0;
+}
+
+static int proc_eeh_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, proc_eeh_show, NULL);
+}
+
+static 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)
+{
+	struct proc_dir_entry *e;
+
+	if (platform_is_pseries()) {
+		e = create_proc_entry("ppc64/eeh", 0, NULL);
+		if (e)
+			e->proc_fops = &proc_eeh_operations;
+	}
+
+	return 0;
+}
+__initcall(eeh_init_proc);