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eeh.c

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

#include <linux/delay.h>
#include <linux/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 <linux/of.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>


/** 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, 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 (60*1000)

/* 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;
static int ibm_get_config_addr_info;
static int ibm_get_config_addr_info2;
static int ibm_configure_bridge;

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. Its here
 * in BSS, and not dynamically alloced, so that it ends up in
 * RMO where RTAS can access it.
 */
static unsigned char slot_errbuf[RTAS_ERROR_LOG_MAX];
static DEFINE_SPINLOCK(slot_errbuf_lock);
static int eeh_error_buf_size;

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

/* System monitoring statistics */
static unsigned long no_device;
static unsigned long no_dn;
static unsigned long no_cfg_addr;
static unsigned long ignored_check;
static unsigned long total_mmio_ffs;
static unsigned long false_positives;
static unsigned long slot_resets;

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

/* --------------------------------------------------------------- */
/* Below lies the EEH event infrastructure */

static void rtas_slot_error_detail(struct pci_dn *pdn, int severity,
                                   char *driver_log, size_t loglen)
{
      int config_addr;
      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);

      /* Use PE configuration address, if present */
      config_addr = pdn->eeh_config_addr;
      if (pdn->eeh_pe_config_addr)
            config_addr = pdn->eeh_pe_config_addr;

      rc = rtas_call(ibm_slot_error_detail,
                     8, 1, NULL, config_addr,
                     BUID_HI(pdn->phb->buid),
                     BUID_LO(pdn->phb->buid),
                     virt_to_phys(driver_log), loglen,
                     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);
}

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

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

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

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

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

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

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

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

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

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

            for (i=0; i<=8; i++) {
                  rtas_read_config(pdn, cap+4*i, 4, &cfg);
                  n += scnprintf(buf+n, len-n, "%02x:%x\n", 4*i, cfg);
                  printk(KERN_WARNING "EEH: PCI-E %02x: %08x\n", i, cfg);
            }

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

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

      /* Gather status on devices under the bridge */
      if (dev->class >> 16 == PCI_BASE_CLASS_BRIDGE) {
            struct device_node *dn;

            for_each_child_of_node(pdn->node, dn) {
                  pdn = PCI_DN(dn);
                  if (pdn)
                        n += gather_pci_data(pdn, buf+n, len-n);
            }
      }

      return n;
}

void eeh_slot_error_detail(struct pci_dn *pdn, int severity)
{
      size_t loglen = 0;
      pci_regs_buf[0] = 0;

      rtas_pci_enable(pdn, EEH_THAW_MMIO);
      loglen = gather_pci_data(pdn, pci_regs_buf, EEH_PCI_REGS_LOG_LEN);

      rtas_slot_error_detail(pdn, severity, pci_regs_buf, loglen);
}

/**
 * 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;
      int config_addr;

      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;
      }

      /* Use PE configuration address, if present */
      config_addr = pdn->eeh_config_addr;
      if (pdn->eeh_pe_config_addr)
            config_addr = pdn->eeh_pe_config_addr;

      return rtas_call(token, 3, outputs, rets, config_addr,
                   BUID_HI(pdn->phb->buid), BUID_LO(pdn->phb->buid));
}

/**
 * eeh_wait_for_slot_status - returns error status of slot
 * @pdn pci device node
 * @max_wait_msecs maximum number to millisecs to wait
 *
 * Return negative value if a permanent error, else return
 * Partition Endpoint (PE) status value.
 *
 * If @max_wait_msecs is positive, then this routine will
 * sleep until a valid status can be obtained, or until
 * the max allowed wait time is exceeded, in which case
 * a -2 is returned.
 */
int
eeh_wait_for_slot_status(struct pci_dn *pdn, int max_wait_msecs)
{
      int rc;
      int rets[3];
      int mwait;

      while (1) {
            rc = read_slot_reset_state(pdn, rets);
            if (rc) return rc;
            if (rets[1] == 0) return -1;  /* EEH is not supported */

            if (rets[0] != 5) return rets[0]; /* return actual status */

            if (rets[2] == 0) return -1; /* permanently unavailable */

            if (max_wait_msecs <= 0) break;

            mwait = rets[2];
            if (mwait <= 0) {
                  printk (KERN_WARNING
                          "EEH: Firmware returned bad wait value=%d\n", mwait);
                  mwait = 1000;
            } else if (mwait > 300*1000) {
                  printk (KERN_WARNING
                          "EEH: Firmware is taking too long, time=%d\n", mwait);
                  mwait = 300*1000;
            }
            max_wait_msecs -= mwait;
            msleep (mwait);
      }

      printk(KERN_WARNING "EEH: Timed out waiting for slot status\n");
      return -2;
}

/**
 * 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
 */
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 children 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 *parent, int mode_flag)
{
      struct device_node *dn;

      for_each_child_of_node(parent, dn) {
            if (PCI_DN(dn)) {
                  /* Mark the pci device driver too */
                  struct pci_dev *dev = PCI_DN(dn)->pcidev;

                  PCI_DN(dn)->eeh_mode |= mode_flag;

                  if (dev && dev->driver)
                        dev->error_state = pci_channel_io_frozen;

                  __eeh_mark_slot(dn, mode_flag);
            }
      }
}

void eeh_mark_slot (struct device_node *dn, int mode_flag)
{
      struct pci_dev *dev;
      dn = find_device_pe (dn);

      /* Back up one, since config addrs might be shared */
      if (!pcibios_find_pci_bus(dn) && PCI_DN(dn->parent))
            dn = dn->parent;

      PCI_DN(dn)->eeh_mode |= mode_flag;

      /* Mark the pci device too */
      dev = PCI_DN(dn)->pcidev;
      if (dev)
            dev->error_state = pci_channel_io_frozen;

      __eeh_mark_slot(dn, mode_flag);
}

static void __eeh_clear_slot(struct device_node *parent, int mode_flag)
{
      struct device_node *dn;

      for_each_child_of_node(parent, dn) {
            if (PCI_DN(dn)) {
                  PCI_DN(dn)->eeh_mode &= ~mode_flag;
                  PCI_DN(dn)->eeh_check_count = 0;
                  __eeh_clear_slot(dn, mode_flag);
            }
      }
}

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);
      
      /* Back up one, since config addrs might be shared */
      if (!pcibios_find_pci_bus(dn) && PCI_DN(dn->parent))
            dn = dn->parent;

      PCI_DN(dn)->eeh_mode &= ~mode_flag;
      PCI_DN(dn)->eeh_check_count = 0;
      __eeh_clear_slot(dn, 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;
      const char *location;

      total_mmio_ffs++;

      if (!eeh_subsystem_enabled)
            return 0;

      if (!dn) {
            no_dn++;
            return 0;
      }
      dn = find_device_pe(dn);
      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) {
            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 && !pdn->eeh_pe_config_addr) {
            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 == 0) {
                  location = of_get_property(dn, "ibm,loc-code", NULL);
                  printk (KERN_ERR "EEH: %d reads ignored for recovering device at "
                        "location=%s driver=%s pci addr=%s\n",
                        pdn->eeh_check_count, location,
                        dev->driver->name, pci_name(dev));
                  printk (KERN_ERR "EEH: Might be infinite loop in %s driver\n",
                        dev->driver->name);
                  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 = 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);
            false_positives++;
            pdn->eeh_false_positives ++;
            rc = 0;
            goto dn_unlock;
      }

      /* Note that config-io to empty slots may fail;
       * they are empty when they don't have children. */
      if ((rets[0] == 5) && (rets[2] == 0) && (dn->child == NULL)) {
            false_positives++;
            pdn->eeh_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);
            false_positives++;
            pdn->eeh_false_positives ++;
            rc = 0;
            goto dn_unlock;
      }

      /* If not the kind of error we know about, punt. */
      if (rets[0] != 1 && rets[0] != 2 && rets[0] != 4 && rets[0] != 5) {
            false_positives++;
            pdn->eeh_false_positives ++;
            rc = 0;
            goto dn_unlock;
      }

      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);

      /* 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. */
      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) {
            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 */

/**
 * rtas_pci_enable - enable MMIO or DMA transfers for this slot
 * @pdn pci device node
 */

int
rtas_pci_enable(struct pci_dn *pdn, int function)
{
      int config_addr;
      int rc;

      /* Use PE configuration address, if present */
      config_addr = pdn->eeh_config_addr;
      if (pdn->eeh_pe_config_addr)
            config_addr = pdn->eeh_pe_config_addr;

      rc = rtas_call(ibm_set_eeh_option, 4, 1, NULL,
                     config_addr,
                     BUID_HI(pdn->phb->buid),
                     BUID_LO(pdn->phb->buid),
                        function);

      if (rc)
            printk(KERN_WARNING "EEH: Unexpected state change %d, err=%d dn=%s\n",
                    function, rc, pdn->node->full_name);

      rc = eeh_wait_for_slot_status (pdn, PCI_BUS_RESET_WAIT_MSEC);
      if ((rc == 4) && (function == EEH_THAW_MMIO))
            return 0;

      return rc;
}

/**
 * rtas_pci_slot_reset - raises/lowers the pci #RST line
 * @pdn pci device node
 * @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 config_addr;
      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;
      }

      /* Use PE configuration address, if present */
      config_addr = pdn->eeh_config_addr;
      if (pdn->eeh_pe_config_addr)
            config_addr = pdn->eeh_pe_config_addr;

      rc = rtas_call(ibm_set_slot_reset,4,1, NULL,
                     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);
}

/**
 * pcibios_set_pcie_slot_reset - Set PCI-E reset state
 * @dev:    pci device struct
 * @state:  reset state to enter
 *
 * Return value:
 *    0 if success
 **/
int pcibios_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state)
{
      struct device_node *dn = pci_device_to_OF_node(dev);
      struct pci_dn *pdn = PCI_DN(dn);

      switch (state) {
      case pcie_deassert_reset:
            rtas_pci_slot_reset(pdn, 0);
            break;
      case pcie_hot_reset:
            rtas_pci_slot_reset(pdn, 1);
            break;
      case pcie_warm_reset:
            rtas_pci_slot_reset(pdn, 3);
            break;
      default:
            return -EINVAL;
      };

      return 0;
}

/**
 * rtas_set_slot_reset -- assert the pci #RST line for 1/4 second
 * @pdn: pci device node to be reset.
 *
 *  Return 0 if success, else a non-zero value.
 */

static void __rtas_set_slot_reset(struct pci_dn *pdn)
{
      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);
}

int rtas_set_slot_reset(struct pci_dn *pdn)
{
      int i, rc;

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

            rc = eeh_wait_for_slot_status(pdn, PCI_BUS_RESET_WAIT_MSEC);
            if (rc == 0)
                  return 0;

            if (rc < 0) {
                  printk(KERN_ERR "EEH: unrecoverable slot failure %s\n",
                         pdn->node->full_name);
                  return -1;
            }
            printk(KERN_ERR "EEH: bus reset %d failed on slot %s, rc=%d\n",
                   i+1, pdn->node->full_name, rc);
      }

      return -1;
}

/* ------------------------------------------------------- */
/** 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
 * @pdn: pci device node
 *
 * 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;
      u32 cmd;

      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]);

      /* Restore PERR & SERR bits, some devices require it,
         don't touch the other command bits */
      rtas_read_config(pdn, PCI_COMMAND, 4, &cmd);
      if (pdn->config_space[1] & PCI_COMMAND_PARITY)
            cmd |= PCI_COMMAND_PARITY;
      else
            cmd &= ~PCI_COMMAND_PARITY;
      if (pdn->config_space[1] & PCI_COMMAND_SERR)
            cmd |= PCI_COMMAND_SERR;
      else
            cmd &= ~PCI_COMMAND_SERR;
      rtas_write_config(pdn, PCI_COMMAND, 4, cmd);
}

/**
 * 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_mode & EEH_MODE_SUPPORTED) && !IS_BRIDGE(pdn->class_code))
            __restore_bars (pdn);

      for_each_child_of_node(pdn->node, dn)
            eeh_restore_bars (PCI_DN(dn));
}

/**
 * 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_dn *pdn)
{
      int i;

      if (!pdn )
            return;
      
      for (i = 0; i < 16; i++)
            rtas_read_config(pdn, i * 4, 4, &pdn->config_space[i]);
}

void
rtas_configure_bridge(struct pci_dn *pdn)
{
      int config_addr;
      int rc;

      /* Use PE configuration address, if present */
      config_addr = pdn->eeh_config_addr;
      if (pdn->eeh_pe_config_addr)
            config_addr = pdn->eeh_pe_config_addr;

      rc = rtas_call(ibm_configure_bridge,3,1, NULL,
                     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

00916 struct eeh_early_enable_info {
      unsigned int buid_hi;
      unsigned int buid_lo;
};

static int get_pe_addr (int config_addr,
                        struct eeh_early_enable_info *info)
{
      unsigned int rets[3];
      int ret;

      /* Use latest config-addr token on power6 */
      if (ibm_get_config_addr_info2 != RTAS_UNKNOWN_SERVICE) {
            /* Make sure we have a PE in hand */
            ret = rtas_call (ibm_get_config_addr_info2, 4, 2, rets,
                  config_addr, info->buid_hi, info->buid_lo, 1);
            if (ret || (rets[0]==0))
                  return 0;

            ret = rtas_call (ibm_get_config_addr_info2, 4, 2, rets,
                  config_addr, info->buid_hi, info->buid_lo, 0);
            if (ret)
                  return 0;
            return rets[0];
      }

      /* Use older config-addr token on power5 */
      if (ibm_get_config_addr_info != RTAS_UNKNOWN_SERVICE) {
            ret = rtas_call (ibm_get_config_addr_info, 4, 2, rets,
                  config_addr, info->buid_hi, info->buid_lo, 0);
            if (ret)
                  return 0;
            return rets[0];
      }
      return 0;
}

/* Enable eeh for the given device node. */
static void *early_enable_eeh(struct device_node *dn, void *data)
{
      unsigned int rets[3];
      struct eeh_early_enable_info *info = data;
      int ret;
      const u32 *class_code = of_get_property(dn, "class-code", NULL);
      const u32 *vendor_id = of_get_property(dn, "vendor-id", NULL);
      const u32 *device_id = of_get_property(dn, "device-id", NULL);
      const u32 *regs;
      int enable;
      struct pci_dn *pdn = PCI_DN(dn);

      pdn->class_code = 0;
      pdn->eeh_mode = 0;
      pdn->eeh_check_count = 0;
      pdn->eeh_freeze_count = 0;
      pdn->eeh_false_positives = 0;

      if (!of_device_is_available(dn))
            return NULL;

      /* 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;
      }
      pdn->class_code = *class_code;

      /* 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 = of_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);

            enable = 0;
            if (ret == 0) {
                  pdn->eeh_config_addr = regs[0];

                  /* If the newer, better, ibm,get-config-addr-info is supported, 
                   * then use that instead. */
                  pdn->eeh_pe_config_addr = get_pe_addr(pdn->eeh_config_addr, info);

                  /* Some older systems (Power4) allow the
                   * ibm,set-eeh-option call to succeed even on nodes
                   * where EEH is not supported. Verify support
                   * explicitly. */
                  ret = read_slot_reset_state(pdn, rets);
                  if ((ret == 0) && (rets[1] == 1))
                        enable = 1;
            }

            if (enable) {
                  eeh_subsystem_enabled = 1;
                  pdn->eeh_mode |= EEH_MODE_SUPPORTED;

#ifdef DEBUG
                  printk(KERN_DEBUG "EEH: %s: eeh enabled, config=%x pe_config=%x\n",
                         dn->full_name, pdn->eeh_config_addr, pdn->eeh_pe_config_addr);
#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);
      }

      eeh_save_bars(pdn);
      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");
      ibm_get_config_addr_info = rtas_token("ibm,get-config-addr-info");
      ibm_get_config_addr_info2 = rtas_token("ibm,get-config-addr-info2");
      ibm_configure_bridge = rtas_token ("ibm,configure-bridge");

      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.
 */
static 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;

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

      info.buid_hi = BUID_HI(phb->buid);
      info.buid_lo = BUID_LO(phb->buid);
      early_enable_eeh(dn, &info);
}

void eeh_add_device_tree_early(struct device_node *dn)
{
      struct device_node *sib;

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

/**
 * eeh_add_device_late - perform EEH initialization for the indicated pci device
 * @dev: pci device for which to set up EEH
 *
 * This routine must be used to complete EEH initialization for PCI
 * devices that were added after system boot (e.g. hotplug, dlpar).
 */
static 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_sysfs_add_device(dev);
}

void eeh_add_device_tree_late(struct pci_bus *bus)
{
      struct pci_dev *dev;

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

/**
 * eeh_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.
 */
static 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);
      eeh_sysfs_remove_device(dev);

      dn = pci_device_to_OF_node(dev);
      if (PCI_DN(dn)->pcidev) {
            PCI_DN(dn)->pcidev = NULL;
            pci_dev_put (dev);
      }
}

void eeh_remove_bus_device(struct pci_dev *dev)
{
      struct pci_bus *bus = dev->subordinate;
      struct pci_dev *child, *tmp;

      eeh_remove_device(dev);

      if (bus && dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
            list_for_each_entry_safe(child, tmp, &bus->devices, bus_list)
                   eeh_remove_bus_device(child);
      }
}
EXPORT_SYMBOL_GPL(eeh_remove_bus_device);

static int proc_eeh_show(struct seq_file *m, void *v)
{
      if (0 == eeh_subsystem_enabled) {
            seq_printf(m, "EEH Subsystem is globally disabled\n");
            seq_printf(m, "eeh_total_mmio_ffs=%ld\n", total_mmio_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_slot_resets=%ld\n",
                        no_device, no_dn, no_cfg_addr, 
                        ignored_check, total_mmio_ffs, 
                        false_positives,
                        slot_resets);
      }

      return 0;
}

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

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

static int __init eeh_init_proc(void)
{
      if (machine_is(pseries))
            proc_create("ppc64/eeh", 0, NULL, &proc_eeh_operations);
      return 0;
}
__initcall(eeh_init_proc);

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