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eeh_cache.c

/*
 * eeh_cache.c
 * PCI address cache; allows the lookup of PCI devices based on I/O address
 *
 * Copyright IBM Corporation 2004
 * Copyright Linas Vepstas <linas@austin.ibm.com> 2004
 *
 * 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/list.h>
#include <linux/pci.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
#include <asm/atomic.h>
#include <asm/pci-bridge.h>
#include <asm/ppc-pci.h>


/**
 * 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).
 */
00049 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;
};

00058 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.
 */
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 = kmalloc(sizeof(struct pci_io_addr_range), GFP_ATOMIC);
      if (!piar)
            return NULL;

      pci_dev_get(dev);
      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;

      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;
      }

      /* 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);
      }
}

/**
 * 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.
 */
void pci_addr_cache_insert_device(struct pci_dev *dev)
{
      unsigned long flags;

      /* Ignore PCI bridges */
      if ((dev->class >> 16) == PCI_BASE_CLASS_BRIDGE)
            return;

      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;

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);
                  pci_dev_put(piar->pcidev);
                  kfree(piar);
                  goto restart;
            }
            n = rb_next(n);
      }
}

/**
 * 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.
 */
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 scanned for devices (after all device resources are known).
 */
void __init pci_addr_cache_build(void)
{
      struct device_node *dn;
      struct pci_dev *dev = NULL;

      spin_lock_init(&pci_io_addr_cache_root.piar_lock);

      while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {

            pci_addr_cache_insert_device(dev);

            dn = pci_device_to_OF_node(dev);
            if (!dn)
                  continue;
            pci_dev_get(dev);  /* matching put is in eeh_remove_device() */
            PCI_DN(dn)->pcidev = dev;

            eeh_sysfs_add_device(dev);
      }

#ifdef DEBUG
      /* Verify tree built up above, echo back the list of addrs. */
      pci_addr_cache_print(&pci_io_addr_cache_root);
#endif
}


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