linux/arch/powerpc/platforms/pseries/eeh_cache.c
<<
>>
Prefs
   1/*
   2 * eeh_cache.c
   3 * PCI address cache; allows the lookup of PCI devices based on I/O address
   4 *
   5 * Copyright IBM Corporation 2004
   6 * Copyright Linas Vepstas <linas@austin.ibm.com> 2004
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License as published by
  10 * the Free Software Foundation; either version 2 of the License, or
  11 * (at your option) any later version.
  12 *
  13 * This program is distributed in the hope that it will be useful,
  14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 * GNU General Public License for more details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with this program; if not, write to the Free Software
  20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  21 */
  22
  23#include <linux/list.h>
  24#include <linux/pci.h>
  25#include <linux/rbtree.h>
  26#include <linux/slab.h>
  27#include <linux/spinlock.h>
  28#include <linux/atomic.h>
  29#include <asm/pci-bridge.h>
  30#include <asm/ppc-pci.h>
  31
  32
  33/**
  34 * The pci address cache subsystem.  This subsystem places
  35 * PCI device address resources into a red-black tree, sorted
  36 * according to the address range, so that given only an i/o
  37 * address, the corresponding PCI device can be **quickly**
  38 * found. It is safe to perform an address lookup in an interrupt
  39 * context; this ability is an important feature.
  40 *
  41 * Currently, the only customer of this code is the EEH subsystem;
  42 * thus, this code has been somewhat tailored to suit EEH better.
  43 * In particular, the cache does *not* hold the addresses of devices
  44 * for which EEH is not enabled.
  45 *
  46 * (Implementation Note: The RB tree seems to be better/faster
  47 * than any hash algo I could think of for this problem, even
  48 * with the penalty of slow pointer chases for d-cache misses).
  49 */
  50struct pci_io_addr_range
  51{
  52        struct rb_node rb_node;
  53        unsigned long addr_lo;
  54        unsigned long addr_hi;
  55        struct pci_dev *pcidev;
  56        unsigned int flags;
  57};
  58
  59static struct pci_io_addr_cache
  60{
  61        struct rb_root rb_root;
  62        spinlock_t piar_lock;
  63} pci_io_addr_cache_root;
  64
  65static inline struct pci_dev *__pci_get_device_by_addr(unsigned long addr)
  66{
  67        struct rb_node *n = pci_io_addr_cache_root.rb_root.rb_node;
  68
  69        while (n) {
  70                struct pci_io_addr_range *piar;
  71                piar = rb_entry(n, struct pci_io_addr_range, rb_node);
  72
  73                if (addr < piar->addr_lo) {
  74                        n = n->rb_left;
  75                } else {
  76                        if (addr > piar->addr_hi) {
  77                                n = n->rb_right;
  78                        } else {
  79                                pci_dev_get(piar->pcidev);
  80                                return piar->pcidev;
  81                        }
  82                }
  83        }
  84
  85        return NULL;
  86}
  87
  88/**
  89 * pci_get_device_by_addr - Get device, given only address
  90 * @addr: mmio (PIO) phys address or i/o port number
  91 *
  92 * Given an mmio phys address, or a port number, find a pci device
  93 * that implements this address.  Be sure to pci_dev_put the device
  94 * when finished.  I/O port numbers are assumed to be offset
  95 * from zero (that is, they do *not* have pci_io_addr added in).
  96 * It is safe to call this function within an interrupt.
  97 */
  98struct pci_dev *pci_get_device_by_addr(unsigned long addr)
  99{
 100        struct pci_dev *dev;
 101        unsigned long flags;
 102
 103        spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
 104        dev = __pci_get_device_by_addr(addr);
 105        spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
 106        return dev;
 107}
 108
 109#ifdef DEBUG
 110/*
 111 * Handy-dandy debug print routine, does nothing more
 112 * than print out the contents of our addr cache.
 113 */
 114static void pci_addr_cache_print(struct pci_io_addr_cache *cache)
 115{
 116        struct rb_node *n;
 117        int cnt = 0;
 118
 119        n = rb_first(&cache->rb_root);
 120        while (n) {
 121                struct pci_io_addr_range *piar;
 122                piar = rb_entry(n, struct pci_io_addr_range, rb_node);
 123                printk(KERN_DEBUG "PCI: %s addr range %d [%lx-%lx]: %s\n",
 124                       (piar->flags & IORESOURCE_IO) ? "i/o" : "mem", cnt,
 125                       piar->addr_lo, piar->addr_hi, pci_name(piar->pcidev));
 126                cnt++;
 127                n = rb_next(n);
 128        }
 129}
 130#endif
 131
 132/* Insert address range into the rb tree. */
 133static struct pci_io_addr_range *
 134pci_addr_cache_insert(struct pci_dev *dev, unsigned long alo,
 135                      unsigned long ahi, unsigned int flags)
 136{
 137        struct rb_node **p = &pci_io_addr_cache_root.rb_root.rb_node;
 138        struct rb_node *parent = NULL;
 139        struct pci_io_addr_range *piar;
 140
 141        /* Walk tree, find a place to insert into tree */
 142        while (*p) {
 143                parent = *p;
 144                piar = rb_entry(parent, struct pci_io_addr_range, rb_node);
 145                if (ahi < piar->addr_lo) {
 146                        p = &parent->rb_left;
 147                } else if (alo > piar->addr_hi) {
 148                        p = &parent->rb_right;
 149                } else {
 150                        if (dev != piar->pcidev ||
 151                            alo != piar->addr_lo || ahi != piar->addr_hi) {
 152                                printk(KERN_WARNING "PIAR: overlapping address range\n");
 153                        }
 154                        return piar;
 155                }
 156        }
 157        piar = kmalloc(sizeof(struct pci_io_addr_range), GFP_ATOMIC);
 158        if (!piar)
 159                return NULL;
 160
 161        pci_dev_get(dev);
 162        piar->addr_lo = alo;
 163        piar->addr_hi = ahi;
 164        piar->pcidev = dev;
 165        piar->flags = flags;
 166
 167#ifdef DEBUG
 168        printk(KERN_DEBUG "PIAR: insert range=[%lx:%lx] dev=%s\n",
 169                          alo, ahi, pci_name (dev));
 170#endif
 171
 172        rb_link_node(&piar->rb_node, parent, p);
 173        rb_insert_color(&piar->rb_node, &pci_io_addr_cache_root.rb_root);
 174
 175        return piar;
 176}
 177
 178static void __pci_addr_cache_insert_device(struct pci_dev *dev)
 179{
 180        struct device_node *dn;
 181        struct pci_dn *pdn;
 182        int i;
 183
 184        dn = pci_device_to_OF_node(dev);
 185        if (!dn) {
 186                printk(KERN_WARNING "PCI: no pci dn found for dev=%s\n", pci_name(dev));
 187                return;
 188        }
 189
 190        /* Skip any devices for which EEH is not enabled. */
 191        pdn = PCI_DN(dn);
 192        if (!(pdn->eeh_mode & EEH_MODE_SUPPORTED) ||
 193            pdn->eeh_mode & EEH_MODE_NOCHECK) {
 194#ifdef DEBUG
 195                printk(KERN_INFO "PCI: skip building address cache for=%s - %s\n",
 196                       pci_name(dev), pdn->node->full_name);
 197#endif
 198                return;
 199        }
 200
 201        /* Walk resources on this device, poke them into the tree */
 202        for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
 203                unsigned long start = pci_resource_start(dev,i);
 204                unsigned long end = pci_resource_end(dev,i);
 205                unsigned int flags = pci_resource_flags(dev,i);
 206
 207                /* We are interested only bus addresses, not dma or other stuff */
 208                if (0 == (flags & (IORESOURCE_IO | IORESOURCE_MEM)))
 209                        continue;
 210                if (start == 0 || ~start == 0 || end == 0 || ~end == 0)
 211                         continue;
 212                pci_addr_cache_insert(dev, start, end, flags);
 213        }
 214}
 215
 216/**
 217 * pci_addr_cache_insert_device - Add a device to the address cache
 218 * @dev: PCI device whose I/O addresses we are interested in.
 219 *
 220 * In order to support the fast lookup of devices based on addresses,
 221 * we maintain a cache of devices that can be quickly searched.
 222 * This routine adds a device to that cache.
 223 */
 224void pci_addr_cache_insert_device(struct pci_dev *dev)
 225{
 226        unsigned long flags;
 227
 228        /* Ignore PCI bridges */
 229        if ((dev->class >> 16) == PCI_BASE_CLASS_BRIDGE)
 230                return;
 231
 232        spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
 233        __pci_addr_cache_insert_device(dev);
 234        spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
 235}
 236
 237static inline void __pci_addr_cache_remove_device(struct pci_dev *dev)
 238{
 239        struct rb_node *n;
 240
 241restart:
 242        n = rb_first(&pci_io_addr_cache_root.rb_root);
 243        while (n) {
 244                struct pci_io_addr_range *piar;
 245                piar = rb_entry(n, struct pci_io_addr_range, rb_node);
 246
 247                if (piar->pcidev == dev) {
 248                        rb_erase(n, &pci_io_addr_cache_root.rb_root);
 249                        pci_dev_put(piar->pcidev);
 250                        kfree(piar);
 251                        goto restart;
 252                }
 253                n = rb_next(n);
 254        }
 255}
 256
 257/**
 258 * pci_addr_cache_remove_device - remove pci device from addr cache
 259 * @dev: device to remove
 260 *
 261 * Remove a device from the addr-cache tree.
 262 * This is potentially expensive, since it will walk
 263 * the tree multiple times (once per resource).
 264 * But so what; device removal doesn't need to be that fast.
 265 */
 266void pci_addr_cache_remove_device(struct pci_dev *dev)
 267{
 268        unsigned long flags;
 269
 270        spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
 271        __pci_addr_cache_remove_device(dev);
 272        spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
 273}
 274
 275/**
 276 * pci_addr_cache_build - Build a cache of I/O addresses
 277 *
 278 * Build a cache of pci i/o addresses.  This cache will be used to
 279 * find the pci device that corresponds to a given address.
 280 * This routine scans all pci busses to build the cache.
 281 * Must be run late in boot process, after the pci controllers
 282 * have been scanned for devices (after all device resources are known).
 283 */
 284void __init pci_addr_cache_build(void)
 285{
 286        struct device_node *dn;
 287        struct pci_dev *dev = NULL;
 288
 289        spin_lock_init(&pci_io_addr_cache_root.piar_lock);
 290
 291        for_each_pci_dev(dev) {
 292                pci_addr_cache_insert_device(dev);
 293
 294                dn = pci_device_to_OF_node(dev);
 295                if (!dn)
 296                        continue;
 297                pci_dev_get(dev);  /* matching put is in eeh_remove_device() */
 298                PCI_DN(dn)->pcidev = dev;
 299
 300                eeh_sysfs_add_device(dev);
 301        }
 302
 303#ifdef DEBUG
 304        /* Verify tree built up above, echo back the list of addrs. */
 305        pci_addr_cache_print(&pci_io_addr_cache_root);
 306#endif
 307}
 308
 309