arch/powerpc/kernel/eeh_cache.c

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