arch/powerpc/platforms/pseries/eeh_cache.c

   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 <asm/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  */
  50 struct 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
  59 static struct pci_io_addr_cache
  60 {
  61         struct rb_root rb_root;
  62         spinlock_t piar_lock;
  63 } pci_io_addr_cache_root;
  64
  65 static 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  */
  98 struct 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  */
 114 static 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. */
 133 static struct pci_io_addr_range *
 134 pci_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
 178 static 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  */
 224 void 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
 237 static inline void __pci_addr_cache_remove_device(struct pci_dev *dev)
 238 {
 239         struct rb_node *n;
 240
 241 restart:
 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  */
 266 void 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  */
 284 void __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