arch/powerpc/kernel/eeh_cache.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   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
   9 #include <linux/list.h>
  10 #include <linux/pci.h>
  11 #include <linux/rbtree.h>
  12 #include <linux/slab.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/atomic.h>
  15 #include <asm/pci-bridge.h>
  16 #include <asm/debugfs.h>
  17 #include <asm/ppc-pci.h>
  18
  19
  20 /**
  21  * DOC: Overview
  22  *
  23  * The pci address cache subsystem.  This subsystem places
  24  * PCI device address resources into a red-black tree, sorted
  25  * according to the address range, so that given only an i/o
  26  * address, the corresponding PCI device can be **quickly**
  27  * found. It is safe to perform an address lookup in an interrupt
  28  * context; this ability is an important feature.
  29  *
  30  * Currently, the only customer of this code is the EEH subsystem;
  31  * thus, this code has been somewhat tailored to suit EEH better.
  32  * In particular, the cache does *not* hold the addresses of devices
  33  * for which EEH is not enabled.
  34  *
  35  * (Implementation Note: The RB tree seems to be better/faster
  36  * than any hash algo I could think of for this problem, even
  37  * with the penalty of slow pointer chases for d-cache misses).
  38  */
  39
  40 struct pci_io_addr_range {
  41         struct rb_node rb_node;
  42         resource_size_t addr_lo;
  43         resource_size_t addr_hi;
  44         struct eeh_dev *edev;
  45         struct pci_dev *pcidev;
  46         unsigned long flags;
  47 };
  48
  49 static struct pci_io_addr_cache {
  50         struct rb_root rb_root;
  51         spinlock_t piar_lock;
  52 } pci_io_addr_cache_root;
  53
  54 static inline struct eeh_dev *__eeh_addr_cache_get_device(unsigned long addr)
  55 {
  56         struct rb_node *n = pci_io_addr_cache_root.rb_root.rb_node;
  57
  58         while (n) {
  59                 struct pci_io_addr_range *piar;
  60                 piar = rb_entry(n, struct pci_io_addr_range, rb_node);
  61
  62                 if (addr < piar->addr_lo)
  63                         n = n->rb_left;
  64                 else if (addr > piar->addr_hi)
  65                         n = n->rb_right;
  66                 else
  67                         return piar->edev;
  68         }
  69
  70         return NULL;
  71 }
  72
  73 /**
  74  * eeh_addr_cache_get_dev - Get device, given only address
  75  * @addr: mmio (PIO) phys address or i/o port number
  76  *
  77  * Given an mmio phys address, or a port number, find a pci device
  78  * that implements this address.  I/O port numbers are assumed to be offset
  79  * from zero (that is, they do *not* have pci_io_addr added in).
  80  * It is safe to call this function within an interrupt.
  81  */
  82 struct eeh_dev *eeh_addr_cache_get_dev(unsigned long addr)
  83 {
  84         struct eeh_dev *edev;
  85         unsigned long flags;
  86
  87         spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
  88         edev = __eeh_addr_cache_get_device(addr);
  89         spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
  90         return edev;
  91 }
  92
  93 #ifdef DEBUG
  94 /*
  95  * Handy-dandy debug print routine, does nothing more
  96  * than print out the contents of our addr cache.
  97  */
  98 static void eeh_addr_cache_print(struct pci_io_addr_cache *cache)
  99 {
 100         struct rb_node *n;
 101         int cnt = 0;
 102
 103         n = rb_first(&cache->rb_root);
 104         while (n) {
 105                 struct pci_io_addr_range *piar;
 106                 piar = rb_entry(n, struct pci_io_addr_range, rb_node);
 107                 pr_info("PCI: %s addr range %d [%pap-%pap]: %s\n",
 108                        (piar->flags & IORESOURCE_IO) ? "i/o" : "mem", cnt,
 109                        &piar->addr_lo, &piar->addr_hi, pci_name(piar->pcidev));
 110                 cnt++;
 111                 n = rb_next(n);
 112         }
 113 }
 114 #endif
 115
 116 /* Insert address range into the rb tree. */
 117 static struct pci_io_addr_range *
 118 eeh_addr_cache_insert(struct pci_dev *dev, resource_size_t alo,
 119                       resource_size_t ahi, unsigned long flags)
 120 {
 121         struct rb_node **p = &pci_io_addr_cache_root.rb_root.rb_node;
 122         struct rb_node *parent = NULL;
 123         struct pci_io_addr_range *piar;
 124
 125         /* Walk tree, find a place to insert into tree */
 126         while (*p) {
 127                 parent = *p;
 128                 piar = rb_entry(parent, struct pci_io_addr_range, rb_node);
 129                 if (ahi < piar->addr_lo) {
 130                         p = &parent->rb_left;
 131                 } else if (alo > piar->addr_hi) {
 132                         p = &parent->rb_right;
 133                 } else {
 134                         if (dev != piar->pcidev ||
 135                             alo != piar->addr_lo || ahi != piar->addr_hi) {
 136                                 pr_warn("PIAR: overlapping address range\n");
 137                         }
 138                         return piar;
 139                 }
 140         }
 141         piar = kzalloc(sizeof(struct pci_io_addr_range), GFP_ATOMIC);
 142         if (!piar)
 143                 return NULL;
 144
 145         piar->addr_lo = alo;
 146         piar->addr_hi = ahi;
 147         piar->edev = pci_dev_to_eeh_dev(dev);
 148         piar->pcidev = dev;
 149         piar->flags = flags;
 150
 151         eeh_edev_dbg(piar->edev, "PIAR: insert range=[%pap:%pap]\n",
 152                  &alo, &ahi);
 153
 154         rb_link_node(&piar->rb_node, parent, p);
 155         rb_insert_color(&piar->rb_node, &pci_io_addr_cache_root.rb_root);
 156
 157         return piar;
 158 }
 159
 160 static void __eeh_addr_cache_insert_dev(struct pci_dev *dev)
 161 {
 162         struct eeh_dev *edev;
 163         int i;
 164
 165         edev = pci_dev_to_eeh_dev(dev);
 166         if (!edev) {
 167                 pr_warn("PCI: no EEH dev found for %s\n",
 168                         pci_name(dev));
 169                 return;
 170         }
 171
 172         /* Skip any devices for which EEH is not enabled. */
 173         if (!edev->pe) {
 174                 dev_dbg(&dev->dev, "EEH: Skip building address cache\n");
 175                 return;
 176         }
 177
 178         /*
 179          * Walk resources on this device, poke the first 7 (6 normal BAR and 1
 180          * ROM BAR) into the tree.
 181          */
 182         for (i = 0; i <= PCI_ROM_RESOURCE; i++) {
 183                 resource_size_t start = pci_resource_start(dev,i);
 184                 resource_size_t end = pci_resource_end(dev,i);
 185                 unsigned long flags = pci_resource_flags(dev,i);
 186
 187                 /* We are interested only bus addresses, not dma or other stuff */
 188                 if (0 == (flags & (IORESOURCE_IO | IORESOURCE_MEM)))
 189                         continue;
 190                 if (start == 0 || ~start == 0 || end == 0 || ~end == 0)
 191                          continue;
 192                 eeh_addr_cache_insert(dev, start, end, flags);
 193         }
 194 }
 195
 196 /**
 197  * eeh_addr_cache_insert_dev - Add a device to the address cache
 198  * @dev: PCI device whose I/O addresses we are interested in.
 199  *
 200  * In order to support the fast lookup of devices based on addresses,
 201  * we maintain a cache of devices that can be quickly searched.
 202  * This routine adds a device to that cache.
 203  */
 204 void eeh_addr_cache_insert_dev(struct pci_dev *dev)
 205 {
 206         unsigned long flags;
 207
 208         spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
 209         __eeh_addr_cache_insert_dev(dev);
 210         spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
 211 }
 212
 213 static inline void __eeh_addr_cache_rmv_dev(struct pci_dev *dev)
 214 {
 215         struct rb_node *n;
 216
 217 restart:
 218         n = rb_first(&pci_io_addr_cache_root.rb_root);
 219         while (n) {
 220                 struct pci_io_addr_range *piar;
 221                 piar = rb_entry(n, struct pci_io_addr_range, rb_node);
 222
 223                 if (piar->pcidev == dev) {
 224                         eeh_edev_dbg(piar->edev, "PIAR: remove range=[%pap:%pap]\n",
 225                                  &piar->addr_lo, &piar->addr_hi);
 226                         rb_erase(n, &pci_io_addr_cache_root.rb_root);
 227                         kfree(piar);
 228                         goto restart;
 229                 }
 230                 n = rb_next(n);
 231         }
 232 }
 233
 234 /**
 235  * eeh_addr_cache_rmv_dev - remove pci device from addr cache
 236  * @dev: device to remove
 237  *
 238  * Remove a device from the addr-cache tree.
 239  * This is potentially expensive, since it will walk
 240  * the tree multiple times (once per resource).
 241  * But so what; device removal doesn't need to be that fast.
 242  */
 243 void eeh_addr_cache_rmv_dev(struct pci_dev *dev)
 244 {
 245         unsigned long flags;
 246
 247         spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
 248         __eeh_addr_cache_rmv_dev(dev);
 249         spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
 250 }
 251
 252 /**
 253  * eeh_addr_cache_init - Initialize a cache of I/O addresses
 254  *
 255  * Initialize a cache of pci i/o addresses.  This cache will be used to
 256  * find the pci device that corresponds to a given address.
 257  */
 258 void eeh_addr_cache_init(void)
 259 {
 260         spin_lock_init(&pci_io_addr_cache_root.piar_lock);
 261 }
 262
 263 static int eeh_addr_cache_show(struct seq_file *s, void *v)
 264 {
 265         struct pci_io_addr_range *piar;
 266         struct rb_node *n;
 267         unsigned long flags;
 268
 269         spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags);
 270         for (n = rb_first(&pci_io_addr_cache_root.rb_root); n; n = rb_next(n)) {
 271                 piar = rb_entry(n, struct pci_io_addr_range, rb_node);
 272
 273                 seq_printf(s, "%s addr range [%pap-%pap]: %s\n",
 274                        (piar->flags & IORESOURCE_IO) ? "i/o" : "mem",
 275                        &piar->addr_lo, &piar->addr_hi, pci_name(piar->pcidev));
 276         }
 277         spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
 278
 279         return 0;
 280 }
 281 DEFINE_SHOW_ATTRIBUTE(eeh_addr_cache);
 282
 283 void eeh_cache_debugfs_init(void)
 284 {
 285         debugfs_create_file_unsafe("eeh_address_cache", 0400,
 286                         powerpc_debugfs_root, NULL,
 287                         &eeh_addr_cache_fops);
 288 }