drivers/pci/access.c

   1 #include <linux/delay.h>
   2 #include <linux/pci.h>
   3 #include <linux/module.h>
   4 #include <linux/sched.h>
   5 #include <linux/slab.h>
   6 #include <linux/ioport.h>
   7 #include <linux/wait.h>
   8
   9 #include "pci.h"
  10
  11 /*
  12  * This interrupt-safe spinlock protects all accesses to PCI
  13  * configuration space.
  14  */
  15
  16 static DEFINE_SPINLOCK(pci_lock);
  17
  18 /*
  19  *  Wrappers for all PCI configuration access functions.  They just check
  20  *  alignment, do locking and call the low-level functions pointed to
  21  *  by pci_dev->ops.
  22  */
  23
  24 #define PCI_byte_BAD 0
  25 #define PCI_word_BAD (pos & 1)
  26 #define PCI_dword_BAD (pos & 3)
  27
  28 #define PCI_OP_READ(size,type,len) \
  29 int pci_bus_read_config_##size \
  30         (struct pci_bus *bus, unsigned int devfn, int pos, type *value) \
  31 {                                                                       \
  32         int res;                                                        \
  33         unsigned long flags;                                            \
  34         u32 data = 0;                                                   \
  35         if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
  36         spin_lock_irqsave(&pci_lock, flags);                            \
  37         res = bus->ops->read(bus, devfn, pos, len, &data);              \
  38         *value = (type)data;                                            \
  39         spin_unlock_irqrestore(&pci_lock, flags);                       \
  40         return res;                                                     \
  41 }
  42
  43 #define PCI_OP_WRITE(size,type,len) \
  44 int pci_bus_write_config_##size \
  45         (struct pci_bus *bus, unsigned int devfn, int pos, type value)  \
  46 {                                                                       \
  47         int res;                                                        \
  48         unsigned long flags;                                            \
  49         if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
  50         spin_lock_irqsave(&pci_lock, flags);                            \
  51         res = bus->ops->write(bus, devfn, pos, len, value);             \
  52         spin_unlock_irqrestore(&pci_lock, flags);                       \
  53         return res;                                                     \
  54 }
  55
  56 PCI_OP_READ(byte, u8, 1)
  57 PCI_OP_READ(word, u16, 2)
  58 PCI_OP_READ(dword, u32, 4)
  59 PCI_OP_WRITE(byte, u8, 1)
  60 PCI_OP_WRITE(word, u16, 2)
  61 PCI_OP_WRITE(dword, u32, 4)
  62
  63 EXPORT_SYMBOL(pci_bus_read_config_byte);
  64 EXPORT_SYMBOL(pci_bus_read_config_word);
  65 EXPORT_SYMBOL(pci_bus_read_config_dword);
  66 EXPORT_SYMBOL(pci_bus_write_config_byte);
  67 EXPORT_SYMBOL(pci_bus_write_config_word);
  68 EXPORT_SYMBOL(pci_bus_write_config_dword);
  69
  70 /**
  71  * pci_bus_set_ops - Set raw operations of pci bus
  72  * @bus:        pci bus struct
  73  * @ops:        new raw operations
  74  *
  75  * Return previous raw operations
  76  */
  77 struct pci_ops *pci_bus_set_ops(struct pci_bus *bus, struct pci_ops *ops)
  78 {
  79         struct pci_ops *old_ops;
  80         unsigned long flags;
  81
  82         spin_lock_irqsave(&pci_lock, flags);
  83         old_ops = bus->ops;
  84         bus->ops = ops;
  85         spin_unlock_irqrestore(&pci_lock, flags);
  86         return old_ops;
  87 }
  88 EXPORT_SYMBOL(pci_bus_set_ops);
  89
  90 /**
  91  * pci_read_vpd - Read one entry from Vital Product Data
  92  * @dev:        pci device struct
  93  * @pos:        offset in vpd space
  94  * @count:      number of bytes to read
  95  * @buf:        pointer to where to store result
  96  *
  97  */
  98 ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf)
  99 {
 100         if (!dev->vpd || !dev->vpd->ops)
 101                 return -ENODEV;
 102         return dev->vpd->ops->read(dev, pos, count, buf);
 103 }
 104 EXPORT_SYMBOL(pci_read_vpd);
 105
 106 /**
 107  * pci_write_vpd - Write entry to Vital Product Data
 108  * @dev:        pci device struct
 109  * @pos:        offset in vpd space
 110  * @count:      number of bytes to write
 111  * @buf:        buffer containing write data
 112  *
 113  */
 114 ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf)
 115 {
 116         if (!dev->vpd || !dev->vpd->ops)
 117                 return -ENODEV;
 118         return dev->vpd->ops->write(dev, pos, count, buf);
 119 }
 120 EXPORT_SYMBOL(pci_write_vpd);
 121
 122 /*
 123  * The following routines are to prevent the user from accessing PCI config
 124  * space when it's unsafe to do so.  Some devices require this during BIST and
 125  * we're required to prevent it during D-state transitions.
 126  *
 127  * We have a bit per device to indicate it's blocked and a global wait queue
 128  * for callers to sleep on until devices are unblocked.
 129  */
 130 static DECLARE_WAIT_QUEUE_HEAD(pci_ucfg_wait);
 131
 132 static noinline void pci_wait_ucfg(struct pci_dev *dev)
 133 {
 134         DECLARE_WAITQUEUE(wait, current);
 135
 136         __add_wait_queue(&pci_ucfg_wait, &wait);
 137         do {
 138                 set_current_state(TASK_UNINTERRUPTIBLE);
 139                 spin_unlock_irq(&pci_lock);
 140                 schedule();
 141                 spin_lock_irq(&pci_lock);
 142         } while (dev->block_ucfg_access);
 143         __remove_wait_queue(&pci_ucfg_wait, &wait);
 144 }
 145
 146 #define PCI_USER_READ_CONFIG(size,type)                                 \
 147 int pci_user_read_config_##size                                         \
 148         (struct pci_dev *dev, int pos, type *val)                       \
 149 {                                                                       \
 150         int ret = 0;                                                    \
 151         u32 data = -1;                                                  \
 152         if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
 153         spin_lock_irq(&pci_lock);                                       \
 154         if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev);       \
 155         ret = dev->bus->ops->read(dev->bus, dev->devfn,                 \
 156                                         pos, sizeof(type), &data);      \
 157         spin_unlock_irq(&pci_lock);                                     \
 158         *val = (type)data;                                              \
 159         return ret;                                                     \
 160 }
 161
 162 #define PCI_USER_WRITE_CONFIG(size,type)                                \
 163 int pci_user_write_config_##size                                        \
 164         (struct pci_dev *dev, int pos, type val)                        \
 165 {                                                                       \
 166         int ret = -EIO;                                                 \
 167         if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
 168         spin_lock_irq(&pci_lock);                                       \
 169         if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev);       \
 170         ret = dev->bus->ops->write(dev->bus, dev->devfn,                \
 171                                         pos, sizeof(type), val);        \
 172         spin_unlock_irq(&pci_lock);                                     \
 173         return ret;                                                     \
 174 }
 175
 176 PCI_USER_READ_CONFIG(byte, u8)
 177 PCI_USER_READ_CONFIG(word, u16)
 178 PCI_USER_READ_CONFIG(dword, u32)
 179 PCI_USER_WRITE_CONFIG(byte, u8)
 180 PCI_USER_WRITE_CONFIG(word, u16)
 181 PCI_USER_WRITE_CONFIG(dword, u32)
 182
 183 /* VPD access through PCI 2.2+ VPD capability */
 184
 185 #define PCI_VPD_PCI22_SIZE (PCI_VPD_ADDR_MASK + 1)
 186
 187 struct pci_vpd_pci22 {
 188         struct pci_vpd base;
 189         struct mutex lock;
 190         u16     flag;
 191         bool    busy;
 192         u8      cap;
 193 };
 194
 195 /*
 196  * Wait for last operation to complete.
 197  * This code has to spin since there is no other notification from the PCI
 198  * hardware. Since the VPD is often implemented by serial attachment to an
 199  * EEPROM, it may take many milliseconds to complete.
 200  */
 201 static int pci_vpd_pci22_wait(struct pci_dev *dev)
 202 {
 203         struct pci_vpd_pci22 *vpd =
 204                 container_of(dev->vpd, struct pci_vpd_pci22, base);
 205         unsigned long timeout = jiffies + HZ/20 + 2;
 206         u16 status;
 207         int ret;
 208
 209         if (!vpd->busy)
 210                 return 0;
 211
 212         for (;;) {
 213                 ret = pci_user_read_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 214                                                 &status);
 215                 if (ret)
 216                         return ret;
 217
 218                 if ((status & PCI_VPD_ADDR_F) == vpd->flag) {
 219                         vpd->busy = false;
 220                         return 0;
 221                 }
 222
 223                 if (time_after(jiffies, timeout))
 224                         return -ETIMEDOUT;
 225                 if (fatal_signal_pending(current))
 226                         return -EINTR;
 227                 if (!cond_resched())
 228                         udelay(10);
 229         }
 230 }
 231
 232 static ssize_t pci_vpd_pci22_read(struct pci_dev *dev, loff_t pos, size_t count,
 233                                   void *arg)
 234 {
 235         struct pci_vpd_pci22 *vpd =
 236                 container_of(dev->vpd, struct pci_vpd_pci22, base);
 237         int ret;
 238         loff_t end = pos + count;
 239         u8 *buf = arg;
 240
 241         if (pos < 0 || pos > vpd->base.len || end > vpd->base.len)
 242                 return -EINVAL;
 243
 244         if (mutex_lock_killable(&vpd->lock))
 245                 return -EINTR;
 246
 247         ret = pci_vpd_pci22_wait(dev);
 248         if (ret < 0)
 249                 goto out;
 250
 251         while (pos < end) {
 252                 u32 val;
 253                 unsigned int i, skip;
 254
 255                 ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 256                                                  pos & ~3);
 257                 if (ret < 0)
 258                         break;
 259                 vpd->busy = true;
 260                 vpd->flag = PCI_VPD_ADDR_F;
 261                 ret = pci_vpd_pci22_wait(dev);
 262                 if (ret < 0)
 263                         break;
 264
 265                 ret = pci_user_read_config_dword(dev, vpd->cap + PCI_VPD_DATA, &val);
 266                 if (ret < 0)
 267                         break;
 268
 269                 skip = pos & 3;
 270                 for (i = 0;  i < sizeof(u32); i++) {
 271                         if (i >= skip) {
 272                                 *buf++ = val;
 273                                 if (++pos == end)
 274                                         break;
 275                         }
 276                         val >>= 8;
 277                 }
 278         }
 279 out:
 280         mutex_unlock(&vpd->lock);
 281         return ret ? ret : count;
 282 }
 283
 284 static ssize_t pci_vpd_pci22_write(struct pci_dev *dev, loff_t pos, size_t count,
 285                                    const void *arg)
 286 {
 287         struct pci_vpd_pci22 *vpd =
 288                 container_of(dev->vpd, struct pci_vpd_pci22, base);
 289         const u8 *buf = arg;
 290         loff_t end = pos + count;
 291         int ret = 0;
 292
 293         if (pos < 0 || (pos & 3) || (count & 3) || end > vpd->base.len)
 294                 return -EINVAL;
 295
 296         if (mutex_lock_killable(&vpd->lock))
 297                 return -EINTR;
 298
 299         ret = pci_vpd_pci22_wait(dev);
 300         if (ret < 0)
 301                 goto out;
 302
 303         while (pos < end) {
 304                 u32 val;
 305
 306                 val = *buf++;
 307                 val |= *buf++ << 8;
 308                 val |= *buf++ << 16;
 309                 val |= *buf++ << 24;
 310
 311                 ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA, val);
 312                 if (ret < 0)
 313                         break;
 314                 ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 315                                                  pos | PCI_VPD_ADDR_F);
 316                 if (ret < 0)
 317                         break;
 318
 319                 vpd->busy = true;
 320                 vpd->flag = 0;
 321                 ret = pci_vpd_pci22_wait(dev);
 322
 323                 pos += sizeof(u32);
 324         }
 325 out:
 326         mutex_unlock(&vpd->lock);
 327         return ret ? ret : count;
 328 }
 329
 330 static void pci_vpd_pci22_release(struct pci_dev *dev)
 331 {
 332         kfree(container_of(dev->vpd, struct pci_vpd_pci22, base));
 333 }
 334
 335 static const struct pci_vpd_ops pci_vpd_pci22_ops = {
 336         .read = pci_vpd_pci22_read,
 337         .write = pci_vpd_pci22_write,
 338         .release = pci_vpd_pci22_release,
 339 };
 340
 341 int pci_vpd_pci22_init(struct pci_dev *dev)
 342 {
 343         struct pci_vpd_pci22 *vpd;
 344         u8 cap;
 345
 346         cap = pci_find_capability(dev, PCI_CAP_ID_VPD);
 347         if (!cap)
 348                 return -ENODEV;
 349         vpd = kzalloc(sizeof(*vpd), GFP_ATOMIC);
 350         if (!vpd)
 351                 return -ENOMEM;
 352
 353         vpd->base.len = PCI_VPD_PCI22_SIZE;
 354         vpd->base.ops = &pci_vpd_pci22_ops;
 355         mutex_init(&vpd->lock);
 356         vpd->cap = cap;
 357         vpd->busy = false;
 358         dev->vpd = &vpd->base;
 359         return 0;
 360 }
 361
 362 /**
 363  * pci_vpd_truncate - Set available Vital Product Data size
 364  * @dev:        pci device struct
 365  * @size:       available memory in bytes
 366  *
 367  * Adjust size of available VPD area.
 368  */
 369 int pci_vpd_truncate(struct pci_dev *dev, size_t size)
 370 {
 371         if (!dev->vpd)
 372                 return -EINVAL;
 373
 374         /* limited by the access method */
 375         if (size > dev->vpd->len)
 376                 return -EINVAL;
 377
 378         dev->vpd->len = size;
 379         if (dev->vpd->attr)
 380                 dev->vpd->attr->size = size;
 381
 382         return 0;
 383 }
 384 EXPORT_SYMBOL(pci_vpd_truncate);
 385
 386 /**
 387  * pci_block_user_cfg_access - Block userspace PCI config reads/writes
 388  * @dev:        pci device struct
 389  *
 390  * When user access is blocked, any reads or writes to config space will
 391  * sleep until access is unblocked again.  We don't allow nesting of
 392  * block/unblock calls.
 393  */
 394 void pci_block_user_cfg_access(struct pci_dev *dev)
 395 {
 396         unsigned long flags;
 397         int was_blocked;
 398
 399         spin_lock_irqsave(&pci_lock, flags);
 400         was_blocked = dev->block_ucfg_access;
 401         dev->block_ucfg_access = 1;
 402         spin_unlock_irqrestore(&pci_lock, flags);
 403
 404         /* If we BUG() inside the pci_lock, we're guaranteed to hose
 405          * the machine */
 406         BUG_ON(was_blocked);
 407 }
 408 EXPORT_SYMBOL_GPL(pci_block_user_cfg_access);
 409
 410 /**
 411  * pci_unblock_user_cfg_access - Unblock userspace PCI config reads/writes
 412  * @dev:        pci device struct
 413  *
 414  * This function allows userspace PCI config accesses to resume.
 415  */
 416 void pci_unblock_user_cfg_access(struct pci_dev *dev)
 417 {
 418         unsigned long flags;
 419
 420         spin_lock_irqsave(&pci_lock, flags);
 421
 422         /* This indicates a problem in the caller, but we don't need
 423          * to kill them, unlike a double-block above. */
 424         WARN_ON(!dev->block_ucfg_access);
 425
 426         dev->block_ucfg_access = 0;
 427         wake_up_all(&pci_ucfg_wait);
 428         spin_unlock_irqrestore(&pci_lock, flags);
 429 }
 430 EXPORT_SYMBOL_GPL(pci_unblock_user_cfg_access);