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 DEFINE_RAW_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         raw_spin_lock_irqsave(&pci_lock, flags);                        \
  37         res = bus->ops->read(bus, devfn, pos, len, &data);              \
  38         *value = (type)data;                                            \
  39         raw_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         raw_spin_lock_irqsave(&pci_lock, flags);                        \
  51         res = bus->ops->write(bus, devfn, pos, len, value);             \
  52         raw_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         raw_spin_lock_irqsave(&pci_lock, flags);
  83         old_ops = bus->ops;
  84         bus->ops = ops;
  85         raw_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_cfg_wait);
 131
 132 static noinline void pci_wait_cfg(struct pci_dev *dev)
 133 {
 134         DECLARE_WAITQUEUE(wait, current);
 135
 136         __add_wait_queue(&pci_cfg_wait, &wait);
 137         do {
 138                 set_current_state(TASK_UNINTERRUPTIBLE);
 139                 raw_spin_unlock_irq(&pci_lock);
 140                 schedule();
 141                 raw_spin_lock_irq(&pci_lock);
 142         } while (dev->block_cfg_access);
 143         __remove_wait_queue(&pci_cfg_wait, &wait);
 144 }
 145
 146 /* Returns 0 on success, negative values indicate error. */
 147 #define PCI_USER_READ_CONFIG(size,type)                                 \
 148 int pci_user_read_config_##size                                         \
 149         (struct pci_dev *dev, int pos, type *val)                       \
 150 {                                                                       \
 151         int ret = 0;                                                    \
 152         u32 data = -1;                                                  \
 153         if (PCI_##size##_BAD)                                           \
 154                 return -EINVAL;                                         \
 155         raw_spin_lock_irq(&pci_lock);                           \
 156         if (unlikely(dev->block_cfg_access))                            \
 157                 pci_wait_cfg(dev);                                      \
 158         ret = dev->bus->ops->read(dev->bus, dev->devfn,                 \
 159                                         pos, sizeof(type), &data);      \
 160         raw_spin_unlock_irq(&pci_lock);                         \
 161         *val = (type)data;                                              \
 162         if (ret > 0)                                                    \
 163                 ret = -EINVAL;                                          \
 164         return ret;                                                     \
 165 }
 166
 167 /* Returns 0 on success, negative values indicate error. */
 168 #define PCI_USER_WRITE_CONFIG(size,type)                                \
 169 int pci_user_write_config_##size                                        \
 170         (struct pci_dev *dev, int pos, type val)                        \
 171 {                                                                       \
 172         int ret = -EIO;                                                 \
 173         if (PCI_##size##_BAD)                                           \
 174                 return -EINVAL;                                         \
 175         raw_spin_lock_irq(&pci_lock);                           \
 176         if (unlikely(dev->block_cfg_access))                            \
 177                 pci_wait_cfg(dev);                                      \
 178         ret = dev->bus->ops->write(dev->bus, dev->devfn,                \
 179                                         pos, sizeof(type), val);        \
 180         raw_spin_unlock_irq(&pci_lock);                         \
 181         if (ret > 0)                                                    \
 182                 ret = -EINVAL;                                          \
 183         return ret;                                                     \
 184 }
 185
 186 PCI_USER_READ_CONFIG(byte, u8)
 187 PCI_USER_READ_CONFIG(word, u16)
 188 PCI_USER_READ_CONFIG(dword, u32)
 189 PCI_USER_WRITE_CONFIG(byte, u8)
 190 PCI_USER_WRITE_CONFIG(word, u16)
 191 PCI_USER_WRITE_CONFIG(dword, u32)
 192
 193 /* VPD access through PCI 2.2+ VPD capability */
 194
 195 #define PCI_VPD_PCI22_SIZE (PCI_VPD_ADDR_MASK + 1)
 196
 197 struct pci_vpd_pci22 {
 198         struct pci_vpd base;
 199         struct mutex lock;
 200         u16     flag;
 201         bool    busy;
 202         u8      cap;
 203 };
 204
 205 /*
 206  * Wait for last operation to complete.
 207  * This code has to spin since there is no other notification from the PCI
 208  * hardware. Since the VPD is often implemented by serial attachment to an
 209  * EEPROM, it may take many milliseconds to complete.
 210  *
 211  * Returns 0 on success, negative values indicate error.
 212  */
 213 static int pci_vpd_pci22_wait(struct pci_dev *dev)
 214 {
 215         struct pci_vpd_pci22 *vpd =
 216                 container_of(dev->vpd, struct pci_vpd_pci22, base);
 217         unsigned long timeout = jiffies + HZ/20 + 2;
 218         u16 status;
 219         int ret;
 220
 221         if (!vpd->busy)
 222                 return 0;
 223
 224         for (;;) {
 225                 ret = pci_user_read_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 226                                                 &status);
 227                 if (ret < 0)
 228                         return ret;
 229
 230                 if ((status & PCI_VPD_ADDR_F) == vpd->flag) {
 231                         vpd->busy = false;
 232                         return 0;
 233                 }
 234
 235                 if (time_after(jiffies, timeout)) {
 236                         dev_printk(KERN_DEBUG, &dev->dev,
 237                                    "vpd r/w failed.  This is likely a firmware "
 238                                    "bug on this device.  Contact the card "
 239                                    "vendor for a firmware update.");
 240                         return -ETIMEDOUT;
 241                 }
 242                 if (fatal_signal_pending(current))
 243                         return -EINTR;
 244                 if (!cond_resched())
 245                         udelay(10);
 246         }
 247 }
 248
 249 static ssize_t pci_vpd_pci22_read(struct pci_dev *dev, loff_t pos, size_t count,
 250                                   void *arg)
 251 {
 252         struct pci_vpd_pci22 *vpd =
 253                 container_of(dev->vpd, struct pci_vpd_pci22, base);
 254         int ret;
 255         loff_t end = pos + count;
 256         u8 *buf = arg;
 257
 258         if (pos < 0 || pos > vpd->base.len || end > vpd->base.len)
 259                 return -EINVAL;
 260
 261         if (mutex_lock_killable(&vpd->lock))
 262                 return -EINTR;
 263
 264         ret = pci_vpd_pci22_wait(dev);
 265         if (ret < 0)
 266                 goto out;
 267
 268         while (pos < end) {
 269                 u32 val;
 270                 unsigned int i, skip;
 271
 272                 ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 273                                                  pos & ~3);
 274                 if (ret < 0)
 275                         break;
 276                 vpd->busy = true;
 277                 vpd->flag = PCI_VPD_ADDR_F;
 278                 ret = pci_vpd_pci22_wait(dev);
 279                 if (ret < 0)
 280                         break;
 281
 282                 ret = pci_user_read_config_dword(dev, vpd->cap + PCI_VPD_DATA, &val);
 283                 if (ret < 0)
 284                         break;
 285
 286                 skip = pos & 3;
 287                 for (i = 0;  i < sizeof(u32); i++) {
 288                         if (i >= skip) {
 289                                 *buf++ = val;
 290                                 if (++pos == end)
 291                                         break;
 292                         }
 293                         val >>= 8;
 294                 }
 295         }
 296 out:
 297         mutex_unlock(&vpd->lock);
 298         return ret ? ret : count;
 299 }
 300
 301 static ssize_t pci_vpd_pci22_write(struct pci_dev *dev, loff_t pos, size_t count,
 302                                    const void *arg)
 303 {
 304         struct pci_vpd_pci22 *vpd =
 305                 container_of(dev->vpd, struct pci_vpd_pci22, base);
 306         const u8 *buf = arg;
 307         loff_t end = pos + count;
 308         int ret = 0;
 309
 310         if (pos < 0 || (pos & 3) || (count & 3) || end > vpd->base.len)
 311                 return -EINVAL;
 312
 313         if (mutex_lock_killable(&vpd->lock))
 314                 return -EINTR;
 315
 316         ret = pci_vpd_pci22_wait(dev);
 317         if (ret < 0)
 318                 goto out;
 319
 320         while (pos < end) {
 321                 u32 val;
 322
 323                 val = *buf++;
 324                 val |= *buf++ << 8;
 325                 val |= *buf++ << 16;
 326                 val |= *buf++ << 24;
 327
 328                 ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA, val);
 329                 if (ret < 0)
 330                         break;
 331                 ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 332                                                  pos | PCI_VPD_ADDR_F);
 333                 if (ret < 0)
 334                         break;
 335
 336                 vpd->busy = true;
 337                 vpd->flag = 0;
 338                 ret = pci_vpd_pci22_wait(dev);
 339                 if (ret < 0)
 340                         break;
 341
 342                 pos += sizeof(u32);
 343         }
 344 out:
 345         mutex_unlock(&vpd->lock);
 346         return ret ? ret : count;
 347 }
 348
 349 static void pci_vpd_pci22_release(struct pci_dev *dev)
 350 {
 351         kfree(container_of(dev->vpd, struct pci_vpd_pci22, base));
 352 }
 353
 354 static const struct pci_vpd_ops pci_vpd_pci22_ops = {
 355         .read = pci_vpd_pci22_read,
 356         .write = pci_vpd_pci22_write,
 357         .release = pci_vpd_pci22_release,
 358 };
 359
 360 int pci_vpd_pci22_init(struct pci_dev *dev)
 361 {
 362         struct pci_vpd_pci22 *vpd;
 363         u8 cap;
 364
 365         cap = pci_find_capability(dev, PCI_CAP_ID_VPD);
 366         if (!cap)
 367                 return -ENODEV;
 368         vpd = kzalloc(sizeof(*vpd), GFP_ATOMIC);
 369         if (!vpd)
 370                 return -ENOMEM;
 371
 372         vpd->base.len = PCI_VPD_PCI22_SIZE;
 373         vpd->base.ops = &pci_vpd_pci22_ops;
 374         mutex_init(&vpd->lock);
 375         vpd->cap = cap;
 376         vpd->busy = false;
 377         dev->vpd = &vpd->base;
 378         return 0;
 379 }
 380
 381 /**
 382  * pci_vpd_truncate - Set available Vital Product Data size
 383  * @dev:        pci device struct
 384  * @size:       available memory in bytes
 385  *
 386  * Adjust size of available VPD area.
 387  */
 388 int pci_vpd_truncate(struct pci_dev *dev, size_t size)
 389 {
 390         if (!dev->vpd)
 391                 return -EINVAL;
 392
 393         /* limited by the access method */
 394         if (size > dev->vpd->len)
 395                 return -EINVAL;
 396
 397         dev->vpd->len = size;
 398         if (dev->vpd->attr)
 399                 dev->vpd->attr->size = size;
 400
 401         return 0;
 402 }
 403 EXPORT_SYMBOL(pci_vpd_truncate);
 404
 405 /**
 406  * pci_cfg_access_lock - Lock PCI config reads/writes
 407  * @dev:        pci device struct
 408  *
 409  * When access is locked, any userspace reads or writes to config
 410  * space and concurrent lock requests will sleep until access is
 411  * allowed via pci_cfg_access_unlocked again.
 412  */
 413 void pci_cfg_access_lock(struct pci_dev *dev)
 414 {
 415         might_sleep();
 416
 417         raw_spin_lock_irq(&pci_lock);
 418         if (dev->block_cfg_access)
 419                 pci_wait_cfg(dev);
 420         dev->block_cfg_access = 1;
 421         raw_spin_unlock_irq(&pci_lock);
 422 }
 423 EXPORT_SYMBOL_GPL(pci_cfg_access_lock);
 424
 425 /**
 426  * pci_cfg_access_trylock - try to lock PCI config reads/writes
 427  * @dev:        pci device struct
 428  *
 429  * Same as pci_cfg_access_lock, but will return 0 if access is
 430  * already locked, 1 otherwise. This function can be used from
 431  * atomic contexts.
 432  */
 433 bool pci_cfg_access_trylock(struct pci_dev *dev)
 434 {
 435         unsigned long flags;
 436         bool locked = true;
 437
 438         raw_spin_lock_irqsave(&pci_lock, flags);
 439         if (dev->block_cfg_access)
 440                 locked = false;
 441         else
 442                 dev->block_cfg_access = 1;
 443         raw_spin_unlock_irqrestore(&pci_lock, flags);
 444
 445         return locked;
 446 }
 447 EXPORT_SYMBOL_GPL(pci_cfg_access_trylock);
 448
 449 /**
 450  * pci_cfg_access_unlock - Unlock PCI config reads/writes
 451  * @dev:        pci device struct
 452  *
 453  * This function allows PCI config accesses to resume.
 454  */
 455 void pci_cfg_access_unlock(struct pci_dev *dev)
 456 {
 457         unsigned long flags;
 458
 459         raw_spin_lock_irqsave(&pci_lock, flags);
 460
 461         /* This indicates a problem in the caller, but we don't need
 462          * to kill them, unlike a double-block above. */
 463         WARN_ON(!dev->block_cfg_access);
 464
 465         dev->block_cfg_access = 0;
 466         wake_up_all(&pci_cfg_wait);
 467         raw_spin_unlock_irqrestore(&pci_lock, flags);
 468 }
 469 EXPORT_SYMBOL_GPL(pci_cfg_access_unlock);