linux/drivers/pci/access.c
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   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
  16DEFINE_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) \
  29int 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) \
  44int 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
  56PCI_OP_READ(byte, u8, 1)
  57PCI_OP_READ(word, u16, 2)
  58PCI_OP_READ(dword, u32, 4)
  59PCI_OP_WRITE(byte, u8, 1)
  60PCI_OP_WRITE(word, u16, 2)
  61PCI_OP_WRITE(dword, u32, 4)
  62
  63EXPORT_SYMBOL(pci_bus_read_config_byte);
  64EXPORT_SYMBOL(pci_bus_read_config_word);
  65EXPORT_SYMBOL(pci_bus_read_config_dword);
  66EXPORT_SYMBOL(pci_bus_write_config_byte);
  67EXPORT_SYMBOL(pci_bus_write_config_word);
  68EXPORT_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 */
  77struct 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}
  88EXPORT_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 */
  98ssize_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}
 104EXPORT_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 */
 114ssize_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}
 120EXPORT_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 */
 130static DECLARE_WAIT_QUEUE_HEAD(pci_cfg_wait);
 131
 132static 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)                                 \
 148int 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}                                                                       \
 166EXPORT_SYMBOL_GPL(pci_user_read_config_##size);
 167
 168/* Returns 0 on success, negative values indicate error. */
 169#define PCI_USER_WRITE_CONFIG(size,type)                                \
 170int pci_user_write_config_##size                                        \
 171        (struct pci_dev *dev, int pos, type val)                        \
 172{                                                                       \
 173        int ret = -EIO;                                                 \
 174        if (PCI_##size##_BAD)                                           \
 175                return -EINVAL;                                         \
 176        raw_spin_lock_irq(&pci_lock);                           \
 177        if (unlikely(dev->block_cfg_access))                            \
 178                pci_wait_cfg(dev);                                      \
 179        ret = dev->bus->ops->write(dev->bus, dev->devfn,                \
 180                                        pos, sizeof(type), val);        \
 181        raw_spin_unlock_irq(&pci_lock);                         \
 182        if (ret > 0)                                                    \
 183                ret = -EINVAL;                                          \
 184        return ret;                                                     \
 185}                                                                       \
 186EXPORT_SYMBOL_GPL(pci_user_write_config_##size);
 187
 188PCI_USER_READ_CONFIG(byte, u8)
 189PCI_USER_READ_CONFIG(word, u16)
 190PCI_USER_READ_CONFIG(dword, u32)
 191PCI_USER_WRITE_CONFIG(byte, u8)
 192PCI_USER_WRITE_CONFIG(word, u16)
 193PCI_USER_WRITE_CONFIG(dword, u32)
 194
 195/* VPD access through PCI 2.2+ VPD capability */
 196
 197#define PCI_VPD_PCI22_SIZE (PCI_VPD_ADDR_MASK + 1)
 198
 199struct pci_vpd_pci22 {
 200        struct pci_vpd base;
 201        struct mutex lock;
 202        u16     flag;
 203        bool    busy;
 204        u8      cap;
 205};
 206
 207/*
 208 * Wait for last operation to complete.
 209 * This code has to spin since there is no other notification from the PCI
 210 * hardware. Since the VPD is often implemented by serial attachment to an
 211 * EEPROM, it may take many milliseconds to complete.
 212 *
 213 * Returns 0 on success, negative values indicate error.
 214 */
 215static int pci_vpd_pci22_wait(struct pci_dev *dev)
 216{
 217        struct pci_vpd_pci22 *vpd =
 218                container_of(dev->vpd, struct pci_vpd_pci22, base);
 219        unsigned long timeout = jiffies + HZ/20 + 2;
 220        u16 status;
 221        int ret;
 222
 223        if (!vpd->busy)
 224                return 0;
 225
 226        for (;;) {
 227                ret = pci_user_read_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 228                                                &status);
 229                if (ret < 0)
 230                        return ret;
 231
 232                if ((status & PCI_VPD_ADDR_F) == vpd->flag) {
 233                        vpd->busy = false;
 234                        return 0;
 235                }
 236
 237                if (time_after(jiffies, timeout)) {
 238                        dev_printk(KERN_DEBUG, &dev->dev,
 239                                   "vpd r/w failed.  This is likely a firmware "
 240                                   "bug on this device.  Contact the card "
 241                                   "vendor for a firmware update.");
 242                        return -ETIMEDOUT;
 243                }
 244                if (fatal_signal_pending(current))
 245                        return -EINTR;
 246                if (!cond_resched())
 247                        udelay(10);
 248        }
 249}
 250
 251static ssize_t pci_vpd_pci22_read(struct pci_dev *dev, loff_t pos, size_t count,
 252                                  void *arg)
 253{
 254        struct pci_vpd_pci22 *vpd =
 255                container_of(dev->vpd, struct pci_vpd_pci22, base);
 256        int ret;
 257        loff_t end = pos + count;
 258        u8 *buf = arg;
 259
 260        if (pos < 0 || pos > vpd->base.len || end > vpd->base.len)
 261                return -EINVAL;
 262
 263        if (mutex_lock_killable(&vpd->lock))
 264                return -EINTR;
 265
 266        ret = pci_vpd_pci22_wait(dev);
 267        if (ret < 0)
 268                goto out;
 269
 270        while (pos < end) {
 271                u32 val;
 272                unsigned int i, skip;
 273
 274                ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 275                                                 pos & ~3);
 276                if (ret < 0)
 277                        break;
 278                vpd->busy = true;
 279                vpd->flag = PCI_VPD_ADDR_F;
 280                ret = pci_vpd_pci22_wait(dev);
 281                if (ret < 0)
 282                        break;
 283
 284                ret = pci_user_read_config_dword(dev, vpd->cap + PCI_VPD_DATA, &val);
 285                if (ret < 0)
 286                        break;
 287
 288                skip = pos & 3;
 289                for (i = 0;  i < sizeof(u32); i++) {
 290                        if (i >= skip) {
 291                                *buf++ = val;
 292                                if (++pos == end)
 293                                        break;
 294                        }
 295                        val >>= 8;
 296                }
 297        }
 298out:
 299        mutex_unlock(&vpd->lock);
 300        return ret ? ret : count;
 301}
 302
 303static ssize_t pci_vpd_pci22_write(struct pci_dev *dev, loff_t pos, size_t count,
 304                                   const void *arg)
 305{
 306        struct pci_vpd_pci22 *vpd =
 307                container_of(dev->vpd, struct pci_vpd_pci22, base);
 308        const u8 *buf = arg;
 309        loff_t end = pos + count;
 310        int ret = 0;
 311
 312        if (pos < 0 || (pos & 3) || (count & 3) || end > vpd->base.len)
 313                return -EINVAL;
 314
 315        if (mutex_lock_killable(&vpd->lock))
 316                return -EINTR;
 317
 318        ret = pci_vpd_pci22_wait(dev);
 319        if (ret < 0)
 320                goto out;
 321
 322        while (pos < end) {
 323                u32 val;
 324
 325                val = *buf++;
 326                val |= *buf++ << 8;
 327                val |= *buf++ << 16;
 328                val |= *buf++ << 24;
 329
 330                ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA, val);
 331                if (ret < 0)
 332                        break;
 333                ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 334                                                 pos | PCI_VPD_ADDR_F);
 335                if (ret < 0)
 336                        break;
 337
 338                vpd->busy = true;
 339                vpd->flag = 0;
 340                ret = pci_vpd_pci22_wait(dev);
 341                if (ret < 0)
 342                        break;
 343
 344                pos += sizeof(u32);
 345        }
 346out:
 347        mutex_unlock(&vpd->lock);
 348        return ret ? ret : count;
 349}
 350
 351static void pci_vpd_pci22_release(struct pci_dev *dev)
 352{
 353        kfree(container_of(dev->vpd, struct pci_vpd_pci22, base));
 354}
 355
 356static const struct pci_vpd_ops pci_vpd_pci22_ops = {
 357        .read = pci_vpd_pci22_read,
 358        .write = pci_vpd_pci22_write,
 359        .release = pci_vpd_pci22_release,
 360};
 361
 362int pci_vpd_pci22_init(struct pci_dev *dev)
 363{
 364        struct pci_vpd_pci22 *vpd;
 365        u8 cap;
 366
 367        cap = pci_find_capability(dev, PCI_CAP_ID_VPD);
 368        if (!cap)
 369                return -ENODEV;
 370        vpd = kzalloc(sizeof(*vpd), GFP_ATOMIC);
 371        if (!vpd)
 372                return -ENOMEM;
 373
 374        vpd->base.len = PCI_VPD_PCI22_SIZE;
 375        vpd->base.ops = &pci_vpd_pci22_ops;
 376        mutex_init(&vpd->lock);
 377        vpd->cap = cap;
 378        vpd->busy = false;
 379        dev->vpd = &vpd->base;
 380        return 0;
 381}
 382
 383/**
 384 * pci_vpd_truncate - Set available Vital Product Data size
 385 * @dev:        pci device struct
 386 * @size:       available memory in bytes
 387 *
 388 * Adjust size of available VPD area.
 389 */
 390int pci_vpd_truncate(struct pci_dev *dev, size_t size)
 391{
 392        if (!dev->vpd)
 393                return -EINVAL;
 394
 395        /* limited by the access method */
 396        if (size > dev->vpd->len)
 397                return -EINVAL;
 398
 399        dev->vpd->len = size;
 400        if (dev->vpd->attr)
 401                dev->vpd->attr->size = size;
 402
 403        return 0;
 404}
 405EXPORT_SYMBOL(pci_vpd_truncate);
 406
 407/**
 408 * pci_cfg_access_lock - Lock PCI config reads/writes
 409 * @dev:        pci device struct
 410 *
 411 * When access is locked, any userspace reads or writes to config
 412 * space and concurrent lock requests will sleep until access is
 413 * allowed via pci_cfg_access_unlocked again.
 414 */
 415void pci_cfg_access_lock(struct pci_dev *dev)
 416{
 417        might_sleep();
 418
 419        raw_spin_lock_irq(&pci_lock);
 420        if (dev->block_cfg_access)
 421                pci_wait_cfg(dev);
 422        dev->block_cfg_access = 1;
 423        raw_spin_unlock_irq(&pci_lock);
 424}
 425EXPORT_SYMBOL_GPL(pci_cfg_access_lock);
 426
 427/**
 428 * pci_cfg_access_trylock - try to lock PCI config reads/writes
 429 * @dev:        pci device struct
 430 *
 431 * Same as pci_cfg_access_lock, but will return 0 if access is
 432 * already locked, 1 otherwise. This function can be used from
 433 * atomic contexts.
 434 */
 435bool pci_cfg_access_trylock(struct pci_dev *dev)
 436{
 437        unsigned long flags;
 438        bool locked = true;
 439
 440        raw_spin_lock_irqsave(&pci_lock, flags);
 441        if (dev->block_cfg_access)
 442                locked = false;
 443        else
 444                dev->block_cfg_access = 1;
 445        raw_spin_unlock_irqrestore(&pci_lock, flags);
 446
 447        return locked;
 448}
 449EXPORT_SYMBOL_GPL(pci_cfg_access_trylock);
 450
 451/**
 452 * pci_cfg_access_unlock - Unlock PCI config reads/writes
 453 * @dev:        pci device struct
 454 *
 455 * This function allows PCI config accesses to resume.
 456 */
 457void pci_cfg_access_unlock(struct pci_dev *dev)
 458{
 459        unsigned long flags;
 460
 461        raw_spin_lock_irqsave(&pci_lock, flags);
 462
 463        /* This indicates a problem in the caller, but we don't need
 464         * to kill them, unlike a double-block above. */
 465        WARN_ON(!dev->block_cfg_access);
 466
 467        dev->block_cfg_access = 0;
 468        wake_up_all(&pci_cfg_wait);
 469        raw_spin_unlock_irqrestore(&pci_lock, flags);
 470}
 471EXPORT_SYMBOL_GPL(pci_cfg_access_unlock);
 472
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