drivers/pci/access.c

   1 #include <linux/pci.h>
   2 #include <linux/module.h>
   3 #include <linux/ioport.h>
   4
   5 #include "pci.h"
   6
   7 /*
   8  * This interrupt-safe spinlock protects all accesses to PCI
   9  * configuration space.
  10  */
  11
  12 static DEFINE_SPINLOCK(pci_lock);
  13
  14 /*
  15  *  Wrappers for all PCI configuration access functions.  They just check
  16  *  alignment, do locking and call the low-level functions pointed to
  17  *  by pci_dev->ops.
  18  */
  19
  20 #define PCI_byte_BAD 0
  21 #define PCI_word_BAD (pos & 1)
  22 #define PCI_dword_BAD (pos & 3)
  23
  24 #define PCI_OP_READ(size,type,len) \
  25 int pci_bus_read_config_##size \
  26         (struct pci_bus *bus, unsigned int devfn, int pos, type *value) \
  27 {                                                                       \
  28         int res;                                                        \
  29         unsigned long flags;                                            \
  30         u32 data = 0;                                                   \
  31         if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
  32         spin_lock_irqsave(&pci_lock, flags);                            \
  33         res = bus->ops->read(bus, devfn, pos, len, &data);              \
  34         *value = (type)data;                                            \
  35         spin_unlock_irqrestore(&pci_lock, flags);                       \
  36         return res;                                                     \
  37 }
  38
  39 #define PCI_OP_WRITE(size,type,len) \
  40 int pci_bus_write_config_##size \
  41         (struct pci_bus *bus, unsigned int devfn, int pos, type value)  \
  42 {                                                                       \
  43         int res;                                                        \
  44         unsigned long flags;                                            \
  45         if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
  46         spin_lock_irqsave(&pci_lock, flags);                            \
  47         res = bus->ops->write(bus, devfn, pos, len, value);             \
  48         spin_unlock_irqrestore(&pci_lock, flags);                       \
  49         return res;                                                     \
  50 }
  51
  52 PCI_OP_READ(byte, u8, 1)
  53 PCI_OP_READ(word, u16, 2)
  54 PCI_OP_READ(dword, u32, 4)
  55 PCI_OP_WRITE(byte, u8, 1)
  56 PCI_OP_WRITE(word, u16, 2)
  57 PCI_OP_WRITE(dword, u32, 4)
  58
  59 EXPORT_SYMBOL(pci_bus_read_config_byte);
  60 EXPORT_SYMBOL(pci_bus_read_config_word);
  61 EXPORT_SYMBOL(pci_bus_read_config_dword);
  62 EXPORT_SYMBOL(pci_bus_write_config_byte);
  63 EXPORT_SYMBOL(pci_bus_write_config_word);
  64 EXPORT_SYMBOL(pci_bus_write_config_dword);
  65
  66 static u32 pci_user_cached_config(struct pci_dev *dev, int pos)
  67 {
  68         u32 data;
  69
  70         data = dev->saved_config_space[pos/sizeof(dev->saved_config_space[0])];
  71         data >>= (pos % sizeof(dev->saved_config_space[0])) * 8;
  72         return data;
  73 }
  74
  75 #define PCI_USER_READ_CONFIG(size,type)                                 \
  76 int pci_user_read_config_##size                                         \
  77         (struct pci_dev *dev, int pos, type *val)                       \
  78 {                                                                       \
  79         unsigned long flags;                                            \
  80         int ret = 0;                                                    \
  81         u32 data = -1;                                                  \
  82         if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
  83         spin_lock_irqsave(&pci_lock, flags);                            \
  84         if (likely(!dev->block_ucfg_access))                            \
  85                 ret = dev->bus->ops->read(dev->bus, dev->devfn,         \
  86                                         pos, sizeof(type), &data);      \
  87         else if (pos < sizeof(dev->saved_config_space))                 \
  88                 data = pci_user_cached_config(dev, pos);                \
  89         spin_unlock_irqrestore(&pci_lock, flags);                       \
  90         *val = (type)data;                                              \
  91         return ret;                                                     \
  92 }
  93
  94 #define PCI_USER_WRITE_CONFIG(size,type)                                \
  95 int pci_user_write_config_##size                                        \
  96         (struct pci_dev *dev, int pos, type val)                        \
  97 {                                                                       \
  98         unsigned long flags;                                            \
  99         int ret = -EIO;                                                 \
 100         if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
 101         spin_lock_irqsave(&pci_lock, flags);                            \
 102         if (likely(!dev->block_ucfg_access))                            \
 103                 ret = dev->bus->ops->write(dev->bus, dev->devfn,        \
 104                                         pos, sizeof(type), val);        \
 105         spin_unlock_irqrestore(&pci_lock, flags);                       \
 106         return ret;                                                     \
 107 }
 108
 109 PCI_USER_READ_CONFIG(byte, u8)
 110 PCI_USER_READ_CONFIG(word, u16)
 111 PCI_USER_READ_CONFIG(dword, u32)
 112 PCI_USER_WRITE_CONFIG(byte, u8)
 113 PCI_USER_WRITE_CONFIG(word, u16)
 114 PCI_USER_WRITE_CONFIG(dword, u32)
 115
 116 /**
 117  * pci_block_user_cfg_access - Block userspace PCI config reads/writes
 118  * @dev:        pci device struct
 119  *
 120  * This function blocks any userspace PCI config accesses from occurring.
 121  * When blocked, any writes will be bit bucketed and reads will return the
 122  * data saved using pci_save_state for the first 64 bytes of config
 123  * space and return 0xff for all other config reads.
 124  **/
 125 void pci_block_user_cfg_access(struct pci_dev *dev)
 126 {
 127         unsigned long flags;
 128
 129         pci_save_state(dev);
 130
 131         /* spinlock to synchronize with anyone reading config space now */
 132         spin_lock_irqsave(&pci_lock, flags);
 133         dev->block_ucfg_access = 1;
 134         spin_unlock_irqrestore(&pci_lock, flags);
 135 }
 136 EXPORT_SYMBOL_GPL(pci_block_user_cfg_access);
 137
 138 /**
 139  * pci_unblock_user_cfg_access - Unblock userspace PCI config reads/writes
 140  * @dev:        pci device struct
 141  *
 142  * This function allows userspace PCI config accesses to resume.
 143  **/
 144 void pci_unblock_user_cfg_access(struct pci_dev *dev)
 145 {
 146         unsigned long flags;
 147
 148         /* spinlock to synchronize with anyone reading saved config space */
 149         spin_lock_irqsave(&pci_lock, flags);
 150         dev->block_ucfg_access = 0;
 151         spin_unlock_irqrestore(&pci_lock, flags);
 152 }
 153 EXPORT_SYMBOL_GPL(pci_unblock_user_cfg_access);