drivers/pci/access.c

#include <linux/pci.h>
#include <linux/module.h>
#include <linux/ioport.h>

/*
 * This interrupt-safe spinlock protects all accesses to PCI
 * configuration space.
 */

static DEFINE_SPINLOCK(pci_lock);

/*
 *  Wrappers for all PCI configuration access functions.  They just check
 *  alignment, do locking and call the low-level functions pointed to
 *  by pci_dev->ops.
 */

#define PCI_byte_BAD 0
#define PCI_word_BAD (pos & 1)
#define PCI_dword_BAD (pos & 3)

#define PCI_OP_READ(size,type,len) \
int pci_bus_read_config_##size \
	(struct pci_bus *bus, unsigned int devfn, int pos, type *value)	\
{									\
	int res;							\
	unsigned long flags;						\
	u32 data = 0;							\
	if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;	\
	spin_lock_irqsave(&pci_lock, flags);				\
	res = bus->ops->read(bus, devfn, pos, len, &data);		\
	*value = (type)data;						\
	spin_unlock_irqrestore(&pci_lock, flags);			\
	return res;							\
}

#define PCI_OP_WRITE(size,type,len) \
int pci_bus_write_config_##size \
	(struct pci_bus *bus, unsigned int devfn, int pos, type value)	\
{									\
	int res;							\
	unsigned long flags;						\
	if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;	\
	spin_lock_irqsave(&pci_lock, flags);				\
	res = bus->ops->write(bus, devfn, pos, len, value);		\
	spin_unlock_irqrestore(&pci_lock, flags);			\
	return res;							\
}

PCI_OP_READ(byte, u8, 1)
PCI_OP_READ(word, u16, 2)
PCI_OP_READ(dword, u32, 4)
PCI_OP_WRITE(byte, u8, 1)
PCI_OP_WRITE(word, u16, 2)
PCI_OP_WRITE(dword, u32, 4)

EXPORT_SYMBOL(pci_bus_read_config_byte);
EXPORT_SYMBOL(pci_bus_read_config_word);
EXPORT_SYMBOL(pci_bus_read_config_dword);
EXPORT_SYMBOL(pci_bus_write_config_byte);
EXPORT_SYMBOL(pci_bus_write_config_word);
EXPORT_SYMBOL(pci_bus_write_config_dword);