Linux-2.6驱动开发 3 I/O

I/O操作，可以直接在物理地址上操作，也可以映上到内存后在内存地址上操作，也可同时使用物理地址和内存地址进行操作。

3.1 I/O Ports

#include <linux/ioport.h>

struct resource *request_region(unsigned long first, unsigned long n,

                                const char *name);

void release_region(unsigned long start, unsigned long n);

int check_region(unsigned long first, unsigned long n);

 

#include <asm/io.h>

unsigned inb(unsigned port);

void outb(unsigned char byte, unsigned port);

unsigned inw(unsigned port);

void outw(unsigned short word, unsigned port);

unsigned inl(unsigned port);

void outl(unsigned longword, unsigned port);

void insb(unsigned port, void *addr, unsigned long count);

void outsb(unsigned port, void *addr, unsigned long count);

void insw(unsigned port, void *addr, unsigned long count);

void outsw(unsigned port, void *addr, unsigned long count);

void insl(unsigned port, void *addr, unsigned long count);

void outsl(unsigned port, void *addr, unsigned long count);

3.2 I/O Memory

#include <linux/ioport.h>

struct resource *request_mem_region(unsigned long start, unsigned long len,

                                    char *name);

void release_mem_region(unsigned long start, unsigned long len);

int check_mem_region(unsigned long start, unsigned long len);

 

#include <asm/io.h>

void *ioremap(unsigned long phys_addr, unsigned long size);

void *ioremap_nocache(unsigned long phys_addr, unsigned long size);

void iounmap(void * addr);

unsigned int ioread8(void *addr);

unsigned int ioread16(void *addr);

unsigned int ioread32(void *addr);

void iowrite8(u8 value, void *addr);

void iowrite16(u16 value, void *addr);

void iowrite32(u32 value, void *addr);

void ioread8_rep(void *addr, void *buf, unsigned long count);

void ioread16_rep(void *addr, void *buf, unsigned long count);

void ioread32_rep(void *addr, void *buf, unsigned long count);

void iowrite8_rep(void *addr, const void *buf, unsigned long count);

void iowrite16_rep(void *addr, const void *buf, unsigned long count);

void iowrite32_rep(void *addr, const void *buf, unsigned long count);

void memset_io(void *addr, u8 value, unsigned int count);

void memcpy_fromio(void *dest, void *source, unsigned int count);

void memcpy_toio(void *dest, void *source, unsigned int count);

以下是相同功能，但安全性较低，是比较旧的函数：

unsigned readb(address);

unsigned readw(address);

unsigned readl(address);

void writeb(unsigned value, address);

void writew(unsigned value, address);

void writel(unsigned value, address);

3.3 同时使用I/O Ports 方式和 I/O Memory方式

void *ioport_map(unsigned long port, unsigned int count);

void ioport_unmap(void *addr);

 

先调用I/O Ports方试的request_region，再调用ioport_map，就可以使用两种不同函数进行I/O操作了。