本章介绍下列与硬件管理相关的符号:
#include <linux/kernel.h>
void barrier(void)这个"软件"内存屏蔽要求编译器对待所有内存是跨这个指令而非易失的.
#include <asm/system.h>
void rmb(void);
void read_barrier_depends(void);
void wmb(void);
void mb(void);硬件内存屏障. 它们请求 CPU(和编译器)来检查所有的跨这个指令的内存读, 写, 或都有.
#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 doubleword, unsigned port);用来读和写 I/O 端口的函数. 它们还可以被用户空间程序调用, 如果它们有正当的权限来存取端口.
unsigned inb_p(unsigned port);
如果在一次 I/O 操作后需要一个小延时, 你可以使用在前一项中介绍的这些函数的 6 个暂停对应部分; 这些暂停函数有以 _p 结尾的名子.
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);这些"字串函数"被优化为传送数据从一个输入端口到一个内存区, 或者其他的方式. 这些传送通过读或写到同一端口 count 次来完成.
#include <linux/ioport.h>
struct resource *request_region(unsigned long start, unsigned long len, char *name);
void release_region(unsigned long start, unsigned long len);
int check_region(unsigned long start, unsigned long len);I/O 端口的资源分配器. 这个检查函数成功返回 0 并且在错误时小于 0.
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);为内存区处理资源分配的函数
#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 *virt_addr);ioremap 重映射一个物理地址范围到处理器的虚拟地址空间, 使它对内核可用. iounmap 释放映射当不再需要它时.
#include <asm/io.h>
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);用来使用 I/O 内存的存取者函数.
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);I/O 内存原语的"重复"版本.
unsigned readb(address);
unsigned readw(address);
unsigned readl(address);
void writeb(unsigned value, address);
void writew(unsigned value, address);
void writel(unsigned value, address);
memset_io(address, value, count);
memcpy_fromio(dest, source, nbytes);
memcpy_toio(dest, source, nbytes);旧的, 类型不安全的存取 I/O 内存的函数.
void *ioport_map(unsigned long port, unsigned int count);
void ioport_unmap(void *addr);一个想对待 I/O 端口如同它们是 I/O 内存的驱动作者, 可以传递它们的端口给 ioport_map. 这个映射应当在不需要的时候恢复( 使用 ioport_unmap )