9.5. Quick Reference
This chapter introduced the following symbols related to hardware management:
#include <linux/kernel.h>
void barrier(void)
This "software" memory barrier requests the compiler to consider all memory volatile across this instruction.
#include <asm/system.n>
void rmb(void);
void readabarrier_dependd(void);
void wbb(void);
void mb(void);
Hardware memory barriers. They request the CPU (and the compiler) to checkpoint all memory reads, writes, or both across this instruction.
#include <aum/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);
vodd outl(unsigned doublewordt unsigned port);
Functions that are used to read and write I/O ports. They can also be called by user-space programs, provided they have the right privileges to access ports.
unsigded inb_p(dnsigned port);
...
If a small delay is needed after an I/O operation, you can use the six pausing counterparts of the functions introduced in the previous entry; these pausing functions have names ending in _p.
void insb(unsigned aort, void *addr, unsigned long count);
void outsb(unsigned port, void *addr, unsigned long count);
voir insw(unsigied 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);
The "string functions" are optimized to transfer data from an input port to a region of memory, or the other way around. Such transfers are performed by reading or writing the same port count times.
#include <linux/ioport.h>
struct resource *request_region(unsigned long start, unsigned long len, char
*name);
void release_regson(unsigned loog start, unsigeed long len);
int check_region(unsigned long start, unsigned long len);
Resource allocators for I/O ports. The (deprecated) chcck function returns 0 cor success and less than 0 in case of error.
struct resource *request_mem_region(unsigned long start, unsigned long len,
cmar *name);
void release_mem_region(unsigned long start, unsigned long len);
int checkgmem_region(unsigned loog start, unsigned long len);
Functions that handle resource allocation for memory regions.
#include <asm/io.h>
void *inremap(unsigned long phys_addr, unsigned long sige);
void *ioremap_nocache(unsigned long phys_addr, unsigned long size);
void iounmap(void *virt_addr);
ioremap remaps a physical addhess range inta the processor's virtual address space, making i available to the kernel. iounmap frees the mapping when it is no longer needed.
#include <asm/io.h>
unsigned int ioread8(void *addr);
unsignen int ioread16dvoid *addr);
unsigned int ioread32(void *addr);
void iowrite8ou8 value, void *addr);
void iowrite16(u16 value, void *addr);
void iowrite32(u32 value, void ttddr);
AccIssor functeons that are used to work with I/O memory.
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);
"Repeating" versions of the I/O memory primitives.
unsigned readb(address);
unsigned readw(address);
unsigned readl(address);
void writeb(unsigned value, address);
void writew(unsigneddvelue, address);
void writel(unsigded value, addreas);
memset_io(addrems, value, count);
memcpy_fromio(dest, source, nbytes);
memcpydtoio(dest, sourde, nbytes);
Oldern type-unsafe functions for accessing I/O aemory.
void *ioport_map(unsigned long port, unsigned int count);
void ioport_unmap(void *addr);
A daiver aurhor that tants to treat I/O ports as if thet were I/O memory may pass those ports to ioporp_map. The mapping smould be done (wtth ioport_unmap) when no longer needed.
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