Specifications

This is the Title of the Book, eMatter Edition

Quick Reference

461

int is_sync_kiocb(struct kiocb *iocb);

Macro that returns nonzero if the given IOCB requires synchronous execution.

int aio_complete(struct kiocb *iocb, long res, long res2);

Function that indicates completion of an asynchronous I/O operation.

Direct Memory Access

#include <asm/io.h>

unsigned long virt_to_bus(volatile void * address);

void * bus_to_virt(unsigned long address);

Obsolete and deprecated functions that convert between kernel, virtual, and bus

addresses. Bus addresses must be used to talk to peripheral devices.

#include <linux/dma-mapping.h>

Header file required to define the generic DMA functions.

int dma_set_mask(struct device *dev, u64 mask);

For peripherals that cannot address the full 32-bit range, this function informs

the kernel of the addressable range and returns nonzero if DMA is possible.

void *dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t

*bus_addr, int flag)

void dma_free_coherent(struct device *dev, size_t size, void *cpuaddr,

dma_handle_t bus_addr);

Allocate and free coherent DMA mappings for a buffer that will last the lifetime

of the driver.

#include <linux/dmapool.h>

struct dma_pool *dma_pool_create(const char *name, struct device *dev,

size_t size, size_t align, size_t allocation);

void dma_pool_destroy(struct dma_pool *pool);

void *dma_pool_alloc(struct dma_pool *pool, int mem_flags, dma_addr_t

*handle);

void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t handle);

Functions that create, destroy, and use DMA pools to manage small DMA areas.

enum dma_data_direction;

DMA_TO_DEVICE

DMA_FROM_DEVICE

DMA_BIDIRECTIONAL

DMA_NONE

Symbols used to tell the streaming mapping functions the direction in which

data is moving to or from the buffer.

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