enum dma_data_direction direction);

void dma_unmap_single(struct device *dev, dma_addr_t dma_addr,

size_t size,

enum dma_data_direction direction);

4、页面映射

dma_addr_t dma_map_page(struct device *dev, struct page *page,

unsigned long offset, size_t size,

enum dma_data_direction direction);

void dma_unmap_page(struct device *dev, dma_addr_t dma_addr,

size_t size,

enum dma_data_direction direction);

5、有关scatter/gather的函数：

int dma_map_sg(struct device *dev, struct scatterlist *sg,

int nents, enum dma_data_direction direction);

void dma_unmap_sg(struct device *dev, struct scatterlist *sg,

int nhwentries, enum dma_data_direction direction);

6、非一致性映射（Noncoherent DMA mappings）

void *dma_alloc_noncoherent(struct device *dev, size_t size,

dma_addr_t *dma_handle, int flag);

void dma_sync_single_range(struct device *dev, dma_addr_t dma_handle,

unsigned long offset, size_t size,

enum dma_data_direction direction);

void dma_free_noncoherent(struct device *dev, size_t size,

void *cpu_addr, dma_addr_t dma_handle);

7、DAC (double address cycle)

int pci_dac_set_dma_mask(struct pci_dev *dev, u64 mask);

void pci_dac_dma_sync_single(struct pci_dev *dev,

dma64_addr_t dma_addr,

size_t len, int direction);

21、 互斥

新增seqlock主要用于：

1、少量的数据保护

2、数据比较简单(没有指针)，并且使用频率很高

3、对不产生任何副作用的数据的访问

4、访问时写者不被饿死

＜linux/seqlock.h＞

初始化

seqlock_t lock1 = SEQLOCK_UNLOCKED;

或seqlock_t lock2; seqlock_init(&lock2);

void write_seqlock(seqlock_t *sl);

void write_sequnlock(seqlock_t *sl);

int write_tryseqlock(seqlock_t *sl);

void write_seqlock_irqsave(seqlock_t *sl, long flags);

void write_sequnlock_irqrestore(seqlock_t *sl, long flags);

void write_seqlock_irq(seqlock_t *sl);

void write_sequnlock_irq(seqlock_t *sl);

void write_seqlock_bh(seqlock_t *sl);

void write_sequnlock_bh(seqlock_t *sl);

unsigned int read_seqbegin(seqlock_t *sl);

int read_seqretry(seqlock_t *sl, unsigned

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