内核操作 Linux2.6内核驱动移植参考 （2）

19、 新增创建VFS的"libfs"

libfs给创建一个新的文件系统提供了大量的API.

主要是对struct file_system_type的实现。

参考源代码：

drivers/hotplug/pci_hotplug_core.c

drivers/usb/core/inode.c

drivers/oprofile/oprofilefs.c

fs/ramfs/inode.c

fs/nfsd/nfsctl.c (simple_fill_super() example)

20、 DMA的变化

未变化的有：

void *pci_alloc_consistent(struct pci_dev *dev, size_t size,

dma_addr_t *dma_handle);

void pci_free_consistent(struct pci_dev *dev, size_t size,

void *cpu_addr, dma_addr_t dma_handle);

变化的有：

1、 void *dma_alloc_coherent(struct device *dev, size_t size,

dma_addr_t *dma_handle, int flag);

void dma_free_coherent(struct device *dev, size_t size,

void *cpu_addr, dma_addr_t dma_handle);

2、列举了映射方向：

enum dma_data_direction {

DMA_BIDIRECTIONAL = 0,

DMA_TO_DEVICE = 1,

DMA_FROM_DEVICE = 2,

DMA_NONE = 3,

};

3、单映射

dma_addr_t dma_map_single(struct device *dev, void *addr,

size_t size,

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 int iv);

unsigned int read_seqbegin_irqsave(seqlock_t *sl, long flags);

int read_seqretry_irqrestore(seqlock_t *sl, unsigned int iv, long

flags);

22、 内核可剥夺

＜linux/preempt.h＞

preempt_disable()；

preempt_enable_no_resched()；

preempt_enable_noresched()；

preempt_check_resched()；

23、 眠和唤醒

1、原来的函数可用，新增下列函数：

prepare_to_wait_exclusive()；

prepare_to_wait()；

2、等待队列的变化

typedef int (*wait_queue_func_t)(wait_queue_t *wait,

unsigned mode, int sync);

void init_waitqueue_func_entry(wait_queue_t *queue,

wait_queue_func_t func);

24、 新增完成事件（completion events）

＜linux/completion.h＞

init_completion(&my_comp);

void wait_for_completion(struct completion *comp);

void complete(struct completion *comp);

void complete_all(struct completion *comp);

25、 RCU（Read-copy-update）

rcu_read_lock();

void call_rcu(struct rcu_head *head, void (*func)(void *arg),

void *arg);

26、 中断处理

1、中断处理有返回值了。

IRQ_RETVAL(handled)；

2、cli(), sti(), save_flags(), 和 restore_flags()不再有效，应该使用local_save

_flags() 或local_irq_disable()。

3、synchronize_irq()函数有改动

4、新增int can_request_irq(unsigned int irq, unsigned long flags);

5、 request_irq() 和free_irq() 从 ＜linux/sched.h＞改到了 ＜linux/interrupt.h＞

27、 异步I/O(AIO)

＜linux/aio.h＞

ssize_t (*aio_read) (struct kiocb *iocb, char __user *buffer,

size_t count, loff_t pos);

ssize_t (*aio_write) (struct kiocb *iocb, const char __user *buffer,

size_t count, loff_t pos);

int (*aio_fsync) (struct kiocb *, int datasync);

新增到了file_operation结构中。

is_sync_kiocb(struct kiocb *iocb)；

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

28、 网络驱动

1、struct net_device *alloc_netdev(int sizeof_priv, const char *name,

void (*setup)(struct net_device *));

struct net_device *alloc_etherdev(int sizeof_priv);

2、新增NAPI(New API)

void netif_rx_schedule(struct net_device *dev);

void netif_rx_complete(struct net_device *dev);

int netif_rx_ni(struct sk_buff *skb);

(老版本为netif_rx())

29、 USB驱动

老版本struct usb_driver取消了，新的结构体为

struct usb_class_driver {

char *name;

struct file_operations *fops;

mode_t mode;

int minor_base;

};

int usb_submit_urb(struct urb *urb, int mem_flags);

int (*probe) (struct usb_interface *intf,

const struct usb_device_id *id);

30、 block I/O 层

这一部分做的改动最大。不祥叙。

31、 mmap()

int remap_page_range(struct vm_area_struct *vma, unsigned long from,

unsigned long to, unsigned long size,

pgprot_t prot);

int io_remap_page_range(struct vm_area_struct *vma, unsigned long from,

unsigned long to, unsigned long size,

pgprot_t prot);

struct page *(*nopage)(struct vm_area_struct *area,

unsigned long address,

int *type);

int (*populate)(struct vm_area_struct *area, unsigned long address,

unsigned long len, pgprot_t prot, unsigned long pgoff,

int nonblock);

int install_page(struct mm_struct *mm, struct vm_area_struct *vma,

unsigned long addr, struct page *page,

pgprot_t prot);

struct page *vmalloc_to_page(void *address);

32、 零拷贝块I/O(Zero-copy block I/O)

struct bio *bio_map_user(struct block_device *bdev,

unsigned long uaddr,

unsigned int len,

int write_to_vm);

void bio_unmap_user(struct bio *bio, int write_to_vm);

int get_user_pages(struct task_struct *task,

struct mm_struct *mm,

unsigned long start,

int len,

int write,

int force,

struct page **pages,

struct vm_area_struct **vmas);

33、 高端内存操作kmaps

void *kmap_atomic(struct page *page, enum km_type type);

void kunmap_atomic(void *address, enum km_type type);

struct page *kmap_atomic_to_page(void *address);

老版本：kmap() 和 kunmap()。

34、 驱动模型

主要用于设备管理。

1、 sysfs

2、 Kobjects