Linux2.6内核驱动移植参考（3）

weiriver 发表于 2004-4-20 16:36:38

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

推荐文章：
http://www-900.ibm.com/developerWorks/cn/linux/kernel/l-kernel26/index.shtml#1
http://www-900.ibm.com/developerWorks/cn/linux/l-inside/index.shtml#h1
(over)

jinzhcheng 发表于 2004-4-21 09:35:56

多谢!

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中国Linux公社论坛's Archiver

Linux2.6内核驱动移植参考（3）