linux3.4.2之块设备驱动完整程序

 /*参考drivers/block/xd.c
 *以及drivers/block/z2ram.c
 */
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/mm.h>
 #include <linux/fs.h>
 #include <linux/kernel.h>
 #include <linux/timer.h>
 #include <linux/genhd.h>
 #include <linux/hdreg.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
 #include <linux/wait.h>
 #include <linux/blkdev.h>
 #include <linux/mutex.h>
 #include <linux/blkpg.h>
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/gfp.h>

 #include <asm/uaccess.h>
 #include <asm/dma.h>

 static struct gendisk *ramblock_disk;
 static struct request_queue *ramblock_queue;
 static DEFINE_SPINLOCK(ramblock_lock);

 #define RAMBLOCKSIZE (1024*1024)
 static int major;
 static unsigned char *ramblock;

 static int ramblock_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {

     geo->heads = ;
     geo->sectors = ;
     geo->cylinders = RAMBLOCKSIZE///;
     return ;
 }

 static const struct block_device_operations ramblock_fops = {
     .owner    = THIS_MODULE,
     .getgeo = ramblock_getgeo,
 };

 static void do_ramblock_request (struct request_queue * q)
 {
       static int cnt = ;
       struct request *req;

       printk("do_ramblock_request %d : \n",++cnt);
       req = blk_fetch_request(q);
       while(req){
           unsigned long start = blk_rq_pos(req) << ; //源
         unsigned long len  = blk_rq_cur_bytes(req);  //长度
         /*目的：req->buffer*/
         if (rq_data_dir(req) == READ)
                 memcpy(req->buffer, ramblock+start, len);
             else
                 memcpy(ramblock+start, req->buffer, len);

          if (!__blk_end_request_cur(req, ))
             req = blk_fetch_request(q);
       }
 }

 static int ramblock_init(void)
 {
     ramblock_disk = alloc_disk(); //次设备号个数，分区数+1

     ramblock_queue = blk_init_queue(do_ramblock_request, &ramblock_lock);

     major = register_blkdev(, "ramblock"); // /dev/ramblock

         ramblock_disk->major = major;
         ramblock_disk->first_minor = ;
         sprintf(ramblock_disk->disk_name, "ramblock");
         ramblock_disk->fops = &ramblock_fops;
         ramblock_disk->queue = ramblock_queue;
         set_capacity(ramblock_disk, RAMBLOCKSIZE/);  //设置容量，以扇区512字节为单位

         ramblock = kzalloc(RAMBLOCKSIZE,GFP_KERNEL);
         if(ramblock == NULL){
           printk("alloc ramblock failed!\n");
           return -;
         }
         add_disk(ramblock_disk);
     return ;
 }

 static void ramblock_exit(void)
 {
        del_gendisk(ramblock_disk);
        unregister_blkdev(major,"ramblock");
        blk_cleanup_queue(ramblock_queue);
        put_disk(ramblock_disk);
        kfree(ramblock);
 }

 module_init(ramblock_init);
 module_exit(ramblock_exit);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("1653699780@qq.com");