Tiny210块设备驱动之内存模拟磁盘

ramblock.c驱动源码：

#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/blkpg.h"

#include "linux/delay.h"

#include "linux/io.h"

#include "linux/gfp.h"

#include "linux/slab.h"

#include "asm/system.h"

#include "asm/uaccess.h"

#include "asm/dma.h"

#define RAMDISK_SIZE (1024*1024)

static DEFINE_SPINLOCK(ramdisk_lock);

static const struct block_device_operations ramdisk_fops = {

    .owner    = THIS_MODULE,

};

static struct gendisk *ramblock_disk;

static struct request_queue *ramblock_queue;

static unsigned char *ram_buff;

static int major;

static void ramblock_do_request(struct request_queue * q)

{

    struct request *req;

    printk("do:ramblock_do_request\n");

    req = blk_fetch_request(q);

    while (req) 

    {

        //源或目的

        unsigned long offset = blk_rq_pos(req) * 512;

        //目的或源

        //req->buffer

        //长度

        unsigned long len  = blk_rq_cur_bytes(req);

        if (rq_data_dir(req) == READ)

            memcpy(req->buffer, ram_buff+offset, len);

        else

            memcpy(ram_buff+offset, req->buffer, len);

        // wrap up, 0 = success, -errno = fail 

        if (!__blk_end_request_cur(req, 0))

            req = blk_fetch_request(q);

    }

}

static int ramblock_init(void)

{

    //获得主设备号

    major = register_blkdev(major, "ramdisk");

    //1.分配一个gendisk结构体

    ramblock_disk = alloc_disk(16);

    //2.设置

    //2.1设置一个请求队列

    ramblock_queue = blk_init_queue(ramblock_do_request, &ramdisk_lock);

    ramblock_disk->queue = ramblock_queue;

    //2.2设置其他信息

    ramblock_disk->major = major;

    ramblock_disk->first_minor = 0;

    sprintf(ramblock_disk->disk_name, "ramdisk");

    ramblock_disk->fops = &ramdisk_fops;

    set_capacity(ramblock_disk, RAMDISK_SIZE);

    //3.硬件相关

    ram_buff = kzalloc(RAMDISK_SIZE, GFP_KERNEL);

    //4.注册

    add_disk(ramblock_disk);

    return 0;

}

static void ramblock_exit(void)

{

    unregister_blkdev(major, "ramdisk");

    del_gendisk(ramblock_disk);

    put_disk(ramblock_disk);

    blk_cleanup_queue(ramblock_queue);

    kfree(ram_buff);

}

module_init(ramblock_init);

module_exit(ramblock_exit);

MODULE_LICENSE("GPL");