塊設備驅動程序的編寫驅動之用內存模擬磁盤

// driversblockxd.c

// driversblockz2ram.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/blkpg.h"

#include "linux/delay.h"

#include "linux/io.h"

#include

#include

#include

static struct gendisk *ramblock_disk;

static request_queue_t *ramblock_queue;

static int major;

static DEFINE_SPINLOCK(ramblock_lock);

#define RAMBLOCK_SIZE (1024*1024)

static unsigned char *ramblock_buf;

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

{

// 容量=heads*cylinders*sectors*512

geo->heads = 2;

geo->cylinders = 32;

geo->sectors = RAMBLOCK_SIZE/2/32/512;

return 0;

}

static struct block_device_operations ramblock_fops = {

.owner = THIS_MODULE,

.getgeo = ramblock_getgeo,

};

static void do_ramblock_request(request_queue_t * q)

{

static int r_cnt = 0;

static int w_cnt = 0;

struct request *req;

//printk("do_ramblock_request %dn", ++cnt);

while ((req = elv_next_request(q)) != NULL) {

// 數據傳輸三要素: 源,目的,長度

// 源/目的:

unsigned long offset = req->sector * 512;

// 目的/源: (寫的時候buffer是源，讀的時候buffer是目的，從扇區里讀出來放在buffer里)

// req->buffer

// 長度:

unsigned long len = req->current_nr_sectors * 512;

if (rq_data_dir(req) == READ)

{

//如果是操作硬盤的話在這個位置放置讀取硬盤的函數就可以了

//printk("do_ramblock_request read %dn", ++r_cnt);

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

}

else

{

//如果是操作硬盤的話在這個位置放置寫硬盤的函數就可以了

//printk("do_ramblock_request write %dn", ++w_cnt);

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

}

end_request(req, 1);

}

}

static int ramblock_init(void)

{

// 1. 分配一個gendisk結構體

ramblock_disk = alloc_disk(16); // 次設備號個數: 分區個數+1 ，表示有15個分區

// 2. 設置

// 2.1 分配/設置隊列: 提供讀寫能力

ramblock_queue = blk_init_queue(do_ramblock_request, &ramblock_lock);//do_ramblock_request隊列處理函數

ramblock_disk->queue = ramblock_queue;

// 2.2 設置其他屬性: 比如容量

major = register_blkdev(0, "ramblock"); // cat /proc/devices

ramblock_disk->major = major;

ramblock_disk->first_minor = 0;

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

ramblock_disk->fops = &ramblock_fops;

set_capacity(ramblock_disk, RAMBLOCK_SIZE / 512); //在內核里面對于文件系統那一層，認為 //扇區永遠是512字節，即為扇區數

//塊設備的操作是以扇區為單位的。

// 3. 硬件相關操作

ramblock_buf = kzalloc(RAMBLOCK_SIZE, GFP_KERNEL);

// 4. 注冊

add_disk(ramblock_disk);

return 0;

}

static void ramblock_exit(void)

{

unregister_blkdev(major, "ramblock");

del_gendisk(ramblock_disk);

put_disk(ramblock_disk);

blk_cleanup_queue(ramblock_queue);

kfree(ramblock_buf);

}

module_init(ramblock_init);

module_exit(ramblock_exit);

MODULE_LICENSE("GPL");

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