块设备驱动

来源：互联网发布：windows 重叠io 编辑：程序博客网时间：2024/05/16 13:46
http://bbs.chinaunix.net/thread-2017377-1-1.html
一下代码是<< 深入linux设备驱动程序内核机制>>中有关块设备的
http://blog.csdn.net/feixiaoxing/article/details/11701797
make_request
#include <linux/module.h>#include <linux/kernel.h>#include <linux/init.h>#include <linux/fs.h>#include <linux/types.h>#include <linux/fcntl.h>#include <linux/vmalloc.h>#include <linux/blkdev.h>#include <linux/hdreg.h>#define RAMHD_NAME "ramhd"#define RAMHD_MAX_DEVICE 2#define RAMHD_MAX_PARTITIONS 4#define RAMHD_SECTOR_SIZE 512#define RAMHD_SECTORS 16#define RAMHD_HEADS 4#define RAMHD_CYLINDERS 256#define RAMHD_SECTOR_TOTAL (RAMHD_SECTORS * RAMHD_HEADS *RAMHD_CYLINDERS)#define RAMHD_SIZE (RAMHD_SECTOR_SIZE * RAMHD_SECTOR_TOTAL) //8mbtypedef struct {    unsigned char* data;    struct request_queue* queue;    struct gendisk* gd;}RAMHD_DEV;static char* sdisk[RAMHD_MAX_DEVICE] = {NULL};static RAMHD_DEV* rdev[RAMHD_MAX_DEVICE] = {NULL};static dev_t ramhd_major;static int ramhd_space_init(void){    int i;    int err = 0;    for(i = 0; i < RAMHD_MAX_DEVICE; i++){        sdisk[i] = vmalloc(RAMHD_SIZE);        if(!sdisk[i]){            err = -ENOMEM;            return err;        }                memset(sdisk[i], 0, RAMHD_SIZE);    }        return err;}static void ramhd_space_clean(void){    int i;    for(i = 0; i < RAMHD_MAX_DEVICE; i++){        vfree(sdisk[i]);    }}static int ramhd_open(struct block_device* bdev, fmode_t mode){    return 0;}static int ramhd_release(struct gendisk*gd, fmode_t mode){    return 0;}static int ramhd_ioctl(struct block_device* bdev, fmode_t mode, unsigned int cmd, unsigned long arg){    int err;    struct hd_geometry geo;        switch(cmd)    {        case HDIO_GETGEO:            err = !access_ok(VERIFY_WRITE, arg, sizeof(geo));            if(err)                return -EFAULT;                            geo.cylinders = RAMHD_CYLINDERS;            geo.heads = RAMHD_HEADS;            geo.sectors = RAMHD_SECTORS;            geo.start = get_start_sect(bdev);                        if(copy_to_user((void*)arg, &geo, sizeof(geo)))                return -EFAULT;                        return 0;    }        return -ENOTTY;}static struct block_device_operations ramhd_fops = {    .owner = THIS_MODULE,    .open = ramhd_open,    .release = ramhd_release,    .ioctl = ramhd_ioctl,};static int ramhd_make_request(struct request_queue* q, struct bio* bio){    char* pRHdata;    char* pBuffer;    struct bio_vec* bvec;    int i;    int err = 0;        struct block_device* bdev = bio->bi_bdev;    RAMHD_DEV* pdev = bdev->bd_disk->private_data;        if(((bio->bi_sector * RAMHD_SECTOR_SIZE) + bio->bi_size) > RAMHD_SIZE){        err = -EIO;        return err;    }        pRHdata = pdev->data + (bio->bi_sector * RAMHD_SECTOR_SIZE);    bio_for_each_segment(bvec, bio, i){        pBuffer = kmap(bvec->bv_page) + bvec->bv_offset;        switch(bio_data_dir(bio)){            case READ:                memcpy(pBuffer, pRHdata, bvec->bv_len);                flush_dcache_page(bvec->bv_page);                break;                            case WRITE:                flush_dcache_page(bvec->bv_page);                memcpy(pRHdata, pBuffer, bvec->bv_len);                break;                            default:                kunmap(bvec->bv_page);                goto out;        }                kunmap(bvec->bv_page);        pRHdata += bvec->bv_len;    }    out:    bio_endio(bio, err);    return 0;}static int alloc_ramdev(void){    int i;    for(i = 0; i < RAMHD_MAX_DEVICE; i++){        rdev[i] = kzalloc(sizeof(RAMHD_DEV), GFP_KERNEL);        if(!rdev[i]){            return -ENOMEM;        }    }        return 0;}static void clean_ramdev(void){    int i;        for(i = 0; i < RAMHD_MAX_DEVICE; i++){        if(rdev[i])            kfree(rdev[i]);    }}static int __init ramhd_init(void){    int i;        ramhd_space_init();    alloc_ramdev();        ramhd_major = register_blkdev(0, RAMHD_NAME);        for(i = 0; i < RAMHD_MAX_DEVICE; i++){        rdev[i]->data = sdisk[i];        rdev[i]->queue = blk_alloc_queue(GFP_KERNEL);        blk_queue_make_request(rdev[i]->queue, ramhd_make_request);                rdev[i]->gd = alloc_disk(RAMHD_MAX_PARTITIONS);        rdev[i]->gd->major = ramhd_major;        rdev[i]->gd->first_minor = i * RAMHD_MAX_PARTITIONS;        rdev[i]->gd->fops = &ramhd_fops;        rdev[i]->gd->queue = rdev[i]->queue;        rdev[i]->gd->private_data = rdev[i];        sprintf(rdev[i]->gd->disk_name, "ramhd%c", 'a' +i);        rdev[i]->gd->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;        set_capacity(rdev[i]->gd, RAMHD_SECTOR_TOTAL);        add_disk(rdev[i]->gd);    }        return 0;}static void __exit ramhd_exit(void){    int i;    for(i = 0; i < RAMHD_MAX_DEVICE; i++){        del_gendisk(rdev[i]->gd);        put_disk(rdev[i]->gd);        blk_cleanup_queue(rdev[i]->queue);    }        clean_ramdev();    ramhd_space_clean();    unregister_blkdev(ramhd_major, RAMHD_NAME);}module_init(ramhd_init);module_exit(ramhd_exit);MODULE_AUTHOR("dennis__chen@ AMDLinuxFGL");MODULE_DESCRIPTION("The ramdisk implementation with request function");MODULE_LICENSE("GPL");
request
http://blog.csdn.net/qingtian2006/article/details/8825880
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