nfblock.c

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/*
 * ARAnyM block device driver
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/genhd.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include <linux/slab.h>

#include <asm/natfeat.h>

static long nfhd_id;

enum {
    /* emulation entry points */
    NFHD_READ_WRITE = 10,
    NFHD_GET_CAPACITY = 14,

    /* skip ACSI devices */
    NFHD_DEV_OFFSET = 8,
};

static inline s32 nfhd_read_write(u32 major, u32 minor, u32 rwflag, u32 recno,
                  u32 count, u32 buf)
{
    return nf_call(nfhd_id + NFHD_READ_WRITE, major, minor, rwflag, recno,
               count, buf);
}

static inline s32 nfhd_get_capacity(u32 major, u32 minor, u32 *blocks,
                    u32 *blocksize)
{
    return nf_call(nfhd_id + NFHD_GET_CAPACITY, major, minor, blocks,
               blocksize);
}

static LIST_HEAD(nfhd_list);

static int major_num;
module_param(major_num, int, 0);

struct nfhd_device {
    struct list_head list;
    int id;
    u32 blocks, bsize;
    int bshift;
    struct request_queue *queue;
    struct gendisk *disk;
};

static void nfhd_make_request(struct request_queue *queue, struct bio *bio)
{
    struct nfhd_device *dev = queue->queuedata;
    struct bio_vec *bvec;
    int i, dir, len, shift;
    sector_t sec = bio->bi_sector;

    dir = bio_data_dir(bio);
    shift = dev->bshift;
    bio_for_each_segment(bvec, bio, i) {
        len = bvec->bv_len;
        len >>= 9;
        nfhd_read_write(dev->id, 0, dir, sec >> shift, len >> shift,
                bvec_to_phys(bvec));
        sec += len;
    }
    bio_endio(bio, 0);
}

static int nfhd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
    struct nfhd_device *dev = bdev->bd_disk->private_data;

    geo->cylinders = dev->blocks >> (6 - dev->bshift);
    geo->heads = 4;
    geo->sectors = 16;

    return 0;
}

static const struct block_device_operations nfhd_ops = {
    .owner  = THIS_MODULE,
    .getgeo = nfhd_getgeo,
};

static int __init nfhd_init_one(int id, u32 blocks, u32 bsize)
{
    struct nfhd_device *dev;
    int dev_id = id - NFHD_DEV_OFFSET;

    pr_info("nfhd%u: found device with %u blocks (%u bytes)\n", dev_id,
        blocks, bsize);

    if (bsize < 512 || (bsize & (bsize - 1))) {
        pr_warn("nfhd%u: invalid block size\n", dev_id);
        return -EINVAL;
    }

    dev = kmalloc(sizeof(struct nfhd_device), GFP_KERNEL);
    if (!dev)
        goto out;

    dev->id = id;
    dev->blocks = blocks;
    dev->bsize = bsize;
    dev->bshift = ffs(bsize) - 10;

    dev->queue = blk_alloc_queue(GFP_KERNEL);
    if (dev->queue == NULL)
        goto free_dev;

    dev->queue->queuedata = dev;
    blk_queue_make_request(dev->queue, nfhd_make_request);
    blk_queue_logical_block_size(dev->queue, bsize);

    dev->disk = alloc_disk(16);
    if (!dev->disk)
        goto free_queue;

    dev->disk->major = major_num;
    dev->disk->first_minor = dev_id * 16;
    dev->disk->fops = &nfhd_ops;
    dev->disk->private_data = dev;
    sprintf(dev->disk->disk_name, "nfhd%u", dev_id);
    set_capacity(dev->disk, (sector_t)blocks * (bsize / 512));
    dev->disk->queue = dev->queue;

    add_disk(dev->disk);

    list_add_tail(&dev->list, &nfhd_list);

    return 0;

free_queue:
    blk_cleanup_queue(dev->queue);
free_dev:
    kfree(dev);
out:
    return -ENOMEM;
}

static int __init nfhd_init(void)
{
    u32 blocks, bsize;
    int i;

    nfhd_id = nf_get_id("XHDI");
    if (!nfhd_id)
        return -ENODEV;

    major_num = register_blkdev(major_num, "nfhd");
    if (major_num <= 0) {
        pr_warn("nfhd: unable to get major number\n");
        return major_num;
    }

    for (i = NFHD_DEV_OFFSET; i < 24; i++) {
        if (nfhd_get_capacity(i, 0, &blocks, &bsize))
            continue;
        nfhd_init_one(i, blocks, bsize);
    }

    return 0;
}

static void __exit nfhd_exit(void)
{
    struct nfhd_device *dev, *next;

    list_for_each_entry_safe(dev, next, &nfhd_list, list) {
        list_del(&dev->list);
        del_gendisk(dev->disk);
        put_disk(dev->disk);
        blk_cleanup_queue(dev->queue);
        kfree(dev);
    }
    unregister_blkdev(major_num, "nfhd");
}

module_init(nfhd_init);
module_exit(nfhd_exit);

MODULE_LICENSE("GPL");