amiga.c

ARM 嵌入式 系统 设计与实例开发 实验教材 二源码

/*
 *  fs/partitions/amiga.c
 *
 *  Code extracted from drivers/block/genhd.c
 *
 *  Copyright (C) 1991-1998  Linus Torvalds
 *  Re-organised Feb 1998 Russell King
 */

#include <linux/fs.h>
#include <linux/genhd.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/blk.h>

#include <asm/byteorder.h>
#include <linux/affs_hardblocks.h>

#include "check.h"
#include "amiga.h"

static __inline__ u32
checksum_block(u32 *m, int size)
{
	u32 sum = 0;

	while (size--)
		sum += be32_to_cpu(*m++);
	return sum;
}

int
amiga_partition(struct gendisk *hd, struct block_device *bdev,
		unsigned long first_sector, int first_part_minor)
{
	Sector sect;
	unsigned char *data;
	struct RigidDiskBlock *rdb;
	struct PartitionBlock *pb;
	int start_sect, nr_sects, blk, part, res = 0;
	kdev_t dev = to_kdev_t(bdev->bd_dev);

	for (blk = 0; ; blk++, put_dev_sector(sect)) {
		if (blk == RDB_ALLOCATION_LIMIT)
			goto rdb_done;
		data = read_dev_sector(bdev, blk, &sect);
		if (!data) {
			if (warn_no_part)
				printk("Dev %s: unable to read RDB block %d\n",
				       bdevname(dev), blk);
			goto rdb_done;
		}
		if (*(u32 *)data != cpu_to_be32(IDNAME_RIGIDDISK))
			continue;

		rdb = (struct RigidDiskBlock *)data;
		if (checksum_block((u32 *)data, be32_to_cpu(rdb->rdb_SummedLongs) & 0x7F) == 0)
			break;
		/* Try again with 0xdc..0xdf zeroed, Windows might have
		 * trashed it.
		 */
		*(u32 *)(data+0xdc) = 0;
		if (checksum_block((u32 *)data,
				be32_to_cpu(rdb->rdb_SummedLongs) & 0x7F)==0) {
			printk("Warning: Trashed word at 0xd0 in block %d "
				"ignored in checksum calculation\n",blk);
			break;
		}

		printk("Dev %s: RDB in block %d has bad checksum\n",
			       bdevname(dev),blk);
	}

	printk(" RDSK");
	blk = be32_to_cpu(rdb->rdb_PartitionList);
	put_dev_sector(sect);
	for (part = 1; blk>0 && part<=16; part++, put_dev_sector(sect)) {
		data = read_dev_sector(bdev, blk, &sect);
		if (!data) {
			if (warn_no_part)
				printk("Dev %s: unable to read partition block %d\n",
				       bdevname(dev),blk);
			goto rdb_done;
		}
		pb  = (struct PartitionBlock *)data;
		blk = be32_to_cpu(pb->pb_Next);
		if (pb->pb_ID != cpu_to_be32(IDNAME_PARTITION))
			continue;
		if (checksum_block((u32 *)pb, be32_to_cpu(pb->pb_SummedLongs) & 0x7F) != 0 )
			continue;

		/* Tell Kernel about it */

		nr_sects = (be32_to_cpu(pb->pb_Environment[10]) + 1 -
			    be32_to_cpu(pb->pb_Environment[9])) *
			   be32_to_cpu(pb->pb_Environment[3]) *
			   be32_to_cpu(pb->pb_Environment[5]);
		if (!nr_sects)
			continue;
		start_sect = be32_to_cpu(pb->pb_Environment[9]) *
			     be32_to_cpu(pb->pb_Environment[3]) *
			     be32_to_cpu(pb->pb_Environment[5]);
		add_gd_partition(hd,first_part_minor,start_sect,nr_sects);
		first_part_minor++;
		res = 1;
	}
	printk("\n");

rdb_done:
	return res;
}