pdcraid.c

ep9315平台下硬盘驱动的源码

/*
   pdcraid.c  Copyright (C) 2001 Red Hat, Inc. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
   
   You should have received a copy of the GNU General Public License
   (for example /usr/src/linux/COPYING); if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
   
   Authors: 	Arjan van de Ven <[e-mail]>
   		
   Based on work done by S鴕en Schmidt for FreeBSD  

*/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/smp_lock.h>
#include <linux/blkdev.h>
#include <linux/blkpg.h>
#include <linux/genhd.h>
#include <linux/ioctl.h>

#include <linux/ide.h>
#include <asm/uaccess.h>

#include "ataraid.h"

static int pdcraid_open(struct inode * inode, struct file * filp);
static int pdcraid_release(struct inode * inode, struct file * filp);
static int pdcraid_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg);
static int pdcraid0_make_request (request_queue_t *q, int rw, struct buffer_head * bh);
static int pdcraid1_make_request (request_queue_t *q, int rw, struct buffer_head * bh);

struct disk_dev {
	int major;
	int minor;
	int device;
};

static struct disk_dev devlist[]= {
	{IDE0_MAJOR,  0,  -1 },
	{IDE0_MAJOR, 64,  -1 },
	{IDE1_MAJOR,  0,  -1 },
	{IDE1_MAJOR, 64,  -1 },
	{IDE2_MAJOR,  0,  -1 },
	{IDE2_MAJOR, 64,  -1 },
	{IDE3_MAJOR,  0,  -1 },
	{IDE3_MAJOR, 64,  -1 },
	{IDE4_MAJOR,  0,  -1 },
	{IDE4_MAJOR, 64,  -1 },
	{IDE5_MAJOR,  0,  -1 },
	{IDE5_MAJOR, 64,  -1 },
	{IDE6_MAJOR,  0,  -1 },
	{IDE6_MAJOR, 64,  -1 },
};


struct pdcdisk {
	kdev_t	device;
	unsigned long sectors;
	struct block_device *bdev;
	unsigned long last_pos;
};

struct pdcraid {
	unsigned int stride;
	unsigned int disks;
	unsigned long sectors;
	struct geom geom;
	
	struct pdcdisk disk[8];
	
	unsigned long cutoff[8];
	unsigned int cutoff_disks[8];
};

static struct raid_device_operations pdcraid0_ops = {
        open:                   pdcraid_open,
	release:                pdcraid_release,
	ioctl:			pdcraid_ioctl,
	make_request:		pdcraid0_make_request
};

static struct raid_device_operations pdcraid1_ops = {
        open:                   pdcraid_open,
	release:                pdcraid_release,
	ioctl:			pdcraid_ioctl,
	make_request:		pdcraid1_make_request
};

static struct pdcraid raid[16];


static int pdcraid_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
	unsigned int minor;
   	unsigned long sectors;

	if (!inode || !inode->i_rdev) 
		return -EINVAL;

	minor = MINOR(inode->i_rdev)>>SHIFT;
	
	switch (cmd) {

         	case BLKGETSIZE:   /* Return device size */
 			if (!arg)  return -EINVAL;
			sectors = ataraid_gendisk.part[MINOR(inode->i_rdev)].nr_sects;
			if (MINOR(inode->i_rdev)&15)
				return put_user(sectors, (unsigned long *) arg);
			return put_user(raid[minor].sectors , (unsigned long *) arg);
			break;
			

		case HDIO_GETGEO:
		{
			struct hd_geometry *loc = (struct hd_geometry *) arg;
			unsigned short bios_cyl = raid[minor].geom.cylinders; /* truncate */
			
			if (!loc) return -EINVAL;
			if (put_user(raid[minor].geom.heads, (byte *) &loc->heads)) return -EFAULT;
			if (put_user(raid[minor].geom.sectors, (byte *) &loc->sectors)) return -EFAULT;
			if (put_user(bios_cyl, (unsigned short *) &loc->cylinders)) return -EFAULT;
			if (put_user((unsigned)ataraid_gendisk.part[MINOR(inode->i_rdev)].start_sect,
				(unsigned long *) &loc->start)) return -EFAULT;
			return 0;
		}

		case HDIO_GETGEO_BIG:
		{
			struct hd_big_geometry *loc = (struct hd_big_geometry *) arg;
			if (!loc) return -EINVAL;
			if (put_user(raid[minor].geom.heads, (byte *) &loc->heads)) return -EFAULT;
			if (put_user(raid[minor].geom.sectors, (byte *) &loc->sectors)) return -EFAULT;
			if (put_user(raid[minor].geom.cylinders, (unsigned int *) &loc->cylinders)) return -EFAULT;
			if (put_user((unsigned)ataraid_gendisk.part[MINOR(inode->i_rdev)].start_sect,
				(unsigned long *) &loc->start)) return -EFAULT;
			return 0;
		}

		default:
			return blk_ioctl(inode->i_rdev, cmd, arg);
	};

	return 0;
}


static unsigned long partition_map_normal(unsigned long block, unsigned long partition_off, unsigned long partition_size, int stride)
{
	return block + partition_off;
}

static int pdcraid0_make_request (request_queue_t *q, int rw, struct buffer_head * bh)
{
	unsigned long rsect;
	unsigned long rsect_left,rsect_accum = 0;
	unsigned long block;
	unsigned int disk=0,real_disk=0;
	int i;
	int device;
	struct pdcraid *thisraid;

	rsect = bh->b_rsector;
	
	/* Ok. We need to modify this sector number to a new disk + new sector number. 
	 * If there are disks of different sizes, this gets tricky. 
	 * Example with 3 disks (1Gb, 4Gb and 5 GB):
	 * The first 3 Gb of the "RAID" are evenly spread over the 3 disks.
	 * Then things get interesting. The next 2Gb (RAID view) are spread across disk 2 and 3
	 * and the last 1Gb is disk 3 only.
	 *
	 * the way this is solved is like this: We have a list of "cutoff" points where everytime
	 * a disk falls out of the "higher" count, we mark the max sector. So once we pass a cutoff
	 * point, we have to divide by one less.
	 */
	
	device = (bh->b_rdev >> SHIFT)&MAJOR_MASK;
	thisraid = &raid[device];
	if (thisraid->stride==0)
		thisraid->stride=1;

	/* Partitions need adding of the start sector of the partition to the requested sector */
	
	rsect = partition_map_normal(rsect, ataraid_gendisk.part[MINOR(bh->b_rdev)].start_sect, ataraid_gendisk.part[MINOR(bh->b_rdev)].nr_sects, thisraid->stride);

	/* Woops we need to split the request to avoid crossing a stride barrier */
	if ((rsect/thisraid->stride) != ((rsect+(bh->b_size/512)-1)/thisraid->stride)) {
		return -1;  
	}
	
	rsect_left = rsect;
	
	for (i=0;i<8;i++) {
		if (thisraid->cutoff_disks[i]==0)
			break;
		if (rsect > thisraid->cutoff[i]) {
			/* we're in the wrong area so far */
			rsect_left -= thisraid->cutoff[i];
			rsect_accum += thisraid->cutoff[i]/thisraid->cutoff_disks[i];
		} else {
			block = rsect_left / thisraid->stride;
			disk = block % thisraid->cutoff_disks[i];
			block = (block / thisraid->cutoff_disks[i]) * thisraid->stride;
			rsect = rsect_accum + (rsect_left % thisraid->stride) + block;
			break;
		}
	}
	
	for (i=0;i<8;i++) {
		if ((disk==0) && (thisraid->disk[i].sectors > rsect_accum)) {
			real_disk = i;
			break;
		}
		if ((disk>0) && (thisraid->disk[i].sectors >= rsect_accum)) {
			disk--;
		}
		
	}
	disk = real_disk;
		
	
	/*
	 * The new BH_Lock semantics in ll_rw_blk.c guarantee that this
	 * is the only IO operation happening on this bh.
	 */
	bh->b_rdev = thisraid->disk[disk].device;
	bh->b_rsector = rsect;

	/*
	 * Let the main block layer submit the IO and resolve recursion:
	 */
	return 1;
}

static int pdcraid1_write_request(request_queue_t *q, int rw, struct buffer_head * bh)
{
	struct buffer_head *bh1;
	struct ataraid_bh_private *private;
	int device;
	int i;

	device = (bh->b_rdev >> SHIFT)&MAJOR_MASK;
	private = ataraid_get_private();
	if (private==NULL)
		BUG();

	private->parent = bh;
	
	atomic_set(&private->count,raid[device].disks);


	for (i = 0; i< raid[device].disks; i++) { 
		bh1=ataraid_get_bhead();
		/* If this ever fails we're doomed */
		if (!bh1)
			BUG();
	
		/* dupe the bufferhead and update the parts that need to be different */
		memcpy(bh1, bh, sizeof(*bh));
		
		bh1->b_end_io = ataraid_end_request;
		bh1->b_private = private;
		bh1->b_rsector += ataraid_gendisk.part[MINOR(bh->b_rdev)].start_sect; /* partition offset */
		bh1->b_rdev = raid[device].disk[i].device;

		/* update the last known head position for the drive */
		raid[device].disk[i].last_pos = bh1->b_rsector+(bh1->b_size>>9);

		generic_make_request(rw,bh1);
	}
	return 0;
}

static int pdcraid1_read_request (request_queue_t *q, int rw, struct buffer_head * bh)
{
	int device;
	int dist;
	int bestsofar,bestdist,i;
	static int previous;

	/* Reads are simple in principle. Pick a disk and go. 
	   Initially I cheat by just picking the one which the last known
	   head position is closest by.
	   Later on, online/offline checking and performance needs adding */
	
	device = (bh->b_rdev >> SHIFT)&MAJOR_MASK;
	bh->b_rsector += ataraid_gendisk.part[MINOR(bh->b_rdev)].start_sect;

	bestsofar = 0; 
	bestdist = raid[device].disk[0].last_pos - bh->b_rsector;
	if (bestdist<0) 
		bestdist=-bestdist;
	if (bestdist>4095)
		bestdist=4095;