pdcraid.c

ep9315平台下硬盘驱动的源码

	for (i=1 ; i<raid[device].disks; i++) {
		dist = raid[device].disk[i].last_pos - bh->b_rsector;
		if (dist<0) 
			dist = -dist;
		if (dist>4095)
			dist=4095;
		
		if (bestdist==dist) {  /* it's a tie; try to do some read balancing */
			if ((previous>bestsofar)&&(previous<=i))  
				bestsofar = i;
			previous = (previous + 1) % raid[device].disks;
		} else if (bestdist>dist) {
			bestdist = dist;
			bestsofar = i;
		}
	
	}
	
	bh->b_rdev = raid[device].disk[bestsofar].device; 
	raid[device].disk[bestsofar].last_pos = bh->b_rsector+(bh->b_size>>9);

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


static int pdcraid1_make_request (request_queue_t *q, int rw, struct buffer_head * bh)
{
	/* Read and Write are totally different cases; split them totally here */
	if (rw==READA)
		rw = READ;
	
	if (rw==READ)
		return pdcraid1_read_request(q,rw,bh);
	else
		return pdcraid1_write_request(q,rw,bh);
}

#include "pdcraid.h"

static unsigned long calc_pdcblock_offset (int major,int minor)
{
	unsigned long lba = 0;
	kdev_t dev;
	ide_drive_t *ideinfo;
	
	dev = MKDEV(major,minor);
	ideinfo = get_info_ptr (dev);
	if (ideinfo==NULL)
		return 0;
	
	
	/* first sector of the last cluster */
	if (ideinfo->head==0) 
		return 0;
	if (ideinfo->sect==0)
		return 0;
	lba = (ideinfo->capacity / (ideinfo->head*ideinfo->sect));
	lba = lba * (ideinfo->head*ideinfo->sect);
	lba = lba - ideinfo->sect;

	return lba;
}


static int read_disk_sb (int major, int minor, unsigned char *buffer,int bufsize)
{
	int ret = -EINVAL;
	struct buffer_head *bh = NULL;
	kdev_t dev = MKDEV(major,minor);
	unsigned long sb_offset;

	if (blksize_size[major]==NULL)   /* device doesn't exist */
		return -EINVAL;
                       
	
	/*
	 * Calculate the position of the superblock,
	 * it's at first sector of the last cylinder
	 */
	sb_offset = calc_pdcblock_offset(major,minor)/8;
	/* The /8 transforms sectors into 4Kb blocks */

	if (sb_offset==0)
		return -1;	
	
	set_blocksize (dev, 4096);

	bh = bread (dev, sb_offset, 4096);
	
	if (bh) {
		memcpy (buffer, bh->b_data, bufsize);
	} else {
		printk(KERN_ERR "pdcraid: Error reading superblock.\n");
		goto abort;
	}
	ret = 0;
abort:
	if (bh)
		brelse (bh);
	return ret;
}

static unsigned int calc_sb_csum (unsigned int* ptr)
{	
	unsigned int sum;
	int count;
	
	sum = 0;
	for (count=0;count<511;count++)
		sum += *ptr++;
	
	return sum;
}

static int cookie = 0;

static void __init probedisk(int devindex,int device, int raidlevel)
{
	int i;
	int major, minor;
        struct promise_raid_conf *prom;
	static unsigned char block[4096];
	struct block_device *bdev;

	if (devlist[devindex].device!=-1) /* already assigned to another array */
		return;
	
	major = devlist[devindex].major;
	minor = devlist[devindex].minor; 

        if (read_disk_sb(major,minor,(unsigned char*)&block,sizeof(block)))
        	return;
                                                                                                                 
        prom = (struct promise_raid_conf*)&block[512];

        /* the checksums must match */
	if (prom->checksum != calc_sb_csum((unsigned int*)prom))
		return;
	if (prom->raid.type!=raidlevel) /* different raidlevel */
		return;

	if ((cookie!=0) && (cookie != prom->raid.magic_1)) /* different array */
		return;
	
	cookie = prom->raid.magic_1;

	/* This looks evil. But basically, we have to search for our adapternumber
	   in the arraydefinition, both of which are in the superblock */	
        for (i=0;(i<prom->raid.total_disks)&&(i<8);i++) {
        	if ( (prom->raid.disk[i].channel== prom->raid.channel) &&
        	     (prom->raid.disk[i].device == prom->raid.device) ) {

        	        bdev = bdget(MKDEV(major,minor));
        	        if (bdev && blkdev_get(bdev, FMODE_READ|FMODE_WRITE, 0, BDEV_RAW) == 0) {
				raid[device].disk[i].bdev = bdev;
			}
			raid[device].disk[i].device = MKDEV(major,minor);
			raid[device].disk[i].sectors = prom->raid.disk_secs;
			raid[device].stride = (1<<prom->raid.raid0_shift);
			raid[device].disks = prom->raid.total_disks;
			raid[device].sectors = prom->raid.total_secs;
			raid[device].geom.heads = prom->raid.heads+1;
			raid[device].geom.sectors = prom->raid.sectors;
			raid[device].geom.cylinders = prom->raid.cylinders+1;
			devlist[devindex].device=device;
        	     }
        }
	               
}

static void __init fill_cutoff(int device)
{
	int i,j;
	unsigned long smallest;
	unsigned long bar;
	int count;
	
	bar = 0;
	for (i=0;i<8;i++) {
		smallest = ~0;
		for (j=0;j<8;j++) 
			if ((raid[device].disk[j].sectors < smallest) && (raid[device].disk[j].sectors>bar))
				smallest = raid[device].disk[j].sectors;
		count = 0;
		for (j=0;j<8;j++) 
			if (raid[device].disk[j].sectors >= smallest)
				count++;
				
		smallest = smallest * count;
		bar = smallest;
		raid[device].cutoff[i] = smallest;
		raid[device].cutoff_disks[i] = count;
	}
}
			   
static __init int pdcraid_init_one(int device,int raidlevel)
{
	int i, count;

	for (i=0; i<14; i++)
		probedisk(i, device, raidlevel);
	
	if (raidlevel==0)
		fill_cutoff(device);
	
	/* Initialize the gendisk structure */
	
	ataraid_register_disk(device,raid[device].sectors);        
		
	count=0;
	
	for (i=0;i<8;i++) {
		if (raid[device].disk[i].device!=0) {
			printk(KERN_INFO "Drive %i is %li Mb (%i / %i) \n",
				i,raid[device].disk[i].sectors/2048,MAJOR(raid[device].disk[i].device),MINOR(raid[device].disk[i].device));
			count++;
		}
	}
	if (count) {
		printk(KERN_INFO "Raid%i array consists of %i drives. \n",raidlevel,count);
		return 0;
	} else {
		return -ENODEV;
	}
}

static __init int pdcraid_init(void)
{
	int retval, device, count = 0;

	do {
		cookie = 0;
		device=ataraid_get_device(&pdcraid0_ops);
		if (device<0)
			break;
		retval = pdcraid_init_one(device,0);
		if (retval) {
			ataraid_release_device(device);
			break;
		} else {
			count++;
		}
	} while (1);

	do {
	
		cookie = 0;
		device=ataraid_get_device(&pdcraid1_ops);
		if (device<0)
			break;
		retval = pdcraid_init_one(device,1);
		if (retval) {
			ataraid_release_device(device);
			break;
		} else {
			count++;
		}
	} while (1);

	if (count) {
		printk(KERN_INFO "Promise Fasttrak(tm) Softwareraid driver for linux version 0.03beta\n");
		return 0;
	}
	printk(KERN_DEBUG "Promise Fasttrak(tm) Softwareraid driver 0.03beta: No raid array found\n");
	return -ENODEV;
}

static void __exit pdcraid_exit (void)
{
	int i,device;
	for (device = 0; device<16; device++) {
		for (i=0;i<8;i++) {
			struct block_device *bdev = raid[device].disk[i].bdev;
			raid[device].disk[i].bdev = NULL;
			if (bdev)
				blkdev_put(bdev, BDEV_RAW);
		}	
		if (raid[device].sectors)
			ataraid_release_device(device);
	}
}

static int pdcraid_open(struct inode * inode, struct file * filp) 
{
	MOD_INC_USE_COUNT;
	return 0;
}
static int pdcraid_release(struct inode * inode, struct file * filp)
{	
	MOD_DEC_USE_COUNT;
	return 0;
}

module_init(pdcraid_init);
module_exit(pdcraid_exit);
MODULE_LICENSE("GPL");