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Diffstat (limited to 'linux/src/drivers/scsi/scsicam.c')
| -rw-r--r-- | linux/src/drivers/scsi/scsicam.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/linux/src/drivers/scsi/scsicam.c b/linux/src/drivers/scsi/scsicam.c new file mode 100644 index 0000000..2c6f637 --- /dev/null +++ b/linux/src/drivers/scsi/scsicam.c @@ -0,0 +1,230 @@ +/* + * scsicam.c - SCSI CAM support functions, use for HDIO_GETGEO, etc. + * + * Copyright 1993, 1994 Drew Eckhardt + * Visionary Computing + * (Unix and Linux consulting and custom programming) + * drew@Colorado.EDU + * +1 (303) 786-7975 + * + * For more information, please consult the SCSI-CAM draft. + */ + +/* + * Don't import our own symbols, as this would severely mess up our + * symbol tables. + */ +#define _SCSI_SYMS_VER_ +#define __NO_VERSION__ +#include <linux/module.h> + +#include <linux/fs.h> +#include <linux/genhd.h> +#include <linux/kernel.h> +#include <linux/blk.h> +#include <asm/unaligned.h> +#include "scsi.h" +#include "hosts.h" +#include "sd.h" + +static int partsize(struct buffer_head *bh, unsigned long capacity, + unsigned int *cyls, unsigned int *hds, unsigned int *secs); +static int setsize(unsigned long capacity,unsigned int *cyls,unsigned int *hds, + unsigned int *secs); + +/* + * Function : int scsicam_bios_param (Disk *disk, int dev, int *ip) + * + * Purpose : to determine the BIOS mapping used for a drive in a + * SCSI-CAM system, storing the results in ip as required + * by the HDIO_GETGEO ioctl(). + * + * Returns : -1 on failure, 0 on success. + * + */ + +int scsicam_bios_param (Disk *disk, /* SCSI disk */ + kdev_t dev, /* Device major, minor */ + int *ip /* Heads, sectors, cylinders in that order */) { + + struct buffer_head *bh; + int ret_code; + int size = disk->capacity; + unsigned long temp_cyl; + + if (!(bh = bread(MKDEV(MAJOR(dev), MINOR(dev)&~0xf), 0, 1024))) + return -1; + + /* try to infer mapping from partition table */ + ret_code = partsize (bh, (unsigned long) size, (unsigned int *) ip + 2, + (unsigned int *) ip + 0, (unsigned int *) ip + 1); + brelse (bh); + + if (ret_code == -1) { + /* pick some standard mapping with at most 1024 cylinders, + and at most 62 sectors per track - this works up to + 7905 MB */ + ret_code = setsize ((unsigned long) size, (unsigned int *) ip + 2, + (unsigned int *) ip + 0, (unsigned int *) ip + 1); + } + + /* if something went wrong, then apparently we have to return + a geometry with more than 1024 cylinders */ + if (ret_code || ip[0] > 255 || ip[1] > 63) { + ip[0] = 64; + ip[1] = 32; + temp_cyl = size / (ip[0] * ip[1]); + if (temp_cyl > 65534) { + ip[0] = 255; + ip[1] = 63; + } + ip[2] = size / (ip[0] * ip[1]); + } + + return 0; +} + +/* + * Function : static int partsize(struct buffer_head *bh, unsigned long + * capacity,unsigned int *cyls, unsigned int *hds, unsigned int *secs); + * + * Purpose : to determine the BIOS mapping used to create the partition + * table, storing the results in *cyls, *hds, and *secs + * + * Returns : -1 on failure, 0 on success. + * + */ + +static int partsize(struct buffer_head *bh, unsigned long capacity, + unsigned int *cyls, unsigned int *hds, unsigned int *secs) { + struct partition *p, *largest = NULL; + int i, largest_cyl; + int cyl, ext_cyl, end_head, end_cyl, end_sector; + unsigned int logical_end, physical_end, ext_physical_end; + + + if (*(unsigned short *) (bh->b_data+510) == 0xAA55) { + for (largest_cyl = -1, p = (struct partition *) + (0x1BE + bh->b_data), i = 0; i < 4; ++i, ++p) { + if (!p->sys_ind) + continue; +#ifdef DEBUG + printk ("scsicam_bios_param : partition %d has system \n", + i); +#endif + cyl = p->cyl + ((p->sector & 0xc0) << 2); + if (cyl > largest_cyl) { + largest_cyl = cyl; + largest = p; + } + } + } + + if (largest) { + end_cyl = largest->end_cyl + ((largest->end_sector & 0xc0) << 2); + end_head = largest->end_head; + end_sector = largest->end_sector & 0x3f; + + if( end_head + 1 == 0 || end_sector == 0 ) return -1; + +#ifdef DEBUG + printk ("scsicam_bios_param : end at h = %d, c = %d, s = %d\n", + end_head, end_cyl, end_sector); +#endif + + physical_end = end_cyl * (end_head + 1) * end_sector + + end_head * end_sector + end_sector; + + /* This is the actual _sector_ number at the end */ + logical_end = get_unaligned(&largest->start_sect) + + get_unaligned(&largest->nr_sects); + + /* This is for >1023 cylinders */ + ext_cyl= (logical_end-(end_head * end_sector + end_sector)) + /(end_head + 1) / end_sector; + ext_physical_end = ext_cyl * (end_head + 1) * end_sector + + end_head * end_sector + end_sector; + +#ifdef DEBUG + printk("scsicam_bios_param : logical_end=%d physical_end=%d ext_physical_end=%d ext_cyl=%d\n" + ,logical_end,physical_end,ext_physical_end,ext_cyl); +#endif + + if ((logical_end == physical_end) || + (end_cyl==1023 && ext_physical_end==logical_end)) { + *secs = end_sector; + *hds = end_head + 1; + *cyls = capacity / ((end_head + 1) * end_sector); + return 0; + } + +#ifdef DEBUG + printk ("scsicam_bios_param : logical (%u) != physical (%u)\n", + logical_end, physical_end); +#endif + } + return -1; +} + +/* + * Function : static int setsize(unsigned long capacity,unsigned int *cyls, + * unsigned int *hds, unsigned int *secs); + * + * Purpose : to determine a near-optimal int 0x13 mapping for a + * SCSI disk in terms of lost space of size capacity, storing + * the results in *cyls, *hds, and *secs. + * + * Returns : -1 on failure, 0 on success. + * + * Extracted from + * + * WORKING X3T9.2 + * DRAFT 792D + * + * + * Revision 6 + * 10-MAR-94 + * Information technology - + * SCSI-2 Common access method + * transport and SCSI interface module + * + * ANNEX A : + * + * setsize() converts a read capacity value to int 13h + * head-cylinder-sector requirements. It minimizes the value for + * number of heads and maximizes the number of cylinders. This + * will support rather large disks before the number of heads + * will not fit in 4 bits (or 6 bits). This algorithm also + * minimizes the number of sectors that will be unused at the end + * of the disk while allowing for very large disks to be + * accommodated. This algorithm does not use physical geometry. + */ + +static int setsize(unsigned long capacity,unsigned int *cyls,unsigned int *hds, + unsigned int *secs) { + unsigned int rv = 0; + unsigned long heads, sectors, cylinders, temp; + + cylinders = 1024L; /* Set number of cylinders to max */ + sectors = 62L; /* Maximize sectors per track */ + + temp = cylinders * sectors; /* Compute divisor for heads */ + heads = capacity / temp; /* Compute value for number of heads */ + if (capacity % temp) { /* If no remainder, done! */ + heads++; /* Else, increment number of heads */ + temp = cylinders * heads; /* Compute divisor for sectors */ + sectors = capacity / temp; /* Compute value for sectors per + track */ + if (capacity % temp) { /* If no remainder, done! */ + sectors++; /* Else, increment number of sectors */ + temp = heads * sectors; /* Compute divisor for cylinders */ + cylinders = capacity / temp;/* Compute number of cylinders */ + } + } + if (cylinders == 0) rv=(unsigned)-1;/* Give error if 0 cylinders */ + + *cyls = (unsigned int) cylinders; /* Stuff return values */ + *secs = (unsigned int) sectors; + *hds = (unsigned int) heads; + return(rv); +} |