LCOV - code coverage report
Current view: top level - lkbce/drivers/scsi - scsicam.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 0 86 0.0 %
Date: 2017-01-25 Functions: 0 4 0.0 %

          Line data    Source code
       1             : /*
       2             :  * scsicam.c - SCSI CAM support functions, use for HDIO_GETGEO, etc.
       3             :  *
       4             :  * Copyright 1993, 1994 Drew Eckhardt
       5             :  *      Visionary Computing 
       6             :  *      (Unix and Linux consulting and custom programming)
       7             :  *      drew@Colorado.EDU
       8             :  *      +1 (303) 786-7975
       9             :  *
      10             :  * For more information, please consult the SCSI-CAM draft.
      11             :  */
      12             : 
      13             : #include <linux/module.h>
      14             : #include <linux/fs.h>
      15             : #include <linux/genhd.h>
      16             : #include <linux/kernel.h>
      17             : #include <linux/blkdev.h>
      18             : #include <linux/buffer_head.h>
      19             : #include <asm/unaligned.h>
      20             : 
      21             : #include <scsi/scsicam.h>
      22             : 
      23             : 
      24             : static int setsize(unsigned long capacity, unsigned int *cyls, unsigned int *hds,
      25             :                    unsigned int *secs);
      26             : 
      27             : /**
      28             :  * scsi_bios_ptable - Read PC partition table out of first sector of device.
      29             :  * @dev: from this device
      30             :  *
      31             :  * Description: Reads the first sector from the device and returns %0x42 bytes
      32             :  *              starting at offset %0x1be.
      33             :  * Returns: partition table in kmalloc(GFP_KERNEL) memory, or NULL on error.
      34             :  */
      35             : unsigned char *scsi_bios_ptable(struct block_device *dev)
      36             : {
      37           0 :         unsigned char *res = kmalloc(66, GFP_KERNEL);
      38           0 :         if (res) {
      39           0 :                 struct block_device *bdev = dev->bd_contains;
      40           0 :                 Sector sect;
      41           0 :                 void *data = read_dev_sector(bdev, 0, &sect);
      42           0 :                 if (data) {
      43           0 :                         memcpy(res, data + 0x1be, 66);
      44           0 :                         put_dev_sector(sect);
      45             :                 } else {
      46           0 :                         kfree(res);
      47           0 :                         res = NULL;
      48             :                 }
      49             :         }
      50           0 :         return res;
      51             : }
      52             : EXPORT_SYMBOL(scsi_bios_ptable);
      53             : 
      54             : /**
      55             :  * scsicam_bios_param - Determine geometry of a disk in cylinders/heads/sectors.
      56             :  * @bdev: which device
      57             :  * @capacity: size of the disk in sectors
      58             :  * @ip: return value: ip[0]=heads, ip[1]=sectors, ip[2]=cylinders
      59             :  *
      60             :  * Description : determine the BIOS mapping/geometry used for a drive in a
      61             :  *      SCSI-CAM system, storing the results in ip as required
      62             :  *      by the HDIO_GETGEO ioctl().
      63             :  *
      64             :  * Returns : -1 on failure, 0 on success.
      65             :  */
      66             : 
      67             : int scsicam_bios_param(struct block_device *bdev, sector_t capacity, int *ip)
      68             : {
      69           0 :         unsigned char *p;
      70           0 :         u64 capacity64 = capacity;      /* Suppress gcc warning */
      71           0 :         int ret;
      72             : 
      73           0 :         p = scsi_bios_ptable(bdev);
      74           0 :         if (!p)
      75           0 :                 return -1;
      76             : 
      77             :         /* try to infer mapping from partition table */
      78           0 :         ret = scsi_partsize(p, (unsigned long)capacity, (unsigned int *)ip + 2,
      79             :                                (unsigned int *)ip + 0, (unsigned int *)ip + 1);
      80           0 :         kfree(p);
      81             : 
      82           0 :         if (ret == -1 && capacity64 < (1ULL << 32)) {
      83             :                 /* pick some standard mapping with at most 1024 cylinders,
      84             :                    and at most 62 sectors per track - this works up to
      85             :                    7905 MB */
      86           0 :                 ret = setsize((unsigned long)capacity, (unsigned int *)ip + 2,
      87             :                        (unsigned int *)ip + 0, (unsigned int *)ip + 1);
      88             :         }
      89             : 
      90             :         /* if something went wrong, then apparently we have to return
      91             :            a geometry with more than 1024 cylinders */
      92           0 :         if (ret || ip[0] > 255 || ip[1] > 63) {
      93           0 :                 if ((capacity >> 11) > 65534) {
      94           0 :                         ip[0] = 255;
      95           0 :                         ip[1] = 63;
      96             :                 } else {
      97           0 :                         ip[0] = 64;
      98           0 :                         ip[1] = 32;
      99             :                 }
     100             : 
     101           0 :                 if (capacity > 65535*63*255)
     102           0 :                         ip[2] = 65535;
     103             :                 else
     104           0 :                         ip[2] = (unsigned long)capacity / (ip[0] * ip[1]);
     105             :         }
     106             : 
     107           0 :         return 0;
     108             : }
     109             : EXPORT_SYMBOL(scsicam_bios_param);
     110             : 
     111             : /**
     112             :  * scsi_partsize - Parse cylinders/heads/sectors from PC partition table
     113             :  * @buf: partition table, see scsi_bios_ptable()
     114             :  * @capacity: size of the disk in sectors
     115             :  * @cyls: put cylinders here
     116             :  * @hds: put heads here
     117             :  * @secs: put sectors here
     118             :  *
     119             :  * Description: determine the BIOS mapping/geometry used to create the partition
     120             :  *      table, storing the results in *cyls, *hds, and *secs 
     121             :  *
     122             :  * Returns: -1 on failure, 0 on success.
     123             :  */
     124             : 
     125             : int scsi_partsize(unsigned char *buf, unsigned long capacity,
     126             :                unsigned int *cyls, unsigned int *hds, unsigned int *secs)
     127             : {
     128           0 :         struct partition *p = (struct partition *)buf, *largest = NULL;
     129           0 :         int i, largest_cyl;
     130           0 :         int cyl, ext_cyl, end_head, end_cyl, end_sector;
     131           0 :         unsigned int logical_end, physical_end, ext_physical_end;
     132           0 : 
     133           0 : 
     134           0 :         if (*(unsigned short *) (buf + 64) == 0xAA55) {
     135           0 :                 for (largest_cyl = -1, i = 0; i < 4; ++i, ++p) {
     136           0 :                         if (!p->sys_ind)
     137           0 :                                 continue;
     138           0 : #ifdef DEBUG
     139           0 :                         printk("scsicam_bios_param : partition %d has system \n",
     140           0 :                                i);
     141           0 : #endif
     142           0 :                         cyl = p->cyl + ((p->sector & 0xc0) << 2);
     143           0 :                         if (cyl > largest_cyl) {
     144           0 :                                 largest_cyl = cyl;
     145           0 :                                 largest = p;
     146             :                         }
     147             :                 }
     148             :         }
     149           0 :         if (largest) {
     150           0 :                 end_cyl = largest->end_cyl + ((largest->end_sector & 0xc0) << 2);
     151           0 :                 end_head = largest->end_head;
     152           0 :                 end_sector = largest->end_sector & 0x3f;
     153             : 
     154           0 :                 if (end_head + 1 == 0 || end_sector == 0)
     155           0 :                         return -1;
     156             : 
     157             : #ifdef DEBUG
     158             :                 printk("scsicam_bios_param : end at h = %d, c = %d, s = %d\n",
     159             :                        end_head, end_cyl, end_sector);
     160             : #endif
     161             : 
     162           0 :                 physical_end = end_cyl * (end_head + 1) * end_sector +
     163             :                     end_head * end_sector + end_sector;
     164             : 
     165             :                 /* This is the actual _sector_ number at the end */
     166           0 :                 logical_end = get_unaligned(&largest->start_sect)
     167             :                     + get_unaligned(&largest->nr_sects);
     168             : 
     169             :                 /* This is for >1023 cylinders */
     170           0 :                 ext_cyl = (logical_end - (end_head * end_sector + end_sector))
     171             :                     / (end_head + 1) / end_sector;
     172           0 :                 ext_physical_end = ext_cyl * (end_head + 1) * end_sector +
     173             :                     end_head * end_sector + end_sector;
     174             : 
     175             : #ifdef DEBUG
     176             :                 printk("scsicam_bios_param : logical_end=%d physical_end=%d ext_physical_end=%d ext_cyl=%d\n"
     177             :                   ,logical_end, physical_end, ext_physical_end, ext_cyl);
     178             : #endif
     179             : 
     180           0 :                 if ((logical_end == physical_end) ||
     181             :                   (end_cyl == 1023 && ext_physical_end == logical_end)) {
     182           0 :                         *secs = end_sector;
     183           0 :                         *hds = end_head + 1;
     184           0 :                         *cyls = capacity / ((end_head + 1) * end_sector);
     185           0 :                         return 0;
     186             :                 }
     187             : #ifdef DEBUG
     188             :                 printk("scsicam_bios_param : logical (%u) != physical (%u)\n",
     189             :                        logical_end, physical_end);
     190             : #endif
     191             :         }
     192           0 :         return -1;
     193             : }
     194             : EXPORT_SYMBOL(scsi_partsize);
     195             : 
     196             : /*
     197             :  * Function : static int setsize(unsigned long capacity,unsigned int *cyls,
     198             :  *      unsigned int *hds, unsigned int *secs);
     199             :  *
     200             :  * Purpose : to determine a near-optimal int 0x13 mapping for a
     201             :  *      SCSI disk in terms of lost space of size capacity, storing
     202             :  *      the results in *cyls, *hds, and *secs.
     203             :  *
     204             :  * Returns : -1 on failure, 0 on success.
     205             :  *
     206             :  * Extracted from
     207             :  *
     208             :  * WORKING                                                    X3T9.2
     209             :  * DRAFT                                                        792D
     210             :  * see http://www.t10.org/ftp/t10/drafts/cam/cam-r12b.pdf
     211             :  *
     212             :  *                                                        Revision 6
     213             :  *                                                         10-MAR-94
     214             :  * Information technology -
     215             :  * SCSI-2 Common access method
     216             :  * transport and SCSI interface module
     217             :  * 
     218             :  * ANNEX A :
     219             :  *
     220             :  * setsize() converts a read capacity value to int 13h
     221             :  * head-cylinder-sector requirements. It minimizes the value for
     222             :  * number of heads and maximizes the number of cylinders. This
     223             :  * will support rather large disks before the number of heads
     224             :  * will not fit in 4 bits (or 6 bits). This algorithm also
     225             :  * minimizes the number of sectors that will be unused at the end
     226             :  * of the disk while allowing for very large disks to be
     227             :  * accommodated. This algorithm does not use physical geometry. 
     228             :  */
     229             : 
     230             : static int setsize(unsigned long capacity, unsigned int *cyls, unsigned int *hds,
     231             :                    unsigned int *secs)
     232             : {
     233           0 :         unsigned int rv = 0;
     234           0 :         unsigned long heads, sectors, cylinders, temp;
     235           0 : 
     236           0 :         cylinders = 1024L;      /* Set number of cylinders to max */
     237           0 :         sectors = 62L;          /* Maximize sectors per track */
     238             : 
     239           0 :         temp = cylinders * sectors;     /* Compute divisor for heads */
     240           0 :         heads = capacity / temp;        /* Compute value for number of heads */
     241           0 :         if (capacity % temp) {  /* If no remainder, done! */
     242           0 :                 heads++;        /* Else, increment number of heads */
     243           0 :                 temp = cylinders * heads;       /* Compute divisor for sectors */
     244           0 :                 sectors = capacity / temp;      /* Compute value for sectors per
     245             :                                                    track */
     246           0 :                 if (capacity % temp) {  /* If no remainder, done! */
     247           0 :                         sectors++;      /* Else, increment number of sectors */
     248           0 :                         temp = heads * sectors;         /* Compute divisor for cylinders */
     249           0 :                         cylinders = capacity / temp;    /* Compute number of cylinders */
     250             :                 }
     251             :         }
     252           0 :         if (cylinders == 0)
     253           0 :                 rv = (unsigned) -1;     /* Give error if 0 cylinders */
     254             : 
     255           0 :         *cyls = (unsigned int) cylinders;       /* Stuff return values */
     256           0 :         *secs = (unsigned int) sectors;
     257           0 :         *hds = (unsigned int) heads;
     258           0 :         return (rv);
     259             : }

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