\ *****************************************************************************
\ * Copyright (c) 2004, 2008 IBM Corporation
\ * All rights reserved.
\ * This program and the accompanying materials
\ * are made available under the terms of the BSD License
\ * which accompanies this distribution, and is available at
\ * http://www.opensource.org/licenses/bsd-license.php
\ *
\ * Contributors:
\ *     IBM Corporation - initial implementation
\ ****************************************************************************/


\ Set debug-disk-label? to true to get debug messages for the disk-label code.
false VALUE debug-disk-label?

\ This value defines the maximum number of blocks (512b) to load from a PREP
\ partition. This is required to keep the load time in reasonable limits if the
\ PREP partition becomes big.
\ If we ever want to put a large kernel with initramfs from a PREP partition
\ we might need to increase this value. The default value is 16384 blocks (8MB)
d# 16384 value max-prep-partition-blocks

s" disk-label" device-name

0 INSTANCE VALUE partition
0 INSTANCE VALUE part-offset

0 INSTANCE VALUE part-start
0 INSTANCE VALUE lpart-start
0 INSTANCE VALUE part-size
0 INSTANCE VALUE dos-logical-partitions

0 INSTANCE VALUE block-size
0 INSTANCE VALUE block

0 INSTANCE VALUE args
0 INSTANCE VALUE args-len


INSTANCE VARIABLE block#  \ variable to store logical sector#
INSTANCE VARIABLE hit#    \ partition counter
INSTANCE VARIABLE success-flag

\ ISO9660 specific information
0ff constant END-OF-DESC
3 constant  PARTITION-ID
48 constant VOL-PART-LOC


\ DOS partition label (MBR) specific structures

STRUCT
       1b8 field mbr>boot-loader
        /l field mbr>disk-signature
        /w field mbr>null
        40 field mbr>partition-table
        /w field mbr>magic

CONSTANT /mbr

STRUCT
        /c field part-entry>active
        /c field part-entry>start-head
        /c field part-entry>start-sect
        /c field part-entry>start-cyl
        /c field part-entry>id
        /c field part-entry>end-head
        /c field part-entry>end-sect
        /c field part-entry>end-cyl
        /l field part-entry>sector-offset
        /l field part-entry>sector-count

CONSTANT /partition-entry


\ Defined by IEEE 1275-1994 (3.8.1)

: offset ( d.rel -- d.abs )
   part-offset xlsplit d+
;

: seek  ( pos.lo pos.hi -- status )
   offset
   debug-disk-label? IF 2dup ." seek-parent: pos.hi=0x" u. ." pos.lo=0x" u. THEN
   s" seek" $call-parent
   debug-disk-label? IF dup ." status=" . cr THEN
;

: read ( addr len -- actual )
   debug-disk-label? IF 2dup swap ." read-parent: addr=0x" u. ." len=" .d THEN
   s" read" $call-parent
   debug-disk-label? IF dup ." actual=" .d cr THEN
;


\ read sector to array "block"
: read-sector ( sector-number -- )
   \ block-size is 0x200 on disks, 0x800 on cdrom drives
   block-size * 0 seek drop      \ seek to sector
   block block-size read drop    \ read sector
;

: (.part-entry) ( part-entry )
   cr ." part-entry>active:        " dup part-entry>active c@ .d
   cr ." part-entry>start-head:    " dup part-entry>start-head c@ .d
   cr ." part-entry>start-sect:    " dup part-entry>start-sect c@ .d
   cr ." part-entry>start-cyl:     " dup part-entry>start-cyl  c@ .d
   cr ." part-entry>id:            " dup part-entry>id c@ .d
   cr ." part-entry>end-head:      " dup part-entry>end-head c@ .d
   cr ." part-entry>end-sect:      " dup part-entry>end-sect c@ .d
   cr ." part-entry>end-cyl:       " dup part-entry>end-cyl c@ .d
   cr ." part-entry>sector-offset: " dup part-entry>sector-offset l@-le .d
   cr ." part-entry>sector-count:  " dup part-entry>sector-count l@-le .d
   cr
;

: (.name) r@ begin cell - dup @ <colon> = UNTIL xt>name cr type space ;

: init-block ( -- )
   s" block-size" ['] $call-parent CATCH IF ABORT" parent has no block-size." THEN
   to block-size
   d# 2048 alloc-mem
   dup d# 2048 erase
   to block
   debug-disk-label? IF
      ." init-block: block-size=" block-size .d ." block=0x" block u. cr
   THEN
;


\ This word returns true if the currently loaded block has _NO_ MBR magic
: no-mbr? ( -- true|false )
   0 read-sector block mbr>magic w@-le aa55 <>
;

: pc-extended-partition? ( part-entry-addr -- true|false )
   part-entry>id c@      ( id )
   dup 5 = swap          ( true|false id )
   dup f = swap          ( true|false true|false id )
   85 =                  ( true|false true|false true|false )
   or or                 ( true|false )
;

: partition>part-entry ( partition -- part-entry )
   1- /partition-entry * block mbr>partition-table +
;

: partition>start-sector ( partition -- sector-offset )
   partition>part-entry part-entry>sector-offset l@-le
;

: count-dos-logical-partitions ( -- #logical-partitions )
   no-mbr? IF 0 EXIT THEN
   0 5 1 DO                                ( current )
      i partition>part-entry               ( current part-entry )
      dup pc-extended-partition? IF
         part-entry>sector-offset l@-le    ( current sector )
         dup to part-start to lpart-start  ( current )
         BEGIN
            part-start read-sector          \ read EBR
            1 partition>start-sector IF
               \ ." Logical Partition found at " part-start .d cr
               1+
            THEN \ another logical partition
            2 partition>start-sector
            ( current relative-sector )
            ?dup IF lpart-start + to part-start false ELSE true THEN
         UNTIL
      ELSE
         drop
      THEN
   LOOP
;

: (get-dos-partition-params) ( ext-part-start part-entry -- offset count active? id )
   dup part-entry>sector-offset l@-le rot + swap ( offset part-entry )
   dup part-entry>sector-count l@-le swap        ( offset count part-entry )
   dup part-entry>active c@ 80 = swap            ( offset count active? part-entry )
   part-entry>id c@                              ( offset count active? id )
;

: find-dos-partition ( partition# -- false | offset count active? id true )
   to partition 0 to part-start 0 to part-offset

   \ no negative partitions
   partition 0<= IF 0 to partition false EXIT THEN

   \ load MBR and check it
   no-mbr? IF 0 to partition false EXIT THEN

   partition 4 <= IF \ Is this a primary partition?
      0 partition partition>part-entry
      (get-dos-partition-params)
      \ FIXME sanity checks?
      true EXIT
   ELSE
      partition 4 - 0 5 1 DO                      ( logical-partition current )
         i partition>part-entry                   ( log-part current part-entry )
         dup pc-extended-partition? IF
            part-entry>sector-offset l@-le        ( log-part current sector )
            dup to part-start to lpart-start      ( log-part current )
            BEGIN
               part-start read-sector             \ read EBR
               1 partition>start-sector IF        \ first partition entry
                  1+ 2dup = IF                    ( log-part current )
                     2drop
                     part-start 1 partition>part-entry
                     (get-dos-partition-params)
                     true UNLOOP EXIT
                  THEN
                  2 partition>start-sector
                  ( log-part current relative-sector )

                  ?dup IF lpart-start + to part-start false ELSE true THEN
               ELSE
                  true
               THEN
            UNTIL
         ELSE
            drop
         THEN
      LOOP
      2drop false
   THEN
;

: try-dos-partition ( -- okay? )
   \ Read partition table and check magic.
   no-mbr? IF cr ." No DOS disk-label found." cr false EXIT THEN

   count-dos-logical-partitions TO dos-logical-partitions

   debug-disk-label? IF
      ." Found " dos-logical-partitions .d ." logical partitions" cr
      ." Partition = " partition .d cr
   THEN

   partition 1 5 dos-logical-partitions +
   within 0= IF
      cr ." Partition # not 1-" 4 dos-logical-partitions + . cr false EXIT
   THEN

   \ Could/should check for valid partition here...  the magic is not enough really.

   \ Get the partition offset.

   partition find-dos-partition IF
     ( offset count active? id )
     2drop drop
     block-size * to part-offset
     true
   ELSE
     false
   THEN
;

\ Check for an ISO-9660 filesystem on the disk
\ : try-iso9660-partition ( -- true|false )
\ implement me if you can ;-)
\ ;


\ Check for an ISO-9660 filesystem on the disk
\ (cf. CHRP IEEE 1275 spec., chapter 11.1.2.3)
: has-iso9660-filesystem  ( -- TRUE|FALSE )
   \ Seek to the begining of logical 2048-byte sector 16
   \ refer to Chapter C.11.1 in PAPR 2.0 Spec
   \ was: 10 read-sector, but this might cause trouble if you
   \ try booting an ISO image from a device with 512b sectors.
   10 800 * 0 seek drop      \ seek to sector
   block 800 read drop       \ read sector
   \ Check for CD-ROM volume magic:
   block c@ 1 =
   block 1+ 5 s" CD001"  str=
   and
   dup IF 800 to block-size THEN
;


\ Load from first active DOS boot partition.

\ NOTE: block-size is always 512 bytes for DOS partition tables.

: load-from-dos-boot-partition ( addr -- size )
   no-mbr? IF FALSE EXIT THEN  \ read MBR and check for DOS disk-label magic

   count-dos-logical-partitions TO dos-logical-partitions

   debug-disk-label? IF
      ." Found " dos-logical-partitions .d ." logical partitions" cr
      ." Partition = " partition .d cr
   THEN

   \ Now walk through the partitions:
   5 dos-logical-partitions + 1 DO
      \ ." checking partition " i .
      i find-dos-partition IF        ( addr offset count active? id )
         41 = and                    ( addr offset count prep-boot-part? )
         IF                          ( addr offset count )
            max-prep-partition-blocks min  \ reduce load size
            swap                     ( addr count offset )
            block-size * to part-offset
            0 0 seek drop            ( addr offset )
            block-size * read        ( size )
            UNLOOP EXIT
         ELSE
            2drop                    ( addr )
         THEN
      THEN
   LOOP
   drop 0
;


\ load from a bootable partition

: load-from-boot-partition ( addr -- size )
   load-from-dos-boot-partition
   \ More boot partition formats ...
;


\ Extract the boot loader path from a bootinfo.txt file
\ In: address and length of buffer where the bootinfo.txt has been loaded to.
\ Out: string address and length of the boot loader (within the input buffer)
\      or a string with length = 0 when parsing failed.

\ Here is a sample bootinfo file:
\ <chrp-boot>
\   <description>Linux Distribution</description>
\   <os-name>Linux</os-name>
\   <boot-script>boot &device;:1,\boot\yaboot.ibm</boot-script>
\   <icon size=64,64 color-space=3,3,2>
\     <bitmap>[..]</bitmap>
\   </icon>
\ </chrp-boot>

: parse-bootinfo-txt  ( addr len -- str len )
   2dup s" <boot-script>" find-substr       ( addr len pos1 )
   2dup = IF
      \ String not found
      3drop 0 0 EXIT
   THEN
   dup >r - swap r> + swap                  ( addr1 len1 )
   2dup [char] \ findchar drop              ( addr1 len1 pos2 )
   dup >r - swap r> + swap                  ( addr2 len2 )
   2dup s" </boot-script>" find-substr nip  ( addr2 len3 )
;

\ Try to load \ppc\bootinfo.txt from the disk (used mainly on CD-ROMs), and if
\ available, get the boot loader path from this file and load it.
\ See the "CHRP system binding to IEEE 1275" specification for more information
\ about bootinfo.txt. An example file can be found in the comment of
\ parse-bootinfo-txt ( addr len -- str len )

: load-chrp-boot-file ( addr -- size )
   \ Create bootinfo.txt path name and load that file:
   my-self parent ihandle>phandle node>path
   s" :\ppc\bootinfo.txt" $cat strdup       ( addr str len )
   open-dev dup 0= IF 2drop 0 EXIT THEN
   >r dup                                   ( addr addr R:ihandle )
   dup s" load" r@ $call-method             ( addr addr size R:ihandle )
   r> close-dev                             ( addr addr size )

   \ Now parse the information from bootinfo.txt:
   parse-bootinfo-txt                       ( addr fnstr fnlen )
   dup 0= IF 3drop 0 EXIT THEN
   \ Create the full path to the boot loader:
   my-self parent ihandle>phandle node>path ( addr fnstr fnlen nstr nlen )
   s" :" $cat 2swap $cat strdup             ( addr str len )
   \ Update the bootpath:
   2dup encode-string s" bootpath" set-chosen
   \ And finally load the boot loader itself:
   open-dev dup 0= IF ." failed to load CHRP boot loader." 2drop 0 EXIT THEN
   >r s" load" r@ $call-method              ( size R:ihandle )
   r> close-dev                             ( size )
;

\ parse partition number from my-args

\ my-args has the following format
\ [<partition>[,<path>]]

\ | example my-args  | example boot command      |
\ +------------------+---------------------------+
\ | 1,\boot\vmlinuz  | boot disk:1,\boot\vmlinuz |
\ | 2                | boot disk:2               |

\ 0 means the whole disk, this is the same behavior
\ as if no partition is specified (yaboot wants this).

: parse-partition ( -- okay? )
   0 to partition
   0 to part-offset

   my-args to args-len to args

   \ Fix up the "0" thing yaboot does.
   args-len 1 = IF args c@ [char] 0 = IF 0 to args-len THEN THEN

   \ Check for "full disk" arguments.
   my-args [char] , findchar 0= IF true EXIT THEN drop \ no comma
   my-args [char] , split to args-len to args
   dup 0= IF 2drop true EXIT THEN \ no first argument

   \ Check partition #.
   base @ >r decimal $number r> base !
   IF cr ." Not a partition #" false EXIT THEN

   \ Store part #, done.
   to partition
   true
;


\ try-files and try-partitions

: (interpose-filesystem) ( str len -- )
   find-package IF args args-len rot interpose THEN
;

: try-dos-files ( -- found? )
   no-mbr? IF false EXIT THEN

   \ block 0 byte 0-2 is a jump instruction in all FAT
   \ filesystems.
   \ e9 and eb are jump instructions in x86 assembler.
   block c@ e9 <> IF
      block c@ eb <>
      block 2+ c@ 90 <> or
      IF false EXIT THEN
   THEN
   s" fat-files" (interpose-filesystem)
   true
;

: try-ext2-files ( -- found? )
   2 read-sector               \ read first superblock
   block d# 56 + w@-le         \ fetch s_magic
   ef53 <> IF false EXIT THEN  \ s_magic found?
   s" ext2-files" (interpose-filesystem)
   true
;


: try-iso9660-files
   has-iso9660-filesystem 0= IF false exit THEN
   s" iso-9660" (interpose-filesystem)
   true
;

: try-files ( -- found? )
   \ If no path, then full disk.
   args-len 0= IF true EXIT THEN

   try-dos-files IF true EXIT THEN
   try-ext2-files IF true EXIT THEN
   try-iso9660-files IF true EXIT THEN

   \ ... more filesystem types here ...

   false
;

: try-partitions ( -- found? )
   try-dos-partition IF try-files EXIT THEN
   \ try-iso9660-partition IF try-files EXIT THEN
   \ ... more partition types here...
   false
;

\ Interface functions for disk-label package
\ as defined by IEEE 1275-1994 3.8.1

: close ( -- )
   debug-disk-label? IF ." Closing disk-label: block=0x" block u. ." block-size=" block-size .d cr THEN
   block d# 2048 free-mem
;


: open ( -- true|false )
   init-block

   parse-partition 0= IF
      close
      false EXIT
   THEN

   partition IF
       try-partitions
   ELSE
       try-files
   THEN
   dup 0= IF debug-disk-label? IF ." not found." cr THEN close THEN \ free memory again
;


\ Boot & Load w/o arguments is assumed to be boot from boot partition

: load ( addr -- size )
   debug-disk-label? IF
      ." load: " dup u. cr
   THEN

   args-len IF
      TRUE ABORT" Load done w/o filesystem"
   ELSE
      partition IF
         0 0 seek drop
         max-prep-partition-blocks 200 *  read
      ELSE
         has-iso9660-filesystem IF
             dup load-chrp-boot-file ?dup 0 > IF nip EXIT THEN
         THEN
         load-from-boot-partition
         dup 0= ABORT" No boot partition found"
      THEN
   THEN
;