/*
?*??linux/kernel/arch/arm/drivers/block/fd1772.c
?*??based?on?ataflop.c?in?the?m68k?Linux
?*??Copyright?（C）?1993??Greg?Harp
?*??Atari?Support?by?Bjoern?Brauel?Roman?Hodek
?*??Archimedes?Support?by?Dave?Gilbert?（gilbertd@cs.man.ac.uk）
?*
?*??Big?cleanup?Sep?11..14?1994?Roman?Hodek:
?*???-?Driver?now?works?interrupt?driven
?*???-?Support?for?two?drives;?should?work?but?I?cannot?test?that?:-（
?*???-?Reading?is?done?in?whole?tracks?and?buffered?to?speed?up?things
?*???-?Disk?change?detection?and?drive?deselecting?after?motor-off
?*?????similar?to?TOS
?*???-?Autodetection?of?disk?format?（DD/HD）;?untested?yet?because?I
?*?????don‘t?have?an?HD?drive?:-（
?*
?*??Fixes?Nov?13?1994?Martin?Schaller:
?*???-?Autodetection?works?now
?*???-?Support?for?5?1/4“?disks
?*???-?Removed?drive?type?（unknown?on?atari）
?*???-?Do?seeks?with?8?Mhz
?*
?*??Changes?by?Andreas?Schwab:
?*???-?After?errors?in?multiple?read?mode?try?again?reading?single?sectors
?*??（Feb?1995）:
?*???-?Clean?up?error?handling
?*???-?Set?blk_size?for?proper?size?checking
?*???-?Initialize?track?register?when?testing?presence?of?floppy
?*???-?Implement?some?ioctl‘s
?*
?*??Changes?by?Torsten?Lang:
?*???-?When?probing?the?floppies?we?should?add?the?FDC1772CMDADD_H?flag?since
?*?????the?FDC1772?will?otherwise?wait?forever?when?no?disk?is?inserted...
?*
?*??Things?left?to?do:
?*???-?Formatting
?*???-?Maybe?a?better?strategy?for?disk?change?detection?（does?anyone
?*?????know?one?）
?*???-?There?are?some?strange?problems?left:?The?strangest?one?is
?*?????that?at?least?on?my?TT?（4+4MB）?the?first?2?Bytes?of?the?last
?*?????page?of?the?TT-Ram?（!）?change?their?contents?（some?bits?get
?*?????set）?while?a?floppy?DMA?is?going?on.?But?there?are?no?accesses
?*?????to?these?memory?locations?from?the?kernel...?（I?tested?that?by
?*?????making?the?page?read-only）.?I?cannot?explain?what‘s?going?on...
?*???-?Sometimes?the?drive-change-detection?stops?to?work.?The
?*?????function?is?still?called?but?the?WP?bit?always?reads?as?0...
?*?????Maybe?a?problem?with?the?status?reg?mode?or?a?timing?problem.
?*?????Note?10/12/94:?The?change?detection?now?seems?to?work?reliably.
?*?????There?is?no?proof?but?I‘ve?seen?no?hang?for?a?long?time...
?*
?*?ARCHIMEDES?changes:?（gilbertd@cs.man.ac.uk）
?*?????26/12/95?-?Changed?all?names?starting?with?FDC?to?FDC1772
?*????????????????Removed?all?references?to?clock?speed?of?FDC?-?we‘re?stuck?with?8MHz
?*????????????????Modified?disk_type?structure?to?remove?HD?formats
?*
?*??????7/?1/96?-?Wrote?FIQ?code?removed?most?remaining?atariisms
?*
?*?????13/?1/96?-?Well?I?think?its?read?a?single?sector;?but?there?is?a?problem
?*????????????????fd_rwsec_done?which?is?called?in?FIQ?mode?starts?another?transfer
?*????????????????off?（in?fd_rwsec）?while?still?in?FIQ?mode.??Because?its?still?in
?*????????????????FIQ?mode?it?can‘t?service?the?DMA?and?loses?data.?So?need?to
?*????????????????heavily?restructure.
?*?????14/?1/96?-?Found?that?the?definitions?of?the?register?numbers?of?the
?*??????????