• Michael Karcher's avatar
    Refine support for the JEDEC Software Data Protection · 972cec28
    Michael Karcher authored
    
    This patch removes the extremely dangerous unprotect_jedec function
    which is not used at all within flashrom code, and renames the
    misleadingly named protect_jedec function to start_program_jedec.
    
    Calls to protect_jedec after flashing are removed, because a) on LPC
    chips, the command sent by protoct_jedec is not even in the datasheet
    and b) on parallel chips, the block write command issued before already
    contained the software protection sequence, so software protection is
    definitely enabled.
    
    This patch also removes two clones of protect_jedec
    
    Background: JEDEC Software Data Protection started as an optional
    feature, which was disabled on the first single-voltage-flash chips.
    The software data protection is the need to prefix a write with a magic
    "write enable" command, while without write protection every write
    access into the chip's address space modifies flash content. This magic
    write enable command also tells the flash chip that the programmer
    obviously support sending write-enable commands and turns off the "any
    write modifies flash content" mode. There also exist a two-command (6
    writes) sequence that disables Software Data Protection completey, which
    should only ever be used to prepare updating with a device that can't
    handle software data protection.
    
    Corresponding to flashrom svn r783.
    Signed-off-by: default avatarMichael Karcher <flashrom@mkarcher.dialup.fu-berlin.de>
    Acked-by: default avatarSean Nelson <audiohacked@gmail.com>
    Acked-by: default avatarCarl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
    972cec28
82802ab.c 5.07 KB