• Paul Gortmaker's avatar
    sbc8548: relocate 64MB user flash to sane boundary · 3fd673cf
    Paul Gortmaker authored
    The current situation has the 64MB user flash at an awkward
    alignment; shifted back from 0xfc00_0000 by 8M, to leave an 8MB hole
    for the soldered on boot flash @ EOM.  But to switch to optionally
    supporting booting off the 64MB flash, the 64MB will then be mapped
    at the sane address of 0xfc00_0000.
    
    This leads to awkward things when programming the 64MB flash prior
    to transitioning to it -- i.e. even though the chip spans from
    0xfb80_0000 to 0xff7f_ffff, you would have to program a u-boot image
    into the two sectors from 0xfbf0_0000 --> 0xfbff_ffff so that it was
    in the right place when JP12/SW2.8 were switched to make the 64MB on
    /CS0. (i.e. the chip is only looking at the bits in mask 0x3ff_ffff)
    
    We also have to have three TLB entries responsible for dealing with
    mapping the 64MB flash due to this 8MB of misalignment.
    
    In the end, there is address space from 0xec00_0000 to 0xefff_ffff
    where we can map it, and then the transition from booting from one
    config to the other will be a simple 0xec --> 0xfc mapping.  Plus we
    can toss out a TLB entry.
    
    Note that TLB0 is kept at 64MB and not shrunk down to the 8MB boot
    flash; this means we won't have to change it when the alternate
    config uses the full 64MB for booting, in TLB0.
    Signed-off-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
    Signed-off-by: default avatarKumar Gala <galak@kernel.crashing.org>
    3fd673cf
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