• Stefan Roese's avatar
    mtd: cfi_cmdset_0002: Support Persistent Protection Bits (PPB) locking · 1648eaaa
    Stefan Roese authored
    Currently cfi_cmdset_0002.c does not support PPB locking of sectors. This
    patch adds support for this locking/unlocking mechanism. It is needed on
    some platforms, since newer U-Boot versions do support this PPB locking
    and protect for example their environment sector(s) this way.
    This PPB locking/unlocking will be enabled for all devices supported by
    cfi_cmdset_0002 reporting 8 in the CFI word 0x49 (Sector Protect/Unprotect
    Please note that PPB locking does support sector-by-sector locking. But
    the whole chip can only be unlocked together. So unlocking one sector
    will automatically unlock all sectors of this device. Because of this
    chip limitation, the PPB unlocking function saves the current locking
    status of all sectors before unlocking the whole device. After unlocking
    the saved locking status is re-configured. This way only the addressed
    sectors will be unlocked.
    To selectively enable this advanced sector protection mechanism, the
    device-tree property "use-advanced-sector-protection" has been created.
    To enable support for this locking this property needs to be present in the
    flash DT node. E.g.:
    nor_flash@0,0 {
    	compatible = "amd,s29gl256n", "cfi-flash";
    	bank-width = <2>;
    Tested with Spansion S29GL512S10THI and Micron JS28F512M29EWx flash
    Signed-off-by: default avatarStefan Roese <sr@denx.de>
    Tested-by: default avatarHolger Brunck <holger.brunck@keymile.com>
    Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
cfi_cmdset_0002.c 70.4 KB