• Oliver Schinagl's avatar
    ARM: sunxi: Initial support for Allwinner's Security ID fuses · 9fd379e9
    Oliver Schinagl authored
    Allwinner has electric fuses (efuse) on their line of chips. This driver
    reads those fuses, seeds the kernel entropy and exports them as a sysfs
    node.
    
    These fuses are most likely to be programmed at the factory, encoding
    things like Chip ID, some sort of serial number, etc. and appear to be
    reasonably unique.
    While in theory, these should be writeable by the user, it will probably
    be inconvenient to do so. Allwinner recommends that a certain input pin,
    labeled 'efuse_vddq', be connected to GND. To write these fuses however,
    a 2.5 V programming voltage needs to be applied to this pin.
    
    Even so, they can still be used to generate a board-unique mac from,
    board unique RSA key and seed the kernel RNG.
    
    On sun7i additional storage is available, this is initially used for an
    UEFI BOOT key, Secure JTAG key, HDMI-HDCP key and vendor specific keys.
    
    Currently supported are the following known chips:
    Allwinner sun4i (A10)
    Allwinner sun5i (A10s, A13)
    Allwinner sun7i (A20)
    Signed-off-by: default avatarOliver Schinagl <oliver@schinagl.nl>
    Acked-by: default avatarMaxime Ripard <maxime.ripard@free-electrons.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    9fd379e9
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