Re: [PATCHv7 1/2] ARM: sunxi: Initial support for Allwinner'sSecurity ID fuses

From: Maxime Ripard
Date: Tue Sep 03 2013 - 07:21:44 EST


On Tue, Sep 03, 2013 at 12:33:27PM +0200, oliver+list@xxxxxxxxxxx wrote:
> From: Oliver Schinagl <oliver@xxxxxxxxxxx>
>
> 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: Oliver Schinagl <oliver@xxxxxxxxxxx>

Acked-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>

Thanks!
Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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