linux-kernel - Re: [linux-sunxi] Re: [PATCH] nvmem: sunxi-sid: add support for A64/H5's SID controller

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Message-ID: <20170919115502.exfbpdwb3c3eenee@flea.lan>
Date:   Tue, 19 Sep 2017 13:55:02 +0200
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Icenowy Zheng <icenowy@...c.io>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Chen-Yu Tsai <wens@...e.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com
Subject: Re: [linux-sunxi] Re: [PATCH] nvmem: sunxi-sid: add support for
 A64/H5's SID controller

On Tue, Sep 19, 2017 at 04:23:14PM +0800, Icenowy Zheng wrote:
> 
> 
> 于 2017年9月19日 GMT+08:00 下午4:20:19, Maxime Ripard <maxime.ripard@...e-electrons.com> 写到:
> >On Mon, Sep 18, 2017 at 11:42:04PM +0800, Icenowy Zheng wrote:
> >> Allwinner A64/H5 SoCs come with a SID controller like the one in H3,
> >but
> >> without the silicon bug that makes the initial value at 0x200 wrong,
> >so
> >> the value at 0x200 can be directly read.
> >> 
> >> Add support for this kind of SID controller.
> >> 
> >> Signed-off-by: Icenowy Zheng <icenowy@...c.io>
> >> ---
> >>  Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt | 1
> >+
> >>  drivers/nvmem/sunxi_sid.c                                       | 6
> >++++++
> >>  2 files changed, 7 insertions(+)
> >> 
> >> diff --git
> >a/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt
> >b/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt
> >> index ef06d061913c..6ea0836939ee 100644
> >> --- a/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt
> >> +++ b/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt
> >> @@ -5,6 +5,7 @@ Required properties:
> >>    "allwinner,sun4i-a10-sid"
> >>    "allwinner,sun7i-a20-sid"
> >>    "allwinner,sun8i-h3-sid"
> >> +  "allwinner,sun50i-a64-sid"
> >>  
> >>  - reg: Should contain registers location and length
> >>  
> >> diff --git a/drivers/nvmem/sunxi_sid.c b/drivers/nvmem/sunxi_sid.c
> >> index 0d6648be93b8..3c9fd4fb9207 100644
> >> --- a/drivers/nvmem/sunxi_sid.c
> >> +++ b/drivers/nvmem/sunxi_sid.c
> >> @@ -199,10 +199,16 @@ static const struct sunxi_sid_cfg sun8i_h3_cfg
> >= {
> >>  	.need_register_readout = true,
> >>  };
> >>  
> >> +static const struct sunxi_sid_cfg sun50i_a64_cfg = {
> >> +	.value_offset = 0x200,
> >> +	.size = 0x100,
> >> +};
> >> +
> >
> >How did you get those values?
> 
> In the BSP U-Boot headers.

This should be mentionned in your commit log then.

> >Also, it's reported that the SID can only be accessed in secure
> >mode, did you test it?
> 
> Yes, however the secure is broken again, and this only
> happen if Secure Boot bit is burned.

Is broken again, meaning?

As far as I know, the only breakage we've had is on the A80 / A83T,
but we don't have anything like it on the A64, do we?

> If it's really burned, we will have no clean way to access SID.

Well, in such a case we shouldn't access it either, so..

Maxime

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

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