linux-kernel - Re: [PATCH v3 0/5] dts patches for qcom tsens support

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Message-ID: <20160825031328.GI15161@tuxbot>
Date:   Wed, 24 Aug 2016 20:13:28 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Paolo Pisati <p.pisati@...il.com>
Cc:     Andy Gross <andy.gross@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/5] dts patches for qcom tsens support

On Wed 24 Aug 03:22 PDT 2016, Paolo Pisati wrote:

> On Wed, Aug 17, 2016 at 02:33:40PM -0500, Andy Gross wrote:
> > On Wed, Aug 17, 2016 at 10:48:43AM +0530, Rajendra Nayak wrote:
> > > Hey Andy,
> > > 
> > > This is a respin of v2 with some minor fixes pointed out by Rob.
> > > Please pull these in for 4.9
> > > 
> > > Thanks,
> > > Rajendra
> > 
> > I pulled these in.
> 
> Did you try to read the content of the qfprom from userspace?
> 
> $ uname -a
> Linux dragon410c 4.8.0-rc1+ #6 SMP PREEMPT Wed Aug 24 11:11:02 CEST 2016 aarch64
> aarch64 aarch64 GNU/Linux
> $ lsmod 
> Module                  Size  Used by
> nvmem_qfprom           16384  0
> nvmem_core             24576  1 nvmem_qfprom
> $ ls -la /sys/bus/nvmem/devices/                                                                             
> total 0
> drwxr-xr-x 2 root root 0 Aug 24 10:17 .
> drwxr-xr-x 4 root root 0 Aug 24 10:15 ..
> lrwxrwxrwx 1 root root 0 Aug 24 10:17 qfprom0 ->
> ../../../devices/platform/soc/5c000.qfprom/qfprom0
> $ cat /sys/bus/nvmem/devices/qfprom0/nvmem 
> 
> [spontaneous reboot]
> 
> This using agross's for-next tree as of today ("54ba896 Merge branch
> 'arm64-defconfig-for-4.9' into all-for-4.8") and defconfig.

This was reported in some other forum as well, after some investigation
we concluded that it looks like one of the entries are locked down -
probably from some security reason.

I'm not aware of any way to query this configuration. But the main use
case for the qfprom is in-kernel access to certain elements and that we
do get from the driver as is...

Regards,
Bjorn