Re: [RFC PATCH v6 1/2] hw/misc/sifive_u_otp: Add write function and write-once protection

[Green Wan]

On Wed, Oct 14, 2020 at 1:37 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> Hi Green,
>
> On Mon, Sep 28, 2020 at 6:12 PM Green Wan <green.wan@sifive.com> wrote:
> >
> >  - Add write operation to update fuse data bit when PWE bit is on.
> >  - Add array, fuse_wo, to store the 'written' status for all bits
> >    of OTP to block the write operation.
> >
> > Signed-off-by: Green Wan <green.wan@sifive.com>
> > Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> > ---
> >  hw/misc/sifive_u_otp.c         | 30 +++++++++++++++++++++++++++++-
> >  include/hw/misc/sifive_u_otp.h |  3 +++
> >  2 files changed, 32 insertions(+), 1 deletion(-)
> >
>
> I am not sure how you tested this. I wrote a simple U-Boot command to
> call U-Boot sifive-otp driver to test the write functionality, but it
> failed.
>
> => misc write otp@10070000 0 80200000 10
                                                      ^^^^^^^^^
Quick ask, how about 'md 80200000'?

I didn't use 'misc write' command. I can check afterward.

> => misc read  otp@10070000 0 80400000 10
> => md 80400000
> 80400000: ffffffff ffffffff ffffffff ffffffff    ................
> 80400010: 00000000 00000000 00000000 00000000    ................
> 80400020: 00000000 00000000 00000000 00000000    ................
> 80400030: 00000000 00000000 00000000 00000000    ................
> 80400040: 00000000 00000000 00000000 00000000    ................
> 80400050: 00000000 00000000 00000000 00000000    ................
> 80400060: 00000000 00000000 00000000 00000000    ................
> 80400070: 00000000 00000000 00000000 00000000    ................
> 80400080: 00000000 00000000 00000000 00000000    ................
> 80400090: 00000000 00000000 00000000 00000000    ................
> 804000a0: 00000000 00000000 00000000 00000000    ................
> 804000b0: 00000000 00000000 00000000 00000000    ................
> 804000c0: 00000000 00000000 00000000 00000000    ................
> 804000d0: 00000000 00000000 00000000 00000000    ................
> 804000e0: 00000000 00000000 00000000 00000000    ................
> 804000f0: 00000000 00000000 00000000 00000000    ................
> => misc write otp@10070000 0 80200010 10
> => misc read  otp@10070000 0 80400010 10
> => md 80400000
> 80400000: ffffffff ffffffff ffffffff ffffffff    ................
> 80400010: ffffffff ffffffff ffffffff ffffffff    ................
> 80400020: 00000000 00000000 00000000 00000000    ................
> 80400030: 00000000 00000000 00000000 00000000    ................
> 80400040: 00000000 00000000 00000000 00000000    ................
> 80400050: 00000000 00000000 00000000 00000000    ................
> 80400060: 00000000 00000000 00000000 00000000    ................
> 80400070: 00000000 00000000 00000000 00000000    ................
> 80400080: 00000000 00000000 00000000 00000000    ................
> 80400090: 00000000 00000000 00000000 00000000    ................
> 804000a0: 00000000 00000000 00000000 00000000    ................
> 804000b0: 00000000 00000000 00000000 00000000    ................
> 804000c0: 00000000 00000000 00000000 00000000    ................
> 804000d0: 00000000 00000000 00000000 00000000    ................
> 804000e0: 00000000 00000000 00000000 00000000    ................
> 804000f0: 00000000 00000000 00000000 00000000    ................
>
> But it can read the serial number at offset 0x3f0
>
> => misc read  otp@10070000 3f0 80400010 10
> => md 80400000
> 80400000: ffffffff ffffffff ffffffff ffffffff    ................
> 80400010: 00000001 fffffffe ffffffff ffffffff    ................
> 80400020: 00000000 00000000 00000000 00000000    ................
> 80400030: 00000000 00000000 00000000 00000000    ................
> 80400040: 00000000 00000000 00000000 00000000    ................
> 80400050: 00000000 00000000 00000000 00000000    ................
> 80400060: 00000000 00000000 00000000 00000000    ................
> 80400070: 00000000 00000000 00000000 00000000    ................
> 80400080: 00000000 00000000 00000000 00000000    ................
> 80400090: 00000000 00000000 00000000 00000000    ................
> 804000a0: 00000000 00000000 00000000 00000000    ................
> 804000b0: 00000000 00000000 00000000 00000000    ................
> 804000c0: 00000000 00000000 00000000 00000000    ................
> 804000d0: 00000000 00000000 00000000 00000000    ................
> 804000e0: 00000000 00000000 00000000 00000000    ................
> 804000f0: 00000000 00000000 00000000 00000000    ................
>
> Regards,
> Bin