lkml.org 
[lkml]   [2021]   [Mar]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] mtd: add OTP (one-time-programmable) erase ioctl
Hi,

Am 2021-03-02 13:46, schrieb Miquel Raynal:
> Michael Walle <michael@walle.cc> wrote on Tue, 2 Mar 2021 12:09:27
> +0100:
>
>> This may sound like a contradiction but some SPI-NOR flashes really
>> support erasing their OTP region until it is finally locked. Having
>> the
>> possibility to erase an OTP region might come in handy during
>> development.
>>
>> The ioctl argument follows the OTPLOCK style.
>>
>> Signed-off-by: Michael Walle <michael@walle.cc>
>> ---
>> OTP support for SPI-NOR flashes may be merged soon:
>> https://lore.kernel.org/linux-mtd/20210216162807.13509-1-michael@walle.cc/
>>
>> Tudor suggested to add support for the OTP erase operation most
>> SPI-NOR
>> flashes have:
>> https://lore.kernel.org/linux-mtd/d4f74b1b-fa1b-97ec-858c-d807fe1f9e57@microchip.com/
>>
>> Therefore, this is an RFC to get some feedback on the MTD side, once
>> this
>> is finished, I can post a patch for mtd-utils. Then we'll have a
>> foundation
>> to add the support to SPI-NOR.
>>

[..]

>> +int mtd_erase_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t
>> len)
>> +{
>> + struct mtd_info *master = mtd_get_master(mtd);
>> +
>> + if (!master->_erase_user_prot_reg)
>> + return -EOPNOTSUPP;
>> + if (!len)
>> + return 0;
>
> Should we add a sanity check enforcing that we don't try to access
> beyond the end of the OTP area?

This is checked in the op itself, as it is done for all the
other OTP read/write/lock ops.

Right at the moment, I don't see how this could be achieved in
an elegant way. Without additional changes, you'd have to call
mtd_get_user_prot_info() and iterate over the returned values
and figure out whether from and len are valid.

[..]

-michael

\
 
 \ /
  Last update: 2021-03-02 17:10    [W:0.066 / U:0.696 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site