CC: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Brian Norris <computersforpeace@gmail.com>
From: Scott Branden <sbranden@broadcom.com>
Subject: Adding OTP-only device to MTD or CHAR subsystem?
Message-ID: <5681C3E4.4090506@broadcom.com>
Date: Mon, 28 Dec 2015 15:21:08 -0800
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Greg/Brian/Arnd,

We have OTP device drivers for accessing OTP memory in our SoCs.

I looking for the right place and model to place such OTP device drivers.

1) Should we follow the bfin-otp model in drivers/char?  This doesn't 
seem like the right place to put it although following the bfin example 
is quite simple to implement.  We actually had a custom set of Ioctl's 
that I changed to use the standard file access model used by the bfin 
driver.  But a custom util is still needed to issue an OTPLOCK command. 
  I'm guess mtd-utils has such abilities (or should).

2) Instead, should we start adding OTP-only drivers into the MTD 
subsystem?  Onenand and CFI based MTD devices already have OTP 
programmable regions.  If we created a new OTP device type in the MTD 
subsystem this looks like a good thing to do.  mtd-utils could/should be 
used to access the OTP device then along with standard fileio operations.

3) Or some other suggestion of where to place OTP device drivers?

Regards,
  Scott
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