From: Arnd Bergmann <arnd@arndb.de>
To: Scott Branden <sbranden@broadcom.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Brian Norris <computersforpeace@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>
Subject: Re: Adding OTP-only device to MTD or CHAR subsystem?
Date: Tue, 29 Dec 2015 00:38:21 +0100
Message-ID: <3668194.4jROlECW6L@wuerfel>
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On Monday 28 December 2015 15:21:08 Scott Branden wrote:
> 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?

I think drivers/nvmem is now the right place for this.

	Arnd
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