linux-kernel - Re: [RESEND PATCH v2 0/9] eeprom: at24: at24cs series serial number read

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Message-ID: <CAMpxmJVag2E4GFSUW10vqCS32cCg0ymqkz=BOE1XS_qo655vBQ@mail.gmail.com>
Date:	Fri, 11 Dec 2015 14:55:10 +0100
From:	Bartosz Golaszewski <bgolaszewski@...libre.com>
To:	Wolfram Sang <wsa@...-dreams.de>
Cc:	linux-i2c <linux-i2c@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v2 0/9] eeprom: at24: at24cs series serial number read

2015-12-11 13:08 GMT+01:00 Wolfram Sang <wsa@...-dreams.de>:
> On Wed, Dec 02, 2015 at 11:25:17AM +0100, Bartosz Golaszewski wrote:
>> Chips from the at24cs EEPROM series have an additional read-only memory area
>> containing a factory pre-programmed serial number. In order to access it, a
>> dummy write must be executed before reading the serial number bytes.
>
> Can't you instantiate a read-only EEPROM on this second address? Or a
> seperate driver attaching to this address? What is the advantage of
> having this in at24?
>

The regular memory area and serial number read-only block share the
internal address pointer. We must ensure that there's no race
conditions between normal EEPROM reads/writes and serial number reads.

Best regards,
Bartosz Golaszewski
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