[PATCH 1/2] misc/at24: Add at24c512b eeprom support

Liu Ying liu.y.victor at gmail.com
Wed Jan 23 08:40:26 EST 2013

2013/1/23 Wolfram Sang <w.sang at pengutronix.de>:
> On Wed, Jan 23, 2013 at 01:24:52PM +0100, Linus Walleij wrote:
>> On Wed, Jan 23, 2013 at 7:32 AM, Liu Ying <Ying.Liu at freescale.com> wrote:
>> > This patch adds at24c512b eeprom support.
>> > The datasheet of at24c512b can be found at:
>> > http://www.alldatasheet.com/datasheet-pdf/pdf/
>> > 256958/ATMEL/AT24C512B-TH-B.html
>> >
>> > Signed-off-by: Liu Ying <Ying.Liu at freescale.com>
>> Arnd Bergmann is the misc maintainer, route this by him.
> I usually take at24 patches via my I2C tree.
> But not this one, though. The 512b can equally use the 512 entry. The
> devicetree should contain both entries, the 512 one as a fallback. (And
> the vendor is not "at24"!)

There are some difference between 24c512 and 24c512b about the system
reset procedure, according to the two devices' spec:
24c512b:(a) Create a start bit condition, (b)clock 9 cycles, (c)
create another start bit followed by stop bit condition.
24c512:(a) Clock up to 9 cycles, (b) look for SDA high in each cycle
while SCL is high and then, (c) create a start condition as SDA is
Could this be a reason to add an entry for 24c512b?

About the vendor name, I took the at24c32 node in
arch/arm/boot/dts/imx28-evk.dts as a reference:

                                at24 at 51 {
                                        compatible = "at24,24c32";
                                        pagesize = <32>;
                                        reg = <0x51>;

Now, I think the correct vendor name should be "at" or "atmel".


> Regards,
>    Wolfram
> --
> Pengutronix e.K.                           | Wolfram Sang                |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Best Regards,
Liu Ying

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