From: Felix Radensky <felix@embedded-sol.com>
To: Scott Wood <scottwood@freescale.com>
Cc: "linuxppc-dev@ozlabs.org list" <linuxppc-dev@ozlabs.org>,
"linuxppc-embedded@ozlabs.org" <linuxppc-embedded@ozlabs.org>
Subject: Re: I2C mux and device tree
Date: Tue, 28 Oct 2008 00:33:30 +0200 [thread overview]
Message-ID: <490641BA.4030808@embedded-sol.com> (raw)
In-Reply-To: <490625B0.3050203@freescale.com>
Hi, Scott
Scott Wood wrote:
> [added linuxppc-dev for a wider audience]
>
> Felix Radensky wrote:
>> I run linux-2.6.26 on custom 460EX based board.
>> This platform has PCA9548 I2C mux on I2C bus 0.
>> I was wondering how can I describe the mux itself
>> and devices behind it (e.g RTC and temperature sensors)
>> in the device tree.
>
> Describe it as a node that is both an i2c client and an i2c controller.
>
> The Sun i2c binding says that i2c devices should have two reg cells,
> the first being the bus number within the controller, and the second
> being a shifted-left-by-one i2c bus address (as opposed to the
> one-cell non-shifted address we currently use, because the Sun binding
> wasn't known to us at the time).
>
> We could extend of_register_i2c_devices to understand two-cell
> addresses, and call it once for each sub-bus with the bus number as a
> parameter.
>
That would be nice.
I have everything working now, using platform data and
i2c_register_board_info() in board setup
code. But it would be great to have everything defined in device tree.
>> If this is impossible at the moment, what other means
>> exist to work with devices behind the mux ? I have
>> found the pca954x patch and related virtual i2c patch
>> and was able to integrate them intro my kernel.
>
> You'll have to update it to be a new-style i2c device, unless there's
> a newer version floating around that what a quick google search turned
> up.
>
The latest version uses new-style i2c device, see
http://www.mail-archive.com/i2c%40lm-sensors.org/msg01538.html
Unfortunately it was not accepted.
> -Scott
>
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
prev parent reply other threads:[~2008-10-27 23:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-25 9:02 I2C mux and device tree Felix Radensky
2008-10-27 20:33 ` Scott Wood
2008-10-27 22:33 ` Felix Radensky [this message]
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