Writing to the OCOTP on mx28 boards

Writing to the OCOTP on mx28 boards

[Maxime Ripard]

Hi everyone,

I'm trying to write down some data to the /dev/ocotp file, which is
basically a one time programming chip containing four bytes.

Using the command mw -b -d /dev/ocotp 0-3 0x01020304 writes down only
"4" to the first byte of the OCOTP, which is not quite what I was
expecting. What's the correct syntax for the mw command?

Thanks,
Maxime


-- 
Maxime Ripard, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

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Re: Writing to the OCOTP on mx28 boards

[Maxime Ripard]

Le 28/09/2012 14:08, Maxime Ripard a écrit :
> Hi everyone,
> 
> I'm trying to write down some data to the /dev/ocotp file, which is
> basically a one time programming chip containing four bytes.
> 
> Using the command mw -b -d /dev/ocotp 0-3 0x01020304 writes down only
> "4" to the first byte of the OCOTP, which is not quite what I was
> expecting. What's the correct syntax for the mw command?

Ok, just found out, it should be
mw -l -d /dev/ocotp 0-3 0x01020304

Thanks to Franck Jullien :)

-- 
Maxime Ripard, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

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Re: Writing to the OCOTP on mx28 boards

[Sascha Hauer]

On Fri, Sep 28, 2012 at 02:23:32PM +0200, Maxime Ripard wrote:
> Le 28/09/2012 14:08, Maxime Ripard a écrit :
> > Hi everyone,
> > 
> > I'm trying to write down some data to the /dev/ocotp file, which is
> > basically a one time programming chip containing four bytes.
> > 
> > Using the command mw -b -d /dev/ocotp 0-3 0x01020304 writes down only
> > "4" to the first byte of the OCOTP, which is not quite what I was
> > expecting. What's the correct syntax for the mw command?
> 
> Ok, just found out, it should be
> mw -l -d /dev/ocotp 0-3 0x01020304

Not quite. 0-3 is wrong, though appearantly happens to work. It should
be:

mw -d /dev/ocotp 0 0x01020304

(-l can be skipped, as 32bit accesses are default). If you want to write
multiple words you can do a:

mw -d /dev/ocotp 0 0xdeadbeef 0x12345678 0x11223344

The 0-3 notation is only for 'md'

Sascha


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Re: Writing to the OCOTP on mx28 boards

[Maxime Ripard]

Hi Sascha,

Le 28/09/2012 14:42, Sascha Hauer a écrit :
> On Fri, Sep 28, 2012 at 02:23:32PM +0200, Maxime Ripard wrote:
>> Le 28/09/2012 14:08, Maxime Ripard a écrit :
>>> Hi everyone,
>>>
>>> I'm trying to write down some data to the /dev/ocotp file, which is
>>> basically a one time programming chip containing four bytes.
>>>
>>> Using the command mw -b -d /dev/ocotp 0-3 0x01020304 writes down only
>>> "4" to the first byte of the OCOTP, which is not quite what I was
>>> expecting. What's the correct syntax for the mw command?
>>
>> Ok, just found out, it should be
>> mw -l -d /dev/ocotp 0-3 0x01020304
> 
> Not quite. 0-3 is wrong, though appearantly happens to work. It should
> be:
> 
> mw -d /dev/ocotp 0 0x01020304
> 
> (-l can be skipped, as 32bit accesses are default). If you want to write
> multiple words you can do a:
> 
> mw -d /dev/ocotp 0 0xdeadbeef 0x12345678 0x11223344
> 
> The 0-3 notation is only for 'md'

Ok, I see.

Thanks!

Maxime

-- 
Maxime Ripard, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

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