From mboxrd@z Thu Jan  1 00:00:00 1970
From: grinberg@compulab.co.il (Igor Grinberg)
Date: Fri, 30 Mar 2012 18:34:01 +0300
Subject: How to add GPIO outputs to the PXA2xx MFP configuration?
In-Reply-To: <1333119961.87678.YahooMailClassic@web29013.mail.ird.yahoo.com>
References: <1333119961.87678.YahooMailClassic@web29013.mail.ird.yahoo.com>
Message-ID: <4F75D269.7030500@compulab.co.il>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org



On 03/30/12 18:06, Paul Parsons wrote:
> --- On Fri, 30/3/12, Igor Grinberg <grinberg@compulab.co.il> wrote:
>> On 03/28/12 20:12, Paul Parsons
>> wrote:
>>> On PXA2xx platforms, the MFP API (described in
>> Documentation/arm/pxa/mfp.txt)
>>> provides values for the following:
>>>
>>> 1. GPIO inputs (e.g. GPIO105_GPIO).
>>> 2. Alternate function inputs (e.g. GPIO105_CIF_DD_1).
>>> 3. Alternate function outputs (e.g.
>> GPIO105_KP_MKOUT_2).
>>>
>>> It does not provide values for GPIO outputs (i.e. AF0
>> outputs).
>>>
>>> One cannot use the macro used by the MFP API internally
>> - MFP_CFG_OUT() - to
>>> define new GPIO output values, since that macro is
>> forbidden in platform code.
>>>
>>> Without the ability to add GPIO outputs to the MFP
>> configuration, it is not
>>> possible to drive GPIO outputs high during sleep mode.
>>>
>>> This would be useful, for example, on the hx4700
>> platform, where driving the
>>> infrared powerdown GPIO 105 high during sleep mode
>> would save some mA.
>>>
>>> So my question is: what method should one use to add
>> GPIO outputs to the MFP
>>> configuration?
>>>
>>> One possible method, namely manually defining values in
>> the platform code:
>>>
>>>     MFP_PIN_GPIO105 | MFP_AF0 |
>> MFP_DIR_OUT | MFP_LPM_DRIVE_HIGH,
>>
>> Have you tried:
>> GPIO105_GPIO | MFP_LPM_DRIVE_HIGH,
>> ?
>>
>> This way it works on other boards.
> 
> Hello Igor,
> 
> GPIO105_GPIO expands to a GPIO input - MFP_CFG_IN(GPIO105, AF0) -
> not an output.

Yeah, I know... but read in mfp-pxa2xx.h, lines 6-20:
/*
 * the following MFP_xxx bit definitions in mfp.h are re-used for pxa2xx:
 *
 *  MFP_PIN(x)
 *  MFP_AFx
 *  MFP_LPM_DRIVE_{LOW, HIGH}
 *  MFP_LPM_EDGE_x
 *
 * other MFP_x bit definitions will be ignored
 *
 * and adds the below two bits specifically for pxa2xx:
 *
 * bit     23 - Input/Output (PXA2xx specific)
 * bit     24 - Wakeup Enable(PXA2xx specific)
 */

This means, that there is no difference between: MFP_CFG_IN and MFP_CFG_OUT for PXA2xx.
The reason for this is that PXA2xx h/w does not have a dedicated MFP registers.
All goes through the GPIO controller, so the whole MFP for PXA2xx is only to conform
to newer "PXA" platform features...


-- 
Regards,
Igor.