From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <524FDF54.5000207@metafoo.de> Date: Sat, 05 Oct 2013 11:43:48 +0200 From: Lars-Peter Clausen MIME-Version: 1.0 To: leroy christophe CC: Jonathan Cameron , linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, patrick.vasseur@c-s.fr Subject: Re: [PATCH] IIO AD7923 iio_consumer support References: <201310050821.r958LBqP012933@localhost.localdomain> <524FD0AB.7020209@metafoo.de> <524FD976.9060708@c-s.fr> <524FDD4F.7080406@metafoo.de> <524FDE35.3050008@c-s.fr> In-Reply-To: <524FDE35.3050008@c-s.fr> Content-Type: text/plain; charset=ISO-8859-1 List-ID: On 10/05/2013 11:39 AM, leroy christophe wrote: > > Le 05/10/2013 11:35, Lars-Peter Clausen a écrit : >> On 10/05/2013 11:18 AM, leroy christophe wrote: >>> Le 05/10/2013 10:41, Lars-Peter Clausen a écrit : >>>> On 10/05/2013 10:21 AM, Christophe Leroy wrote: >>>>> + .consumer_channel = "channel_0", >>>>> + .adc_channel_label = "0", >>>>> + }, >>>>> + { >>>>> + .consumer_dev_name = AD7923_NAME, >>>>> + .consumer_channel = "channel_1", >>>>> + .adc_channel_label = "1", >>>>> + }, >>>>> + { >>>>> + .consumer_dev_name = AD7923_NAME, >>>>> + .consumer_channel = "channel_2", >>>>> + .adc_channel_label = "2", >>>>> + }, >>>>> + { >>>>> + .consumer_dev_name = AD7923_NAME, >>>>> + .consumer_channel = "channel_3", >>>>> + .adc_channel_label = "3", >>>>> + }, >>>>> + { } >>>>> +}; >>>> This is a mapping between channel names of the provider between the channel >>>> names of the consumer. So it is specific to a certain combination of >>>> consumer and provider and usually depend on how things are physically wired >>>> on your board. As such there can be no generic mapping and this needs to go >>>> into your machine/board driver. The mapping is usually passed to the IIO >>>> driver via its platform data. >>>> >>>> So e.g. imagine you have a provider like this driver and you have a >>>> consumer >>>> that has a "voltage" channel. And on your board channel 3 of the ADC is >>>> what >>>> you want to route to that consumer. Then your mapping would look like this: >>>> >>>> { >>>> .consumer_dev_name = "your_consumer_device.1", >>>> .consumer_channel = "voltage", >>>> .adc_channel_label = "AIN3", >>>> } >>>> >>>> And in your consumer driver you'd do: >>>> >>>> channel = iio_channel_get(dev, "voltage"); >>>> >>>> >>> Thanks for the explanation. >>> >>> Can the mapping be retrieved via of_platform ? >>> >>> Indeed, the only exemple I found was in the lp8788_adc driver, which >>> includes iio/machine.h and declares a default mapping, but it is based on >>> platform_data, not of_platform. >>> >> If you are using device tree you can specify the mapping inside the >> devicetree. Have a look at >> Documentation/devicetree/bindings/iio/iio-bindings.txt >> >> > Yes, I saw that. Is there anything that shall be done in the driver to > support it, or is it automatic ? It should work out of the box. Just make sure to set the #io-channel-cells property for the ADC device node in the devicetree. - Lars