linux-kernel - Re: [PATCHv2 2/3] misc: add support for bmp18x chips to the bmp085 driver

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Message-ID: <20120306221752.GB18235@skinner.xfiles.lan>
Date:	Tue, 6 Mar 2012 23:17:52 +0100
From:	Eric Andersson <eric.andersson@...xphere.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
	alan@...rguk.ukuu.org.uk, zhengguang.guo@...ch-sensortec.com,
	peter.moeller@...bosch.com,
	Stefan Nilsson <stefan.nilsson@...xphere.com>
Subject: Re: [PATCHv2 2/3] misc: add support for bmp18x chips to the bmp085
 driver

On 21:27 Tue 06 Mar     , Arnd Bergmann wrote:
> On Tuesday 06 March 2012, Eric Andersson wrote:
> > The bmp18x chip family comes in an I2C respectively SPI variant.
> > Hence, the bmp085 driver was split to support both buses.
> > 
> > Tested-by: Zhengguang Guo <zhengguang.guo@...ch-sensortec.com>
> > Reviewed-by: Stefan Nilsson <stefan.nilsson@...xphere.com>
> > Signed-off-by: Eric Andersson <eric.andersson@...xphere.com>
> 
> (adding Mark Brown to Cc)
> 
> I don't know much about regmap, but your description sounds like you
> should be using it here, to simplify the differences between i2c and
> spi in your driver instead of implementing your own abstraction
> layer.
> 
> >  config BMP085
> >  	tristate "BMP085 digital pressure sensor"
> > -	depends on I2C && SYSFS
> > +	depends on (I2C || SPI_MASTER) && SYSFS
> >  	help
> > -	  If you say yes here you get support for the Bosch Sensortec
> > -	  BMP085 digital pressure sensor.
> > +	  Say Y here if you want support for Bosch Sensortec's digital
> > +	  pressure sensors BMP085 and BMP18x.
> >  
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called bmp085.
> >  
> > +config BMP085_I2C
> > +	tristate "support I2C bus connection"
> > +	depends on BMP085 && I2C
> > +	help
> > +	  Say Y here if you want to support Bosch Sensortec's digital pressure
> > +	  sensor hooked to an I2C bus.
> > +
> > +	  To compile this driver as a module, choose M here: the
> > +	  module will be called bmp085-i2c.
> > +
> > +config BMP085_SPI
> > +	tristate "support SPI bus connection"
> > +	depends on BMP085 && SPI_MASTER
> > +	help
> > +	  Say Y here if you want to support Bosch Sensortec's digital pressure
> > +	  sensor hooked to an SPI bus.
> > +
> > +	  To compile this driver as a module, choose M here: the
> > +	  module will be called bmp085-spi.
> > +
> 
> IMHO this would be better expressed if you make CONFIG_BMP085 a hidden
> option that is selected when either BMP085_I2C or BMP085_SPI are enabled.
> Otherwise you make it possible to build just the base driver but neither
> of the front-ends, which is a bit pointless.

This setup is inspired from other drivers such as ad525x_dpot.c and
ad714x.c, which also have their own bus abstraction. If regmap is a more
generic way of solving this I am all for it!

-- 
Best regards,
 Eric

http://www.unixphere.com
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