Message-ID: <20080723191918.GC26938@trinity.fluff.org>
Date:	Wed, 23 Jul 2008 20:19:18 +0100
From:	Ben Dooks <ben-linux@...ff.org>
To:	Jonathan Cameron <Jonathan.Cameron@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	spi-devel-general@...ts.sourceforge.net,
	LM Sensors <lm-sensors@...sensors.org>, mgross@...ux.intel.com,
	Dmitry Torokhov <dtor@...l.ru>,
	David Brownell <david-b@...bell.net>, hmh@....eng.br,
	Jean Delvare <khali@...ux-fr.org>,
	Ben Nizette <bn@...sdigital.com>
Subject: Re: [spi-devel-general] [Patch 0/4] IndustrialIO subsystem (ADCs, accelerometers etc)

On Wed, Jul 23, 2008 at 06:00:29PM +0100, Jonathan Cameron wrote:
> Dear All,
> 
> The need for an industrialio subsystem was discussed in
> http://lkml.org/lkml/2008/5/20/135

The name is really bad, this sounds like something for doing large
scale industrial process control.
 
> Firstly thanks to all the people who have contributed to the discussion
> of this in the past.
> 
> In brief the intention is provide a kernel subsystem directed towards the
> handling on sensors (and later related output devices) such as ADC's,
> accelerometers and many others.

We've already got an perfectly good hwmon framework, do we really need
to do this again?

> Key features of the subsystem include:
> 
> * Provision of sysfs access for direct reading from devices (similar to hwmon
>   but without the buffering / update rate restrictions)
> 
> * Provision of chrdevs through which events may be passed to userspace in a
>   similar fashion to the input subsystem.  These events may be anything from
>   hardware thresholds set on the sensor itself to sw / hw ring buffer event
>   notifications (50% full etc).
> 
> * Provision of access via chrdevs to hardware ring buffers on devices that
>   provide them.
> 
> * Software ring buffer support to allow semi regular capture of data form the
>   device.  Typically this will be driven from either datardy events, or from
>   a periodic timer interrupt (to this end a very simple wrapper for periodic
>   RTC's is included. This will move to more generic timer interfaces as and when
>   they become available.  For now available rtc's must be registered with the
>   subsystem via the industrialio_register_ptimer function form within a board
>   init.
> 
> * A set of sample drivers illustrating the main 'classes' of device. By classes
>   I really mean devices that are interfaced with in a similar way.
> 
> The subsystem is now in a functional state with a small set of drivers:
> 
> Max1363 (supports numerous Maxim i2c ADC's) (tested with max1363 and max1238 chips)
>    - Uses a periodic timer to provide ring buffer mode.
>    - All reads form these devices are scan modes so direct single element access
>      is not provided.
>    - Monitor mode on max1363 is not yet supported (need to do a bit debugging of
>      the board I have so as to be able to test this).
> 
> ST LIS3L02DQ - SPI accelerometer.
>    - Uses a datardy interrupt to driver a software ring buffer.
>    - Most functionality of this device is supported.
> 
> VTI SCA3000 (tested with an e05)
>    - Hardware ring buffer.
> 
> More drivers in preparation.
> 
> Next focus will be on cleaning up / implementing a more generic timer framework
> and allowing the system to partly run if not all dependencies are met 
> (particularly availability of timers).
> 
> An initial set of patches will be attached to this thread shortly.

-- 
Ben

Q:      What's a light-year?
A:      One-third less calories than a regular year.

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