Re: [spi-devel-general] [Patch 0/4] IndustrialIO subsystem (ADCs, accelerometers etc)

From: Ben Dooks
Date: Wed Jul 23 2008 - 15:19:33 EST

On Wed, Jul 23, 2008 at 06:00:29PM +0100, Jonathan Cameron wrote:
> Dear All,
> The need for an industrialio subsystem was discussed in

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.


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

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