Re: [PATCH] drivers/misc: Altera Cyclone active serial implementation

[Baruch Siach <baruch@tkos.co.il>]

Hi Greg,

On Sat, Nov 06, 2010 at 11:19:30AM -0700, Greg KH wrote:
> On Wed, Nov 03, 2010 at 04:21:35PM +0200, Baruch Siach wrote:
> > From: Alex Gershgorin <agersh@rambler.ru>
> > 
> > The active serial protocol can be used to program Altera Cyclone FPGA devices.
> > This driver uses the kernel gpio interface to implement the active serial
> > protocol.
> > 
> > Signed-off-by: Alex Gershgorin <agersh@rambler.ru>
> > Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> > ---

[snip]

> > +static struct class *cyclone_as_class;
> 
> Please don't create your own class just for a single driver.  Just use
> the misc class interface instead, as all you really want/need here is a
> character device node, right?

Searching for 'mist' under include/linux/ I couldn't find this "misc class 
interface". Can you enlighten me?

I did find the "miscdevices" interface in include/linux/miscdevice.h.  I also 
tried this one before going on to create a class of my own. However, this 
interface seems to be limited to singleton devices. Can I use 
MISC_DYNAMIC_MINOR to create multiple device nodes? Is there any example for 
this?

> And as discussed at the Plumbers conference this past week, we don't
> want to add any new 'struct class' implementations to the kernel from
> now on, as it's the overall wrong thing to do.
> 
> > --- /dev/null
> > +++ b/include/linux/cyclone_as.h
> 
> Why do you need a .h file at all?

Look at the content of this file. I need to pass GPIO numbers from the 
platform code under arch/ to the driver. For this I use a platform_data 
struct, which must be visible to the platform code. Is there a better way to 
do this?

baruch

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