Re: Multiple drivers. help

[Takashi Iwai <tiwai@suse.de>]

At Mon, 21 Apr 2003 22:41:15 -0400,
Manuel Jander wrote:
> 
> Hi,
> 
> 
> With the current Aureal Driver we have the following dilema:
> We support 3 soundcards: the AU8810, AU8820 and AU8830.
> They are very similar to each other and share a lot of code (almost 
> all). But they use different register address offsets and "sizes" of 
> some resources.
> So we have one .c file and one .h file for each card. All that in one
> directory which is pci/au88x0/. How do I make it to compile on or 
> another driver ?
> 
> The configure script story is allready OK. selscting the different
> drivers triggers different CONFIG_SND_XXXXX environment variables to 
> appear in the makefiles,
> but :
> how can that info be transmitted to header file #ifdef's ?
> The corresponding CONFIG_SND_AU8810, CONFIG_SND_AU8820 and
> CONFIG_SND_AU8830 defines of the Makefile's aren't recognized inside
> any header file.

CONFIG_SND_AU8810_MODULE is defined (found in include/config1.h).
but please note that CONFIG_SND_AU8810 may be defined instead of
XXX_MODULE if the driver is built into the kernel.  so, you need to
check both in ifdef.

IIUC, you want to have several modules in a single directory
(pci/au88x0).  suppose that each module has its lowlevel routines and
common routines.  then the modules will be the top entries

	snd-au8810.o
	snd-au8820.o
	snd-au8830.o

and a common module

	snd-au88x0-lib.o

an example for this case is found in isa/sb directory.

alternatively, if each driver "includes" the common source file but is
compiled in different condition via ifdef, there will be no common
module.

in au8810.c:
	...
	#include "au88x0_common.c"
	...

in au88x0_common.c:
	...
	#if defined(CONFIG_SND_AU8810) || defined(CONFIG_SND_AU8810_MODULE)
	// au8810 specific
	#endif
	#if defined(CONFIG_SND_AU8820) || defined(CONFIG_SND_AU8820_MODULE)
	// au8810 specific
	#endif
	
however, usually we define a constant for a file instead of checking
CONFIG_XXX, namely,

in au8810.c
	#define USE_AU8810
	#include "au88x0_common.c"
	...

in au88x0_common.c:
	...
	#ifdef USE_AU8810
	...

examples are pci/ens1370.c (ens1371.c) and isa/opti9xx.


ciao,

Takashi


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