pcspkr.c

pcspkr.c

[Paul Mackerras]

Vojtech,

I like the way that the code for doing the beeps via the PC speaker
has been pulled out into its own little module.

We have a situation on PPC where we would want the PC speaker input
device to be compiled in to the kernel but only registered and
initialized on some machines but not on others.  We can run the same
kernel binary on powermac, CHRP and PReP machines.  The CHRP and PReP
machines have a PC-style southbridge, including the ISA timer/counter
that pcspkr.c uses.  On powermacs there is no ISA bus, and to make a
beep it is necessary to push a suitable waveform out through the
audio.

So what we want is some way to decide at runtime whether to register
the pc-speaker input device or not.

Suggestions?

Thanks,
Paul.

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Re: pcspkr.c

[Vojtech Pavlik]

On Tue, Aug 27, 2002 at 12:03:11PM +1000, Paul Mackerras wrote:
> Vojtech,
>
> I like the way that the code for doing the beeps via the PC speaker
> has been pulled out into its own little module.
>
> We have a situation on PPC where we would want the PC speaker input
> device to be compiled in to the kernel but only registered and
> initialized on some machines but not on others.  We can run the same
> kernel binary on powermac, CHRP and PReP machines.  The CHRP and PReP
> machines have a PC-style southbridge, including the ISA timer/counter
> that pcspkr.c uses.  On powermacs there is no ISA bus, and to make a
> beep it is necessary to push a suitable waveform out through the
> audio.
>
> So what we want is some way to decide at runtime whether to register
> the pc-speaker input device or not.
>
> Suggestions?

1) Future grand vision: the arch-dependent code supplies a list of
devices present in the system in a generic format, and including or not
the speaker, based on what machine we're running on.  The
hotplug/drivermodel core will then load or not load the pcspkr driver as
a module from initramfs.

2) Quick hack: I have no problem with an

	#ifdef CONFIG_PPC
		if (something)
			return -ENODEV;
	#endif

   inside pcspkr_init()

--
Vojtech Pavlik
SuSE Labs

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