Where can I find some documentation/examples?

Where can I find some documentation/examples?

[Dino Klein]

I'm interested in playing with acpi, by writing a simple driver for device PNP0C04 (the FPU), which obviously won't do much.
I am trying to figure out how to populate acpi_driver structure, but I'm not quite clear as to which of the operation a device
should implement.
I've taken a look at the serial driver's use of acpi in order to discover ports, and their resources (in kernel 2.6.0). One thing
puzzled me there, since it seems that it is possible to unload their acpi related, and therefore having it call
acpi_bus_unregister_driver(); however, as far as I can tell, the serial port itself is still being used by the serial driver. This
is why I'm not quite sure about the relationship between a regular linux driver, and the acpi subsystem.
So, any pointers would be appreciated.

Thanks.


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Re: Where can I find some documentation/examples?

[Matthew Wilcox]

On Wed, Jan 07, 2004 at 11:26:08PM -0500, Dino Klein wrote:
> I've taken a look at the serial driver's use of acpi in order to discover ports, and their resources (in kernel 2.6.0). One thing
> puzzled me there, since it seems that it is possible to unload their acpi related, and therefore having it call
> acpi_bus_unregister_driver(); however, as far as I can tell, the serial port itself is still being used by the serial driver. This
> is why I'm not quite sure about the relationship between a regular linux driver, and the acpi subsystem.
> So, any pointers would be appreciated.

You don't necessarily want to take that driver as a good example of
what's needed to write an ACPI driver.  Actually somebody else just
pointed out the same thing to me earlier today.  On the systems I work
on, I use serial console, so it's pretty much mandatory to have 8250
built in and hence the remove method never gets called ;-)

Take a look at something like the button driver instead.

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Re: Where can I find some documentation/examples?

[Dino Klein]

One comment about removing - I didn't mean calling the serial device's 
remove method in the ACPI namespace, but rather having the serial driver 
call serial_unregister() to release the resources.
I would think that if the driver unregisters from the acpi bus, then it 
should also release the resources, after all, wouldn't it be possible that 
after the driver unregisters with the acpi bus, yet still holds the 
resources, couldn't a second serial driver come along and register for the 
same type of devices, and get the same serial device that is already handled 
by the first serial driver?


>On Wed, Jan 07, 2004 at 11:26:08PM -0500, Dino Klein wrote:
> > I've taken a look at the serial driver's use of acpi in order to 
>discover ports, and their resources (in kernel 2.6.0). One thing
> > puzzled me there, since it seems that it is possible to unload their 
>acpi related, and therefore having it call
> > acpi_bus_unregister_driver(); however, as far as I can tell, the serial 
>port itself is still being used by the serial driver. This
> > is why I'm not quite sure about the relationship between a regular linux 
>driver, and the acpi subsystem.
> > So, any pointers would be appreciated.
>
>You don't necessarily want to take that driver as a good example of
>what's needed to write an ACPI driver.  Actually somebody else just
>pointed out the same thing to me earlier today.  On the systems I work
>on, I use serial console, so it's pretty much mandatory to have 8250
>built in and hence the remove method never gets called ;-)
>
>Take a look at something like the button driver instead.

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RE: Where can I find some documentation/examples?

[Yu, Luming]

> One comment about removing - I didn't mean calling the serial 
> device's 
> remove method in the ACPI namespace, but rather having the 
> serial driver 
> call serial_unregister() to release the resources.
> I would think that if the driver unregisters from the acpi 
> bus, then it 
> should also release the resources, after all, wouldn't it be 
> possible that 
> after the driver unregisters with the acpi bus, yet still holds the 
> resources, couldn't a second serial driver come along and 
> register for the 
> same type of devices, and get the same serial device that is 
> already handled 
> by the first serial driver?
> 

As for resources management, ACPI seems to just let other
driver know the resources configuration. So you cannot count 
on acpi for that purpose.


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