Re: [RFC 0/2]convert ACPI driver model to Linux driver model

[Dominik Brodowski <linux-X3ehHDuj6sIIGcDfoQAp7OTW4wlIGRCZ@public.gmane.org>]

Hi,

On Mon, Sep 12, 2005 at 01:22:22PM +0800, Shaohua Li wrote:
> I'm sending the patches out not for merging but for comments. The
> patches try to convert ACPI driver model to Linux driver model. 

Excellent.

> 1. in my mind, acpi should export two sets of info in sysfs. One is
> current namespace subsystem, it should just export the firmware info.
> All acpi device/drivers related info don't export here. The other is
> ACPI bus. It's similar with other buses like PCI bus.

However, there is no physical ACPI bus. Therefore, it shouldn't exist in
/sys/devices/ or /sys/bus/. If they are platform devices (devices which can be
poked at some iomem or ioport address, but aren't on any specific bus), they
should be registered as platform devices; if these are system devices
(core devices for basic operation; can live with IRQs off for suspend and 
resume, or even require that) they should be registered as system devices.

> 2. I regard all devices which don't belong to physical buses in the DSDT
> as ACPI bus devices. Ideally, PCI devices, PNP devices & other devices
> should bind them to their physical buses.

Yes, exactly.

> Since many devices listed in
> DSDT aren't in ACPI bus, this makes it impossible to convert current
> acpi driver model into Linux style.

Indeed. For each device, you need to decide which bus it resides on:
> (CPU is in the bus)

No, CPUs are already registered as system devices. ( /sys/devices/system/cpu/ )
Don't insert them twice into the device tree, please

>  So I'd like to remove the namespace hotplug interface later.
Indeed, let's focus on this stuff later on.

So, let's look at the devices and where they should be registered. In most
cases, it is just a guess on my side; system devices are suspended and
resumed with interrupts off; that most probably should be a decisive point
in this distinction.

+       "PNP0C09", /* EC */
-> system or platform, not sure...

+       "ACPI0003", /* AC */
-> platform

+       "PNP0C0F", /* Link */
-> system. Might this already be registered on some systems? I have
irqrouter, i8237 and i8259 in /sys/devices/system/

+       "PNP0C0A", /* battery */
-> platform

+       "PNP0C0C", "PNP0C0E", "PNP0C0D", "ACPI_FPB" ,"ACPI_FSB", /* button */
-> platform

+       "PNP0C0B", /* fan */
-> platform

+       "PNP0A03", /* PCI root */
-> system or platform, not sure either.... Please make sure that "pci0000:00" or
   whatever is registered as a child of this device.

+       ACPI_POWER_HID, /* power */
-> platform

+       ACPI_PROCESSOR_HID, /* CPU */
-> system, is already there...

+       ACPI_THERMAL_HID, /* thermal */
-> platform


Also, you might think about adding all these devices to "class ACPI".
/sys/class/acpi/ is perfectly valid; there you can add some common
infrastrucutre for _all_ ACPI-enumerated devices, rely on "class interface"
and other methods available.

Thanks,
	Dominik


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