Re: [RFC PATCH 1/3] UART: Add UART subsystem as a bus.

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Thu, Dec 06, 2012 at 07:36:35AM +0000, Zheng, Lv wrote:
> > > > The property should not be in any ACPI specific form or space - just
> > > > attach it directly to the tty from ACPI, DT, driver internal
> > > > knowledge, PCI id, whatever
> > >
> > > The only property that comes into mind is _HID/_CID (referring to the
> > > ACPI
> > > ID) that can be used by userspace to find out type of the device
> > > behind the UART port. I don't know what name would be generic enough
> > > for the property, though.
> > 
> > We just need a set of type names for the sysfs node I think "bluetooth", "ups",
> > "loconet", "serial", "modem", "cir" etc...
> 
> Hi, Mika
> 
> How is this handled in the i2c?

We match the I2C device to the driver using _HID/_CID in the kernel. There
is no userpace involved (except maybe loading the correct driver module).

> I think for OF, type can be filled as "bluetooth", "ups" and etc.
> But for ACPI, the type field of the i2c_board_info is filled as hid in your patches.
> Is this right?

Yes.

> Maybe I just need to add struct acpi_dev_node to the uart_board_info and
> let OF guys add of_node to it.  What's your opinion?

Well, in order to use any ACPI functions and PM you need to have
ACPI_HANDLE(dev) != NULL. If the best place to pass that handle is
uart_board_info (in analogy to i2c_board_info), then yes you should add it
there.