> On 24.07.2015, at 06:09, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote:
>
> I think I'd expect the shared registers to be:
>
> bcm2835aux: misc@0x7e215000 {
> compatible = "brcm,bcm2835-aux";
> reg = <0x7e215000 0x08>;
> };
>
> There are two 4-byte registers outside the UART/SPI blocks, and the
> compatible value should reflect what the block is, not that Linux may
> use a syscon driver to implement the driver for it.
>
> In the client, I'd expect a more semantic naming for the reference;
> something like:
>
> brcm,aux = <&bcm2835aux 4>;
>
> brcm, since it's a custom/vendor-specific property. aux is the name of
> the object that's referenced. Packing the phandle and data together into
> a single property reduces the number of separate properties, and is a
> typical thing to do in a client of a service in DT.
So in the end you are saying we need a separate driver to get written
(because of ‘compatible = "brcm,bcm2835-aux”;’)
That is unless you would allow:
compatible = compatible = "brcm,bcm2835-aux”, “syscon”;
If this is not acceptable, then where should such a driver go in the
kernel tree?
It would essentially implement the following:
bcm2835aux_enable(dev, device-id);
bcm2835aux_disable(dev, device-id);
Which would just set/clean the bits in the register while holding a lock.
As an alternative: maybe we could implement it as an IRQ driver
and when the irq is requested for that device, then the HW-block gets
enabled automatically (and disabled when released).
That way we may not need to have a separate driver that would enable
the uart1, but it would be sufficient to configure it as follows:
uart1: uart@7e215040 {
compatible = "brcm,bcm2835-aux-uart", "ns16550";
reg = <0x7e215040 0x40>;
interrupts = <X 0>;
clock-frequency = <500000000>;
reg-shift = <2>;
no-loopback-test;
status = "disabled";
};
(taken from the foundation device-tree)
Please clarify
Thanks,
Martin--
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