Re: [RFC PATCH 4/5] firmware: smccc: register as platform driver

[Sudeep Holla <sudeep.holla@arm.com>]

On Fri, Dec 19, 2025 at 12:26:30AM -0800, Vedashree Vidwans wrote:
> 
> On 12/9/25 03:47, Sudeep Holla wrote:
> > On Mon, Dec 08, 2025 at 10:13:14PM +0000, Vedashree Vidwans wrote:
> > > - Update driver to be in-built kernel module. This will ensure driver is
> > > installed in kernel and would not require any user intervention.
> > > - Register the LFA driver as a platform driver corresponding to
> > > 'armhf000' device. The driver will be invoked when the device is
> > > detected on a platform.
> > > - Add functionality to register LFA interrupt in the driver probe().
> > > This LFA IRQ number will be retrived from the LFA device node.
> > > - On IRQ, driver will query FW component details and trigger activation
> > > of capable and pending FW component. The driver will loop to update FW
> > > component details after every successful FW component activation.
> > > - Mutex synchronization is implemented to avoid concurrent LFA updates
> > > through interrupt and sysfs interfaces.
> > > 
> > > Device node snippet from LFA spec[1]:
> > > fwu0 {
> > >      compatible = "arm,armhf000";
> > >      memory-region = <&fwu_payload>;
> > >      interrupt-parent = <&ic>;
> > >      interrupts = <0 100 1>; // SPI, Interrupt #100, Edge Rising
> > > };
> > > 
> > 
> > This will be gone in the latest beta of LFA, so please discuss and get
> > an agreement for the LFA device tree bindings.
> > 
> > We don't just use ACPI HID as devicetree compatibles. There are more
> > aligned with ACPI CID IIUC but I don't expect you to use ACPI CID just to
> > match DT compatible as ACPI HID will be defined for LFA.
> > 
> Thank you for your comment.
> Sorry I haven't completely understood the concern here. I am using the ACPI
> HID and device node compatible string provided by the LFA spec.

Yes I know, but take a look at updated specification please [1].

> Please find below ACPI and device tree node from the spec for reference.

Yes they are obsolete as they no longer align with the latest specification.

> In case the LFA spec is updated, I will revise the driver implementation.

Indeed, that is the expectation. That's exactly what I meant.

-- 
Regards,
Sudeep

[1] https://developer.arm.com/documentation/den0147/1-0bet1