Messages in this thread | | | From | Arnd Bergmann <> | Date | Thu, 21 Jan 2021 12:14:24 +0100 | Subject | Re: [RFC PATCH 6/7] arm64: kernel: Apple CPU start driver |
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On Wed, Jan 20, 2021 at 2:27 PM Mohamed Mediouni <mohamed.mediouni@caramail.com> wrote: > diff --git a/Documentation/devicetree/bindings/arm/cpus.yaml b/Documentation/devicetree/bindings/arm/cpus.yaml > index 14cd727d3c4b..a6ff8cb3db1e 100644 > --- a/Documentation/devicetree/bindings/arm/cpus.yaml > +++ b/Documentation/devicetree/bindings/arm/cpus.yaml > @@ -176,6 +176,7 @@ properties: > oneOf: > # On ARM v8 64-bit this property is required > - enum: > + - apple > - psci > - spin-table > # On ARM 32-bit systems this property is optional
This uses a very generic identifier for doing something that may be very specific to a particular SoC generation. It's going to be hard to decide what the right abstraction will be for long-term maintenance, so I'd recommend starting with a boot loader that implements spin-table for secondary startup, and getting back to this after more of the basic stuff works.
> +static int cpu_apple_start_prepare(unsigned int cpu) > +{ > + struct device_node *node; > + struct cpu_apple_start_info *info; > + > + info = per_cpu_ptr(&cpu_apple_start_info, cpu); > + > + if (info->pmgr_start && info->cputrc_rvbar && info->dbg_unlock) > + return 0; > + > + node = of_find_compatible_node(NULL, NULL, "apple,startcpu"); > + if (!node) { > + pr_err("%s: missing startcpu node in device tree.\n", __func__); > + return -EINVAL; > + }
Where is the binding documentation for this? The way you do a separate of_iomap() for each CPU suggests that this is not a great binding to start with. Are these perhaps just individual registers within a larger IP block in the end?
Arnd
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