On 1/25/24 5:01 AM, Théo Lebrun wrote:
Hello,
On Thu Jan 25, 2024 at 8:51 AM CET, Krzysztof Kozlowski wrote:
On 24/01/2024 16:14, Rob Herring wrote:
+
+ pinctrl-b {
+ compatible = "mobileye,eyeq5-b-pinctrl";
+ #pinctrl-cells = <1>;
+ };
+ };
This can all be simplified to:
system-controller@e00000 {
compatible = "mobileye,eyeq5-olb", "syscon";
reg = <0xe00000 0x400>;
#reset-cells = <2>;
#clock-cells = <1>;
clocks = <&xtal>;
clock-names = "ref";
pins { ... };
};
There is no need for sub nodes unless you have reusable blocks or each
block has its own resources in DT.
Yes, however I believe there should be resources here: each subnode
should get its address space. This is a bit tied to implementation,
which currently assumes "everyone can fiddle with everything" in this block.
Theo, can you draw memory map?
It would be a mess. I've counted things up. The first 147 registers are
used in this 0x400 block. There are 31 individual blocks, with 7
registers unused (holes to align next block).
Functions are reset, clocks, LBIST, MBIST, DDR control, GPIO,
accelerator control, CPU entrypoint, PDTrace, IRQs, chip info & ID
stuff, control registers for PCIe / eMMC / Eth / SGMII / DMA / etc.
Some will never get used from Linux, others might. Maybe a moderate
approach would be to create ressources for major blocks and make it
evolve organically, without imposing that all uses lead to a new
ressource creation.
That is usually how nodes are added to DT. If you modeled this
system-controller space as a "simple-bus" instead of a "syscon"
device, you could add nodes as you implement them. Rather than
all at once as you have to by treating this space as one large
blob device.
Andrew
Thanks,
--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
