[PATCH v3 2/5] powerpc: apm82181: create shared dtsi for APM bluestone

[Rob Herring]

On Sat, Sep 19, 2020 at 2:23 PM Christian Lamparter <chunkeey at gmail.com> wrote:
>
> On 2020-09-15 03:05, Rob Herring wrote:
> > On Sun, Sep 06, 2020 at 12:06:12AM +0200, Christian Lamparter wrote:
> >> This patch adds an DTSI-File that can be used by various device-tree
> >> files for APM82181-based devices.
> >>
> >> Some of the nodes (like UART, PCIE, SATA) are used by the uboot and
> >> need to stick with the naming-conventions of the old times'.
> >> I've added comments whenever this was the case.
> >>
> >> Signed-off-by: Chris Blake <chrisrblake93 at gmail.com>
> >> Signed-off-by: Christian Lamparter <chunkeey at gmail.com>
> >> ---
> >> rfc v1 -> v2:
> >>      - removed PKA (this CryptoPU will need driver)
> >>      - stick with compatibles, nodes, ... from either
> >>        Bluestone (APM82181) or Canyonlands (PPC460EX).
> >>      - add labels for NAND and NOR to help with access.
> >> v2 -> v3:
> >>      - nodename of pciex at d.... was changed to pcie at d..
> >>        due to upstream patch.
> >>      - use simple-bus on the ebc, opb and plb nodes
> >> ---
> >>   arch/powerpc/boot/dts/apm82181.dtsi | 466 ++++++++++++++++++++++++++++
> >>   1 file changed, 466 insertions(+)
> >>   create mode 100644 arch/powerpc/boot/dts/apm82181.dtsi
> >>
> >> diff --git a/arch/powerpc/boot/dts/apm82181.dtsi b/arch/powerpc/boot/dts/apm82181.dtsi
> >> new file mode 100644
> >> index 000000000000..60283430978d
> >> --- /dev/null
> >> +++ b/arch/powerpc/boot/dts/apm82181.dtsi
> >> @@ -0,0 +1,466 @@
> >> +// SPDX-License-Identifier: GPL-2.0-or-later
> >> +/*
> >> + * Device Tree template include for various APM82181 boards.
> >> + *
> >> + * The SoC is an evolution of the PPC460EX predecessor.
> >> + * This is why dt-nodes from the canyonlands EBC, OPB, USB,
> >> + * DMA, SATA, EMAC, ... ended up in here.
> >> + *
> >> + * Copyright (c) 2010, Applied Micro Circuits Corporation
> >> + * Author: Tirumala R Marri <tmarri at apm.com>,
> >> + *     Christian Lamparter <chunkeey at gmail.com>,
> >> + *     Chris Blake <chrisrblake93 at gmail.com>
> >> + */
> >> +
> >> +#include <dt-bindings/dma/dw-dmac.h>
> >> +#include <dt-bindings/input/input.h>
> >> +#include <dt-bindings/interrupt-controller/irq.h>
> >> +#include <dt-bindings/gpio/gpio.h>
> >> +
> >> +/ {
> >> +    #address-cells = <2>;
> >> +    #size-cells = <1>;
> >> +    dcr-parent = <&{/cpus/cpu at 0}>;
> >> +
> >> +    aliases {
> >> +            ethernet0 = &EMAC0; /* needed for BSP u-boot */
> >> +    };
> >> +
> >> +    cpus {
> >> +            #address-cells = <1>;
> >> +            #size-cells = <0>;
> >> +
> >> +            CPU0: cpu at 0 {
> >> +                    device_type = "cpu";
> >> +                    model = "PowerPC,apm82181";
> >
> > This doesn't match the existing bluestone dts file.
> >
> > Please separate any restructuring from changes.
>
>
> "I see" (I'm including your comment of the dt-binding as well).
>
> I'm getting the vibe that I better should not touch that bluestone.dts.

I don't know about that.

> An honestly, looking at the series and patches that the APM-engineers
> posted back in the day, I can see why this well is so poisoned... and
> stuff like SATA/AHBDMA/USB/GPIO/CPM/... was missing.
>
> As for the devices. In the spirit of Arnd Bergmann's post of
> <https://lkml.org/lkml/2020/3/30/195>
>
> |It would be nice to move over the the bluestone .dts to the apm82181.dtsi file
> |when that gets added, if only to ensure they use the same description for each
> |node, but that shouldn't stop the addition of the new file if that is needed for
> |distros to make use of a popular device.
> |I see a couple of additional files in openwrt.
>
> I mean I don't have the bluestone dev board, just the consumer devices.

This stuff is old enough, I'd guess no one cares about a dev board.
But we should figure that out and document that with any changes.

> Would it be possible to support those? I can start from a "skeleton" apm82181.dtsi
> This would just include CPU, Memory (SD-RAM+L2C+OCM), UIC (Interrupt-Controller),
> the PLB+OBP+EBC Busses and UART. Just enough to make a board "boot from ram".

This skeleton would be chunks moved over or duplicated? I don't think
we want 2 of the same thing.

The order I would go is split into an apm82181.dtsi with 0 changes to
the built dtb(s). Then make changes/additions you need. As far as
changes to existing bindings, it's only an ABI if someone notices.


Rob