| Message ID | 20210907145501.69161-3-sven@svenpeter.dev |
|---|---|
| State | New |
| Headers | show |
| Series | Apple Mailbox Controller support | expand |
> + - description: > + M3 mailboxes are an older variant with a slightly different MMIO > + interface still found on the M1. > + items: > + - const: apple,t8103-m3-mailbox Would be nice to document an example of where an M3 mailbox is found. > + interrupts: > + minItems: 4 > + items: > + - description: send fifo is empty interrupt > + - description: send fifo is not empty interrupt > + - description: receive fifo is empty interrupt > + - description: receive fifo is not empty interrupt > + > + interrupt-names: > + minItems: 4 > + items: > + - const: send-empty > + - const: send-not-empty > + - const: recv-empty > + - const: recv-not-empty If the names became not-constant the asprintf thing goes away, not sure that's better or worse. > + clocks: > + description: > + Reference to the clock gate phandle(s) if required for this mailbox. > + Optional since not all mailboxes are attached to a clock gate. Do we do anything with the clocks at this point?
On Tue, Sep 7, 2021, at 22:48, Alyssa Rosenzweig wrote: > > > > + - description: > > > > + M3 mailboxes are an older variant with a slightly different MMIO > > > > + interface still found on the M1. > > > > + items: > > > > + - const: apple,t8103-m3-mailbox > > > > > > Would be nice to document an example of where an M3 mailbox is found. > > > > Sure, I can add a comment that this is used for the coprocessor controlling Thunderbolt. > > That raises another issue ... how do we know the M3 code works at all > without TB support yet? It "looks" correct but some of the IRQ handling > stuff is nontrivial. Enabling the mailbox interface just requires a few clocks to be ungated. Then I injected messages manually to verify that the code works. In addition I also brought up parts of the Thunderbolt controller which then allowed the co-processor on the other end of the mailbox to boot. After that I was also able to successfully talk to that processor using the same protocol used by most other processors. > > > > > + interrupts: > > > > + minItems: 4 > > > > + items: > > > > + - description: send fifo is empty interrupt > > > > + - description: send fifo is not empty interrupt > > > > + - description: receive fifo is empty interrupt > > > > + - description: receive fifo is not empty interrupt > > > > + > > > > + interrupt-names: > > > > + minItems: 4 > > > > + items: > > > > + - const: send-empty > > > > + - const: send-not-empty > > > > + - const: recv-empty > > > > + - const: recv-not-empty > > > > > > If the names became not-constant the asprintf thing goes away, not sure > > > that's better or worse. > > > > I'm not sure I understand your comment here. This property just gives a name > > to the interrupts so that they can be referenced by that instead of a magic > > number between 0 and 4 in the driver. > > D'oh, right, retracted. (Both this comment and the corresponding comment > on the driver itself). Sorry about that. > > > > > + clocks: > > > > + description: > > > > + Reference to the clock gate phandle(s) if required for this mailbox. > > > > + Optional since not all mailboxes are attached to a clock gate. > > > > > > Do we do anything with the clocks at this point? > > > > > > > The device tree bindings describe the hardware (as best as we can without proper > > documentation) and some of these mailboxes have clock gates which need to be turned > > on before accessing their MMIO. This driver already tries to do that and works fine > > with the downstream clock driver(s) we have. > > Good enough for me, thanks for clarifying 👍 > > Commit r-b, though Rob will surely point out problems and I'll need to > rereview 😉 > Thanks! Sven
> From: Sven Peter <sven@svenpeter.dev> > Date: Tue, 7 Sep 2021 16:55:00 +0200 > > Apple mailbox controller are found on the M1 and are used for > communication with various co-processors. > > Signed-off-by: Sven Peter <sven@svenpeter.dev> > --- > .../bindings/mailbox/apple,mailbox.yaml | 81 +++++++++++++++++++ > MAINTAINERS | 1 + > 2 files changed, 82 insertions(+) > create mode 100644 Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml Reviewed-by: Mark Kettenis <kettenis@openbsd.org>
diff --git a/Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml b/Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml new file mode 100644 index 000000000000..360d8a162cc5 --- /dev/null +++ b/Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml @@ -0,0 +1,81 @@ +# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/mailbox/apple,mailbox.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Apple Mailbox Controller + +maintainers: + - Hector Martin <marcan@marcan.st> + - Sven Peter <sven@svenpeter.dev> + +description: + The Apple mailbox consists of two FIFOs used to exchange 64+32 bit + messages between the main CPU and a co-processor. Multiple instances + of this mailbox can be found on Apple SoCs. + One of the two FIFOs is used to send data to a co-processor while the other + FIFO is used for the other direction. + Various clients implement different IPC protocols based on these simple + messages and shared memory buffers. + +properties: + compatible: + oneOf: + - description: + ASC mailboxes are the most common variant found on the M1. + items: + - const: apple,t8103-asc-mailbox + + - description: + M3 mailboxes are an older variant with a slightly different MMIO + interface still found on the M1. + items: + - const: apple,t8103-m3-mailbox + + reg: + maxItems: 1 + + interrupts: + minItems: 4 + items: + - description: send fifo is empty interrupt + - description: send fifo is not empty interrupt + - description: receive fifo is empty interrupt + - description: receive fifo is not empty interrupt + + interrupt-names: + minItems: 4 + items: + - const: send-empty + - const: send-not-empty + - const: recv-empty + - const: recv-not-empty + + clocks: + description: + Reference to the clock gate phandle(s) if required for this mailbox. + Optional since not all mailboxes are attached to a clock gate. + + "#mbox-cells": + const: 0 + +required: + - compatible + - reg + - interrupts + - interrupt-names + - "#mbox-cells" + +additionalProperties: false + +examples: + - | + mailbox@77408000 { + compatible = "apple,t8103-asc-mailbox"; + reg = <0x77408000 0x4000>; + interrupts = <1 583 4>, <1 584 4>, <1 585 4>, <1 586 4>; + interrupt-names = "send-empty", "send-not-empty", + "recv-empty", "recv-not-empty"; + #mbox-cells = <0>; + }; diff --git a/MAINTAINERS b/MAINTAINERS index cad1289793db..47de27282c98 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -1720,6 +1720,7 @@ C: irc://irc.oftc.net/asahi-dev T: git https://github.com/AsahiLinux/linux.git F: Documentation/devicetree/bindings/arm/apple.yaml F: Documentation/devicetree/bindings/interrupt-controller/apple,aic.yaml +F: Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml F: Documentation/devicetree/bindings/pinctrl/apple,pinctrl.yaml F: arch/arm64/boot/dts/apple/ F: drivers/irqchip/irq-apple-aic.c
Apple mailbox controller are found on the M1 and are used for communication with various co-processors. Signed-off-by: Sven Peter <sven@svenpeter.dev> --- .../bindings/mailbox/apple,mailbox.yaml | 81 +++++++++++++++++++ MAINTAINERS | 1 + 2 files changed, 82 insertions(+) create mode 100644 Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml