On Mon, Sep 2, 2019 at 2:39 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > On Wed, Aug 28, 2019 at 03:02:58AM +0000, Peng Fan wrote: > > From: Peng Fan <peng.fan@xxxxxxx> > > > > The ARM SMC/HVC mailbox binding describes a firmware interface to trigger > > actions in software layers running in the EL2 or EL3 exception levels. > > The term "ARM" here relates to the SMC instruction as part of the ARM > > instruction set, not as a standard endorsed by ARM Ltd. > > > > Signed-off-by: Peng Fan <peng.fan@xxxxxxx> > > --- > > .../devicetree/bindings/mailbox/arm-smc.yaml | 125 +++++++++++++++++++++ > > 1 file changed, 125 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/mailbox/arm-smc.yaml > > > > diff --git a/Documentation/devicetree/bindings/mailbox/arm-smc.yaml b/Documentation/devicetree/bindings/mailbox/arm-smc.yaml > > new file mode 100644 > > index 000000000000..f8eb28d5e307 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/mailbox/arm-smc.yaml > > @@ -0,0 +1,125 @@ > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/mailbox/arm-smc.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: ARM SMC Mailbox Interface > > + > > +maintainers: > > + - Peng Fan <peng.fan@xxxxxxx> > > + > > +description: | > > + This mailbox uses the ARM smc (secure monitor call) and hvc (hypervisor > > + call) instruction to trigger a mailbox-connected activity in firmware, > > + executing on the very same core as the caller. By nature this operation > > + is synchronous and this mailbox provides no way for asynchronous messages > > + to be delivered the other way round, from firmware to the OS, but > > + asynchronous notification could also be supported. However the value of > > + r0/w0/x0 the firmware returns after the smc call is delivered as a received > > + message to the mailbox framework, so a synchronous communication can be > > + established, for a asynchronous notification, no value will be returned. > > + The exact meaning of both the action the mailbox triggers as well as the > > + return value is defined by their users and is not subject to this binding. > > + > > + One use case of this mailbox is the SCMI interface, which uses shared memory > > + to transfer commands and parameters, and a mailbox to trigger a function > > + call. This allows SoCs without a separate management processor (or when > > + such a processor is not available or used) to use this standardized > > + interface anyway. > > + > > + This binding describes no hardware, but establishes a firmware interface. > > + Upon receiving an SMC using one of the described SMC function identifiers, > > + the firmware is expected to trigger some mailbox connected functionality. > > + The communication follows the ARM SMC calling convention. > > + Firmware expects an SMC function identifier in r0 or w0. The supported > > + identifiers are passed from consumers, or listed in the the arm,func-ids > > + properties as described below. The firmware can return one value in > > + the first SMC result register, it is expected to be an error value, > > + which shall be propagated to the mailbox client. > > + > > + Any core which supports the SMC or HVC instruction can be used, as long as > > + a firmware component running in EL3 or EL2 is handling these calls. > > + > > +properties: > > + compatible: > > + const: arm,smc-mbox > > + > > + "#mbox-cells": > > + const: 1 > > + > > + arm,num-chans: > > + description: The number of channels supported. > > + items: > > + minimum: 1 > > + maximum: 4096 # Should be enough? > > + > > + method: > > + - enum: > > Did you build this with 'make dt_binding_check' as this should be a > warning. This should not be a list entry (i.e. drop the '-'). > > > + - smc > > + - hvc > > + > > + transports: > > arm,transports > > > + - enum: > > + - mem > > + - reg > > + > > + arm,func-ids: > > + description: | > > + An array of 32-bit values specifying the function IDs used by each > > + mailbox channel. Those function IDs follow the ARM SMC calling > > + convention standard [1]. > > + > > + There is one identifier per channel and the number of supported > > + channels is determined by the length of this array. > > + $ref: /schemas/types.yaml#/definitions/uint32-array Also, this doesn't work. You need: allOf: - $ref: /schemas/types.yaml#/definitions/uint32-array > > + minItems: 0 > > + maxItems: 4096 # Should be enough?
