Add bindings for the ARM MHUv3 Mailbox controller. Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx> --- v1 -> v2 - clarified extension descriptions around configurability and discoverability - removed unused labels from the example - using pattern properties to define interrupt-names - bumped interrupt maxItems to 74 (allowing uo to 8 channels per extension) --- .../bindings/mailbox/arm,mhuv3.yaml | 217 ++++++++++++++++++ 1 file changed, 217 insertions(+) create mode 100644 Documentation/devicetree/bindings/mailbox/arm,mhuv3.yaml diff --git a/Documentation/devicetree/bindings/mailbox/arm,mhuv3.yaml b/Documentation/devicetree/bindings/mailbox/arm,mhuv3.yaml new file mode 100644 index 000000000000..d781045521da --- /dev/null +++ b/Documentation/devicetree/bindings/mailbox/arm,mhuv3.yaml @@ -0,0 +1,217 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/mailbox/arm,mhuv3.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: ARM MHUv3 Mailbox Controller + +maintainers: + - Sudeep Holla <sudeep.holla@xxxxxxx> + - Cristian Marussi <cristian.marussi@xxxxxxx> + +description: | + The Arm Message Handling Unit (MHU) Version 3 is a mailbox controller that + enables unidirectional communications with remote processors through various + possible transport protocols. + The controller can optionally support a varying number of extensions that, in + turn, enable different kinds of transport to be used for communication. + Number, type and characteristics of each supported extension can be discovered + dynamically at runtime. + + Given the unidirectional nature of the controller, an MHUv3 mailbox controller + is composed of a MHU Sender (MHUS) containing a PostBox (PBX) block and a MHU + Receiver (MHUR) containing a MailBox (MBX) block, where + + PBX is used to + - Configure the MHU + - Send Transfers to the Receiver + - Optionally receive acknowledgment of a Transfer from the Receiver + + MBX is used to + - Configure the MHU + - Receive Transfers from the Sender + - Optionally acknowledge Transfers sent by the Sender + + Both PBX and MBX need to be present and defined in the DT description if you + need to establish a bidirectional communication, since you will have to + acquire two distinct unidirectional channels, one for each block. + + As a consequence both blocks needs to be represented separately and specified + as distinct DT nodes in order to properly describe their resources. + + Note that, though, thanks to the runtime discoverability, there is no need to + identify the type of blocks with distinct compatibles. + + Following are the MHUv3 possible extensions. + + - Doorbell Extension (DBE): DBE defines a type of channel called a Doorbell + Channel (DBCH). DBCH enables a single bit Transfer to be sent from the + Sender to Receiver. The Transfer indicates that an event has occurred. + When DBE is implemented, the number of DBCHs that an implementation of the + MHU can support is between 1 and 128, numbered starting from 0 in ascending + order and discoverable at run-time. + Each DBCH contains 32 individual fields, referred to as flags, each of which + can be used independently. It is possible for the Sender to send multiple + Transfers at once using a single DBCH, so long as each Transfer uses + a different flag in the DBCH. + Optionally, data may be transmitted through an out-of-band shared memory + region, wherein the MHU Doorbell is used strictly as an interrupt generation + mechanism, but this is out of the scope of these bindings. + + - FastChannel Extension (FCE): FCE defines a type of channel called a Fast + Channel (FCH). FCH is intended for lower overhead communication between + Sender and Receiver at the expense of determinism. An FCH allows the Sender + to update the channel value at any time, regardless of whether the previous + value has been seen by the Receiver. When the Receiver reads the channel's + content it gets the last value written to the channel. + FCH is considered lossy in nature, and means that the Sender has no way of + knowing if, or when, the Receiver will act on the Transfer. + FCHs are expected to behave as RAM which generates interrupts when writes + occur to the locations within the RAM. + When FCE is implemented, the number of FCHs that an implementation of the + MHU can support is between 1-1024, if the FastChannel word-size is 32-bits, + or between 1-512, when the FastChannel word-size is 64-bits. + FCHs are numbered from 0 in ascending order. + Note that the number of FCHs and the word-size are implementation defined, + not configurable but discoverable at run-time. + Optionally, data may be transmitted through an out-of-band shared memory + region, wherein the MHU FastChannel is used as an interrupt generation + mechanism which carries also a pointer to such out-of-band data, but this + is out of the scope of these bindings. + + - FIFO Extension (FE): FE defines a Channel type called a FIFO Channel (FFCH). + FFCH allows a Sender to send + - Multiple Transfers to the Receiver without having to wait for the + previous Transfer to be acknowledged by the Receiver, as long as the + FIFO has room for the Transfer. + - Transfers which require the Receiver to provide acknowledgment. + - Transfers which have in-band payload. + In all cases, the data is guaranteed to be observed by the Receiver in the + same order which the Sender sent it. + When FE is implemented, the number of FFCHs that an implementation of the + MHU can support is between 1 and 64, numbered starting from 0 in ascending + order. The number of FFCHs, their depth (same for all implemented FFCHs) and + the access-granularity are implementation defined, not configurable but + discoverable at run-time. + Optionally, additional data may be transmitted through an out-of-band shared + memory region, wherein the MHU FIFO is used to transmit, in order, a small + part of the payload (like a header) and a reference to the shared memory + area holding the remaining, bigger, chunk of the payload, but this is out of + the scope of these bindings. + +properties: + compatible: + const: arm,mhuv3 + + reg: + maxItems: 1 + + interrupts: + minItems: 1 + maxItems: 74 + + interrupt-names: + description: | + The MHUv3 controller generates a number of events some of which are used + to generate interrupts; as a consequence it can expose a varying number of + optional PBX/MBX interrupts, representing the events generated during the + operation of the various transport protocols associated with different + extensions. All interrupts of the MHU are level-sensitive. + Some of these optional interrupts are defined per-channel, where the + number of channels effectively available is implementation defined and + run-time discoverable. + In the following names are enumerated using patterns, with per-channel + interrupts implicitly capped at the maximum channels allowed by the + specification for each extension type. + For the sake of simplicity maxItems is anyway capped to a most plausible + number, assuming way less channels would be implemented than actually + possible. + + The only mandatory interrupts on the MHU are: + - combined + - mbx-fch-xfer-<N> but only if mbx-fcgrp-xfer-<N> is not implemented. + + minItems: 1 + maxItems: 74 + items: + oneOf: + - const: combined + description: PBX/MBX Combined interrupt + - const: combined-ffch + description: PBX/MBX FIFO Combined interrupt + - pattern: '^ffch-low-tide-[0-9]+$' + description: PBX/MBX FIFO Channel <N> Low Tide interrupt + - pattern: '^ffch-high-tide-[0-9]+$' + description: PBX/MBX FIFO Channel <N> High Tide interrupt + - pattern: '^ffch-flush-[0-9]+$' + description: PBX/MBX FIFO Channel <N> Flush interrupt + - pattern: '^mbx-dbch-xfer-[0-9]+$' + description: MBX Doorbell Channel <N> Transfer interrupt + - pattern: '^mbx-fch-xfer-[0-9]+$' + description: MBX FastChannel <N> Transfer interrupt + - pattern: '^mbx-fchgrp-xfer-[0-9]+$' + description: MBX FastChannel <N> Group Transfer interrupt + - pattern: '^mbx-ffch-xfer-[0-9]+$' + description: MBX FIFO Channel <N> Transfer interrupt + - pattern: '^pbx-dbch-xfer-ack-[0-9]+$' + description: PBX Doorbell Channel <N> Transfer Ack interrupt + - pattern: '^pbx-ffch-xfer-ack-[0-9]+$' + description: PBX FIFO Channel <N> Transfer Ack interrupt + + '#mbox-cells': + description: | + The first argument in the consumers 'mboxes' property represents the + extension type, the second is for the channel number while the third + depends on extension type. + + Extension type for DBE is 0 and the third parameter represents the + doorbell flag number to use. + Extension type for FCE is 1, third parameter unused. + Extension type for FE is 2, third parameter unused. + + mboxes = <&mhu 0 0 5>; // DBE, Doorbell Channel Window 0, doorbell flag 5. + mboxes = <&mhu 0 1 7>; // DBE, Doorbell Channel Window 1, doorbell flag 7. + mboxes = <&mhu 1 0 0>; // FCE, FastChannel Window 0. + mboxes = <&mhu 1 3 0>; // FCE, FastChannel Window 3. + mboxes = <&mhu 2 1 0>; // FE, FIFO Channel Window 1. + mboxes = <&mhu 2 7 0>; // FE, FIFO Channel Window 7. + const: 3 + + clocks: + maxItems: 1 + +required: + - compatible + - reg + - interrupts + - interrupt-names + - '#mbox-cells' + +additionalProperties: false + +examples: + - | + soc { + #address-cells = <2>; + #size-cells = <2>; + + mailbox@2aaa0000 { + compatible = "arm,mhuv3"; + #mbox-cells = <3>; + reg = <0 0x2aaa0000 0 0x10000>; + clocks = <&clock 0>; + interrupt-names = "combined", "pbx-dbch-xfer-ack-1", + "ffch-high-tide-0"; + interrupts = <0 36 4>, <0 37 4>; + }; + + mailbox@2ab00000 { + compatible = "arm,mhuv3"; + #mbox-cells = <3>; + reg = <0 0x2aab0000 0 0x10000>; + clocks = <&clock 0>; + interrupt-names = "combined", "mbx-dbch-xfer-1", "ffch-low-tide-0"; + interrupts = <0 35 4>, <0 38 4>, <0 39 4>; + }; + }; -- 2.34.1
