Il 19/01/24 07:32, Jason-JH.Lin ha scritto:
Add mediatek,gce-props.yaml for common GCE properties that is used for both mailbox providers and consumers. We place the common property "mediatek,gce-events" in this binding currently. The property "mediatek,gce-events" is used for GCE event ID corresponding to a hardware event signal sent by the hardware or a sofware driver. If the mailbox providers or consumers want to manipulate the value of the event ID, they need to know the specific event ID. Signed-off-by: Jason-JH.Lin <jason-jh.lin@xxxxxxxxxxxx> --- .../bindings/mailbox/mediatek,gce-props.yaml | 52 +++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 Documentation/devicetree/bindings/mailbox/mediatek,gce-props.yaml diff --git a/Documentation/devicetree/bindings/mailbox/mediatek,gce-props.yaml b/Documentation/devicetree/bindings/mailbox/mediatek,gce-props.yaml new file mode 100644 index 000000000000..68b519ff089f --- /dev/null +++ b/Documentation/devicetree/bindings/mailbox/mediatek,gce-props.yaml @@ -0,0 +1,52 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/mailbox/mediatek,gce-props.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: MediaTek Global Command Engine Common Propertes + +maintainers: + - Houlong Wei <houlong.wei@xxxxxxxxxxxx> + +description: + The Global Command Engine (GCE) is an instruction based, multi-threaded, + single-core command dispatcher for MediaTek hardware. The Command Queue + (CMDQ) mailbox driver is a driver for GCE, implemented using the Linux + mailbox framework. It is used to receive messages from mailbox consumers + and configure GCE to execute the specified instruction set in the message. + We use mediatek,gce-mailbox.yaml to define the properties for CMDQ mailbox + driver. A device driver that uses the CMDQ driver to configure its hardware + registers is a mailbox consumer. The mailbox consumer can request a mailbox + channel corresponding to a GCE hardware thread to send a message, specifying + that the GCE thread to configure its hardware. The mailbox provider can also + reserved a mailbox channel to configure GCE hardware register by the spcific + GCE thread. This binding defines the common GCE properties for both mailbox + provider and consumers. + +properties: + mediatek,gce-events: + description: + GCE has an event table in SRAM, consisting of 1024 event IDs (0~1023). + Each event ID has a boolean event value with the default value 0. + The property mediatek,gce-events is used to obtain the event IDs. + Some gce-events are hardware-bound and cannot be changed by software. + For instance, in MT8195, when VDO0_MUTEX is stream done, VDO_MUTEX will + send an event signal to GCE, setting the value of event ID 597 to 1. + Similarly, in MT8188, the value of event ID 574 will be set to 1 when + VOD0_MUTEX is stream done. + On the other hand, some gce-events are not hardware-bound and can be + changed by software. For example, in MT8188, we can set the value of + event ID 855, which is not bound to any hardware, to 1 when the driver + in the secure world completes a task. However, in MT8195, event ID 855 + is already bound to VDEC_LAT1, so we need to select another event ID to + achieve the same purpose. This event ID can be any ID that is not bound + to any hardware and is not yet used in any software driver. + To determine if the event ID is bound to the hardware or used by a + software driver, refer to the GCE header + include/dt-bindings/gce/<chip>-gce.h of each chip. + $ref: /schemas/types.yaml#/definitions/uint32-array + minItems: 1 + maxItems: 1024
maxItems: 1024 seems to be a bit too many... this means that one devicetree node may have up to 1024 gce events, which is impossible! If a driver needed all of the 1024 events, this means that it's not an user of the GCE, but the GCE itself! Imagine seeing a devicetree node with 1024 array entries for mediatek,gce-events... I'd set that to a more sensible value of 32 - eventually we can extend it later, if ever needed. Besides, nice job about all this documentation of the GCE and its events: love it! Cheers, Angelo
