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diff --git a/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt b/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt new file mode 100644 index 000000000..d1a043339 --- /dev/null +++ b/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt @@ -0,0 +1,131 @@ +OMAP2+ Mailbox Driver +===================== + +The OMAP mailbox hardware facilitates communication between different processors +using a queued mailbox interrupt mechanism. The IP block is external to the +various processor subsystems and is connected on an interconnect bus. The +communication is achieved through a set of registers for message storage and +interrupt configuration registers. + +Each mailbox IP block has a certain number of h/w fifo queues and output +interrupt lines. An output interrupt line is routed to an interrupt controller +within a processor subsystem, and there can be more than one line going to a +specific processor's interrupt controller. The interrupt line connections are +fixed for an instance and are dictated by the IP integration into the SoC +(excluding the SoCs that have a Interrupt Crossbar IP). Each interrupt line is +programmable through a set of interrupt configuration registers, and have a rx +and tx interrupt source per h/w fifo. Communication between different processors +is achieved through the appropriate programming of the rx and tx interrupt +sources on the appropriate interrupt lines. + +The number of h/w fifo queues and interrupt lines dictate the usable registers. +All the current OMAP SoCs except for the newest DRA7xx SoC has a single IP +instance. DRA7xx has multiple instances with different number of h/w fifo queues +and interrupt lines between different instances. The interrupt lines can also be +routed to different processor sub-systems on DRA7xx as they are routed through +the Crossbar, a kind of interrupt router/multiplexer. + +Mailbox Device Node: +==================== +A Mailbox device node is used to represent a Mailbox IP instance within a SoC. +The sub-mailboxes are represented as child nodes of this parent node. + +Required properties: +-------------------- +- compatible: Should be one of the following, + "ti,omap2-mailbox" for OMAP2420, OMAP2430 SoCs + "ti,omap3-mailbox" for OMAP3430, OMAP3630 SoCs + "ti,omap4-mailbox" for OMAP44xx, OMAP54xx, AM33xx, + AM43xx and DRA7xx SoCs +- reg: Contains the mailbox register address range (base + address and length) +- interrupts: Contains the interrupt information for the mailbox + device. The format is dependent on which interrupt + controller the OMAP device uses +- ti,hwmods: Name of the hwmod associated with the mailbox +- #mbox-cells: Common mailbox binding property to identify the number + of cells required for the mailbox specifier. Should be + 1 +- ti,mbox-num-users: Number of targets (processor devices) that the mailbox + device can interrupt +- ti,mbox-num-fifos: Number of h/w fifo queues within the mailbox IP block + +Child Nodes: +============ +A child node is used for representing the actual sub-mailbox device that is +used for the communication between the host processor and a remote processor. +Each child node should have a unique node name across all the different +mailbox device nodes. + +Required properties: +-------------------- +- ti,mbox-tx: sub-mailbox descriptor property defining a Tx fifo +- ti,mbox-rx: sub-mailbox descriptor property defining a Rx fifo + +Sub-mailbox Descriptor Data +--------------------------- +Each of the above ti,mbox-tx and ti,mbox-rx properties should have 3 cells of +data that represent the following: + Cell #1 (fifo_id) - mailbox fifo id used either for transmitting + (ti,mbox-tx) or for receiving (ti,mbox-rx) + Cell #2 (irq_id) - irq identifier index number to use from the parent's + interrupts data. Should be 0 for most of the cases, a + positive index value is seen only on mailboxes that have + multiple interrupt lines connected to the MPU processor. + Cell #3 (usr_id) - mailbox user id for identifying the interrupt line + associated with generating a tx/rx fifo interrupt. + +Mailbox Users: +============== +A device needing to communicate with a target processor device should specify +them using the common mailbox binding properties, "mboxes" and the optional +"mbox-names" (please see Documentation/devicetree/bindings/mailbox/mailbox.txt +for details). Each value of the mboxes property should contain a phandle to the +mailbox controller device node and an args specifier that will be the phandle to +the intended sub-mailbox child node to be used for communication. The equivalent +"mbox-names" property value can be used to give a name to the communication channel +to be used by the client user. + + +Example: +-------- + +/* OMAP4 */ +mailbox: mailbox@4a0f4000 { + compatible = "ti,omap4-mailbox"; + reg = <0x4a0f4000 0x200>; + interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>; + ti,hwmods = "mailbox"; + #mbox-cells = <1>; + ti,mbox-num-users = <3>; + ti,mbox-num-fifos = <8>; + mbox_ipu: mbox_ipu { + ti,mbox-tx = <0 0 0>; + ti,mbox-rx = <1 0 0>; + }; + mbox_dsp: mbox_dsp { + ti,mbox-tx = <3 0 0>; + ti,mbox-rx = <2 0 0>; + }; +}; + +dsp { + ... + mboxes = <&mailbox &mbox_dsp>; + ... +}; + +/* AM33xx */ +mailbox: mailbox@480C8000 { + compatible = "ti,omap4-mailbox"; + reg = <0x480C8000 0x200>; + interrupts = <77>; + ti,hwmods = "mailbox"; + #mbox-cells = <1>; + ti,mbox-num-users = <4>; + ti,mbox-num-fifos = <8>; + mbox_wkupm3: wkup_m3 { + ti,mbox-tx = <0 0 0>; + ti,mbox-rx = <0 0 3>; + }; +}; |