140 lines
5.6 KiB
Plaintext
140 lines
5.6 KiB
Plaintext
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.
|
|
|
|
Optional Properties:
|
|
--------------------
|
|
- ti,mbox-send-noirq: Quirk flag to allow the client user of this sub-mailbox
|
|
to send messages without triggering a Tx ready interrupt,
|
|
and to control the Tx ticker. Should be used only on
|
|
sub-mailboxes used to communicate with WkupM3 remote
|
|
processor on AM33xx/AM43xx SoCs.
|
|
|
|
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>;
|
|
};
|
|
};
|