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The OMAP mailbox driver and its existing clients (remoteproc
for OMAP4+) are adapted to use the generic mailbox framework.
The main changes for the adaptation are:
- The tasklet used for Tx is replaced with the state machine from
the generic mailbox framework. The workqueue used for processing
the received messages stays intact for minimizing the effects on
the OMAP mailbox clients.
- The existing exported client API, omap_mbox_get, omap_mbox_put and
omap_mbox_send_msg are deleted, as the framework provides equivalent
functionality. A OMAP-specific omap_mbox_request_channel is added
though to support non-DT way of requesting mailboxes.
- The OMAP mailbox driver is integrated with the mailbox framework
through the proper implementations of mbox_chan_ops, except for
.last_tx_done and .peek_data. The OMAP mailbox driver does not need
these ops, as it is completely interrupt driven.
- The OMAP mailbox driver uses a custom of_xlate controller ops that
allows phandles for the pargs specifier instead of indexing to avoid
any channel registration order dependencies.
- The new framework does not support multiple clients operating on a
single channel, so the reference counting logic is simplified.
- The remoteproc driver (current client) is adapted to use the new API.
The notifier callbacks used within this client is replaced with the
regular callbacks from the newer framework.
- The exported OMAP mailbox API are limited to omap_mbox_save_ctx,
omap_mbox_restore_ctx, omap_mbox_enable_irq & omap_mbox_disable_irq,
with the signature modified to take in the new mbox_chan handle instead
of the OMAP specific omap_mbox handle. The first 2 will be removed when
the OMAP mailbox driver is adapted to runtime_pm. The other exported
API omap_mbox_request_channel will be removed once existing legacy
users are converted to DT.
Signed-off-by: Suman Anna <s-anna@ti.com>
Cc: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
132 lines
5.2 KiB
Plaintext
132 lines
5.2 KiB
Plaintext
OMAP2+ Mailbox Driver
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=====================
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The OMAP mailbox hardware facilitates communication between different processors
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using a queued mailbox interrupt mechanism. The IP block is external to the
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various processor subsystems and is connected on an interconnect bus. The
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communication is achieved through a set of registers for message storage and
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interrupt configuration registers.
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Each mailbox IP block has a certain number of h/w fifo queues and output
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interrupt lines. An output interrupt line is routed to an interrupt controller
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within a processor subsystem, and there can be more than one line going to a
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specific processor's interrupt controller. The interrupt line connections are
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fixed for an instance and are dictated by the IP integration into the SoC
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(excluding the SoCs that have a Interrupt Crossbar IP). Each interrupt line is
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programmable through a set of interrupt configuration registers, and have a rx
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and tx interrupt source per h/w fifo. Communication between different processors
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is achieved through the appropriate programming of the rx and tx interrupt
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sources on the appropriate interrupt lines.
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The number of h/w fifo queues and interrupt lines dictate the usable registers.
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All the current OMAP SoCs except for the newest DRA7xx SoC has a single IP
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instance. DRA7xx has multiple instances with different number of h/w fifo queues
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and interrupt lines between different instances. The interrupt lines can also be
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routed to different processor sub-systems on DRA7xx as they are routed through
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the Crossbar, a kind of interrupt router/multiplexer.
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Mailbox Device Node:
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====================
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A Mailbox device node is used to represent a Mailbox IP instance within a SoC.
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The sub-mailboxes are represented as child nodes of this parent node.
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Required properties:
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--------------------
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- compatible: Should be one of the following,
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"ti,omap2-mailbox" for OMAP2420, OMAP2430 SoCs
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"ti,omap3-mailbox" for OMAP3430, OMAP3630 SoCs
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"ti,omap4-mailbox" for OMAP44xx, OMAP54xx, AM33xx,
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AM43xx and DRA7xx SoCs
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- reg: Contains the mailbox register address range (base
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address and length)
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- interrupts: Contains the interrupt information for the mailbox
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device. The format is dependent on which interrupt
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controller the OMAP device uses
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- ti,hwmods: Name of the hwmod associated with the mailbox
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- #mbox-cells: Common mailbox binding property to identify the number
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of cells required for the mailbox specifier. Should be
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1
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- ti,mbox-num-users: Number of targets (processor devices) that the mailbox
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device can interrupt
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- ti,mbox-num-fifos: Number of h/w fifo queues within the mailbox IP block
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Child Nodes:
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============
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A child node is used for representing the actual sub-mailbox device that is
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used for the communication between the host processor and a remote processor.
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Each child node should have a unique node name across all the different
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mailbox device nodes.
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Required properties:
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--------------------
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- ti,mbox-tx: sub-mailbox descriptor property defining a Tx fifo
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- ti,mbox-rx: sub-mailbox descriptor property defining a Rx fifo
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Sub-mailbox Descriptor Data
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---------------------------
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Each of the above ti,mbox-tx and ti,mbox-rx properties should have 3 cells of
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data that represent the following:
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Cell #1 (fifo_id) - mailbox fifo id used either for transmitting
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(ti,mbox-tx) or for receiving (ti,mbox-rx)
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Cell #2 (irq_id) - irq identifier index number to use from the parent's
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interrupts data. Should be 0 for most of the cases, a
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positive index value is seen only on mailboxes that have
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multiple interrupt lines connected to the MPU processor.
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Cell #3 (usr_id) - mailbox user id for identifying the interrupt line
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associated with generating a tx/rx fifo interrupt.
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Mailbox Users:
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==============
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A device needing to communicate with a target processor device should specify
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them using the common mailbox binding properties, "mboxes" and the optional
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"mbox-names" (please see Documentation/devicetree/bindings/mailbox/mailbox.txt
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for details). Each value of the mboxes property should contain a phandle to the
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mailbox controller device node and an args specifier that will be the phandle to
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the intended sub-mailbox child node to be used for communication. The equivalent
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"mbox-names" property value can be used to give a name to the communication channel
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to be used by the client user.
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Example:
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--------
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/* OMAP4 */
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mailbox: mailbox@4a0f4000 {
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compatible = "ti,omap4-mailbox";
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reg = <0x4a0f4000 0x200>;
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interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
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ti,hwmods = "mailbox";
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#mbox-cells = <1>;
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ti,mbox-num-users = <3>;
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ti,mbox-num-fifos = <8>;
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mbox_ipu: mbox_ipu {
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ti,mbox-tx = <0 0 0>;
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ti,mbox-rx = <1 0 0>;
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};
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mbox_dsp: mbox_dsp {
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ti,mbox-tx = <3 0 0>;
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ti,mbox-rx = <2 0 0>;
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};
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};
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dsp {
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...
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mboxes = <&mailbox &mbox_dsp>;
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...
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};
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/* AM33xx */
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mailbox: mailbox@480C8000 {
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compatible = "ti,omap4-mailbox";
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reg = <0x480C8000 0x200>;
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interrupts = <77>;
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ti,hwmods = "mailbox";
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#mbox-cells = <1>;
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ti,mbox-num-users = <4>;
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ti,mbox-num-fifos = <8>;
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mbox_wkupm3: wkup_m3 {
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ti,mbox-tx = <0 0 0>;
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ti,mbox-rx = <0 0 3>;
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};
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};
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