Re: [PATCH v5 1/4] dt-bindings: mailbox: Document Hi6220 mailbox driver

[Leo Yan]

Hi Rob,

Thanks for reviewing, please see below inline comments.

On Mon, Feb 01, 2016 at 08:08:28AM -0600, Rob Herring wrote:
> On Mon, Feb 01, 2016 at 09:34:44PM +0800, Leo Yan wrote:
> > Document DT binding for Hisilicon Hi6220 mailbox driver.
> > 
> > Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> > ---
> >  .../bindings/mailbox/hisilicon,hi6220-mailbox.txt  | 90 ++++++++++++++++++++++
> >  1 file changed, 90 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/mailbox/hisilicon,hi6220-mailbox.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/mailbox/hisilicon,hi6220-mailbox.txt b/Documentation/devicetree/bindings/mailbox/hisilicon,hi6220-mailbox.txt
> > new file mode 100644
> > index 0000000..96e6acc
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mailbox/hisilicon,hi6220-mailbox.txt
> > @@ -0,0 +1,90 @@
> > +Hisilicon Hi6220 Mailbox Driver
> > +===============================
> > +
> > +Hisilicon Hi6220 mailbox supports up to 32 channels. Each channel
> > +is unidirectional with a maximum message size of 8 words. I/O is
> > +performed using register access (there is no DMA) and the cell
> > +raises an interrupt when messages are received.
> > +
> > +Mailbox Device Node:
> > +====================
> > +
> > +Required properties:
> > +--------------------
> > +- compatible:		Shall be "hisilicon,hi6220-mbox"
> > +- reg:			Contains the mailbox register address range (base
> > +			address and length); the first item is for IPC
> > +			registers, the second item is shared buffer for
> > +			slots.
> > +- #mbox-cells		Common mailbox binding property to identify the number
> > +			of cells required for the mailbox specifier. Should be 1.
> > +- interrupts:		Contains the interrupt information for the mailbox
> > +			device. The format is dependent on which interrupt
> > +			controller the SoCs use.
> > +
> > +Optional Properties:
> > +--------------------
> > +- hi6220,mbox-tx-noirq: Flag to allow the client user of this mailbox driver
> > +			to send messages without triggering a TX completion
> > +			interrupt.
> 
> I don't think this belongs in DT. This should be a flag the client 
> driver sets when it sends messages.

The client driver can set "tx_block = true" so use this flag indicates
the client thread should be blocked until data is transmitted.

But low level mailbox driver can use two method to support "tx_block"
mode:
- One method is to avoid using interrupt and mailbox framework will
  poll with mailbox's idle flag which is set by remote processor
  automatically;
- Another method is to use interrupt to notify data has been
  transmitted and interrupt handler will call completion function to
  wake up blocked client thread;

So this flag is to distinguish these two different hardware mechanism.
Do you think this is make sense or have other suggestion?

> > +
> > +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:
> > +--------------------
> > +- hi6220,mbox-tx:	sub-mailbox descriptor property defining Tx channel
> > +- hi6220,mbox-rx:	sub-mailbox descriptor property defining Rx channel
> > +
> > +Sub-mailbox Descriptor Data
> > +---------------------------
> > +Each of the above hi6220,mbox-tx and hi6220,mbox-rx properties should have 3
> > +cells of data that represent the following:
> > +    Cell #1 (slot_id) - mailbox slot id used either for transmitting
> > +                        (hi6220,mbox-tx) or for receiving (hi6220,mbox-rx)
> > +    Cell #2 (dst_irq) - irq identifier index number which used by MCU.
> > +    Cell #3 (ack_irq) - irq identifier index number with generating a tx/rx
> > +                        interrupt to application processor, mailbox driver
> > +                        used this id to acknowledge interrupt.
> > +
> > +Example:
> > +--------
> > +
> > +	mailbox: mailbox@F7510000 {
> > +		#mbox-cells = <1>;
> > +		compatible = "hisilicon,hi6220-mbox";
> > +		reg = <0x0 0xF7510000 0x0 0x1000>, /* IPC_S */
> > +		      <0x0 0x06DFF800 0x0 0x0800>; /* Mailbox */
> > +		interrupt-parent = <&gic>;
> > +		interrupts = <GIC_SPI 94 IRQ_TYPE_LEVEL_HIGH>;
> > +		mbox_stub_clock: mbox_stub_clock {
> > +			hi6220,mbox-rx = <0 1 10>;
> > +			hi6220,mbox-tx = <1 0 11>;
> > +		};
> > +	};
> > +
> > +
> > +Mailbox client
> > +===============
> > +
> > +"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 second argument is the channel index. It must be 0 (hardware
> 
> 0? But the example has 1.

Will fix.

Thanks,
Leo Yan

> > +support only one channel). 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:
> > +--------
> > +
> > +	stub_clock: stub_clock {
> > +		compatible = "hisilicon,hi6220-stub-clk";
> > +		hisilicon,hi6220-clk-sram = <&sram>;
> > +		#clock-cells = <1>;
> > +		mbox-names = "mbox-tx";
> > +		mboxes = <&mailbox 1>;
> > +	};
> > -- 
> > 1.9.1
> >