Hi Rob,

-----Original Message-----
From: Rob Herring [mailto:robh at kernel.org]
Sent: Thursday, June 21, 2018 3:45 AM
To: A.s. Dong <aisheng.dong@nxp.com>
Cc: linux-arm-kernel at lists.infradead.org; dongas86 at gmail.com;
kernel at pengutronix.de; shawnguo at kernel.org; Fabio Estevam
[off-list ref]; dl-linux-imx [off-list ref]; Mark
Rutland [off-list ref]; devicetree at vger.kernel.org
Subject: Re: [PATCH V2 3/4] dt-bindings: arm: fsl: add scu binding doc

On Sun, Jun 17, 2018 at 08:49:48PM +0800, Dong Aisheng wrote:

quoted

The System Controller Firmware (SCFW) is a low-level system function
which runs on a dedicated Cortex-M core to provide power, clock, and
resource management. It exists on some i.MX8 processors. e.g. i.MX8QM
(QM, QP), and i.MX8QX (QXP, DX).

Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Fabio Estevam <redacted>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree at vger.kernel.org
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
---
v1->v2:
 * remove status
 * changed to mu1
---
 .../devicetree/bindings/arm/freescale/fsl,scu.txt  | 38
++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644
Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt

diff --git
a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
new file mode 100644
index 0000000..9b7c9fe

--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt

@@ -0,0 +1,38 @@
+NXP i.MX System Controller Firmware (SCFW)
+--------------------------------------------------------------------
+
+The System Controller Firmware (SCFW) is a low-level system function
+which runs on a dedicated Cortex-M core to provide power, clock, and
+resource management. It exists on some i.MX8 processors. e.g. i.MX8QM
+(QM, QP), and i.MX8QX (QXP, DX).
+
+The AP communicates with the SC using a multi-ported MU module found
+in the LSIO subsystem. The current definition of this MU module
+provides
+5 remote AP connections to the SC to support up to 5 execution
+environments (TZ, HV, standard Linux, etc.). The SC side of this MU
+module interfaces with the LSIO DSC IP bus. The SC firmware will
+communicate with this MU using the MSI bus.
+
+System Controller Device Node:
+=============================
+
+Required properties:
+-------------------
+- compatible: should be "fsl,imx8qxp-scu" or "fsl,imx8qm-scu"
+- fsl,mu: a phandle to the Message Unit used by SCU. Should be
+	  one of LSIO MU0~M4 for imx8qxp and imx8qm. Users need
+	  to make sure not use the one which is conflict with
+	  other execution environments. e.g. ATF.

Use the mailbox binding even if you don't use the mailbox subsystem.

Looks reasonable. Will change it.

BTW as I said before, the current mailbox binding fixed #mbox-cells to be
at least 1 which is not suitable for i.MX SCU MU as it has only one physical
channel.

I will cook a patch to update it to allow #mbox-cells = <0>.

If any issue please let me know.

Regards
Dong Aisheng

quoted

+
+Examples:
+--------
+lsio_mu1: mu at 5d1c0000 {
+	compatible = "fsl,imx8qxp-mu";
+	reg = <0x0 0x5d1c0000 0x0 0x10000>;
+	interrupts = <GIC_SPI 176 IRQ_TYPE_LEVEL_HIGH>; };
+
+scu {
+	compatible = "fsl,imx8qxp-scu";
+	fsl,mu = <&lsio_mu1>;
+};
--
2.7.4