firmware: Add basic support for TI System Control Interface (TI SCI) protocol

Texas Instrument's System Control Interface (TI SCI) message protocol is
used in Texas Instrument's System on Chip (SoC) such as those in the K3
family AM654 SoC to communicate between various compute processors with
a central system controller entity.

The TI SCI message protocol provides support for management of various
hardware entities within the SoC. Add support driver to allow
communication with system controller entity within the SoC using the
mailbox client.

This is mostly derived from the TI SCI driver in Linux located at
drivers/firmware/ti_sci.c.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/doc/device-tree-bindings/firmware/ti,sci.txt b/doc/device-tree-bindings/firmware/ti,sci.txt
new file mode 100644
index 0000000000..4d40d0dcb6
--- /dev/null
+++ b/doc/device-tree-bindings/firmware/ti,sci.txt
@@ -0,0 +1,76 @@
+Texas Instruments System Control Interface (TI-SCI) Message Protocol
+--------------------------------------------------------------------
+
+Texas Instrument's processors including those belonging to Keystone generation
+of processors have separate hardware entity which is now responsible for the
+management of the System on Chip (SoC) system. These include various system
+level functions as well.
+
+An example of such an SoC is K2G, which contains the system control hardware
+block called Power Management Micro Controller (PMMC). This hardware block is
+initialized early into boot process and provides services to Operating Systems
+on multiple processors including ones running Linux.
+
+See http://processors.wiki.ti.com/index.php/TISCI for protocol definition.
+
+TI-SCI controller Device Node:
+=============================
+
+The TI-SCI node describes the Texas Instrument's System Controller entity node.
+This parent node may optionally have additional children nodes which describe
+specific functionality such as clocks, power domain, reset or additional
+functionality as may be required for the SoC. This hierarchy also describes the
+relationship between the TI-SCI parent node to the child node.
+
+Required properties:
+-------------------
+- compatible: should be "ti,k2g-sci"
+- mbox-names:
+	"rx" - Mailbox corresponding to receive path
+	"tx" - Mailbox corresponding to transmit path
+
+- mboxes: Mailboxes corresponding to the mbox-names. 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.
+
+Optional Properties:
+-------------------
+- reg-names:
+	debug_messages - Map the Debug message region
+- reg:  register space corresponding to the debug_messages
+- ti,system-reboot-controller: If system reboot can be triggered by SoC reboot
+- ti,secure-host: If the host is defined as secure.
+
+Example:
+-------------
+	dmsc: dmsc {
+		compatible = "ti,k2g-sci";
+		ti,host-id = <12>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+	}
+
+
+TI-SCI Client Device Node:
+=========================
+
+Client nodes are maintained as children of the relevant TI-SCI device node.
+
+Example:
+-------------
+	dmsc: dmsc {
+		compatible = "ti,k2g-sci";
+		...
+
+		my_clk_node: clk_node {
+			...
+			...
+		};
+
+		my_pd_node: pd_node {
+			...
+			...
+		};
+	};