summaryrefslogtreecommitdiffstats
path: root/Documentation/devicetree/bindings/fsi
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
commit76cb841cb886eef6b3bee341a2266c76578724ad (patch)
treef5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /Documentation/devicetree/bindings/fsi
parentInitial commit. (diff)
downloadlinux-76cb841cb886eef6b3bee341a2266c76578724ad.tar.xz
linux-76cb841cb886eef6b3bee341a2266c76578724ad.zip
Adding upstream version 4.19.249.upstream/4.19.249upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'Documentation/devicetree/bindings/fsi')
-rw-r--r--Documentation/devicetree/bindings/fsi/fsi-master-ast-cf.txt36
-rw-r--r--Documentation/devicetree/bindings/fsi/fsi-master-gpio.txt28
-rw-r--r--Documentation/devicetree/bindings/fsi/fsi.txt156
3 files changed, 220 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/fsi/fsi-master-ast-cf.txt b/Documentation/devicetree/bindings/fsi/fsi-master-ast-cf.txt
new file mode 100644
index 000000000..3dc752db7
--- /dev/null
+++ b/Documentation/devicetree/bindings/fsi/fsi-master-ast-cf.txt
@@ -0,0 +1,36 @@
+Device-tree bindings for ColdFire offloaded gpio-based FSI master driver
+------------------------------------------------------------------------
+
+Required properties:
+ - compatible =
+ "aspeed,ast2400-cf-fsi-master" for an AST2400 based system
+ or
+ "aspeed,ast2500-cf-fsi-master" for an AST2500 based system
+
+ - clock-gpios = <gpio-descriptor>; : GPIO for FSI clock
+ - data-gpios = <gpio-descriptor>; : GPIO for FSI data signal
+ - enable-gpios = <gpio-descriptor>; : GPIO for enable signal
+ - trans-gpios = <gpio-descriptor>; : GPIO for voltage translator enable
+ - mux-gpios = <gpio-descriptor>; : GPIO for pin multiplexing with other
+ functions (eg, external FSI masters)
+ - memory-region = <phandle>; : Reference to the reserved memory for
+ the ColdFire. Must be 2M aligned on
+ AST2400 and 1M aligned on AST2500
+ - aspeed,sram = <phandle>; : Reference to the SRAM node.
+ - aspeed,cvic = <phandle>; : Reference to the CVIC node.
+
+Examples:
+
+ fsi-master {
+ compatible = "aspeed,ast2500-cf-fsi-master", "fsi-master";
+
+ clock-gpios = <&gpio 0>;
+ data-gpios = <&gpio 1>;
+ enable-gpios = <&gpio 2>;
+ trans-gpios = <&gpio 3>;
+ mux-gpios = <&gpio 4>;
+
+ memory-region = <&coldfire_memory>;
+ aspeed,sram = <&sram>;
+ aspeed,cvic = <&cvic>;
+ }
diff --git a/Documentation/devicetree/bindings/fsi/fsi-master-gpio.txt b/Documentation/devicetree/bindings/fsi/fsi-master-gpio.txt
new file mode 100644
index 000000000..1e4424507
--- /dev/null
+++ b/Documentation/devicetree/bindings/fsi/fsi-master-gpio.txt
@@ -0,0 +1,28 @@
+Device-tree bindings for gpio-based FSI master driver
+-----------------------------------------------------
+
+Required properties:
+ - compatible = "fsi-master-gpio";
+ - clock-gpios = <gpio-descriptor>; : GPIO for FSI clock
+ - data-gpios = <gpio-descriptor>; : GPIO for FSI data signal
+
+Optional properties:
+ - enable-gpios = <gpio-descriptor>; : GPIO for enable signal
+ - trans-gpios = <gpio-descriptor>; : GPIO for voltage translator enable
+ - mux-gpios = <gpio-descriptor>; : GPIO for pin multiplexing with other
+ functions (eg, external FSI masters)
+ - no-gpio-delays; : Don't add extra delays between GPIO
+ accesses. This is useful when the HW
+ GPIO block is running at a low enough
+ frequency.
+
+Examples:
+
+ fsi-master {
+ compatible = "fsi-master-gpio", "fsi-master";
+ clock-gpios = <&gpio 0>;
+ data-gpios = <&gpio 1>;
+ enable-gpios = <&gpio 2>;
+ trans-gpios = <&gpio 3>;
+ mux-gpios = <&gpio 4>;
+ }
diff --git a/Documentation/devicetree/bindings/fsi/fsi.txt b/Documentation/devicetree/bindings/fsi/fsi.txt
new file mode 100644
index 000000000..afb4eccab
--- /dev/null
+++ b/Documentation/devicetree/bindings/fsi/fsi.txt
@@ -0,0 +1,156 @@
+FSI bus & engine generic device tree bindings
+=============================================
+
+The FSI bus is probe-able, so the OS is able to enumerate FSI slaves, and
+engines within those slaves. However, we have a facility to match devicetree
+nodes to probed engines. This allows for fsi engines to expose non-probeable
+busses, which are then exposed by the device tree. For example, an FSI engine
+that is an I2C master - the I2C bus can be described by the device tree under
+the engine's device tree node.
+
+FSI masters may require their own DT nodes (to describe the master HW itself);
+that requirement is defined by the master's implementation, and is described by
+the fsi-master-* binding specifications.
+
+Under the masters' nodes, we can describe the bus topology using nodes to
+represent the FSI slaves and their slave engines. As a basic outline:
+
+ fsi-master {
+ /* top-level of FSI bus topology, bound to an FSI master driver and
+ * exposes an FSI bus */
+
+ fsi-slave@<link,id> {
+ /* this node defines the FSI slave device, and is handled
+ * entirely with FSI core code */
+
+ fsi-slave-engine@<addr> {
+ /* this node defines the engine endpoint & address range, which
+ * is bound to the relevant fsi device driver */
+ ...
+ };
+
+ fsi-slave-engine@<addr> {
+ ...
+ };
+
+ };
+ };
+
+Note that since the bus is probe-able, some (or all) of the topology may
+not be described; this binding only provides an optional facility for
+adding subordinate device tree nodes as children of FSI engines.
+
+FSI masters
+-----------
+
+FSI master nodes declare themselves as such with the "fsi-master" compatible
+value. It's likely that an implementation-specific compatible value will
+be needed as well, for example:
+
+ compatible = "fsi-master-gpio", "fsi-master";
+
+Since the master nodes describe the top-level of the FSI topology, they also
+need to declare the FSI-standard addressing scheme. This requires two cells for
+addresses (link index and slave ID), and no size:
+
+ #address-cells = <2>;
+ #size-cells = <0>;
+
+An optional boolean property can be added to indicate that a particular master
+should not scan for connected devices at initialization time. This is
+necessary in cases where a scan could cause arbitration issues with other
+masters that may be present on the bus.
+
+ no-scan-on-init;
+
+FSI slaves
+----------
+
+Slaves are identified by a (link-index, slave-id) pair, so require two cells
+for an address identifier. Since these are not a range, no size cells are
+required. For an example, a slave on link 1, with ID 2, could be represented
+as:
+
+ cfam@1,2 {
+ reg = <1 2>;
+ [...];
+ }
+
+Each slave provides an address-space, under which the engines are accessible.
+That address space has a maximum of 23 bits, so we use one cell to represent
+addresses and sizes in the slave address space:
+
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+Optionally, a slave can provide a global unique chip ID which is used to
+identify the physical location of the chip in a system specific way
+
+ chip-id = <0>;
+
+FSI engines (devices)
+---------------------
+
+Engines are identified by their address under the slaves' address spaces. We
+use a single cell for address and size. Engine nodes represent the endpoint
+FSI device, and are passed to those FSI device drivers' ->probe() functions.
+
+For example, for a slave using a single 0x400-byte page starting at address
+0xc00:
+
+ engine@c00 {
+ reg = <0xc00 0x400>;
+ };
+
+
+Full example
+------------
+
+Here's an example that illustrates:
+ - an FSI master
+ - connected to an FSI slave
+ - that contains an engine that is an I2C master
+ - connected to an I2C EEPROM
+
+The FSI master may be connected to additional slaves, and slaves may have
+additional engines, but they don't necessarily need to be describe in the
+device tree if no extra platform information is required.
+
+ /* The GPIO-based FSI master node, describing the top level of the
+ * FSI bus
+ */
+ gpio-fsi {
+ compatible = "fsi-master-gpio", "fsi-master";
+ #address-cells = <2>;
+ #size-cells = <0>;
+
+ /* A FSI slave (aka. CFAM) at link 0, ID 0. */
+ cfam@0,0 {
+ reg = <0 0>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ chip-id = <0>;
+
+ /* FSI engine at 0xc00, using a single page. In this example,
+ * it's an I2C master controller, so subnodes describe the
+ * I2C bus.
+ */
+ i2c-controller@c00 {
+ reg = <0xc00 0x400>;
+
+ /* Engine-specific data. In this case, we're describing an
+ * I2C bus, so we're conforming to the generic I2C binding
+ */
+ compatible = "some-vendor,fsi-i2c-controller";
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+ /* I2C endpoint device: an Atmel EEPROM */
+ eeprom@50 {
+ compatible = "atmel,24c256";
+ reg = <0x50>;
+ pagesize = <64>;
+ };
+ };
+ };
+ };