Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 186 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt
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+This binding is a work-in-progress, and are based on some experimental
+work by benh[1].
+
+Sources of clock signal can be represented by any node in the device
+tree.  Those nodes are designated as clock providers.  Clock consumer
+nodes use a phandle and clock specifier pair to connect clock provider
+outputs to clock inputs.  Similar to the gpio specifiers, a clock
+specifier is an array of zero, one or more cells identifying the clock
+output on a device.  The length of a clock specifier is defined by the
+value of a #clock-cells property in the clock provider node.
+
+[1] https://patchwork.ozlabs.org/patch/31551/
+
+==Clock providers==
+
+Required properties:
+#clock-cells:	   Number of cells in a clock specifier; Typically 0 for nodes
+		   with a single clock output and 1 for nodes with multiple
+		   clock outputs.
+
+Optional properties:
+clock-output-names: Recommended to be a list of strings of clock output signal
+		    names indexed by the first cell in the clock specifier.
+		    However, the meaning of clock-output-names is domain
+		    specific to the clock provider, and is only provided to
+		    encourage using the same meaning for the majority of clock
+		    providers.  This format may not work for clock providers
+		    using a complex clock specifier format.  In those cases it
+		    is recommended to omit this property and create a binding
+		    specific names property.
+
+		    Clock consumer nodes must never directly reference
+		    the provider's clock-output-names property.
+
+For example:
+
+    oscillator {
+        #clock-cells = <1>;
+        clock-output-names = "ckil", "ckih";
+    };
+
+- this node defines a device with two clock outputs, the first named
+  "ckil" and the second named "ckih".  Consumer nodes always reference
+  clocks by index. The names should reflect the clock output signal
+  names for the device.
+
+clock-indices:	   If the identifying number for the clocks in the node
+		   is not linear from zero, then this allows the mapping of
+		   identifiers into the clock-output-names array.
+
+For example, if we have two clocks <&oscillator 1> and <&oscillator 3>:
+
+	oscillator {
+		compatible = "myclocktype";
+		#clock-cells = <1>;
+		clock-indices = <1>, <3>;
+		clock-output-names = "clka", "clkb";
+	}
+
+	This ensures we do not have any empty strings in clock-output-names
+
+
+==Clock consumers==
+
+Required properties:
+clocks:		List of phandle and clock specifier pairs, one pair
+		for each clock input to the device.  Note: if the
+		clock provider specifies '0' for #clock-cells, then
+		only the phandle portion of the pair will appear.
+
+Optional properties:
+clock-names:	List of clock input name strings sorted in the same
+		order as the clocks property.  Consumers drivers
+		will use clock-names to match clock input names
+		with clocks specifiers.
+clock-ranges:	Empty property indicating that child nodes can inherit named
+		clocks from this node. Useful for bus nodes to provide a
+		clock to their children.
+
+For example:
+
+    device {
+        clocks = <&osc 1>, <&ref 0>;
+        clock-names = "baud", "register";
+    };
+
+
+This represents a device with two clock inputs, named "baud" and "register".
+The baud clock is connected to output 1 of the &osc device, and the register
+clock is connected to output 0 of the &ref.
+
+==Example==
+
+    /* external oscillator */
+    osc: oscillator {
+        compatible = "fixed-clock";
+        #clock-cells = <0>;
+        clock-frequency  = <32678>;
+        clock-output-names = "osc";
+    };
+
+    /* phase-locked-loop device, generates a higher frequency clock
+     * from the external oscillator reference */
+    pll: pll@4c000 {
+        compatible = "vendor,some-pll-interface"
+        #clock-cells = <1>;
+        clocks = <&osc 0>;
+        clock-names = "ref";
+        reg = <0x4c000 0x1000>;
+        clock-output-names = "pll", "pll-switched";
+    };
+
+    /* UART, using the low frequency oscillator for the baud clock,
+     * and the high frequency switched PLL output for register
+     * clocking */
+    uart@a000 {
+        compatible = "fsl,imx-uart";
+        reg = <0xa000 0x1000>;
+        interrupts = <33>;
+        clocks = <&osc 0>, <&pll 1>;
+        clock-names = "baud", "register";
+    };
+
+This DT fragment defines three devices: an external oscillator to provide a
+low-frequency reference clock, a PLL device to generate a higher frequency
+clock signal, and a UART.
+
+* The oscillator is fixed-frequency, and provides one clock output, named "osc".
+* The PLL is both a clock provider and a clock consumer. It uses the clock
+  signal generated by the external oscillator, and provides two output signals
+  ("pll" and "pll-switched").
+* The UART has its baud clock connected the external oscillator and its
+  register clock connected to the PLL clock (the "pll-switched" signal)
+
+==Assigned clock parents and rates==
+
+Some platforms may require initial configuration of default parent clocks
+and clock frequencies. Such a configuration can be specified in a device tree
+node through assigned-clocks, assigned-clock-parents and assigned-clock-rates
+properties. The assigned-clock-parents property should contain a list of parent
+clocks in the form of a phandle and clock specifier pair and the
+assigned-clock-rates property should contain a list of frequencies in Hz. Both
+these properties should correspond to the clocks listed in the assigned-clocks
+property.
+
+To skip setting parent or rate of a clock its corresponding entry should be
+set to 0, or can be omitted if it is not followed by any non-zero entry.
+
+    uart@a000 {
+        compatible = "fsl,imx-uart";
+        reg = <0xa000 0x1000>;
+        ...
+        clocks = <&osc 0>, <&pll 1>;
+        clock-names = "baud", "register";
+
+        assigned-clocks = <&clkcon 0>, <&pll 2>;
+        assigned-clock-parents = <&pll 2>;
+        assigned-clock-rates = <0>, <460800>;
+    };
+
+In this example the <&pll 2> clock is set as parent of clock <&clkcon 0> and
+the <&pll 2> clock is assigned a frequency value of 460800 Hz.
+
+Configuring a clock's parent and rate through the device node that consumes
+the clock can be done only for clocks that have a single user. Specifying
+conflicting parent or rate configuration in multiple consumer nodes for
+a shared clock is forbidden.
+
+Configuration of common clocks, which affect multiple consumer devices can
+be similarly specified in the clock provider node.
+
+==Protected clocks==
+
+Some platforms or firmwares may not fully expose all the clocks to the OS, such
+as in situations where those clks are used by drivers running in ARM secure
+execution levels. Such a configuration can be specified in device tree with the
+protected-clocks property in the form of a clock specifier list. This property should
+only be specified in the node that is providing the clocks being protected:
+
+   clock-controller@a000f000 {
+        compatible = "vendor,clk95;
+        reg = <0xa000f000 0x1000>
+        #clocks-cells = <1>;
+        ...
+        protected-clocks = <UART3_CLK>, <SPI5_CLK>;
+   };