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authorStephen Warren <swarren@nvidia.com>2013-04-04 16:08:13 -0600
committerStephen Warren <swarren@nvidia.com>2013-04-04 16:08:13 -0600
commit43089433b00a086980fc6e9571535477fb749e84 (patch)
tree194817879be6f5cc5e56bc2ab2c3276af146238c /Documentation
parent8aa15d82df291b398d604b527a20310f10c1c706 (diff)
parent533ddeb1e86f506129ee388a6cc13796dcf31311 (diff)
Merge remote-tracking branch 'linaro_mturquette_linux/clk-for-3.10' into for-3.10/clk
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/arm/sunxi/clocks.txt56
-rw-r--r--Documentation/clk.txt4
-rw-r--r--Documentation/devicetree/bindings/clock/axi-clkgen.txt22
-rw-r--r--Documentation/devicetree/bindings/clock/sunxi.txt44
4 files changed, 124 insertions, 2 deletions
diff --git a/Documentation/arm/sunxi/clocks.txt b/Documentation/arm/sunxi/clocks.txt
new file mode 100644
index 000000000000..e09a88aa3136
--- /dev/null
+++ b/Documentation/arm/sunxi/clocks.txt
@@ -0,0 +1,56 @@
+Frequently asked questions about the sunxi clock system
+=======================================================
+
+This document contains useful bits of information that people tend to ask
+about the sunxi clock system, as well as accompanying ASCII art when adequate.
+
+Q: Why is the main 24MHz oscillator gatable? Wouldn't that break the
+ system?
+
+A: The 24MHz oscillator allows gating to save power. Indeed, if gated
+ carelessly the system would stop functioning, but with the right
+ steps, one can gate it and keep the system running. Consider this
+ simplified suspend example:
+
+ While the system is operational, you would see something like
+
+ 24MHz 32kHz
+ |
+ PLL1
+ \
+ \_ CPU Mux
+ |
+ [CPU]
+
+ When you are about to suspend, you switch the CPU Mux to the 32kHz
+ oscillator:
+
+ 24Mhz 32kHz
+ | |
+ PLL1 |
+ /
+ CPU Mux _/
+ |
+ [CPU]
+
+ Finally you can gate the main oscillator
+
+ 32kHz
+ |
+ |
+ /
+ CPU Mux _/
+ |
+ [CPU]
+
+Q: Were can I learn more about the sunxi clocks?
+
+A: The linux-sunxi wiki contains a page documenting the clock registers,
+ you can find it at
+
+ http://linux-sunxi.org/A10/CCM
+
+ The authoritative source for information at this time is the ccmu driver
+ released by Allwinner, you can find it at
+
+ https://github.com/linux-sunxi/linux-sunxi/tree/sunxi-3.0/arch/arm/mach-sun4i/clock/ccmu
diff --git a/Documentation/clk.txt b/Documentation/clk.txt
index 1943fae014fd..4274a546eb57 100644
--- a/Documentation/clk.txt
+++ b/Documentation/clk.txt
@@ -174,9 +174,9 @@ int clk_foo_enable(struct clk_hw *hw)
};
Below is a matrix detailing which clk_ops are mandatory based upon the
-hardware capbilities of that clock. A cell marked as "y" means
+hardware capabilities of that clock. A cell marked as "y" means
mandatory, a cell marked as "n" implies that either including that
-callback is invalid or otherwise uneccesary. Empty cells are either
+callback is invalid or otherwise unnecessary. Empty cells are either
optional or must be evaluated on a case-by-case basis.
clock hardware characteristics
diff --git a/Documentation/devicetree/bindings/clock/axi-clkgen.txt b/Documentation/devicetree/bindings/clock/axi-clkgen.txt
new file mode 100644
index 000000000000..028b493e97ff
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/axi-clkgen.txt
@@ -0,0 +1,22 @@
+Binding for the axi-clkgen clock generator
+
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be "adi,axi-clkgen".
+- #clock-cells : from common clock binding; Should always be set to 0.
+- reg : Address and length of the axi-clkgen register set.
+- clocks : Phandle and clock specifier for the parent clock.
+
+Optional properties:
+- clock-output-names : From common clock binding.
+
+Example:
+ clock@0xff000000 {
+ compatible = "adi,axi-clkgen";
+ #clock-cells = <0>;
+ reg = <0xff000000 0x1000>;
+ clocks = <&osc 1>;
+ };
diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
new file mode 100644
index 000000000000..20b8479c2760
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/sunxi.txt
@@ -0,0 +1,44 @@
+Device Tree Clock bindings for arch-sunxi
+
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be one of the following:
+ "allwinner,sun4i-osc-clk" - for a gatable oscillator
+ "allwinner,sun4i-pll1-clk" - for the main PLL clock
+ "allwinner,sun4i-cpu-clk" - for the CPU multiplexer clock
+ "allwinner,sun4i-axi-clk" - for the AXI clock
+ "allwinner,sun4i-ahb-clk" - for the AHB clock
+ "allwinner,sun4i-apb0-clk" - for the APB0 clock
+ "allwinner,sun4i-apb1-clk" - for the APB1 clock
+ "allwinner,sun4i-apb1-mux-clk" - for the APB1 clock muxing
+
+Required properties for all clocks:
+- reg : shall be the control register address for the clock.
+- clocks : shall be the input parent clock(s) phandle for the clock
+- #clock-cells : from common clock binding; shall be set to 0.
+
+For example:
+
+osc24M: osc24M@01c20050 {
+ #clock-cells = <0>;
+ compatible = "allwinner,sun4i-osc-clk";
+ reg = <0x01c20050 0x4>;
+ clocks = <&osc24M_fixed>;
+};
+
+pll1: pll1@01c20000 {
+ #clock-cells = <0>;
+ compatible = "allwinner,sun4i-pll1-clk";
+ reg = <0x01c20000 0x4>;
+ clocks = <&osc24M>;
+};
+
+cpu: cpu@01c20054 {
+ #clock-cells = <0>;
+ compatible = "allwinner,sun4i-cpu-clk";
+ reg = <0x01c20054 0x4>;
+ clocks = <&osc32k>, <&osc24M>, <&pll1>;
+};