diff options
author | Stephen Warren <swarren@nvidia.com> | 2013-04-04 16:08:13 -0600 |
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committer | Stephen Warren <swarren@nvidia.com> | 2013-04-04 16:08:13 -0600 |
commit | 43089433b00a086980fc6e9571535477fb749e84 (patch) | |
tree | 194817879be6f5cc5e56bc2ab2c3276af146238c /Documentation | |
parent | 8aa15d82df291b398d604b527a20310f10c1c706 (diff) | |
parent | 533ddeb1e86f506129ee388a6cc13796dcf31311 (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.txt | 56 | ||||
-rw-r--r-- | Documentation/clk.txt | 4 | ||||
-rw-r--r-- | Documentation/devicetree/bindings/clock/axi-clkgen.txt | 22 | ||||
-rw-r--r-- | Documentation/devicetree/bindings/clock/sunxi.txt | 44 |
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>; +}; |