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| author | Meizu OpenSource <patchwork@meizu.com> | 2016-08-15 10:19:42 +0800 |
|---|---|---|
| committer | Meizu OpenSource <patchwork@meizu.com> | 2016-08-15 10:19:42 +0800 |
| commit | d2e1446d81725c351dc73a03b397ce043fb18452 (patch) | |
| tree | 4dbc616b7f92aea39cd697a9084205ddb805e344 /Documentation/arm/sunxi | |
first commit
Diffstat (limited to 'Documentation/arm/sunxi')
| -rw-r--r-- | Documentation/arm/sunxi/README | 19 | ||||
| -rw-r--r-- | Documentation/arm/sunxi/clocks.txt | 56 |
2 files changed, 75 insertions, 0 deletions
diff --git a/Documentation/arm/sunxi/README b/Documentation/arm/sunxi/README new file mode 100644 index 000000000..87a1e8fb6 --- /dev/null +++ b/Documentation/arm/sunxi/README @@ -0,0 +1,19 @@ +ARM Allwinner SoCs +================== + +This document lists all the ARM Allwinner SoCs that are currently +supported in mainline by the Linux kernel. This document will also +provide links to documentation and or datasheet for these SoCs. + +SunXi family +------------ + + Flavors: + Allwinner A10 (sun4i) + Datasheet : http://dl.linux-sunxi.org/A10/A10%20Datasheet%20-%20v1.21%20%282012-04-06%29.pdf + + Allwinner A13 (sun5i) + Datasheet : http://dl.linux-sunxi.org/A13/A13%20Datasheet%20-%20v1.12%20%282012-03-29%29.pdf + + Core: Cortex A8 + Linux kernel mach directory: arch/arm/mach-sunxi
\ No newline at end of file diff --git a/Documentation/arm/sunxi/clocks.txt b/Documentation/arm/sunxi/clocks.txt new file mode 100644 index 000000000..e09a88aa3 --- /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 |
