clk: sunxi-ng: mux: Add clk notifier functions

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On sunxi we support cpufreq by changing the clock rate of PLL-CPU.
It's possible the clock output of the PLL goes out of the CPU's
operational limits when the PLL's multipliers / dividers are changed
and it hasn't stabilized yet. This would result in the CPU hanging.

To circumvent this, we temporarily switch the CPU mux clock to another
stable clock before the rate change, and switch it back after the PLL
stabilizes. This is done with clk notifiers registered on the PLL.

This patch adds common functions for notifiers to reparent mux clocks.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

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Chen-Yu Tsai 2016-08-25 14:21:58 +08:00 • committed by Maxime Ripard

parent ff5294db41

commit 8adfb08605

2 changed files with 50 additions and 0 deletions

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36

drivers/clk/sunxi-ng/ccu_mux.c

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14

drivers/clk/sunxi-ng/ccu_mux.h

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