[PATCH v4 5/5] ARM: dts: sun9i: Add TODO comments for the main and low power clocks

Chen-Yu Tsai
2015-11-29T03:03:10Z

The main (24MHz) clock on the A80 is configurable via the PRCM address
space. The low power/speed (32kHz) clock is from an external chip, the
AC100.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
arch/arm/boot/dts/sun9i-a80.dtsi | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/arch/arm/boot/dts/sun9i-a80.dtsi b/arch/arm/boot/dts/sun9i-a80.dtsi
index a4ce348c0831..eb69a62f6bc4 100644
--- a/arch/arm/boot/dts/sun9i-a80.dtsi
+++ b/arch/arm/boot/dts/sun9i-a80.dtsi
@@ -128,6 +128,17 @@
*/
ranges = <0 0 0 0x20000000>;

+ /*
+ * This clock is actually configurable from the PRCM address
+ * space. The external 24M oscillator can be turned off, and
+ * the clock switched to an internal 16M RC oscillator. Under
+ * normal operation there's no reason to do this, and the
+ * default is to use the external good one, so just model this
+ * as a fixed clock. Also it is not entirely clear if the
+ * osc24M mux in the PRCM affects the entire clock tree, which
+ * would also throw all the PLL clock rates off, or just the
+ * downstream clocks in the PRCM.
+ */
osc24M: osc24M_clk {
#clock-cells = <0>;
compatible = "fixed-clock";
@@ -135,6 +146,13 @@
clock-output-names = "osc24M";
};

+ /*
+ * The 32k clock is from an external source, normally the
+ * AC100 codec/RTC chip. This clock is by default enabled
+ * and clocked at 32768 Hz, from the oscillator connected
+ * to the AC100. It is configurable, but no such driver or
+ * bindings exist yet.
+ */
osc32k: osc32k_clk {
#clock-cells = <0>;
compatible = "fixed-clock";
--
2.6.2