diff mbox series

[3/4] arm64: dts: mediatek: mt8195: Fix systimer 13 MHz clock description

Message ID 20221201084229.3464449-4-wenst@chromium.org
State Accepted
Commit 0f1c806b65d136a5fe0b88adad5ff1cb451fc401
Headers show
Series arm64: dts: mediatek: Fix systimer clock description | expand

Commit Message

Chen-Yu Tsai Dec. 1, 2022, 8:42 a.m. UTC
The systimer block derives its 13 MHz clock by dividing the main 26 MHz
oscillator clock by 2 internally, not through the TOPCKGEN clock
controller.

On the MT8195 this divider is set either by power-on-reset or by the
bootloader. The bootloader may then make the divider unconfigurable to,
but can be read out by, the operating system.

Making the systimer block take the 26 MHz clock directly requires
changing the implementations. As an ABI compatible fix, change the
input clock of the systimer block a fixed factor divide-by-2 clock
that takes the 26 MHz oscillator as its input.

Fixes: 37f2582883be ("arm64: dts: Add mediatek SoC mt8195 and evaluation board")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
 arch/arm64/boot/dts/mediatek/mt8195.dtsi | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Comments

AngeloGioacchino Del Regno Dec. 13, 2022, 11:25 a.m. UTC | #1
Il 01/12/22 09:42, Chen-Yu Tsai ha scritto:
> The systimer block derives its 13 MHz clock by dividing the main 26 MHz
> oscillator clock by 2 internally, not through the TOPCKGEN clock
> controller.
> 
> On the MT8195 this divider is set either by power-on-reset or by the
> bootloader. The bootloader may then make the divider unconfigurable to,
> but can be read out by, the operating system.
> 
> Making the systimer block take the 26 MHz clock directly requires
> changing the implementations. As an ABI compatible fix, change the
> input clock of the systimer block a fixed factor divide-by-2 clock
> that takes the 26 MHz oscillator as its input.
> 
> Fixes: 37f2582883be ("arm64: dts: Add mediatek SoC mt8195 and evaluation board")
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
diff mbox series

Patch

diff --git a/arch/arm64/boot/dts/mediatek/mt8195.dtsi b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
index 5d31536f4c48..60e15833956e 100644
--- a/arch/arm64/boot/dts/mediatek/mt8195.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
@@ -248,6 +248,15 @@  sound: mt8195-sound {
 		status = "disabled";
 	};
 
+	clk13m: fixed-factor-clock-13m {
+		compatible = "fixed-factor-clock";
+		#clock-cells = <0>;
+		clocks = <&clk26m>;
+		clock-div = <2>;
+		clock-mult = <1>;
+		clock-output-names = "clk13m";
+	};
+
 	clk26m: oscillator-26m {
 		compatible = "fixed-clock";
 		#clock-cells = <0>;
@@ -705,7 +714,7 @@  systimer: timer@10017000 {
 				     "mediatek,mt6765-timer";
 			reg = <0 0x10017000 0 0x1000>;
 			interrupts = <GIC_SPI 265 IRQ_TYPE_LEVEL_HIGH 0>;
-			clocks = <&topckgen CLK_TOP_CLK26M_D2>;
+			clocks = <&clk13m>;
 		};
 
 		pwrap: pwrap@10024000 {