From: Takeshi Kihara <takeshi.kihara.df@xxxxxxxxxxx>
Add the device node for the external SCIF_CLK, and describe the clock
inputs for the Baud Rate Generator for External Clock (BRG) for SCIF2,
which can increase serial clock accuracy.
The presence of the SCIF_CLK crystal and its clock frequency depend on
the actual board.
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@xxxxxxxxxxx>
[geert: Enhance patch description]
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
Note: The Ebisu board does not provide SCIF_CLK. However, using the BRG
increases the serial console's clock accurary from 115200+541 bps
to 115200-257 bps.
---
arch/arm64/boot/dts/renesas/r8a77990.dtsi | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/boot/dts/renesas/r8a77990.dtsi b/arch/arm64/boot/dts/renesas/r8a77990.dtsi
index e2c2d1480a68cf1b..6198768264bece81 100644
--- a/arch/arm64/boot/dts/renesas/r8a77990.dtsi
+++ b/arch/arm64/boot/dts/renesas/r8a77990.dtsi
@@ -63,6 +63,13 @@
method = "smc";
};
+ /* External SCIF clock - to be overridden by boards that provide it */
+ scif_clk: scif {
+ compatible = "fixed-clock";
+ #clock-cells = <0>;
+ clock-frequency = <0>;
+ };
+
soc: soc {
compatible = "simple-bus";
interrupt-parent = <&gic>;
@@ -412,8 +419,11 @@
"renesas,rcar-gen3-scif", "renesas,scif";
reg = <0 0xe6e88000 0 64>;
interrupts = <GIC_SPI 164 IRQ_TYPE_LEVEL_HIGH>;
- clocks = <&cpg CPG_MOD 310>;
- clock-names = "fck";
+ clocks = <&cpg CPG_MOD 310>,
+ <&cpg CPG_CORE R8A77990_CLK_S3D1C>,
+ <&scif_clk>;
+ clock-names = "fck", "brg_int", "scif_clk";
+
power-domains = <&sysc R8A77990_PD_ALWAYS_ON>;
resets = <&cpg 310>;
status = "disabled";
--
2.17.1
