* Not specifying reg-shift creates a situation where the register shift is unknown and can only be decoded via special compat cases. * The device tree specification states: "...reg-shift. If unspecified, the default value is 0." https://devicetree-specification.readthedocs.io/en/latest/chapter4-device-bi... * Since the reg-shift for the SiFive boards is *NOT* 0, it shall be defined as 2 --- arch/riscv/dts/fu540-c000.dtsi | 1 + arch/riscv/dts/fu740-c000.dtsi | 2 ++ 2 files changed, 3 insertions(+)

diff --git a/arch/riscv/dts/fu540-c000.dtsi b/arch/riscv/dts/fu540-c000.dtsi index 7db8610534..0bea8cf1e5 100644 --- a/arch/riscv/dts/fu540-c000.dtsi +++ b/arch/riscv/dts/fu540-c000.dtsi @@ -161,6 +161,7 @@ uart0: serial@10010000 { compatible = "sifive,fu540-c000-uart", "sifive,uart0"; reg = <0x0 0x10010000 0x0 0x1000>; + reg-shift = <2>; interrupt-parent = <&plic0>; interrupts = <4>; clocks = <&prci PRCI_CLK_TLCLK>; diff --git a/arch/riscv/dts/fu740-c000.dtsi b/arch/riscv/dts/fu740-c000.dtsi index 7b77c13496..19da3709f0 100644 --- a/arch/riscv/dts/fu740-c000.dtsi +++ b/arch/riscv/dts/fu740-c000.dtsi @@ -164,6 +164,7 @@ uart0: serial@10010000 { compatible = "sifive,fu740-c000-uart", "sifive,uart0"; reg = <0x0 0x10010000 0x0 0x1000>; + reg-shift = <2>; interrupt-parent = <&plic0>; interrupts = <39>; clocks = <&prci FU740_PRCI_CLK_PCLK>; @@ -172,6 +173,7 @@ uart1: serial@10011000 { compatible = "sifive,fu740-c000-uart", "sifive,uart0"; reg = <0x0 0x10011000 0x0 0x1000>; + reg-shift = <2>; interrupt-parent = <&plic0>; interrupts = <40>; clocks = <&prci FU740_PRCI_CLK_PCLK>;