Re: [PATCH v3 11/12] riscv: Add device tree for K210

On 2/4/20 6:32 AM, Bin Meng wrote:

Hi Sean,

On Mon, Feb 3, 2020 at 4:10 AM Sean Anderson seanga2@gmail.com wrote:

...

Where possible, I have tried to find compatible drivers based on the layout of registers. However, I have not tested most of this functionality, and most devices should be considered descriptive at best. I would appreciate if anyone could help identify possibly compatible devices, especially for the timers and rtc.

Should the size of a reg be the size of the documented registers, or the size of the address space which will be routed to that device?

Perhaps we need use the size of the address space routed to that device, in case there is some undocumented registers we need handle.

Ok, I'll go with the whole address space then.

...

diff --git a/arch/riscv/dts/k210.dtsi b/arch/riscv/dts/k210.dtsi new file mode 100644 index 0000000000..cc46b692e6 --- /dev/null +++ b/arch/riscv/dts/k210.dtsi @@ -0,0 +1,496 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*

• • Copyright (C) 2019 Sean Anderson seanga2@gmail.com
• */

+#include <dt-bindings/clock/k210-sysctl.h> +#include <dt-bindings/mfd/k210-sysctl.h> +#include <dt-bindings/reset/k210-sysctl.h>

+/ {

•   /*
  

•    * Although the K210 is a 64-bit CPU, the address bus is only 32-bits
  

•    * wide, and the upper half of all addresses is ignored.
  

•    */
  

•   #address-cells = <1>;
  

•   #size-cells = <1>;
  

•   compatible = "kendryte,k210";
  

•   aliases {
  

•           serial0 = &uarths0;
  

•           serial1 = &uart1;
  

•           serial2 = &uart2;
  

•           serial3 = &uart3;
  

•           spi0 = &spi0;
  

•           spi1 = &spi1;
  

•           spi2 = &spi2;
  

•           spi3 = &spi3;
  

•   };
  

•   clocks {
  

•           in0: oscillator {
  

•                   compatible = "fixed-clock";
  

•                   #clock-cells = <0>;
  

•                   clock-frequency = <26000000>;
  

•           };
  

•   };
  

•   cpus {
  

•           #address-cells = <1>;
  

•           #size-cells = <0>;
  

•           timebase-frequency = <7800000>;
  

•           cpu0: cpu@0 {
  

•                   device_type = "cpu";
  

•                   reg = <0>;
  

•                   compatible = "riscv";
  

•                   riscv,isa = "rv64acdfimsu";
  

•                   mmu-type = "sv39";
  

•                   i-cache-size = <0x8000>;
  

•                   d-cache-size = <0x8000>;
  

•                   clocks = <&sysclk K210_CLK_CPU>;
  

•                   clock-frequency = <390000000>;
  

I wonder there is already clocks property, why do we have another clock-frequency property to provide duplicated information?

This is for compatibility with the existing riscv cpu driver. There is a patch [1] to move the driver over to using clocks, but I think you already expressed that it should be merged into this series (not as a separate series).

[1] https://patchwork.ozlabs.org/project/uboot/list/?series=156381

--Sean