[linux,dev-4.13] ARM: dts: aspeed: Describe random number device

Message ID 20180326051758.16800-1-joel@jms.id.au
State New
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  • [linux,dev-4.13] ARM: dts: aspeed: Describe random number device
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Joel Stanley March 26, 2018, 5:17 a.m.
There is a random number generator that updates a register in the SCU
every second. This is compatible with the timeriomem rng driver in the
kernel.

From the timeriomem_rng bindings:

  quality: estimated number of bits of true entropy per 1024 bits read
  from the rng.  Defaults to zero which causes the kernel's default
  quality to be used instead.  Note that the default quality is usually
  zero which disables using this rng to automatically fill the kernel's
  entropy pool.

As to the recommended value for us to use:

 Rick Altherr <raltherr@google.com> wrote:
 > Quality is #bit of entropy per 1000 bits read.  100 is a
 > conservative value that was suggested by those in the know.

Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 arch/arm/boot/dts/aspeed-g4.dtsi | 7 +++++++
 arch/arm/boot/dts/aspeed-g5.dtsi | 7 +++++++
 2 files changed, 14 insertions(+)

Patch

diff --git a/arch/arm/boot/dts/aspeed-g4.dtsi b/arch/arm/boot/dts/aspeed-g4.dtsi
index 6205228b18ea..3d391b428b25 100644
--- a/arch/arm/boot/dts/aspeed-g4.dtsi
+++ b/arch/arm/boot/dts/aspeed-g4.dtsi
@@ -120,6 +120,13 @@ 
 				pinctrl: pinctrl {
 					compatible = "aspeed,g4-pinctrl";
 				};
+
+				hwrng@78 {
+					compatible = "timeriomem_rng";
+					reg = <0x78 0x4>;
+					period = <1>;
+					quality = <100>;
+				};
 			};
 
 			adc: adc@1e6e9000 {
diff --git a/arch/arm/boot/dts/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed-g5.dtsi
index 0a866da8db32..1468b4ad22dc 100644
--- a/arch/arm/boot/dts/aspeed-g5.dtsi
+++ b/arch/arm/boot/dts/aspeed-g5.dtsi
@@ -157,6 +157,13 @@ 
 					aspeed,external-nodes = <&gfx &lhc>;
 
 				};
+
+				hwrng@78 {
+					compatible = "timeriomem_rng";
+					reg = <0x78 0x4>;
+					period = <1>;
+					quality = <100>;
+				};
 			};
 
 			gfx: display@1e6e6000 {