Add missing cache information to the Rockchip RK356x SoC dtsi, to allow
the userspace, which includes /proc/cpuinfo and lscpu(1), to present proper
RK3566 and RK3568 cache information. Also, it gets rid of the following
error in the kernel log:
cacheinfo: Unable to detect cache hierarchy for CPU 0
The cache parameters for the RK356x dtsi were obtained and partially derived
by hand from the cache size and layout specifications found in the following
datasheets and technical reference manuals:
- Rockchip RK3566 datasheet, version 1.1
- Rockchip RK3568 datasheet, version 1.3
- ARM Cortex-A55 revision r1p0 TRM, version 0100-00
- ARM DynamIQ Shared Unit revision r4p0 TRM, version 0400-02
For future reference, here's a rather detailed summary of the documentation,
which applies to both Rockchip RK3566 and RK3568 SoCs:
- All caches employ the 64-byte cache line length
- Each Cortex-A55 core has 32 KB of L1 4-way, set-associative instruction
cache and 32 KB of L1 4-way, set-associative data cache
- There are no L2 caches, which are per-core and private in Cortex-A55,
because it belongs to the ARM DynamIQ IP core lineup
- The entire SoC has 512 KB of unified L3 16-way, set-associative cache,
which is shared among all four Cortex-A55 CPU cores
- Cortex-A55 cores can be configured without private per-core L2 caches,
in which case the shared L3 cache appears to them as an L2 cache; this
is the case for the RK356x SoCs, so let's use "cache-level = <2>" to
prevent the "huh, no L2 caches, but an L3 cache?" confusion among the
users viewing the data presented to the userspace; another option could
be to have additional 0 KB L2 caches defined, which may be technically
correct, but would probably be even more confusing
Helped-by: Anand Moon <linux.amoon@xxxxxxxxx>
Signed-off-by: Dragan Simic <dsimic@xxxxxxxxxxx>
---
Notes:
As already agreed upon with Anand Moon, this patch replaces the submission
of a similar, albeit a bit incorrect patch [1] that appeared a bit earlier
on the linux-rockchip mailing list.
[1] https://lore.kernel.org/linux-rockchip/20240226182310.4032-1-linux.amoon@xxxxxxxxx/T/#u
arch/arm64/boot/dts/rockchip/rk356x.dtsi | 41 ++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/arch/arm64/boot/dts/rockchip/rk356x.dtsi b/arch/arm64/boot/dts/rockchip/rk356x.dtsi
index c19c0f1b3778..6dfb2d47d3d0 100644
--- a/arch/arm64/boot/dts/rockchip/rk356x.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk356x.dtsi
@@ -57,36 +57,77 @@ cpu0: cpu@0 {
#cooling-cells = <2>;
enable-method = "psci";
operating-points-v2 = <&cpu0_opp_table>;
+ i-cache-size = <0x8000>;
+ i-cache-line-size = <64>;
+ i-cache-sets = <128>;
+ d-cache-size = <0x8000>;
+ d-cache-line-size = <64>;
+ d-cache-sets = <128>;
+ next-level-cache = <&l3_cache>;
};
cpu1: cpu@100 {
device_type = "cpu";
compatible = "arm,cortex-a55";
reg = <0x0 0x100>;
#cooling-cells = <2>;
enable-method = "psci";
operating-points-v2 = <&cpu0_opp_table>;
+ i-cache-size = <0x8000>;
+ i-cache-line-size = <64>;
+ i-cache-sets = <128>;
+ d-cache-size = <0x8000>;
+ d-cache-line-size = <64>;
+ d-cache-sets = <128>;
+ next-level-cache = <&l3_cache>;
};
cpu2: cpu@200 {
device_type = "cpu";
compatible = "arm,cortex-a55";
reg = <0x0 0x200>;
#cooling-cells = <2>;
enable-method = "psci";
operating-points-v2 = <&cpu0_opp_table>;
+ i-cache-size = <0x8000>;
+ i-cache-line-size = <64>;
+ i-cache-sets = <128>;
+ d-cache-size = <0x8000>;
+ d-cache-line-size = <64>;
+ d-cache-sets = <128>;
+ next-level-cache = <&l3_cache>;
};
cpu3: cpu@300 {
device_type = "cpu";
compatible = "arm,cortex-a55";
reg = <0x0 0x300>;
#cooling-cells = <2>;
enable-method = "psci";
operating-points-v2 = <&cpu0_opp_table>;
+ i-cache-size = <0x8000>;
+ i-cache-line-size = <64>;
+ i-cache-sets = <128>;
+ d-cache-size = <0x8000>;
+ d-cache-line-size = <64>;
+ d-cache-sets = <128>;
+ next-level-cache = <&l3_cache>;
};
};
+ /*
+ * There are no private per-core L2 caches, but only the
+ * L3 cache that appears to the CPU cores as L2 caches
+ */
+ l3_cache: l3-cache {
+ compatible = "cache";
+ cache-level = <2>;
+ cache-unified;
+ cache-size = <0x80000>;
+ cache-line-size = <64>;
+ cache-sets = <512>;
+ };
+
cpu0_opp_table: opp-table-0 {
compatible = "operating-points-v2";
opp-shared;
