[PATCH v2] arm64: dts: rockchip: Add cache information to the SoC dtsi for RK3328

[Dragan Simic]

Add missing cache information to the Rockchip RK3328 SoC dtsi, to allow
the userspace, which includes lscpu(1) that uses the virtual files provided
by the kernel under the /sys/devices/system/cpu directory, to display the
proper RK3328 cache information.

While there, use a more self-descriptive label for the L2 cache node, which
also makes it more consistent with other SoC dtsi files.

The cache parameters for the RK3328 dtsi were obtained and partially derived
by hand from the cache size and layout specifications found in the following
datasheets, official vendor websites, and technical reference manuals:

  - Rockchip RK3328 datasheet, version 1.4
  - https://opensource.rock-chips.com/wiki_RK3328, accessed on 2024-02-28
  - ARM Cortex-A53 revision r0p3 TRM, version E

For future reference, here's a brief summary of the documentation:

  - All caches employ the 64-byte cache line length
  - Each Cortex-A53 core has 32 KB of L1 2-way, set-associative instruction
    cache and 32 KB of L1 4-way, set-associative data cache
  - The entire SoC has 256 KB of unified L2 16-way, set-associative cache

The RK3328 SoC dtsi is also used for the single RK3318-based supported board.
Unfortunately, no datasheet is available for the RK3318, but some unofficial
sources state that its L2 cache size is the same as RK3328's, so it's perhaps
safe to assume the same for the L1 instruction and data cache sizes.

Reviewed-by: Anand Moon <linux.amoon at gmail.com>
Signed-off-by: Dragan Simic <dsimic at manjaro.org>
---

Notes:
    Changes in v2:
      - Corrected the patch description to more accurately describe the actual
        effects of the patch to the userspace, as spotted by Diederik de Haas
        while testing a similar patch for the Rockchip RK356x SoC dtsi [1]
      - No changes were made to the actual source code patch
      - Collected one Reviewed-by tag
      - Link to v1: https://lore.kernel.org/linux-rockchip/e61173d87f5f41af80e6f87f8820ce8d06f7c20c.1709491127.git.dsimic@manjaro.org/T/#u
    
    [1] https://lore.kernel.org/linux-rockchip/90122541.GozVr7r7Y5@bagend/

 arch/arm64/boot/dts/rockchip/rk3328.dtsi | 37 ++++++++++++++++++++----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk3328.dtsi b/arch/arm64/boot/dts/rockchip/rk3328.dtsi
index 7b4c15c4a9c3..ac2846c33dc9 100644
--- a/arch/arm64/boot/dts/rockchip/rk3328.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3328.dtsi
@@ -46,47 +46,71 @@ cpu0: cpu at 0 {
 			cpu-idle-states = <&CPU_SLEEP>;
 			dynamic-power-coefficient = <120>;
 			enable-method = "psci";
-			next-level-cache = <&l2>;
 			operating-points-v2 = <&cpu0_opp_table>;
+			i-cache-size = <0x8000>;
+			i-cache-line-size = <64>;
+			i-cache-sets = <256>;
+			d-cache-size = <0x8000>;
+			d-cache-line-size = <64>;
+			d-cache-sets = <128>;
+			next-level-cache = <&l2_cache>;
 		};
 
 		cpu1: cpu at 1 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53";
 			reg = <0x0 0x1>;
 			clocks = <&cru ARMCLK>;
 			#cooling-cells = <2>;
 			cpu-idle-states = <&CPU_SLEEP>;
 			dynamic-power-coefficient = <120>;
 			enable-method = "psci";
-			next-level-cache = <&l2>;
 			operating-points-v2 = <&cpu0_opp_table>;
+			i-cache-size = <0x8000>;
+			i-cache-line-size = <64>;
+			i-cache-sets = <256>;
+			d-cache-size = <0x8000>;
+			d-cache-line-size = <64>;
+			d-cache-sets = <128>;
+			next-level-cache = <&l2_cache>;
 		};
 
 		cpu2: cpu at 2 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53";
 			reg = <0x0 0x2>;
 			clocks = <&cru ARMCLK>;
 			#cooling-cells = <2>;
 			cpu-idle-states = <&CPU_SLEEP>;
 			dynamic-power-coefficient = <120>;
 			enable-method = "psci";
-			next-level-cache = <&l2>;
 			operating-points-v2 = <&cpu0_opp_table>;
+			i-cache-size = <0x8000>;
+			i-cache-line-size = <64>;
+			i-cache-sets = <256>;
+			d-cache-size = <0x8000>;
+			d-cache-line-size = <64>;
+			d-cache-sets = <128>;
+			next-level-cache = <&l2_cache>;
 		};
 
 		cpu3: cpu at 3 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53";
 			reg = <0x0 0x3>;
 			clocks = <&cru ARMCLK>;
 			#cooling-cells = <2>;
 			cpu-idle-states = <&CPU_SLEEP>;
 			dynamic-power-coefficient = <120>;
 			enable-method = "psci";
-			next-level-cache = <&l2>;
 			operating-points-v2 = <&cpu0_opp_table>;
+			i-cache-size = <0x8000>;
+			i-cache-line-size = <64>;
+			i-cache-sets = <256>;
+			d-cache-size = <0x8000>;
+			d-cache-line-size = <64>;
+			d-cache-sets = <128>;
+			next-level-cache = <&l2_cache>;
 		};
 
 		idle-states {
@@ -102,10 +126,13 @@ CPU_SLEEP: cpu-sleep {
 			};
 		};
 
-		l2: l2-cache0 {
+		l2_cache: l2-cache {
 			compatible = "cache";
 			cache-level = <2>;
 			cache-unified;
+			cache-size = <0x40000>;
+			cache-line-size = <64>;
+			cache-sets = <256>;
 		};
 	};