[RFC PATCH 3/3] arm64: dts: renesas: r9a09g057h44-rzv2h-evk: Move SDHI1 dma range from 8-12 GiB

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com>

Relocate SDHI1's AOF-remapped DMA window to physical 8-12 GiB
(0x2_0000_0000-0x2_ffff_ffff), by updating the dma-ranges entry on
aof_sdhi1_bus so that SDHI1's full 4 GiB device-side address space
(child base 0x0, size 4 GiB) is linearly remapped starting at parent
base 0x2_0000_0000.

Since SDHI1's DMA-visible addresses no longer correspond 1:1 to
ordinary system RAM, buffers handed to it must be guaranteed to
physically reside within this window. Add a restricted-dma-pool
reserved-memory region covering the same 8-12 GiB range and attach
it to sdhi1 via memory-region, so the kernel bounces SDHI1's DMA
buffers through this pool instead of allowing dma_alloc_coherent()/
dma_map_sg() to hand back arbitrary physical pages outside the range
the programmed SYS_AOF17 fields can actually reach.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com>
---
 .../boot/dts/renesas/r9a09g057h44-rzv2h-evk.dts  | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/arm64/boot/dts/renesas/r9a09g057h44-rzv2h-evk.dts b/arch/arm64/boot/dts/renesas/r9a09g057h44-rzv2h-evk.dts
index 0926ab891fa5..6845d576af42 100644
--- a/arch/arm64/boot/dts/renesas/r9a09g057h44-rzv2h-evk.dts
+++ b/arch/arm64/boot/dts/renesas/r9a09g057h44-rzv2h-evk.dts
@@ -99,6 +99,17 @@ reg_3p3v: regulator-3p3v {
 		regulator-always-on;
 	};
 
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		sdhi1_aof_pool: sdhi1-aof-pool at 200000000 {
+			compatible = "restricted-dma-pool";
+			reg = <0x2 0x00000000 0x0 0x08000000>;
+		};
+	};
+
 	vqmmc_sdhi1: regulator-vccq-sdhi1 {
 		compatible = "regulator-gpio";
 		regulator-name = "SDHI1 VccQ";
@@ -130,6 +141,10 @@ y1: y1-clock {
 	};
 };
 
+&aof_sdhi1_bus {
+	dma-ranges = <0x0 0x00000000 0x2 0x00000000  0x1 0x00000000>;
+};
+
 &audio_extal_clk {
 	clock-frequency = <22579200>;
 };
@@ -542,6 +557,7 @@ &scif {
 };
 
 &sdhi1 {
+	memory-region = <&sdhi1_aof_pool>;
 	pinctrl-0 = <&sdhi1_pins>;
 	pinctrl-1 = <&sdhi1_pins>;
 	pinctrl-names = "default", "state_uhs";
-- 
2.55.0