[PATCH v32 7/7] arm64: dts: imx8ulp: add reserved memory for EdgeLock Enclave

From: Pankaj Gupta <[email protected]>

Reserve 1MB of DDR for the EdgeLock Enclave. The enclave hardware can only
access DDR in the 0x80000000 - 0xafffffff window, so constrain the pool to
that range with alloc-ranges and let the kernel choose the placement rather
than hardcoding an address.

Provide this as a shared imx8ulp-firmware.dtsi that also enables the hsm0
node and wires up its memory-region, so every i.MX8ULP board can bring up
the enclave with a single include instead of duplicating the reserved
memory node. Include it from imx8ulp-evk.

Signed-off-by: Pankaj Gupta <[email protected]>
Reviewed-by: Frank Li <[email protected]>
---
Changes from v30 to v31:
- Kernel is free to choose the exact placement of the 1 MiB block, as long
  as it lands inside the ELE-accessible window. This avoids hardcoding a
  fixed address.

- Adds a new shared imx8ulp-firmware.dtsi that also enables the hsm0
  node and wires up its memory-region, so every i.MX8ULP board can bring up
  the enclave with a single include instead of duplicating the reserved
  memory node. Include it from imx8ulp-evk.

Reported-by: Frieder Schrempf <[email protected]>
Closes: https://sashiko.dev/#/patchset/[email protected]?part=7
---
 arch/arm64/boot/dts/freescale/imx8ulp-evk.dts      |  3 ++-
 .../arm64/boot/dts/freescale/imx8ulp-firmware.dtsi | 31 ++++++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8ulp-evk.dts b/arch/arm64/boot/dts/freescale/imx8ulp-evk.dts
index 5dea66c1e7aa..885242fd07ce 100644
--- a/arch/arm64/boot/dts/freescale/imx8ulp-evk.dts
+++ b/arch/arm64/boot/dts/freescale/imx8ulp-evk.dts
@@ -1,11 +1,12 @@
 // SPDX-License-Identifier: (GPL-2.0+ OR MIT)
 /*
- * Copyright 2021 NXP
+ * Copyright 2021, 2025 NXP
  */
 
 /dts-v1/;
 
 #include "imx8ulp.dtsi"
+#include "imx8ulp-firmware.dtsi"
 
 / {
 	model = "NXP i.MX8ULP EVK";
diff --git a/arch/arm64/boot/dts/freescale/imx8ulp-firmware.dtsi b/arch/arm64/boot/dts/freescale/imx8ulp-firmware.dtsi
new file mode 100644
index 000000000000..e4bc352f68af
--- /dev/null
+++ b/arch/arm64/boot/dts/freescale/imx8ulp-firmware.dtsi
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright 2025 NXP
+ *
+ * Default reserved memory and EdgeLock Enclave (ELE) enablement shared by
+ * i.MX8ULP boards. Include this from a board dts to bring up the secure
+ * enclave without having to duplicate the reserved-memory node. The ELE
+ * hardware can only access DDR in the 0x80000000 - 0xafffffff window, so the
+ * pool is constrained to that range with alloc-ranges and the kernel is left
+ * to place the 1 MiB region.
+ */
+
+/ {
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		ele_reserved: ele-reserved {
+			compatible = "shared-dma-pool";
+			alloc-ranges = <0 0x80000000 0 0x30000000>;
+			size = <0 0x100000>;
+			no-map;
+		};
+	};
+};
+
+&hsm0 {
+	memory-region = <&ele_reserved>;
+	status = "okay";
+};

-- 
2.43.0