[nrf fromtree] tests: drivers: spi: Run spi_loopback on nrf54lm20b

Enable SPI tests on nrf54lm20b.

Signed-off-by: Sebastian Głąb <sebastian.glab@nordicsemi.no>
(cherry picked from commit 5c92576591d5a693118c0beb6585663858e534fd)

Author: nordic-segl

tests/drivers/spi/spi_loopback/boards/nrf54lm20dk_nrf54lm20b_cpuapp.conf

@@ -0,0 +1 @@
+CONFIG_SPI_IDEAL_TRANSFER_DURATION_SCALING=12

tests/drivers/spi/spi_loopback/boards/nrf54lm20dk_nrf54lm20b_cpuapp.overlay

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2026 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* Test requires following loopback:
+ * P1.13 - P1.14
+ */
+
+&pinctrl {
+	spi21_default: spi21_default {
+		group1 {
+			psels = <NRF_PSEL(SPIM_SCK, 1, 24)>,
+				<NRF_PSEL(SPIM_MISO, 1, 13)>,
+				<NRF_PSEL(SPIM_MOSI, 1, 14)>;
+		};
+	};
+
+	spi21_sleep: spi21_sleep {
+		group1 {
+			psels = <NRF_PSEL(SPIM_SCK, 1, 24)>,
+				<NRF_PSEL(SPIM_MISO, 1, 13)>,
+				<NRF_PSEL(SPIM_MOSI, 1, 14)>;
+			low-power-enable;
+		};
+	};
+};
+
+&spi21 {
+	status = "okay";
+	pinctrl-0 = <&spi21_default>;
+	pinctrl-1 = <&spi21_sleep>;
+	pinctrl-names = "default", "sleep";
+	overrun-character = <0x00>;
+	zephyr,pm-device-runtime-auto;
+
+	slow@0 {
+		compatible = "test-spi-loopback-slow";
+		reg = <0>;
+		spi-max-frequency = <DT_FREQ_M(2)>;
+	};
+
+	dut_fast: fast@0 {
+		compatible = "test-spi-loopback-fast";
+		reg = <0>;
+		spi-max-frequency = <DT_FREQ_M(4)>;
+	};
+};
+
+&gpio1 {
+	status = "okay";
+};

tests/drivers/spi/spi_loopback/boards/nrf54lm20dk_nrf54lm20b_cpuapp_spi00.overlay

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2026 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* Test requires following loopback:
+ * P2.02 - P2.04
+ */
+
+&pinctrl {
+	spi00_default: spi00_default {
+		group1 {
+			psels = <NRF_PSEL(SPIM_MISO, 2, 4)>;
+		};
+
+		group2 {
+			psels = <NRF_PSEL(SPIM_SCK, 2, 1)>,
+				<NRF_PSEL(SPIM_MOSI, 2, 2)>;
+			nordic,drive-mode = <NRF_DRIVE_E0E1>;
+		};
+	};
+
+	spi00_sleep: spi00_sleep {
+		group1 {
+			psels = <NRF_PSEL(SPIM_SCK, 2, 1)>,
+				<NRF_PSEL(SPIM_MISO, 2, 4)>,
+				<NRF_PSEL(SPIM_MOSI, 2, 2)>;
+			low-power-enable;
+		};
+	};
+};
+
+&spi00 {
+	status = "okay";
+	pinctrl-0 = <&spi00_default>;
+	pinctrl-1 = <&spi00_sleep>;
+	pinctrl-names = "default", "sleep";
+	overrun-character = <0x00>;
+	zephyr,pm-device-runtime-auto;
+
+	slow@0 {
+		compatible = "test-spi-loopback-slow";
+		reg = <0>;
+		spi-max-frequency = <DT_FREQ_M(16)>;
+	};
+
+	dut_fast: fast@0 {
+		compatible = "test-spi-loopback-fast";
+		reg = <0>;
+		spi-max-frequency = <DT_FREQ_M(32)>;
+	};
+};
+
+&gpio2 {
+	status = "okay";
+};

tests/drivers/spi/spi_loopback/testcase.yaml

@@ -296,6 +296,7 @@ tests:
     platform_allow:
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
       - nrf7120dk/nrf7120/cpuapp
       - ophelia4ev/nrf54l15/cpuapp
   drivers.spi.nrf54l_16mhz:
@@ -315,9 +316,10 @@ tests:
     harness_config:
       fixture: spi_fast_loopback
     extra_args:
-      - DTC_OVERLAY_FILE="boards/nrf54lm20dk_nrf54lm20a_cpuapp_spi00.overlay"
+      - FILE_SUFFIX=spi00
     platform_allow:
       - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
   drivers.spi.ke1xz_flexio_spi.loopback:
     extra_args: DTC_OVERLAY_FILE="boards/frdm_ke1xz_flexio_spi.overlay"
     filter: CONFIG_DT_HAS_NXP_FLEXIO_ENABLED and