tests: drivers: spi: loopback: add stm32 spi rtio test case

Add a test case for STM32 SPI RTIO.

Signed-off-by: Guillaume Gautier <guillaume.gautier-ext@st.com>
diff --git a/tests/drivers/spi/spi_loopback/overlay-stm32-spi-rtio.conf b/tests/drivers/spi/spi_loopback/overlay-stm32-spi-rtio.conf
new file mode 100644
index 0000000..82d01c1
--- /dev/null
+++ b/tests/drivers/spi/spi_loopback/overlay-stm32-spi-rtio.conf
@@ -0,0 +1,7 @@
+#
+# Copyright (c) 2025 STMicroelectronics
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+CONFIG_SPI_RTIO=y
+CONFIG_SPI_ASYNC=n
diff --git a/tests/drivers/spi/spi_loopback/testcase.yaml b/tests/drivers/spi/spi_loopback/testcase.yaml
index 70037aa..e56f9f2 100644
--- a/tests/drivers/spi/spi_loopback/testcase.yaml
+++ b/tests/drivers/spi/spi_loopback/testcase.yaml
@@ -115,6 +115,30 @@
       - stm32u083c_dk
     integration_platforms:
       - stm32h573i_dk
+  drivers.spi.stm32_spi_rtio.loopback:
+    extra_args: EXTRA_CONF_FILE="overlay-stm32-spi-rtio.conf"
+    platform_allow:
+      - b_u585i_iot02a
+      - nucleo_c071rb
+      - nucleo_f207zg
+      - nucleo_f429zi
+      - nucleo_f746zg
+      - nucleo_f767zi
+      - nucleo_g474re
+      - nucleo_h743zi
+      - nucleo_h753zi
+      - nucleo_h745zi_q/stm32h745xx/m4
+      - nucleo_h745zi_q/stm32h745xx/m7
+      - nucleo_l152re
+      - nucleo_wba55cg
+      - nucleo_wb55rg
+      - nucleo_wl55jc
+      - stm32f3_disco
+      - stm32h573i_dk
+      - stm32n6570_dk/stm32n657xx/sb
+      - stm32u083c_dk
+    integration_platforms:
+      - stm32h573i_dk
   drivers.spi.gd32_spi_interrupt.loopback:
     extra_args: EXTRA_CONF_FILE="overlay-gd32-spi-interrupt.conf"
     platform_allow: