llext: test exporting DT devices to extensions

Add a new test to the simple llext test suite that verifies that DT
devices are properly exported to extensions. This is done by obtaining a
device handle from the DT and then trying to get the same handle at
runtime using the device_get_binding() API.

This test is optional because the current qemu_xtensa platform does not
have any usable DT devices to test with.

The LLEXT heap size is also increased to 64 kbytes to avoid heap
exhaustion when running the new test on mps2_an385.

Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

tests/subsys/llext/simple/prj.conf

@@ -2,7 +2,8 @@ CONFIG_ZTEST=y
 CONFIG_ZTEST_STACK_SIZE=4096
 CONFIG_LOG=y
 CONFIG_LLEXT=y
-CONFIG_LLEXT_HEAP_SIZE=32
+CONFIG_LLEXT_HEAP_SIZE=64
+CONFIG_LLEXT_EXPORT_DEVICES=y
 CONFIG_LLEXT_LOG_LEVEL_DBG=y
 
 CONFIG_APPLICATION_DEFINED_SYSCALL=y

tests/subsys/llext/simple/src/test_llext_simple.c

@@ -5,6 +5,7 @@
  */
 
 #include <zephyr/ztest.h>
+#include <zephyr/device.h>
 #include <zephyr/kernel.h>
 #include <zephyr/fs/fs.h>
 #if defined(CONFIG_FILE_SYSTEM_LITTLEFS)
@@ -108,6 +109,9 @@ static void threads_objects_test_setup(struct llext *, struct k_thread *llext_th
 	k_object_access_grant(&my_sem, llext_thread);
 	k_object_access_grant(&my_thread, llext_thread);
 	k_object_access_grant(&my_thread_stack, llext_thread);
+#if DT_HAS_CHOSEN(zephyr_console)
+	k_object_access_grant(DEVICE_DT_GET(DT_CHOSEN(zephyr_console)), llext_thread);
+#endif
 }
 #else
 /* No need to set up permissions for supervisor mode */

tests/subsys/llext/simple/src/threads_kernel_objects_ext.c

@@ -5,21 +5,47 @@
  */
 
 /*
- * This code demonstrates the use of threads and requires object
- * relocation support.
+ * This code checks the functionality of threads (including synchronization
+ * primitives) and device access from extensions.
+ * This test should be valid from both user and privileged modes.
  */
 
 #include <stdint.h>
 #include <zephyr/llext/symbol.h>
+#include <zephyr/device.h>
 #include <zephyr/kernel.h>
 #include <zephyr/ztest_assert.h>
 
 #include "threads_kernel_objects_ext.h"
 
+/*
+ * This optional check is required because the current qemu_xtensa platform
+ * does not have any usable DT devices to test with.
+ */
+#if DT_HAS_CHOSEN(zephyr_console)
+#define CONSOLE_DT_NODE DT_CHOSEN(zephyr_console)
+#endif
+
 void test_thread(void *arg0, void *arg1, void *arg2)
 {
 	printk("Take semaphore from test thread\n");
 	k_sem_take(&my_sem, K_FOREVER);
+
+#ifdef CONSOLE_DT_NODE
+	const struct device *const console_dev = DEVICE_DT_GET(CONSOLE_DT_NODE);
+	const char *const console_name = DEVICE_DT_NAME(CONSOLE_DT_NODE);
+	const struct device *binding_dev;
+
+	/* Ensure the console device was properly obtained at compile time */
+	zassert_not_null(console_dev);
+
+	/* Try to get the same handle at runtime and verify they match */
+	binding_dev = device_get_binding(console_name);
+	zassert_equal(binding_dev, console_dev);
+
+	/* Verify device API functionality, console must be ready in CI tests */
+	zassert_true(device_is_ready(console_dev));
+#endif
 }
 
 void test_entry(void)