device: introduce struct device_ops

Instead of passing a single init function, create
struct device_ops with the init function inside. This allows to easily
extend device's capabilities in the future without too much breakage,
e.g. to add a de-init call.

Signed-off-by: Gerard Marull-Paretas <[email protected]>

Author: gmarull

include/zephyr/device.h

@@ -451,6 +451,12 @@ typedef uint8_t device_flags_t;
 
 /** @} */
 
+/** Device operations */
+struct device_ops {
+	/** Initialization function */
+	int (*init)(const struct device *dev);
+};
+
 /**
  * @brief Runtime device structure (in ROM) per driver instance
  */
@@ -465,8 +471,8 @@ struct device {
 	struct device_state *state;
 	/** Address of the device instance private data */
 	void *data;
-	/** Initialization function (optional) */
-	int (*init_fn)(const struct device *);
+	/** Device operations */
+	struct device_ops ops;
 	/** Device flags */
 	device_flags_t flags;
 #if defined(CONFIG_DEVICE_DEPS) || defined(__DOXYGEN__)
@@ -1090,7 +1096,7 @@ device_get_dt_nodelabels(const struct device *dev)
 		.api = (api_),								\
 		.state = (state_),							\
 		.data = (data_),							\
-		.init_fn = (init_fn_),							\
+		.ops = { .init = (init_fn_) },						\
 		.flags = (flags_),							\
 		IF_ENABLED(CONFIG_DEVICE_DEPS, (.deps = (deps_),)) /**/			\
 		IF_ENABLED(CONFIG_PM_DEVICE, Z_DEVICE_INIT_PM_BASE(pm_)) /**/		\

kernel/init.c

@@ -306,8 +306,8 @@ static int do_device_init(const struct device *dev)
 {
 	int rc = 0;
 
-	if (dev->init_fn != NULL) {
-		rc = dev->init_fn(dev);
+	if (dev->ops.init != NULL) {
+		rc = dev->ops.init(dev);
 		/* Mark device initialized. If initialization
 		 * failed, record the error condition.
 		 */

tests/lib/devicetree/devices/src/main.c

@@ -86,16 +86,16 @@ ZTEST(devicetree_devices, test_init_get)
 		      DEVICE_DT_GET(TEST_NOLABEL), NULL);
 
 	/* Check init functions */
-	zassert_equal(DEVICE_DT_GET(TEST_GPIO)->init_fn, dev_init);
-	zassert_equal(DEVICE_DT_GET(TEST_I2C)->init_fn, dev_init);
-	zassert_equal(DEVICE_DT_GET(TEST_DEVA)->init_fn, dev_init);
-	zassert_equal(DEVICE_DT_GET(TEST_DEVB)->init_fn, dev_init);
-	zassert_equal(DEVICE_DT_GET(TEST_GPIOX)->init_fn, dev_init);
-	zassert_equal(DEVICE_DT_GET(TEST_DEVC)->init_fn, dev_init);
-	zassert_equal(DEVICE_DT_GET(TEST_PARTITION)->init_fn, dev_init);
-	zassert_equal(DEVICE_DT_GET(TEST_GPIO_INJECTED)->init_fn, dev_init);
-	zassert_equal(DEVICE_GET(manual_dev)->init_fn, dev_init);
-	zassert_equal(DEVICE_DT_GET(TEST_NOLABEL)->init_fn, dev_init);
+	zassert_equal(DEVICE_DT_GET(TEST_GPIO)->ops.init, dev_init);
+	zassert_equal(DEVICE_DT_GET(TEST_I2C)->ops.init, dev_init);
+	zassert_equal(DEVICE_DT_GET(TEST_DEVA)->ops.init, dev_init);
+	zassert_equal(DEVICE_DT_GET(TEST_DEVB)->ops.init, dev_init);
+	zassert_equal(DEVICE_DT_GET(TEST_GPIOX)->ops.init, dev_init);
+	zassert_equal(DEVICE_DT_GET(TEST_DEVC)->ops.init, dev_init);
+	zassert_equal(DEVICE_DT_GET(TEST_PARTITION)->ops.init, dev_init);
+	zassert_equal(DEVICE_DT_GET(TEST_GPIO_INJECTED)->ops.init, dev_init);
+	zassert_equal(DEVICE_GET(manual_dev)->ops.init, dev_init);
+	zassert_equal(DEVICE_DT_GET(TEST_NOLABEL)->ops.init, dev_init);
 }
 
 ZTEST(devicetree_devices, test_init_order)