device: re-implement device_is_ready

Use device_get() instead. Also discourage its usage in favor of
device_get().

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

Author: gmarull

include/zephyr/device.h

@@ -209,7 +209,7 @@ typedef int16_t device_handle_t;
  * device object can be obtained with `DEVICE_DT_GET(node_id)` from any source
  * file that includes `<zephyr/device.h>` (even from extensions, when
  * @kconfig{CONFIG_LLEXT_EXPORT_DEVICES} is enabled). Before using the
- * pointer, the referenced object should be checked using device_is_ready().
+ * pointer, its usage should be registered using device_get().
  *
  * @param node_id The devicetree node identifier.
  * @param init_fn Pointer to the device's initialization function, which will be
@@ -302,8 +302,8 @@ typedef int16_t device_handle_t;
  *
  * If there are multiple, this returns an arbitrary one.
  *
- * If this returns non-NULL, the device must be checked for readiness
- * before use, e.g. with device_is_ready().
+ * If this returns non-NULL, device usage must be notified using
+ * device_get().
  *
  * @param compat lowercase-and-underscores devicetree compatible
  * @return a pointer to a device, or NULL
@@ -323,8 +323,8 @@ typedef int16_t device_handle_t;
  *
  * If there are multiple, this returns an arbitrary one.
  *
- * If this returns non-NULL, the device must be checked for readiness before
- * use, e.g. with device_is_ready().
+ * If this returns non-NULL, device usage must be notified using
+ * device_get().
  *
  * @param compat lowercase-and-underscores devicetree compatible
  * @return a pointer to a device
@@ -817,6 +817,21 @@ __syscall const struct device *device_get_binding(const char *name);
  */
 size_t z_device_get_all_static(const struct device **devices);
 
+/**
+ * Get a device.
+ *
+ * When getting a device, its usage count will be increased and, if not yet
+ * initialized, its initialization routine will be called. This function will
+ * not return until device initialization has finished.
+ *
+ * @param dev Device instance
+ *
+ * @retval -errno Device failed to initialize.
+ * @retval >=0 Device was successfully initialized and can be used. Values > 0
+ * indicate the current reference count.
+ */
+__syscall int device_get(const struct device *dev);
+
 /**
  * @brief Verify that a device is ready for use.
  *
@@ -829,26 +844,17 @@ size_t z_device_get_all_static(const struct device **devices);
  *
  * @param dev pointer to the device in question.
  *
+ * @note Usage of device_get() if preferred, this function will be deprecated
+ * in the future.
+ *
  * @retval true If the device is ready for use.
  * @retval false If the device is not ready for use or if a NULL device pointer
  * is passed as argument.
  */
-__syscall bool device_is_ready(const struct device *dev);
-
-/**
- * Get a device.
- *
- * When getting a device, its usage count will be increased and, if not yet
- * initialized, its initialization routine will be called. This function will
- * not return until device initialization has finished.
- *
- * @param dev Device instance
- *
- * @retval -errno Device failed to initialize.
- * @retval >=0 Device was successfully initialized and can be used. Values > 0
- * indicate the current reference count.
- */
-__syscall int device_get(const struct device *dev);
+static inline bool device_is_ready(const struct device *dev)
+{
+	return device_get(dev) >= 0;
+}
 
 /**
  * @brief Initialize a device.

kernel/device.c

@@ -38,7 +38,7 @@ const struct device *z_impl_device_get_binding(const char *name)
 	/* Return NULL if the device matching 'name' is not ready. */
 	STRUCT_SECTION_FOREACH(device, dev) {
 		if ((dev->name == name) || (strcmp(name, dev->name) == 0)) {
-			return z_impl_device_is_ready(dev) ? dev : NULL;
+			return z_impl_device_get(dev) >= 0 ? dev : NULL;
 		}
 	}
 
@@ -58,14 +58,6 @@ static inline const struct device *z_vrfy_device_get_binding(const char *name)
 	return z_impl_device_get_binding(name_copy);
 }
 #include <zephyr/syscalls/device_get_binding_mrsh.c>
-
-static inline bool z_vrfy_device_is_ready(const struct device *dev)
-{
-	K_OOPS(K_SYSCALL_OBJ_INIT(dev, K_OBJ_ANY));
-
-	return z_impl_device_is_ready(dev);
-}
-#include <zephyr/syscalls/device_is_ready_mrsh.c>
 #endif /* CONFIG_USERSPACE */
 
 #ifdef CONFIG_DEVICE_DT_METADATA
@@ -88,7 +80,7 @@ const struct device *z_impl_device_get_by_dt_nodelabel(const char *nodelabel)
 	STRUCT_SECTION_FOREACH(device, dev) {
 		const struct device_dt_nodelabels *nl = device_get_dt_nodelabels(dev);
 
-		if (!z_impl_device_is_ready(dev) || nl == NULL) {
+		if ((z_impl_device_get(dev) < 0) || nl == NULL) {
 			continue;
 		}
 
@@ -129,19 +121,6 @@ size_t z_device_get_all_static(struct device const **devices)
 	return cnt;
 }
 
-bool z_impl_device_is_ready(const struct device *dev)
-{
-	/*
-	 * if an invalid device pointer is passed as argument, this call
-	 * reports the `device` as not ready for usage.
-	 */
-	if (dev == NULL) {
-		return false;
-	}
-
-	return dev->state->initialized && (dev->state->init_res == 0U);
-}
-
 int z_impl_device_get(const struct device *dev)
 {
 	int ret = 0;