device: Revise how initialization status is being handled

In order to make all device instances constant, driver_api pointer is
not set to NULL anymore if initialization failed.

Instead, have a bitfield dedicated to it.

Fixes #27399

Signed-off-by: Tomasz Bursztyka <[email protected]>

Author: Tomasz Bursztyka

include/device.h

@@ -245,10 +245,7 @@ size_t z_device_get_all_static(struct device **devices);
  *
  * @return true if and only if the device is available for use.
  */
-static inline bool z_device_ready(const struct device *dev)
-{
-	return dev->api != NULL;
-}
+bool z_device_ready(const struct device *dev);
 
 /**
  * @}

include/linker/common-ram.ld

@@ -14,18 +14,27 @@
 #endif
 
 /*
- * Space for storing per device busy bitmap. Since we do not know beforehand
- * the number of devices, we go through the below mechanism to allocate the
- * required space.
+ * Space for storing per device init status and busy bitmap in case PM is
+ * enabled. Since we do not know beforehand the number of devices,
+ * we go through the below mechanism to allocate the required space.
+ * Both are made of 1 bit per-device instance, so we compute the size of
+ * of an entire bitfield, aligned on 32bits.
  */
-#ifdef CONFIG_DEVICE_POWER_MANAGEMENT
 #define DEVICE_COUNT \
 	((__device_end - __device_start) / _DEVICE_STRUCT_SIZEOF)
-#define DEV_BUSY_SZ	(((DEVICE_COUNT + 31) / 32) * 4)
+#define DEVICE_BITFIELD_SIZE	(((DEVICE_COUNT + 31) / 32) * 4)
+
+#define DEVICE_INIT_STATUS_BITFIELD() 		\
+		FILL(0x00);			\
+		__device_init_status_start = .; \
+		. = . + DEVICE_BITFIELD_SIZE;	\
+		__device_init_status_end = .;
+
+#ifdef CONFIG_DEVICE_POWER_MANAGEMENT
 #define DEVICE_BUSY_BITFIELD()			\
-		FILL(0x00) ;			\
+		FILL(0x00);			\
 		__device_busy_start = .;	\
-		. = . + DEV_BUSY_SZ;		\
+		. = . + DEVICE_BITFIELD_SIZE;	\
 		__device_busy_end = .;
 #else
 #define DEVICE_BUSY_BITFIELD()
@@ -44,6 +53,7 @@
 		CREATE_OBJ_LEVEL(device, APPLICATION)
 		CREATE_OBJ_LEVEL(device, SMP)
 		__device_end = .;
+		DEVICE_INIT_STATUS_BITFIELD()
 		DEVICE_BUSY_BITFIELD()
 	} GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
 

kernel/device.c

@@ -23,6 +23,8 @@ extern const struct init_entry __init_SMP_start[];
 extern struct device __device_start[];
 extern struct device __device_end[];
 
+extern uint32_t __device_init_status_start[];
+
 #ifdef CONFIG_DEVICE_POWER_MANAGEMENT
 extern uint32_t __device_busy_start[];
 extern uint32_t __device_busy_end[];
@@ -57,21 +59,18 @@ void z_sys_init_run_level(int32_t level)
 
 	for (entry = levels[level]; entry < levels[level+1]; entry++) {
 		struct device *dev = entry->dev;
-		int retval;
 
 		if (dev != NULL) {
 			z_object_init(dev);
 		}
 
-		retval = entry->init(dev);
-		if (retval != 0) {
-			if (dev) {
-				/* Initialization failed. Clear the API struct
-				 * so that device_get_binding() will not succeed
-				 * for it.
-				 */
-				dev->api = NULL;
-			}
+		if ((entry->init(dev) == 0) && (dev != NULL)) {
+			/* Initialization was successful.
+			 * Set the init status bit so device is declared ready.
+			 */
+			sys_bitfield_set_bit(
+				(mem_addr_t) __device_init_status_start,
+				(dev - __device_start));
 		}
 	}
 }
@@ -121,6 +120,12 @@ size_t z_device_get_all_static(struct device **devices)
 	return __device_end - __device_start;
 }
 
+bool z_device_ready(const struct device *dev)
+{
+	return !!(sys_bitfield_test_bit((mem_addr_t)__device_init_status_start,
+					(dev - __device_start)));
+}
+
 #ifdef CONFIG_DEVICE_POWER_MANAGEMENT
 int device_pm_control_nop(struct device *unused_device,
 		       uint32_t unused_ctrl_command,