device: Refactor device structures

When the device driver model got introduced, there were no concept of
SYS_INIT() which can be seen as software service. These were introduced
afterwards and reusing the device infrastructure for simplicity.
However, it meant to allocate a bit too much for something that only
required an initialization function to be called at right time.

Thus refactoring the devices structures relevantly:
- introducing struct init_entry which is a generic init end-point
- struct deviceconfig is removed and struct device owns everything now.
- SYS_INIT() generates only a struct init_entry via calling
  INIT_ENTRY_DEFINE()
- DEVICE_AND_API_INIT() generates a struct device and calls
  INIT_ENTRY_DEFINE()
- init objects sections are in ROM
- device objects sections are in RAM (but will end up in ROM once they
  will be 'constified')

It also generate a tiny memory gain on both ROM and RAM, which is nice.

Perhaps kernel/device.c could be renamed to something more relevant.

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>

include/linker/linker-defs.h

@@ -45,7 +45,7 @@
  */
 #ifdef CONFIG_DEVICE_POWER_MANAGEMENT
 #define DEVICE_COUNT \
-	((__device_init_end - __device_init_start) / _DEVICE_STRUCT_SIZEOF)
+	((__device_end - __device_start) / _DEVICE_STRUCT_SIZEOF)
 #define DEV_BUSY_SZ	(((DEVICE_COUNT + 31) / 32) * 4)
 #define DEVICE_BUSY_BITFIELD()			\
 		FILL(0x00) ;			\
@@ -57,37 +57,53 @@
 #endif
 
 /*
- * generate a symbol to mark the start of the device initialization objects for
- * the specified level, then link all of those objects (sorted by priority);
- * ensure the objects aren't discarded if there is no direct reference to them
+ * generate a symbol to mark the start of the objects array for
+ * the specified object and level, then link all of those objects
+ * (sorted by priority). Ensure the objects aren't discarded if there is
+ * no direct reference to them
  */
-
-#define DEVICE_INIT_LEVEL(level)				\
-		__device_##level##_start = .;			\
-		KEEP(*(SORT(.init_##level[0-9])));		\
-		KEEP(*(SORT(.init_##level[1-9][0-9])));	\
+#define CREATE_OBJ_LEVEL(object, level)				\
+		__##object##_##level##_start = .;		\
+		KEEP(*(SORT(.##object##_##level[0-9])));	\
+		KEEP(*(SORT(.##object##_##level[1-9][0-9])));	\
 
 /*
- * link in device initialization objects for all devices that are automatically
+ * link in initialization objects for all objects that are automatically
  * initialized by the kernel; the objects are sorted in the order they will be
  * initialized (i.e. ordered by level, sorted by priority within a level)
  */
 
-#define	DEVICE_INIT_SECTIONS()			\
-		__device_init_start = .;	\
-		DEVICE_INIT_LEVEL(PRE_KERNEL_1)	\
-		DEVICE_INIT_LEVEL(PRE_KERNEL_2)	\
-		DEVICE_INIT_LEVEL(POST_KERNEL)	\
-		DEVICE_INIT_LEVEL(APPLICATION)	\
-		DEVICE_INIT_LEVEL(SMP)		\
-		__device_init_end = .;		\
-		DEVICE_BUSY_BITFIELD()		\
+#define	INIT_SECTIONS()					\
+		__init_start = .;			\
+		CREATE_OBJ_LEVEL(init, PRE_KERNEL_1)	\
+		CREATE_OBJ_LEVEL(init, PRE_KERNEL_2)	\
+		CREATE_OBJ_LEVEL(init, POST_KERNEL)	\
+		CREATE_OBJ_LEVEL(init, APPLICATION)	\
+		CREATE_OBJ_LEVEL(init, SMP)		\
+		__init_end = .;				\
 
 
 /* define a section for undefined device initialization levels */
-#define DEVICE_INIT_UNDEFINED_SECTION()		\
+#define INIT_UNDEFINED_SECTION()		\
 		KEEP(*(SORT(.init_[_A-Z0-9]*)))	\
 
+
+/*
+ * link in devices objects, which are tied to the init ones;
+ * the objects are thus sorted the same way as their init object parent
+ * see include/device.h
+ */
+#define	DEVICE_SECTIONS()				\
+		__device_start = .;			\
+		CREATE_OBJ_LEVEL(device, PRE_KERNEL_1)	\
+		CREATE_OBJ_LEVEL(device, PRE_KERNEL_2)	\
+		CREATE_OBJ_LEVEL(device, POST_KERNEL)	\
+		CREATE_OBJ_LEVEL(device, APPLICATION)	\
+		CREATE_OBJ_LEVEL(device, SMP)		\
+		__device_end = .;			\
+		DEVICE_BUSY_BITFIELD()			\
+
+
 /*
  * link in shell initialization objects for all modules that use shell and
  * their shell commands are automatically initialized by the kernel.