lmb: Add 2 config to define the max number of regions

Add 2 configs CONFIG_LMB_MEMORY_REGIONS and CONFIG_LMB_RESERVED_REGIONS
to change independently the max number of the regions in lmb
library.

When CONFIG_LMB_USE_MAX_REGIONS=y, move the lmb property arrays to
struct lmb and manage the array size with the element 'max' of struct
lmb_region; their are still allocated in stack.

When CONFIG_LMB_USE_MAX_REGIONS=n, keep the current location in
struct lmb_region to allow compiler optimization.

Increase CONFIG_LMB_RESERVED_REGIONS is useful to avoid lmb errors in
bootm when the number of reserved regions (not adjacent) is reached:
+ 1 region for relocated U-Boot
+ 1 region for initrd
+ 1 region for relocated linux device tree
+ reserved memory regions present in Linux device tree.

The current limit of 8 regions is reached with only 5 reserved regions
in DT.

see Linux kernel commit bf23c51f1f49 ("memblock: Move memblock arrays
to static storage in memblock.c and make their size a variable")

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

include/lmb.h

@@ -12,20 +12,54 @@
  * Copyright (C) 2001 Peter Bergner, IBM Corp.
  */
 
+/**
+ * struct lmb_property - Description of one region.
+ *
+ * @base: Base address of the region.
+ * @size: Size of the region
+ */
 struct lmb_property {
 	phys_addr_t base;
 	phys_size_t size;
 };
 
+/**
+ * struct lmb_region - Description of a set of region.
+ *
+ * @cnt: Number of regions.
+ * @max: Size of the region array, max value of cnt.
+ * @region: Array of the region properties
+ */
 struct lmb_region {
 	unsigned long cnt;
 	unsigned long max;
+#if IS_ENABLED(CONFIG_LMB_USE_MAX_REGIONS)
 	struct lmb_property region[CONFIG_LMB_MAX_REGIONS];
+#else
+	struct lmb_property *region;
+#endif
 };
 
+/**
+ * struct lmb - Logical memory block handle.
+ *
+ * Clients provide storage for Logical memory block (lmb) handles.
+ * The content of the structure is managed by the lmb library.
+ * A lmb struct is  initialized by lmb_init() functions.
+ * The lmb struct is passed to all other lmb APIs.
+ *
+ * @memory: Description of memory regions.
+ * @reserved: Description of reserved regions.
+ * @memory_regions: Array of the memory regions (statically allocated)
+ * @reserved_regions: Array of the reserved regions (statically allocated)
+ */
 struct lmb {
 	struct lmb_region memory;
 	struct lmb_region reserved;
+#if !IS_ENABLED(CONFIG_LMB_USE_MAX_REGIONS)
+	struct lmb_property memory_regions[CONFIG_LMB_MEMORY_REGIONS];
+	struct lmb_property reserved_regions[CONFIG_LMB_RESERVED_REGIONS];
+#endif
 };
 
 extern void lmb_init(struct lmb *lmb);

lib/Kconfig

@@ -707,14 +707,41 @@ config LMB
 	help
 	  Support the library logical memory blocks.
 
+config LMB_USE_MAX_REGIONS
+	bool "Use a commun number of memory and reserved regions in lmb lib"
+	depends on LMB
+	default y
+	help
+	  Define the number of supported memory regions in the library logical
+	  memory blocks.
+	  This feature allow to reduce the lmb library size by using compiler
+	  optimization when LMB_MEMORY_REGIONS == LMB_RESERVED_REGIONS.
 
 config LMB_MAX_REGIONS
 	int "Number of memory and reserved regions in lmb lib"
-	depends on LMB
+	depends on LMB && LMB_USE_MAX_REGIONS
 	default 8
 	help
 	  Define the number of supported regions, memory and reserved, in the
 	  library logical memory blocks.
+
+config LMB_MEMORY_REGIONS
+	int "Number of memory regions in lmb lib"
+	depends on LMB && !LMB_USE_MAX_REGIONS
+	default 8
+	help
+	  Define the number of supported memory regions in the library logical
+	  memory blocks.
+	  The minimal value is CONFIG_NR_DRAM_BANKS.
+
+config LMB_RESERVED_REGIONS
+	int "Number of reserved regions in lmb lib"
+	depends on LMB && !LMB_USE_MAX_REGIONS
+	default 8
+	help
+	  Define the number of supported reserved regions in the library logical
+	  memory blocks.
+
 endmenu
 
 config PHANDLE_CHECK_SEQ

lib/lmb.c

@@ -95,9 +95,15 @@ static void lmb_coalesce_regions(struct lmb_region *rgn, unsigned long r1,
 
 void lmb_init(struct lmb *lmb)
 {
+#if IS_ENABLED(CONFIG_LMB_USE_MAX_REGIONS)
 	lmb->memory.max = CONFIG_LMB_MAX_REGIONS;
 	lmb->reserved.max = CONFIG_LMB_MAX_REGIONS;
-
+#else
+	lmb->memory.max = CONFIG_LMB_MEMORY_REGIONS;
+	lmb->reserved.max = CONFIG_LMB_RESERVED_REGIONS;
+	lmb->memory.region = lmb->memory_regions;
+	lmb->reserved.region = lmb->reserved_regions;
+#endif
 	lmb->memory.cnt = 0;
 	lmb->reserved.cnt = 0;
 }