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>

2 files changed, 35 insertions, 2 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index e46c51f123..6d2d41de30 100644
--- a/lib/Kconfig
+++ b/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
diff --git a/lib/lmb.c b/lib/lmb.c
index 9fbc56619b..c08c4d942b 100644
--- a/lib/lmb.c
+++ b/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;
 }