armV7R: K3: am654: Allow using SPL BSS pre-relocation

In order to be able to use more advanced driver functionality which often
relies on having BSS initialized during early boot prior to relocation
several things need to be in place:

1) Memory needs to be available for BSS to use. For this, we locate BSS
   at the top of the MCU SRAM area, with the stack starting right below
   it,
2) We need to move the initialization of BSS prior to entering
   board_init_f(). We will do this with a separate commit by turning on
   the respective CONFIG option.

In this commit we also clean up the assignment of the initial SP address
as part of the refactoring, taking into account the pre-decrement post-
increment nature in which the SP is used on ARM.

Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>

diff --git a/include/configs/am65x_evm.h b/include/configs/am65x_evm.h
index 51abab39438e31a27f28c443bf4b14076a112be7..13197459634f2a078961e52880185fc1c89c46e9 100644 (file)
--- a/include/configs/am65x_evm.h
+++ b/include/configs/am65x_evm.h
@@ -19,6 +19,29 @@
 #define CONFIG_SYS_SDRAM_BASE1         0x880000000
 
 /* SPL Loader Configuration */
+#ifdef CONFIG_TARGET_AM654_A53_EVM
+#define CONFIG_SYS_INIT_SP_ADDR         (CONFIG_SPL_TEXT_BASE +        \
+                                        CONFIG_SYS_K3_NON_SECURE_MSRAM_SIZE)
+#else
+/*
+ * Maximum size in memory allocated to the SPL BSS. Keep it as tight as
+ * possible (to allow the build to go through), as this directly affects
+ * our memory footprint. The less we use for BSS the more we have available
+ * for everything else.
+ */
+#define CONFIG_SPL_BSS_MAX_SIZE                0x5000
+/*
+ * Link BSS to be within SPL in a dedicated region located near the top of
+ * the MCU SRAM, this way making it available also before relocation. Note
+ * that we are not using the actual top of the MCU SRAM as there is a memory
+ * location filled in by the boot ROM that we want to read out without any
+ * interference from the C context.
+ */
+#define CONFIG_SPL_BSS_START_ADDR      (CONFIG_SYS_K3_BOOT_PARAM_TABLE_INDEX -\
+                                        CONFIG_SPL_BSS_MAX_SIZE)
+/* Set the stack right below the SPL BSS section */
+#define CONFIG_SYS_INIT_SP_ADDR         CONFIG_SPL_BSS_START_ADDR
+#endif
 
 #ifdef CONFIG_SYS_K3_SPL_ATF
 #define CONFIG_SPL_FS_LOAD_PAYLOAD_NAME        "tispl.bin"
@@ -29,8 +52,6 @@
 #endif
 
 #define CONFIG_SPL_MAX_SIZE            CONFIG_SYS_K3_MAX_DOWNLODABLE_IMAGE_SIZE
-#define CONFIG_SYS_INIT_SP_ADDR         (CONFIG_SPL_TEXT_BASE +        \
-                                       CONFIG_SYS_K3_NON_SECURE_MSRAM_SIZE - 4)
 
 #define CONFIG_SYS_BOOTM_LEN           SZ_64M