[PATCH 4/4] mips: add config options for generic cache setup code

[Daniel Schwierzeck]

Add an own Kconfig symbol for the initial disabling of caches
invoked from generic start code.

Also add an own Kconfig symbols for the initialization of caches
invoked from generic start code.

Until now both code paths could only be disabled with
CONFIG_SKIP_LOWLEVEL_INIT. But this is not flexible enough for
RAM boot scenarios like EJTAG or SPL payload or for machines
which don't require cache initialization or which want to
provide their own cache implementation.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck at gmail.com>

---

 arch/mips/Kconfig     | 24 ++++++++++++++++++++++++
 arch/mips/cpu/start.S |  6 +++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 48e754cc46..eb00ee71bc 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -270,6 +270,30 @@ config MIPS_CACHE_INDEX_BASE
 	  Normally this is CKSEG0. If the MIPS system needs to move this block
 	  to some SRAM or ScratchPad RAM, adapt this option accordingly.
 
+config MIPS_CACHE_SETUP
+	bool "Allow generic start code to initialize and setup caches"
+	default n if SKIP_LOWLEVEL_INIT
+	default y
+	help
+	  This allows the generic start code to invoke the generic initialization
+	  of the CPU caches. Disabling this can be useful for RAM boot scenarios
+	  (EJTAG, SPL payload) or for machines which don't need cache initialization
+	  or which want to provide their own cache implementation.
+
+	  If unsure, say yes.
+
+config MIPS_CACHE_DISABLE
+	bool "Allow generic start code to initially disable caches"
+	default n if SKIP_LOWLEVEL_INIT
+	default y
+	help
+	  This allows the generic start code to initially disable the CPU caches
+	  and run uncached until the caches are initialized and enabled. Disabling
+	  this can be useful on machines which don't need cache initialization or
+	  which want to provide their own cache implementation.
+
+	  If unsure, say yes.
+
 config MIPS_RELOCATION_TABLE_SIZE
 	hex "Relocation table size"
 	range 0x100 0x10000
diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S
index a9f8743717..0c303031ad 100644
--- a/arch/mips/cpu/start.S
+++ b/arch/mips/cpu/start.S
@@ -195,7 +195,7 @@ wr_done:
 	/* Clear timer interrupt (CP0_COUNT cleared on branch to 'reset') */
 	mtc0	zero, CP0_COMPARE
 
-#ifndef CONFIG_SKIP_LOWLEVEL_INIT
+#ifdef CONFIG_MIPS_CACHE_DISABLE
 	/* Disable caches */
 	PTR_LA	t9, mips_cache_disable
 	jalr	t9
@@ -234,12 +234,16 @@ wr_done:
 	jalr	t9
 	 nop
 # endif
+#endif
 
+#ifdef CONFIG_MIPS_CACHE_SETUP
 	/* Initialize caches... */
 	PTR_LA	t9, mips_cache_reset
 	jalr	t9
 	 nop
+#endif
 
+#ifndef CONFIG_SKIP_LOWLEVEL_INIT
 # ifndef CONFIG_SYS_MIPS_CACHE_INIT_RAM_LOAD
 	/* Initialize any external memory */
 	PTR_LA	t9, lowlevel_init
-- 
2.27.0