[U-Boot] [PATCH 3/9] arm: Move CP15 init out of cpu_init_crit()

Simon Glass
2011-10-13T21:05:57Z

Some SOCs have do not start up with their 'main' CPU. The first U-Boot
code may then be executed with a CPU which does not have a CP15, or not a
useful one.

Here we split the initialization of CP15 into a separate call, which can
be performed later if required.

Once the main CPU is running, you should call cpu_init_cp15() to perform
this init as early as possible.

Existing ARMv7 boards which define CONFIG_SKIP_LOWLEVEL_INIT should not
need to change, this CP15 init is still skipped in that case. The only
impact for these boards is that the cpu_init_cp15() will be available
even if it is never used on these boards.

Signed-off-by: Simon Glass <sjg@chromium.org>
---
arch/arm/cpu/armv7/start.S | 24 ++++++++++++++++++------
arch/arm/include/asm/u-boot-arm.h | 3 +++
2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index db8e9d2..7fdd422 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -168,6 +168,7 @@ next:
#endif
/* the mask ROM code should have PLL and others stable */
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
+ bl cpu_reset_cp15
bl cpu_init_crit
#endif

@@ -305,17 +306,16 @@ jump_2_ram:
_board_init_r_ofs:
.word board_init_r - _start

-
-#ifndef CONFIG_SKIP_LOWLEVEL_INIT
/*************************************************************************
*
- * CPU_init_critical registers
+ * cpu_reset_cp15
*
- * setup important registers
- * setup memory timing
+ * Setup CP15 registers (cache, MMU, TLBs). The I-cache is turned on unless
+ * CONFIG_SYS_ICACHE_OFF is defined.
*
*************************************************************************/
-cpu_init_crit:
+.globl cpu_init_cp15
+cpu_init_cp15:
/*
* Invalidate L1 I/D
*/
@@ -340,7 +340,19 @@ cpu_init_crit:
orr r0, r0, #0x00001000 @ set bit 12 (I) I-cache
#endif
mcr p15, 0, r0, c1, c0, 0
+ mov pc, lr @ back to my caller

+
+#ifndef CONFIG_SKIP_LOWLEVEL_INIT
+/*************************************************************************
+ *
+ * CPU_init_critical registers
+ *
+ * setup important registers
+ * setup memory timing
+ *
+ *************************************************************************/
+cpu_init_crit:
/*
* Jump to board specific initialization...
* The Mask ROM will have already initialized
diff --git a/arch/arm/include/asm/u-boot-arm.h b/arch/arm/include/asm/u-boot-arm.h
index d3308f7..4ca75f9 100644
--- a/arch/arm/include/asm/u-boot-arm.h
+++ b/arch/arm/include/asm/u-boot-arm.h
@@ -46,6 +46,9 @@ extern ulong IRQ_STACK_START_IN; /* 8 bytes in IRQ stack */
int cpu_init(void);
int cleanup_before_linux(void);

+/* Set up ARMv7 MMU, caches and TLBs */
+void cpu_init_cp15(void);
+
/* cpu/.../arch/cpu.c */
int arch_cpu_init(void);
int arch_misc_init(void);
--
1.7.3.1