Some systems are configured such that multiple CPUs begin running from
their reset vector following a system reset. If this occurs then U-Boot
will be run on multiple CPUs simultaneously, which causes all sorts of
issues as the multiple instances of U-Boot clobber each other.
Prevent this from happening by simply hanging with an infinite loop if
we run on a CPU whose ID, as determined by GlobalNumber or EBase.CPUNum
as appropriate, is non-zero.
Signed-off-by: Paul Burton <paul.bur...@imgtec.com>
---
Changes in v4:
- Presume Config5 is present for MIPSr6, as the arch says it will be
Changes in v3:
- Fix branch target for MIPSr6 case... Oops!
Changes in v2:
- Rebase atop u-boot-mips/next
- Execute a wait instruction in the loop
- Fill delay slots with NOPs
arch/mips/cpu/start.S | 21 ++++++++++++++++++++-
arch/mips/include/asm/mipsregs.h | 7 +++++++
2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S
index 8f85ede..5eca829 100644
--- a/arch/mips/cpu/start.S
+++ b/arch/mips/cpu/start.S
@@ -108,9 +108,28 @@ ENTRY(_start)
.align 4
reset:
+#if __mips_isa_rev >= 6
+ mfc0 t0, CP0_CONFIG, 5
+ and t0, t0, MIPS_CONF5_VP
+ beqz t0, 1f
+ nop
+
+ b 2f
+ mfc0 t0, CP0_GLOBALNUMBER
+#endif
+
+1: mfc0 t0, CP0_EBASE
+ and t0, t0, EBASE_CPUNUM
+
+ /* Hang if this isn't the first CPU in the system */
+2: beqz t0, 4f
+ nop
+3: wait
+ b 3b
+ nop
/* Clear watch registers */
- MTC0 zero, CP0_WATCHLO
+4: MTC0 zero, CP0_WATCHLO
mtc0 zero, CP0_WATCHHI
/* WP(Watch Pending), SW0/1 should be cleared */
diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index b4c2dff..9ab5063 100644
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -39,6 +39,7 @@
#define CP0_ENTRYLO0 $2
#define CP0_ENTRYLO1 $3
#define CP0_CONF $3
+#define CP0_GLOBALNUMBER $3, 1
#define CP0_CONTEXT $4
#define CP0_PAGEMASK $5
#define CP0_WIRED $6
@@ -361,6 +362,11 @@
#define CAUSEF_BD (_ULCAST_(1) << 31)
/*
+ * Bits in the coprocessor 0 EBase register.
+ */
+#define EBASE_CPUNUM 0x3ff
+
+/*
* Bits in the coprocessor 0 config register.
*/
/* Generic bits. */
@@ -553,6 +559,7 @@
#define MIPS_CONF5_MRP (_ULCAST_(1) << 3)
#define MIPS_CONF5_LLB (_ULCAST_(1) << 4)
#define MIPS_CONF5_MVH (_ULCAST_(1) << 5)
+#define MIPS_CONF5_VP (_ULCAST_(1) << 7)
#define MIPS_CONF5_FRE (_ULCAST_(1) << 8)
#define MIPS_CONF5_UFE (_ULCAST_(1) << 9)
#define MIPS_CONF5_L2C (_ULCAST_(1) << 10)
--
2.10.0
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