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authorKumar Gala <galak@kernel.crashing.org>2011-11-22 06:51:15 -0600
committerKumar Gala <galak@kernel.crashing.org>2011-11-29 08:48:05 -0600
commit43f082bb7fc1c24b32a4abc693869c7d14d42829 (patch)
tree93f965962cb64edbac52e2ff28125641a68a9299 /arch/powerpc/cpu
parenta63d9652757605ec5f7104addc5d38bf10ba8671 (diff)
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powerpc/85xx: Add workaround for erratum CPU-A003999
Erratum A-003999: Running Floating Point instructions requires special initialization. Impact: Floating point arithmetic operations may result in an incorrect value. Workaround: Perform a read modify write to set bit 7 to a 1 in SPR 977 before executing any floating point arithmetic operation. This bit can be set when setting MSR[FP], and can be cleared when clearing MSR[FP]. Alternatively, the bit can be set once at boot time, and never cleared. There will be no performance degradation due to setting this bit. Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/cpu')
-rw-r--r--arch/powerpc/cpu/mpc85xx/cmd_errata.c3
-rw-r--r--arch/powerpc/cpu/mpc85xx/release.S6
-rw-r--r--arch/powerpc/cpu/mpc85xx/start.S6
3 files changed, 15 insertions, 0 deletions
diff --git a/arch/powerpc/cpu/mpc85xx/cmd_errata.c b/arch/powerpc/cpu/mpc85xx/cmd_errata.c
index 253bf08..523f297 100644
--- a/arch/powerpc/cpu/mpc85xx/cmd_errata.c
+++ b/arch/powerpc/cpu/mpc85xx/cmd_errata.c
@@ -53,6 +53,9 @@ static int do_errata(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
#if defined(CONFIG_SYS_P4080_ERRATUM_CPU22)
puts("Work-around for Erratum CPU22 enabled\n");
#endif
+#if defined(CONFIG_SYS_FSL_ERRATUM_CPU_A003999)
+ puts("Work-around for Erratum CPU-A003999 enabled\n");
+#endif
#if defined(CONFIG_SYS_FSL_ERRATUM_DDR_MSYNC_IN)
puts("Work-around for DDR MSYNC_IN Erratum enabled\n");
#endif
diff --git a/arch/powerpc/cpu/mpc85xx/release.S b/arch/powerpc/cpu/mpc85xx/release.S
index 6678ed4..c81e19c 100644
--- a/arch/powerpc/cpu/mpc85xx/release.S
+++ b/arch/powerpc/cpu/mpc85xx/release.S
@@ -68,6 +68,12 @@ __secondary_start_page:
mtspr SPRN_HID1,r3
#endif
+#ifdef CONFIG_SYS_FSL_ERRATUM_CPU_A003999
+ mfspr r3,977
+ oris r3,r3,0x0100
+ mtspr 977,r3
+#endif
+
/* Enable branch prediction */
lis r3,BUCSR_ENABLE@h
ori r3,r3,BUCSR_ENABLE@l
diff --git a/arch/powerpc/cpu/mpc85xx/start.S b/arch/powerpc/cpu/mpc85xx/start.S
index 7bd5cc0..4d37d6e 100644
--- a/arch/powerpc/cpu/mpc85xx/start.S
+++ b/arch/powerpc/cpu/mpc85xx/start.S
@@ -253,6 +253,12 @@ l2_disabled:
mtspr HID1,r0
#endif
+#ifdef CONFIG_SYS_FSL_ERRATUM_CPU_A003999
+ mfspr r3,977
+ oris r3,r3,0x0100
+ mtspr 977,r3
+#endif
+
/* Enable Branch Prediction */
#if defined(CONFIG_BTB)
lis r0,BUCSR_ENABLE@h