powerpc/85xx: add hardware automatically enter altivec idle state

Each core's AltiVec unit may be placed into a power savings mode
by turning off power to the unit. Core hardware will automatically
power down the AltiVec unit after no AltiVec instructions have
executed in N cycles. The AltiVec power-control is triggered by hardware.

Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/cpu_setup_fsl_booke.S b/arch/powerpc/kernel/cpu_setup_fsl_booke.S
index fa6862db8a02..26c09db2ec20 100644
--- a/arch/powerpc/kernel/cpu_setup_fsl_booke.S
+++ b/arch/powerpc/kernel/cpu_setup_fsl_booke.S
@@ -53,6 +53,25 @@ _GLOBAL(__e500_dcache_setup)
         isync
         blr
 
+/*
+ * FIXME - we haven't yet done testing to determine a reasonable default
+ * value for AV_WAIT_IDLE_BIT.
+ */
+#define AV_WAIT_IDLE_BIT                50 /* 1ms, TB frequency is 41.66MHZ */
+_GLOBAL(setup_altivec_idle)
+        mfspr   r3, SPRN_PWRMGTCR0
+
+        /* Enable Altivec Idle */
+        oris    r3, r3, PWRMGTCR0_AV_IDLE_PD_EN@h
+        li      r11, AV_WAIT_IDLE_BIT
+
+        /* Set Automatic AltiVec Idle Count */
+        rlwimi  r3, r11, PWRMGTCR0_AV_IDLE_CNT_SHIFT, PWRMGTCR0_AV_IDLE_CNT
+
+        mtspr   SPRN_PWRMGTCR0, r3
+
+        blr
+
 _GLOBAL(__setup_cpu_e6500)
         mflr    r6
 #ifdef CONFIG_PPC64
@@ -64,6 +83,7 @@ _GLOBAL(__setup_cpu_e6500)
         bl      .setup_lrat_ivor
 1:
 #endif
+        bl      setup_altivec_idle
         bl      __setup_cpu_e5500
         mtlr    r6
         blr
@@ -131,6 +151,7 @@ _GLOBAL(__restore_cpu_e6500)
         beq     1f
         bl      .setup_lrat_ivor
 1:
+        bl      .setup_altivec_idle
         bl      __restore_cpu_e5500
         mtlr    r5
         blr