ENGR00155879: MX6: Enable ARM core to enter WAIT mode when system is idle.

Set the appropriate bit in CCM to allow ARM-CORE to enter WAIT
mode when system is idle.

Signed-off-by: Ranjani Vaidyanathan <ra5478@freescale.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/arch/arm/mach-mx6/mx6_wfi.S b/arch/arm/mach-mx6/mx6_wfi.S
new file mode 100644
index 000000000000..88993f016818
--- /dev/null
+++ b/arch/arm/mach-mx6/mx6_wfi.S
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2010-2011 Freescale Semiconductor, Inc. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <linux/linkage.h>
+
+/*
+ *  mx6_wait
+ *
+ *  Idle the processor (eg, wait for interrupt).
+ *  Make sure DDR is in self-refresh.
+ *  IRQs are already disabled.
+ */
+ENTRY(mx6_wait)
+
+	stmfd   sp!, {r3,r4,r5,r6,r7}     @ Save registers
+
+	wfi
+
+	/*Wait for 170ns due to L2 cache errata (TKT065875) */
+	/*System is more stable only if the wait is closer to ~380ns */
+	/* Each IO read takes about 76ns. */
+
+	ldr   r6, [r0]
+	ldr   r6, [r0, #4]
+	ldr   r6, [r0, #8]
+	ldr   r6, [r0, #0xc]
+	ldr   r6, [r0, #0x10]
+	ldr   r6, [r0, #0x14]
+	ldr   r6, [r0, #0x18]
+	ldr   r6, [r0, #0x1c]
+	ldr   r6, [r0, #0x20]
+	ldr   r6, [r0, #0x24]
+
+    /* Restore registers */
+    ldmfd sp!, {r3,r4,r5,r6,r7}
+    mov     pc, lr
+
+    .type   mx6_do_wait, #object
+ENTRY(mx6_do_wait)
+    .word   mx6_wait
+    .size    mx6_wait, . - mx6_wait