[ARM] tegra: Add arch-specific udelay using TMRUS

Change-Id: If075117642a725ee2ee24a622068274e588a5bc1
Signed-off-by: Colin Cross <ccross@android.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/delay.S b/arch/arm/mach-tegra/delay.S
new file mode 100644
index 000000000000..01123bfe6a0c
--- /dev/null
+++ b/arch/arm/mach-tegra/delay.S
@@ -0,0 +1,50 @@
+/*
+ * arch/arm/mach-tegra/delay.S
+ *
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ *  Colin Cross <ccross@google.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <mach/iomap.h>
+#include <mach/io.h>
+
+    .text
+
+ENTRY(__udelay)
+ENTRY(__const_udelay)
+    ldr r3, =(IO_PPSB_VIRT + TEGRA_TMRUS_BASE - IO_PPSB_PHYS)
+    ldr r1, [r3]
+
+/* r0 - usecs to wait
+ * r1 - initial value of the counter
+ */
+loop:
+    ldr r2, [r3]
+    sub r2, r2, r1
+    cmp r2, r0
+    bls loop
+    mov pc, lr
+ENDPROC(__const_udelay)
+ENDPROC(__udelay)
+
+
+@ Delay routine
+ENTRY(__delay)
+    subs  r0, r0, #1
+    bhi __delay
+    mov pc, lr
+ENDPROC(__delay)