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

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

4 files changed, 93 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 82c6521d04a7..9c4d71ba4595 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -607,6 +607,7 @@ config ARCH_TEGRA
 	select HAVE_CLK
 	select HAVE_SCHED_CLOCK
 	select ARCH_HAS_CPUFREQ
+	select ARCH_PROVIDES_UDELAY
 	help
 	  This enables support for NVIDIA Tegra based systems (Tegra APX,
 	  Tegra 6xx and Tegra 2 series).
diff --git a/arch/arm/mach-tegra/Makefile b/arch/arm/mach-tegra/Makefile
index f0a3f0b728c1..52ec87c5fc48 100644
--- a/arch/arm/mach-tegra/Makefile
+++ b/arch/arm/mach-tegra/Makefile
@@ -6,6 +6,7 @@ obj-y                                   += clock.o
 obj-y                                   += timer.o
 obj-y                                   += pinmux.o
 obj-y                                   += devices.o
+obj-y                                   += delay.o
 obj-y                                   += powergate.o
 obj-$(CONFIG_PM_SLEEP)			+= pm.o
 obj-$(CONFIG_PM_SLEEP)			+= pm-irq.o
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)
diff --git a/arch/arm/mach-tegra/include/mach/delay.h b/arch/arm/mach-tegra/include/mach/delay.h
new file mode 100644
index 000000000000..2defb7b9b658
--- /dev/null
+++ b/arch/arm/mach-tegra/include/mach/delay.h
@@ -0,0 +1,41 @@
+/*
+ * arch/arm/mach-tegra/include/mach/delay.h
+ *
+ * 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.
+ *
+ */
+#ifndef __MACH_TEGRA_DELAY_H
+#define __MACH_TEGRA_DELAY_H
+
+/* needed by loops_per_jiffy calculations */
+extern void __delay(int loops);
+
+extern void __udelay(unsigned long usecs);
+extern void __const_udelay(unsigned long usecs);
+
+/* we don't have any restrictions on maximum udelay length, but we'll enforce
+ * the same restriction as the ARM default so we don't introduce any
+ * incompatibilties in drivers.
+ */
+extern void __bad_udelay(void);
+
+#define MAX_UDELAY_MS 2
+
+#define udelay(n)							\
+	((__builtin_constant_p(n) && (n) > (MAX_UDELAY_MS * 1000)) ?	\
+		__bad_udelay() :					\
+		__udelay(n))
+
+#endif /* defined(__MACH_TEGRA_DELAY_H) */