[U-Boot] [PATCH v4 08/26] armv8: add simple sdelay implementation

[Andre Przywara]

The sunxi DRAM setup code needs an sdelay() implementation, which
wasn't defined for armv8 so far.
Shamelessly copy the armv7 version and adjust it to work in AArch64.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
 arch/arm/cpu/armv8/cpu.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/arm/cpu/armv8/cpu.c b/arch/arm/cpu/armv8/cpu.c
index 5dcb5e2..28a27f7 100644
--- a/arch/arm/cpu/armv8/cpu.c
+++ b/arch/arm/cpu/armv8/cpu.c
@@ -17,6 +17,20 @@
 #include <asm/secure.h>
 #include <linux/compiler.h>
 
+/*
+ * sdelay() - simple spin loop.
+ *
+ * Will delay execution by roughly (@loops * 2) cycles.
+ * This is necessary to be used before timers are accessible.
+ *
+ * A value of "0" will results in 2^64 loops.
+ */
+void sdelay(unsigned long loops)
+{
+	__asm__ volatile ("1:\n" "subs %0, %0, #1\n"
+			  "b.ne 1b" : "=r" (loops) : "0"(loops) : "cc");
+}
+
 int cleanup_before_linux(void)
 {
 	/*
-- 
2.8.2