armv8: add simple sdelay implementation

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@arm.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>

diff --git a/arch/arm/cpu/armv8/cpu.c b/arch/arm/cpu/armv8/cpu.c
index 5dcb5e290b12e5fbd594ed1b3f5ea55cde8ca64c..28a27f724e60c2549c629aad0aa45083051e3217 100644 (file)
--- 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)
 {
        /*