[PATCH v2 1/3] ARM64: lib64: pbl: implement get_time_ns and is_timeout

[Stefan Kerkmann <s.kerkmann@pengutronix.de>]

All ARMv8-A cores implement the 64bit wide generic timer CNTPCT[1], thus
we can use it to implement the get_time_ns and is_timeout helpers which
in turn enable the whole read_poll_timeout class of functions in the
PBL. As it is guaranteed that the timer will not wrap for 40 years no
overflow handling is necessary.

[1]: See "ARM Architecture Reference Manual for A-profile architecture
(rev L.a)", chapter D12 "The Generic Timer in AArch64 state"

Signed-off-by: Stefan Kerkmann <s.kerkmann@pengutronix.de>
---
 arch/arm/lib64/delay.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/arm/lib64/delay.c b/arch/arm/lib64/delay.c
index 78eab33f8d..00b20c5db1 100644
--- a/arch/arm/lib64/delay.c
+++ b/arch/arm/lib64/delay.c
@@ -7,7 +7,7 @@
 void udelay(unsigned long us)
 {
 	unsigned long cntfrq = get_cntfrq();
-	unsigned long ticks = (us * cntfrq) / 1000000;
+	unsigned long ticks = (us * cntfrq) / MSECOND;
 	unsigned long start = get_cntpct();
 
 	while ((long)(start + ticks - get_cntpct()) > 0);
@@ -15,5 +15,18 @@ void udelay(unsigned long us)
 
 void mdelay(unsigned long ms)
 {
-	udelay(ms * 1000);
+	udelay(ms * USECOND);
+}
+
+uint64_t get_time_ns(void)
+{
+	return get_cntpct() * SECOND / get_cntfrq();
+}
+
+int is_timeout(uint64_t start, uint64_t time_offset_ns)
+{
+	if ((int64_t)(start + time_offset_ns - get_time_ns()) < 0)
+		return 1;
+	else
+		return 0;
 }

-- 
2.47.3