[PATCH v3 7/8] ARM64: enable PBL_CLOCKSOURCE compatibility

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

All ARMv8-A cores implement the 64bit wide generic timer CNTPCT[1]. If
the architected timer driver is enabled the barebox PBL automatically is
PBL_CLOCKSOURCE compatible.

The setup of the PBL clocksource is implemented in the newly added PBL
constructors which are called at the end of setup_c. There is one catch
though:

The CNTFRQ_EL0 register[2] must be programmed by the bootrom, barebox or
the tf-a before the `arm_arch_timer_init` call. A later
re-initialization is also possible by calling `arm_arch_timer_init`
again.

[1]: See "ARM Architecture Reference Manual for A-profile architecture
(rev L.a)", chapter D12 "The Generic Timer in AArch64 state"
[2]: See "ARM Architecture Reference Manual for A-profile architecture
(rev L.a)", chapter D12.1.2.1 "Initializing and reading the system
effective frequency"

Signed-off-by: Stefan Kerkmann <s.kerkmann@pengutronix.de>
---
 arch/arm/lib64/Makefile      |  3 ++-
 arch/arm/lib64/clocksource.c | 10 ++++++++++
 arch/arm/lib64/delay.c       | 19 -------------------
 drivers/clocksource/Kconfig  |  1 +
 4 files changed, 13 insertions(+), 20 deletions(-)

diff --git a/arch/arm/lib64/Makefile b/arch/arm/lib64/Makefile
index f28cf81ab3..218de68a54 100644
--- a/arch/arm/lib64/Makefile
+++ b/arch/arm/lib64/Makefile
@@ -10,4 +10,5 @@ obj-pbl-y   += runtime-offset.o
 obj-pbl-y   += setjmp.o
 obj-pbl-y   += reloc.o
 obj-y += io.o
-pbl-y	+= div0.o delay.o
+pbl-$(CONFIG_CLOCKSOURCE_ARM_ARCHITECTED_TIMER)	+= clocksource.o
+pbl-y	+= div0.o
diff --git a/arch/arm/lib64/clocksource.c b/arch/arm/lib64/clocksource.c
new file mode 100644
index 0000000000..f992be09b8
--- /dev/null
+++ b/arch/arm/lib64/clocksource.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <debug_ll.h>
+#include <asm/hardware/arm_architected_timer.h>
+
+__attribute__((constructor)) static void init_arch_clock(void)
+{
+	if (arm_arch_timer_init(0))
+		puts_ll("Failed to setup architected timer\n");
+}
diff --git a/arch/arm/lib64/delay.c b/arch/arm/lib64/delay.c
deleted file mode 100644
index 78eab33f8d..0000000000
--- a/arch/arm/lib64/delay.c
+++ /dev/null
@@ -1,19 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-
-#include <asm/system.h>
-#include <clock.h>
-#include <common.h>
-
-void udelay(unsigned long us)
-{
-	unsigned long cntfrq = get_cntfrq();
-	unsigned long ticks = (us * cntfrq) / 1000000;
-	unsigned long start = get_cntpct();
-
-	while ((long)(start + ticks - get_cntpct()) > 0);
-}
-
-void mdelay(unsigned long ms)
-{
-	udelay(ms * 1000);
-}
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 5ee83d2b38..6cf68d8be4 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -79,6 +79,7 @@ config CLOCKSOURCE_ARM_ARCHITECTED_TIMER
 	bool "ARM architected timer clock source" if COMPILE_TEST
 	default y
 	depends on ARM && (CPU_64v8 || CPU_V7)
+	select PBL_CLOCKSOURCE if CPU_64v8
 
 config CLOCKSOURCE_ARM_GLOBAL_TIMER
 	bool "ARM global timer clock source" if COMPILE_TEST

-- 
2.47.3