clocksource / arch_timer: Parse GTDT to initialize arch timer

Using the information presented by GTDT (Generic Timer Description Table)
to initialize the arch timer (not memory-mapped).

CC: Daniel Lezcano <daniel.lezcano@linaro.org>
CC: Thomas Gleixner <tglx@linutronix.de>
Originally-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Tested-by: Yijing Wang <wangyijing@huawei.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Jon Masters <jcm@redhat.com>
Tested-by: Timur Tabi <timur@codeaurora.org>
Tested-by: Robert Richter <rrichter@cavium.com>
Acked-by: Robert Richter <rrichter@cavium.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c
index 1a7125c3099b..42f9195cf2f8 100644
--- a/arch/arm64/kernel/time.c
+++ b/arch/arm64/kernel/time.c
@@ -35,6 +35,7 @@
 #include <linux/delay.h>
 #include <linux/clocksource.h>
 #include <linux/clk-provider.h>
+#include <linux/acpi.h>
 
 #include <clocksource/arm_arch_timer.h>
 
@@ -72,6 +73,12 @@ void __init time_init(void)
 
         tick_setup_hrtimer_broadcast();
 
+        /*
+         * Since ACPI or FDT will only one be available in the system,
+         * we can use acpi_generic_timer_init() here safely
+         */
+        acpi_generic_timer_init();
+
         arch_timer_rate = arch_timer_get_rate();
         if (!arch_timer_rate)
                 panic("Unable to initialise architected timer.\n");