clocksource: arm_arch_timer: Change clocksource name if CP15 unavailable

The arm and arm64 VDSOs need CP15 access to the architected counter.
If this is unavailable (which is allowed by ARM v7), indicate this by
changing the clocksource name to "arch_mem_counter" before registering
the clocksource.

Suggested by Stephen Boyd.

Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 7e267e3990ab8c58eb246a1bb3d810c0a12f1918..e0e7729d37fd332eed9f5e2aad530170e6992c6c 100644 (file)
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -429,11 +429,19 @@ static void __init arch_counter_register(unsigned type)
        u64 start_count;
 
        /* Register the CP15 based counter if we have one */
-       if (type & ARCH_CP15_TIMER)
+       if (type & ARCH_CP15_TIMER) {
                arch_timer_read_counter = arch_counter_get_cntvct;
-       else
+       } else {
                arch_timer_read_counter = arch_counter_get_cntvct_mem;
 
+               /* If the clocksource name is "arch_sys_counter" the
+                * VDSO will attempt to read the CP15-based counter.
+                * Ensure this does not happen when CP15-based
+                * counter is not available.
+                */
+               clocksource_counter.name = "arch_mem_counter";
+       }
+
        start_count = arch_timer_read_counter();
        clocksource_register_hz(&clocksource_counter, arch_timer_rate);
        cyclecounter.mult = clocksource_counter.mult;