[PATCH 07/10] arm: arch_timer: add arch_counter_enable_user_access

[Mark Rutland]

Several bits in CNTKCTL reset to 0, including PL0VTEN. For platforms
using the generic timer which wish to have a fast gettimeofday vDSO
implementation, these bits must be set to 1 by the kernel.

Add an arch_counter_enable_user_access function for this. As we don't
(currently) use the counter from PL0 on arm, the implementation is an
empty stub.

Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Acked-by: Catalin Marinas <catalin.marinas at arm.com>
Acked-by: Marc Zyngier <marc.zyngier at arm.com>
---
 arch/arm/include/asm/arch_timer.h |    7 +++++++
 arch/arm/kernel/arch_timer.c      |    2 ++
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index 701f2b7..c50e415 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -108,6 +108,13 @@ static inline u64 arch_counter_get_cntvct(void)
 	return cval;
 }
 
+static inline void __cpuinit arch_counter_enable_user_access(void)
+{
+	/*
+	 * Do nothing - the counter is never mapped to userspace threads,
+	 * so we don't care whether access is enabled or not.
+	 */
+}
 
 #else
 static inline int arch_timer_of_register(void)
diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index 10e1657..28b29f0 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -155,6 +155,8 @@ static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
 			enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
 	}
 
+	arch_counter_enable_user_access();
+
 	return 0;
 }
 
-- 
1.7.0.4