Re: [PATCH v3 1/6] ARM/ARM64: arch_timer: add m acros for bits in control register

From: Marc Zyngier
Date: Wed Aug 14 2013 - 05:03:59 EST


Hi Daniel,

On 2013-08-14 09:50, Daniel Lezcano wrote:
On 08/13/2013 07:29 PM, Sudeep KarkadaNagesha wrote:
From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@xxxxxxx>

Add macros to describe the bitfields in the ARM architected timer
control register to make code easy to understand.

Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Reviewed-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@xxxxxxx>
---
arch/arm/include/asm/arch_timer.h | 9 +++++++--
arch/arm64/include/asm/arch_timer.h | 12 ++++++++----
include/clocksource/arm_arch_timer.h | 8 ++++++++
3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index e406d57..9ef74da 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -95,8 +95,13 @@ static inline void arch_counter_set_user_access(void)

asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl));

- /* disable user access to everything */
- cntkctl &= ~((3 << 8) | (7 << 0));
+ /* Disable user access to both physical/virtual counters/timers. */
+ /* Also disable virtual event stream */
+ cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
+ | ARCH_TIMER_USR_VT_ACCESS_EN
+ | ARCH_TIMER_VIRT_EVT_EN
+ | ARCH_TIMER_USR_VCT_ACCESS_EN
+ | ARCH_TIMER_USR_PCT_ACCESS_EN);

asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl));
}
diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index 98abd47..00b09d0 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -101,12 +101,16 @@ static inline void arch_counter_set_user_access(void)
{
u32 cntkctl;

- /* Disable user access to the timers and the physical counter. */
asm volatile("mrs %0, cntkctl_el1" : "=r" (cntkctl));
- cntkctl &= ~((3 << 8) | (1 << 0));

- /* Enable user access to the virtual counter and frequency. */
- cntkctl |= (1 << 1);
+ /* Disable user access to the timers and the physical counter. */
+ cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
+ | ARCH_TIMER_USR_VT_ACCESS_EN
+ | ARCH_TIMER_USR_PCT_ACCESS_EN);
+
+ /* Enable user access to the virtual counter. */
+ cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
+
asm volatile("msr cntkctl_el1, %0" : : "r" (cntkctl));
}

Before doing those changes, I suggest you kill include/asm/arch_timer.h
header file and move the functions directly in the arm_arch_timer.c as
they are only used by it.

How do you suggest to proceed? Having #ifdefs in arm_arch_timer.c to cope with the inline assembly functions present in both arm and arm64 include files? Doesn't seem much of a progress to me...

diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h
index c463ce9..551f7e9 100644
--- a/include/clocksource/arm_arch_timer.h
+++ b/include/clocksource/arm_arch_timer.h
@@ -29,6 +29,14 @@
#define ARCH_TIMER_PHYS_ACCESS 0
#define ARCH_TIMER_VIRT_ACCESS 1

+#define ARCH_TIMER_USR_PCT_ACCESS_EN (1 << 0) /* physical counter */
+#define ARCH_TIMER_USR_VCT_ACCESS_EN (1 << 1) /* virtual counter */
+#define ARCH_TIMER_VIRT_EVT_EN (1 << 2)
+#define ARCH_TIMER_EVT_TRIGGER_SHIFT (4)
+#define ARCH_TIMER_EVT_TRIGGER_MASK (0xF << ARCH_TIMER_EVT_TRIGGER_SHIFT)
+#define ARCH_TIMER_USR_VT_ACCESS_EN (1 << 8) /* virtual timer registers */
+#define ARCH_TIMER_USR_PT_ACCESS_EN (1 << 9) /* physical timer registers */
+
#ifdef CONFIG_ARM_ARCH_TIMER

extern u32 arch_timer_get_rate(void);


M.
--
Fast, cheap, reliable. Pick two.
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