Merge branch 'timer_evtstrm' of git://linux-arm.org/linux-skn into clockevents/3.13

Adds support to configure the rate and enable the event stream for architected
timer. The event streams can be used to impose a timeout on a wfe, to safeguard
against any programming error in case an expected event is not generated or
even to implement wfe-based timeouts for userspace locking implementations.
This feature can be disabled(enabled by default).

Since the timer control register is reset to zero on warm boot, CPU PM notifier
is added to save and restore the value.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

3 files changed, 33 insertions, 5 deletions

diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index 5665134bfa3e..0704e0cf5571 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -87,17 +87,43 @@ static inline u64 arch_counter_get_cntvct(void)
         return cval;
 }
 
-static inline void arch_counter_set_user_access(void)
+static inline u32 arch_timer_get_cntkctl(void)
 {
         u32 cntkctl;
-
         asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl));
+        return cntkctl;
+}
 
-        /* disable user access to everything */
-        cntkctl &= ~((3 << 8) | (7 << 0));
-
+static inline void arch_timer_set_cntkctl(u32 cntkctl)
+{
         asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl));
 }
+
+static inline void arch_counter_set_user_access(void)
+{
+        u32 cntkctl = arch_timer_get_cntkctl();
+
+        /* 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);
+        arch_timer_set_cntkctl(cntkctl);
+}
+
+static inline void arch_timer_evtstrm_enable(int divider)
+{
+        u32 cntkctl = arch_timer_get_cntkctl();
+        cntkctl &= ~ARCH_TIMER_EVT_TRIGGER_MASK;
+        /* Set the divider and enable virtual event stream */
+        cntkctl |= (divider << ARCH_TIMER_EVT_TRIGGER_SHIFT)
+                        | ARCH_TIMER_VIRT_EVT_EN;
+        arch_timer_set_cntkctl(cntkctl);
+        elf_hwcap |= HWCAP_EVTSTRM;
+}
+
 #endif
 
 #endif
diff --git a/arch/arm/include/uapi/asm/hwcap.h b/arch/arm/include/uapi/asm/hwcap.h
index 6d34d080372a..7dcc10d67253 100644
--- a/arch/arm/include/uapi/asm/hwcap.h
+++ b/arch/arm/include/uapi/asm/hwcap.h
@@ -26,5 +26,6 @@
 #define HWCAP_VFPD32    (1 << 19)       /* set if VFP has 32 regs (not 16) */
 #define HWCAP_IDIV      (HWCAP_IDIVA | HWCAP_IDIVT)
 #define HWCAP_LPAE      (1 << 20)
+#define HWCAP_EVTSTRM   (1 << 21)
 
 #endif /* _UAPI__ASMARM_HWCAP_H */
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 0e1e2b3afa45..5d65438685d8 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -975,6 +975,7 @@ static const char *hwcap_str[] = {
         "idivt",
         "vfpd32",
         "lpae",
+        "evtstrm",
         NULL
 };