linux-kernel - [PATCH v6 2/5] ARM: arch_timer: add support to configure and enable event stream

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Message-Id: <1377788142-21388-3-git-send-email-Sudeep.KarkadaNagesha@arm.com>
Date:	Thu, 29 Aug 2013 15:55:39 +0100
From:	Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>
To:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	Sudeep.KarkadaNagesha@....com,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Will Deacon <Will.Deacon@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>,
	Russell King <linux@....linux.org.uk>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Will Deacon <will.deacon@....com>
Subject: [PATCH v6 2/5] ARM: arch_timer: add support to configure and enable event stream

From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>

This patch adds support for configuring the event stream frequency
and enabling it.

It also adds the hwcaps definitions to the user to detect this event
stream feature.

Cc: Russell King <linux@....linux.org.uk>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc: Will Deacon <will.deacon@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
---
 arch/arm/include/asm/arch_timer.h | 27 ++++++++++++++++++++++++---
 arch/arm/include/uapi/asm/hwcap.h |  1 +
 arch/arm/kernel/setup.c           |  1 +
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index 1a3e967..f10cd1c 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -89,11 +89,21 @@ 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;
+}
+
+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 */
@@ -102,9 +112,20 @@ static inline void arch_counter_set_user_access(void)
 			| ARCH_TIMER_VIRT_EVT_EN
 			| ARCH_TIMER_USR_VCT_ACCESS_EN
 			| ARCH_TIMER_USR_PCT_ACCESS_EN);
+	arch_timer_set_cntkctl(cntkctl);
+}
 
-	asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (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 6d34d08..7dcc10d 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 afc2489..305ffc9 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
 };
 
-- 
1.8.1.2


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