From: Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@arm.com> To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Sudeep.KarkadaNagesha@arm.com, Mark Rutland <mark.rutland@arm.com>, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, Russell King <linux@arm.linux.org.uk>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Mathieu Poirier <mathieu.poirier@linaro.org> Subject: [PATCH v3 1/3] drivers: clocksource: configure event stream for ARM arch timer Date: Thu, 25 Jul 2013 10:45:37 +0100 [thread overview] Message-ID: <1374745537-30389-1-git-send-email-Sudeep.KarkadaNagesha@arm.com> (raw) In-Reply-To: <1374492082-13686-2-git-send-email-Sudeep.KarkadaNagesha@arm.com> From: Will Deacon <will.deacon@arm.com> The ARM architected timer can generate events (used for waking up CPUs executing the wfe instruction) at a frequency represented as a power-of-2 divisor of the clock rate. This patch configures the event stream, aiming for a period of 100us between events. This can be used to implement wfe-based timeouts for userspace locking implementations. This patch also adds the hwcaps for the same, so that userspace can detect this feature. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> --- arch/arm/include/asm/arch_timer.h | 6 ++++-- arch/arm/include/uapi/asm/hwcap.h | 1 + arch/arm/kernel/setup.c | 1 + arch/arm64/include/asm/arch_timer.h | 6 +++--- drivers/clocksource/arm_arch_timer.c | 9 ++++++++- include/clocksource/arm_arch_timer.h | 2 ++ 6 files changed, 19 insertions(+), 6 deletions(-) ------------>8--------------------- Hi, This version adds the hwcaps for publishing the event stream feature to the userspace. This patch is now rebased on rmk's fixes branch as it conflicts with ab8d46c0 "ARM: 7788/1: elf: fix lpae hwcap feature reporting in proc/cpuinfo" Regards, Sudeep diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h index e406d57..8963877 100644 --- a/arch/arm/include/asm/arch_timer.h +++ b/arch/arm/include/asm/arch_timer.h @@ -89,16 +89,18 @@ static inline u64 arch_counter_get_cntvct(void) return cval; } -static inline void arch_counter_set_user_access(void) +static inline void arch_counter_set_user_access(int divider) { u32 cntkctl; asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl)); /* disable user access to everything */ - cntkctl &= ~((3 << 8) | (7 << 0)); + cntkctl &= ~((3 << 8) | (0xf << 4) | (3 << 0)); + cntkctl |= (divider << 4) | (1 << 2); asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl)); + elf_hwcap |= HWCAP_EVTSTRM; } #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 96286cb..5191956 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -973,6 +973,7 @@ static const char *hwcap_str[] = { "idivt", "vfpd32", "lpae", + "evtstrm", NULL }; diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index 98abd47..8c1e42f 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -97,16 +97,16 @@ static inline u32 arch_timer_get_cntfrq(void) return val; } -static inline void arch_counter_set_user_access(void) +static inline void arch_counter_set_user_access(int divider) { 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)); + cntkctl &= ~((3 << 8) | (0xf << 4) | (1 << 0)); /* Enable user access to the virtual counter and frequency. */ - cntkctl |= (1 << 1); + cntkctl |= (divider << 4) | (1 << 2) | (1 << 1); asm volatile("msr cntkctl_el1, %0" : : "r" (cntkctl)); } diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index ffadd83..6301ee5 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -125,6 +125,8 @@ static int arch_timer_set_next_event_phys(unsigned long evt, static int arch_timer_setup(struct clock_event_device *clk) { + int evt_stream_div, pos; + clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP; clk->name = "arch_sys_timer"; clk->rating = 450; @@ -153,7 +155,12 @@ static int arch_timer_setup(struct clock_event_device *clk) enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0); } - arch_counter_set_user_access(); + /* Find the closest power of two to the divisor */ + evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ; + pos = fls(evt_stream_div); + if (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))) + pos--; + arch_counter_set_user_access(min(pos, 15)); return 0; } diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h index c463ce9..24dc140 100644 --- a/include/clocksource/arm_arch_timer.h +++ b/include/clocksource/arm_arch_timer.h @@ -29,6 +29,8 @@ #define ARCH_TIMER_PHYS_ACCESS 0 #define ARCH_TIMER_VIRT_ACCESS 1 +#define ARCH_TIMER_EVT_STREAM_FREQ 10000 /* 100us */ + #ifdef CONFIG_ARM_ARCH_TIMER extern u32 arch_timer_get_rate(void); -- 1.8.1.2
WARNING: multiple messages have this Message-ID (diff)
From: Sudeep.KarkadaNagesha@arm.com (Sudeep KarkadaNagesha) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 1/3] drivers: clocksource: configure event stream for ARM arch timer Date: Thu, 25 Jul 2013 10:45:37 +0100 [thread overview] Message-ID: <1374745537-30389-1-git-send-email-Sudeep.KarkadaNagesha@arm.com> (raw) In-Reply-To: <1374492082-13686-2-git-send-email-Sudeep.KarkadaNagesha@arm.com> From: Will Deacon <will.deacon@arm.com> The ARM architected timer can generate events (used for waking up CPUs executing the wfe instruction) at a frequency represented as a power-of-2 divisor of the clock rate. This patch configures the event stream, aiming for a period of 100us between events. This can be used to implement wfe-based timeouts for userspace locking implementations. This patch also adds the hwcaps for the same, so that userspace can detect this feature. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> --- arch/arm/include/asm/arch_timer.h | 6 ++++-- arch/arm/include/uapi/asm/hwcap.h | 1 + arch/arm/kernel/setup.c | 1 + arch/arm64/include/asm/arch_timer.h | 6 +++--- drivers/clocksource/arm_arch_timer.c | 9 ++++++++- include/clocksource/arm_arch_timer.h | 2 ++ 6 files changed, 19 insertions(+), 6 deletions(-) ------------>8--------------------- Hi, This version adds the hwcaps for publishing the event stream feature to the userspace. This patch is now rebased on rmk's fixes branch as it conflicts with ab8d46c0 "ARM: 7788/1: elf: fix lpae hwcap feature reporting in proc/cpuinfo" Regards, Sudeep diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h index e406d57..8963877 100644 --- a/arch/arm/include/asm/arch_timer.h +++ b/arch/arm/include/asm/arch_timer.h @@ -89,16 +89,18 @@ static inline u64 arch_counter_get_cntvct(void) return cval; } -static inline void arch_counter_set_user_access(void) +static inline void arch_counter_set_user_access(int divider) { u32 cntkctl; asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl)); /* disable user access to everything */ - cntkctl &= ~((3 << 8) | (7 << 0)); + cntkctl &= ~((3 << 8) | (0xf << 4) | (3 << 0)); + cntkctl |= (divider << 4) | (1 << 2); asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl)); + elf_hwcap |= HWCAP_EVTSTRM; } #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 96286cb..5191956 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -973,6 +973,7 @@ static const char *hwcap_str[] = { "idivt", "vfpd32", "lpae", + "evtstrm", NULL }; diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index 98abd47..8c1e42f 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -97,16 +97,16 @@ static inline u32 arch_timer_get_cntfrq(void) return val; } -static inline void arch_counter_set_user_access(void) +static inline void arch_counter_set_user_access(int divider) { 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)); + cntkctl &= ~((3 << 8) | (0xf << 4) | (1 << 0)); /* Enable user access to the virtual counter and frequency. */ - cntkctl |= (1 << 1); + cntkctl |= (divider << 4) | (1 << 2) | (1 << 1); asm volatile("msr cntkctl_el1, %0" : : "r" (cntkctl)); } diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index ffadd83..6301ee5 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -125,6 +125,8 @@ static int arch_timer_set_next_event_phys(unsigned long evt, static int arch_timer_setup(struct clock_event_device *clk) { + int evt_stream_div, pos; + clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP; clk->name = "arch_sys_timer"; clk->rating = 450; @@ -153,7 +155,12 @@ static int arch_timer_setup(struct clock_event_device *clk) enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0); } - arch_counter_set_user_access(); + /* Find the closest power of two to the divisor */ + evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ; + pos = fls(evt_stream_div); + if (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))) + pos--; + arch_counter_set_user_access(min(pos, 15)); return 0; } diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h index c463ce9..24dc140 100644 --- a/include/clocksource/arm_arch_timer.h +++ b/include/clocksource/arm_arch_timer.h @@ -29,6 +29,8 @@ #define ARCH_TIMER_PHYS_ACCESS 0 #define ARCH_TIMER_VIRT_ACCESS 1 +#define ARCH_TIMER_EVT_STREAM_FREQ 10000 /* 100us */ + #ifdef CONFIG_ARM_ARCH_TIMER extern u32 arch_timer_get_rate(void); -- 1.8.1.2
next prev parent reply other threads:[~2013-07-25 9:46 UTC|newest] Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-06-18 17:06 [PATCH 0/4] ARM/ARM64 architected timer updates Sudeep KarkadaNagesha 2013-06-18 17:06 ` Sudeep KarkadaNagesha 2013-06-18 17:07 ` [PATCH 1/4] drivers: clocksource: configure event stream for ARM arch timer Sudeep KarkadaNagesha 2013-06-18 17:07 ` Sudeep KarkadaNagesha 2013-06-18 17:07 ` [PATCH 2/4] ARM: arch_timer: add macros for bits in control register Sudeep KarkadaNagesha 2013-06-18 17:07 ` Sudeep KarkadaNagesha 2013-06-18 17:07 ` [PATCH 3/4] ARM/ARM64: arch_timer: remove __cpuinit attribute for arch_counter_set_user_access Sudeep KarkadaNagesha 2013-06-18 17:07 ` Sudeep KarkadaNagesha 2013-06-18 17:58 ` Sudeep KarkadaNagesha 2013-06-18 17:58 ` Sudeep KarkadaNagesha 2013-06-18 17:07 ` [PATCH 4/4] drivers: clocksource: add CPU PM notifier for ARM architected timer Sudeep KarkadaNagesha 2013-06-18 17:07 ` Sudeep KarkadaNagesha 2013-07-02 16:09 ` Jon Medhurst (Tixy) 2013-07-02 16:09 ` Jon Medhurst (Tixy) 2013-07-02 17:24 ` Sudeep KarkadaNagesha 2013-07-02 17:24 ` Sudeep KarkadaNagesha 2013-07-22 11:21 ` [PATCH v2 0/3] ARM/ARM64 architected timer updates Sudeep KarkadaNagesha 2013-07-22 11:21 ` Sudeep KarkadaNagesha 2013-07-22 11:21 ` [PATCH v2 1/3] drivers: clocksource: configure event stream for ARM arch timer Sudeep KarkadaNagesha 2013-07-22 11:21 ` Sudeep KarkadaNagesha 2013-07-23 10:23 ` Catalin Marinas 2013-07-23 10:23 ` Catalin Marinas 2013-07-23 10:33 ` Will Deacon 2013-07-23 10:33 ` Will Deacon 2013-07-23 11:12 ` Catalin Marinas 2013-07-23 11:12 ` Catalin Marinas 2013-07-25 9:45 ` Sudeep KarkadaNagesha [this message] 2013-07-25 9:45 ` [PATCH v3 " Sudeep KarkadaNagesha 2013-08-12 13:32 ` Sudeep KarkadaNagesha 2013-08-12 13:32 ` Sudeep KarkadaNagesha 2013-07-22 11:21 ` [PATCH v2 2/3] ARM: arch_timer: add macros for bits in control register Sudeep KarkadaNagesha 2013-07-22 11:21 ` Sudeep KarkadaNagesha 2013-07-22 11:21 ` [PATCH v2 3/3] drivers: clocksource: add CPU PM notifier for ARM architected timer Sudeep KarkadaNagesha 2013-07-22 11:21 ` Sudeep KarkadaNagesha 2013-08-02 9:32 ` [PATCH v2 0/3] ARM/ARM64 architected timer updates Sudeep KarkadaNagesha 2013-08-02 9:32 ` Sudeep KarkadaNagesha 2013-08-02 9:48 ` Daniel Lezcano 2013-08-02 9:48 ` Daniel Lezcano 2013-08-02 9:55 ` Sudeep KarkadaNagesha 2013-08-02 9:55 ` Sudeep KarkadaNagesha 2013-08-02 12:12 ` Daniel Lezcano 2013-08-02 12:12 ` Daniel Lezcano 2013-08-05 16:25 ` Sudeep KarkadaNagesha 2013-08-05 16:25 ` Sudeep KarkadaNagesha 2013-08-06 8:09 ` Daniel Lezcano 2013-08-06 8:09 ` Daniel Lezcano 2013-08-06 9:01 ` Sudeep KarkadaNagesha 2013-08-06 9:01 ` Sudeep KarkadaNagesha 2013-08-12 13:16 ` Daniel Lezcano 2013-08-12 13:16 ` Daniel Lezcano 2013-08-13 17:29 ` [PATCH v3 0/6] " Sudeep KarkadaNagesha 2013-08-13 17:29 ` Sudeep KarkadaNagesha 2013-08-13 17:29 ` [PATCH v3 1/6] ARM/ARM64: arch_timer: add macros for bits in control register Sudeep KarkadaNagesha 2013-08-13 17:29 ` Sudeep KarkadaNagesha 2013-08-14 8:50 ` Daniel Lezcano 2013-08-14 8:50 ` Daniel Lezcano 2013-08-14 9:03 ` Marc Zyngier 2013-08-14 9:03 ` Marc Zyngier 2013-08-14 9:23 ` Daniel Lezcano 2013-08-14 9:23 ` Daniel Lezcano 2013-08-13 17:29 ` [PATCH v3 2/6] drivers: clocksource: configure event stream for ARM arch timer Sudeep KarkadaNagesha 2013-08-13 17:29 ` Sudeep KarkadaNagesha 2013-08-13 17:29 ` [PATCH v3 3/6] ARM: arch_timer: configure and enable event stream Sudeep KarkadaNagesha 2013-08-13 17:29 ` Sudeep KarkadaNagesha 2013-08-13 17:29 ` [PATCH v3 4/6] ARM64: " Sudeep KarkadaNagesha 2013-08-13 17:29 ` Sudeep KarkadaNagesha 2013-08-20 13:27 ` Will Deacon 2013-08-20 13:27 ` Will Deacon 2013-08-20 14:27 ` Sudeep KarkadaNagesha 2013-08-20 14:27 ` Sudeep KarkadaNagesha 2013-08-20 16:16 ` Will Deacon 2013-08-20 16:16 ` Will Deacon 2013-08-20 16:23 ` Sudeep KarkadaNagesha 2013-08-20 16:23 ` Sudeep KarkadaNagesha 2013-08-20 17:08 ` Sudeep KarkadaNagesha 2013-08-20 17:08 ` Sudeep KarkadaNagesha 2013-08-21 17:52 ` Will Deacon 2013-08-21 17:52 ` Will Deacon 2013-08-13 17:29 ` [PATCH v3 5/6] drivers: clocksource: enable hwcaps for event stream on ARM arch timer Sudeep KarkadaNagesha 2013-08-13 17:29 ` Sudeep KarkadaNagesha 2013-08-13 17:29 ` [PATCH v3 6/6] drivers: clocksource: add CPU PM notifier for ARM architected timer Sudeep KarkadaNagesha 2013-08-13 17:29 ` Sudeep KarkadaNagesha 2013-08-14 9:08 ` [PATCH v3 0/6] ARM/ARM64 architected timer updates Daniel Lezcano 2013-08-14 9:08 ` Daniel Lezcano 2013-08-14 9:17 ` Sudeep KarkadaNagesha 2013-08-14 9:17 ` Sudeep KarkadaNagesha 2013-08-14 10:51 ` Daniel Lezcano 2013-08-14 10:51 ` Daniel Lezcano 2013-08-14 11:03 ` Sudeep KarkadaNagesha 2013-08-14 11:03 ` Sudeep KarkadaNagesha 2013-08-14 15:00 ` Daniel Lezcano 2013-08-14 15:00 ` Daniel Lezcano 2013-08-20 17:14 ` Sudeep KarkadaNagesha 2013-08-20 17:14 ` Sudeep KarkadaNagesha 2013-08-23 9:26 ` Catalin Marinas 2013-08-23 9:26 ` Catalin Marinas 2013-08-23 9:57 ` Sudeep KarkadaNagesha 2013-08-23 9:57 ` Sudeep KarkadaNagesha
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=1374745537-30389-1-git-send-email-Sudeep.KarkadaNagesha@arm.com \ --to=sudeep.karkadanagesha@arm.com \ --cc=catalin.marinas@arm.com \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux@arm.linux.org.uk \ --cc=lorenzo.pieralisi@arm.com \ --cc=mark.rutland@arm.com \ --cc=mathieu.poirier@linaro.org \ --cc=will.deacon@arm.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.