| Message ID | 1374745537-30389-1-git-send-email-Sudeep.KarkadaNagesha@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 25/07/13 10:45, Sudeep KarkadaNagesha wrote: > 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. > Hi Catalin, If you are OK with this patch, can I have your ACK ? Regards, Sudeep > 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); >
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);