From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Thu, 22 Dec 2011 17:27:31 +0000 Subject: [PATCH v2 01/15] ARM: local timers: allow smp_twd to be used standalone In-Reply-To: <1324574865-5367-1-git-send-email-marc.zyngier@arm.com> References: <1324574865-5367-1-git-send-email-marc.zyngier@arm.com> Message-ID: <1324574865-5367-2-git-send-email-marc.zyngier@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Allow smp_twd to be built in a "standalone" version, without relying on the CONFIG_LOCAL_TIMER infrastructure. It mainly relies on a CPU notifier block to stop or start the timer on the right CPU. The CONFIG_ARM_SMP_TWD option selects the new behaviour. Signed-off-by: Marc Zyngier --- arch/arm/Kconfig | 6 +++- arch/arm/include/asm/smp_twd.h | 9 +++++ arch/arm/kernel/smp_twd.c | 79 +++++++++++++++++++++++++++++++++++++++- 3 files changed, 92 insertions(+), 2 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 6f3e186..c37410a 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1522,6 +1522,10 @@ config HAVE_ARM_TWD help This options enables support for the ARM timer and watchdog unit +config ARM_SMP_TWD + bool + select HAVE_ARM_TWD if SMP + choice prompt "Memory split" default VMSPLIT_3G @@ -1560,7 +1564,7 @@ config HOTPLUG_CPU config LOCAL_TIMERS bool "Use local timer interrupts" - depends on SMP + depends on SMP && !ARM_SMP_TWD default y select HAVE_ARM_TWD if (!ARCH_MSM_SCORPIONMP && !EXYNOS4_MCT) help diff --git a/arch/arm/include/asm/smp_twd.h b/arch/arm/include/asm/smp_twd.h index ef9ffba9..934f1bc 100644 --- a/arch/arm/include/asm/smp_twd.h +++ b/arch/arm/include/asm/smp_twd.h @@ -19,10 +19,19 @@ #define TWD_TIMER_CONTROL_IT_ENABLE (1 << 2) struct clock_event_device; +struct resource; extern void __iomem *twd_base; void twd_timer_setup(struct clock_event_device *); void twd_timer_stop(struct clock_event_device *); +#ifdef CONFIG_HAVE_ARM_TWD +int twd_timer_register(struct resource *res, int res_nr); +#else +static inline int twd_timer_register(struct resource *res, int res_nr) +{ + return 0; +} +#endif #endif diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c index 2442bbb..dedbdb4 100644 --- a/arch/arm/kernel/smp_twd.c +++ b/arch/arm/kernel/smp_twd.c @@ -13,11 +13,13 @@ #include #include #include +#include #include #include #include #include +#include #include #include #include @@ -172,7 +174,7 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk) clk->name = "local_timer"; clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP; - clk->rating = 350; + clk->rating = 450; /* Make sure this is higher than broadcast */ clk->set_mode = twd_set_mode; clk->set_next_event = twd_set_next_event; clk->shift = 20; @@ -187,3 +189,78 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk) enable_percpu_irq(clk->irq, 0); } + +#ifdef CONFIG_ARM_SMP_TWD +static struct clock_event_device __percpu *twd_clock_event; +static int twd_ppi; + +static void __cpuinit twd_setup(struct clock_event_device *clk) +{ + clk->cpumask = cpumask_of(smp_processor_id()); + clk->irq = twd_ppi; + twd_timer_setup(clk); +} + +static void __cpuinit twd_teardown(void *data) +{ + struct clock_event_device *clk = data; + twd_timer_stop(clk); +} + +static int __cpuinit twd_cpu_notify(struct notifier_block *self, + unsigned long action, void *data) +{ + int cpu = (int)data; + struct clock_event_device *clk = per_cpu_ptr(twd_clock_event, cpu); + + switch (action) { + case CPU_STARTING: + case CPU_STARTING_FROZEN: + twd_setup(clk); + break; + + case CPU_DOWN_PREPARE: + case CPU_DOWN_PREPARE_FROZEN: + smp_call_function_single(cpu, twd_teardown, clk, 1); + break; + } + + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata twd_cpu_nb = { + .notifier_call = twd_cpu_notify, +}; + +int __init twd_timer_register(struct resource *res, int res_nr) +{ + struct clock_event_device *clk; + + if (!is_smp()) + return -ENODEV; + + if (res_nr != 2 || res[1].start < 0) + return -EINVAL; + + if (twd_base) + return -EBUSY; + + twd_ppi = res[1].start; + twd_base = ioremap(res[0].start, resource_size(&res[0])); + twd_clock_event = alloc_percpu(struct clock_event_device); + if (!twd_base || !twd_clock_event) { + iounmap(twd_base); + twd_base = NULL; + free_percpu(twd_clock_event); + return -ENOMEM; + } + + /* Immediately configure the timer on the boot CPU */ + clk = per_cpu_ptr(twd_clock_event, smp_processor_id()); + twd_setup(clk); + + register_cpu_notifier(&twd_cpu_nb); + + return 0; +} +#endif -- 1.7.7.1