Re: [PATCH v2 11/13] arm64: enable generic clockevent broadcast

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 10/14/2013 01:03 PM, Lorenzo Pieralisi wrote:
> On platforms with power management capabilities, timers that are shut
> down when a CPU enters deep C-states must be emulated using an always-on
> timer and a timer IPI to relay the timer IRQ to target CPUs on an SMP
> system.
>
> This patch enables the generic clockevents broadcast infrastructure for
> arm64, by providing the required Kconfig entries and adding the timer
> IPI infrastructure.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

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

sidenote: there is more and more duplicated code between arm and arm64.

> ---
>   arch/arm64/Kconfig               |  2 ++
>   arch/arm64/include/asm/hardirq.h |  2 +-
>   arch/arm64/kernel/smp.c          | 17 +++++++++++++++++
>   3 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index bcf88e4..be88acd 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1,6 +1,7 @@
>   config ARM64
>   	def_bool y
>   	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
> +	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
>   	select ARCH_WANT_OPTIONAL_GPIOLIB
>   	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
>   	select ARCH_WANT_FRAME_POINTERS
> @@ -12,6 +13,7 @@ config ARM64
>   	select COMMON_CLK
>   	select CPU_PM if (SUSPEND || CPU_IDLE)
>   	select GENERIC_CLOCKEVENTS
> +	select GENERIC_CLOCKEVENTS_BROADCAST if SMP
>   	select GENERIC_IOMAP
>   	select GENERIC_IRQ_PROBE
>   	select GENERIC_IRQ_SHOW
> diff --git a/arch/arm64/include/asm/hardirq.h b/arch/arm64/include/asm/hardirq.h
> index 990c051..ae4801d 100644
> --- a/arch/arm64/include/asm/hardirq.h
> +++ b/arch/arm64/include/asm/hardirq.h
> @@ -20,7 +20,7 @@
>   #include <linux/threads.h>
>   #include <asm/irq.h>
>
> -#define NR_IPI	4
> +#define NR_IPI	5
>
>   typedef struct {
>   	unsigned int __softirq_pending;
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index d5488f8..2ed691e 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -61,6 +61,7 @@ enum ipi_msg_type {
>   	IPI_CALL_FUNC,
>   	IPI_CALL_FUNC_SINGLE,
>   	IPI_CPU_STOP,
> +	IPI_TIMER,
>   };
>
>   /*
> @@ -447,6 +448,7 @@ static const char *ipi_types[NR_IPI] = {
>   	S(IPI_CALL_FUNC, "Function call interrupts"),
>   	S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
>   	S(IPI_CPU_STOP, "CPU stop interrupts"),
> +	S(IPI_TIMER, "Timer broadcast interrupts"),
>   };
>
>   void show_ipi_list(struct seq_file *p, int prec)
> @@ -532,6 +534,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
>   		irq_exit();
>   		break;
>
> +#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
> +	case IPI_TIMER:
> +		irq_enter();
> +		tick_receive_broadcast();
> +		irq_exit();
> +		break;
> +#endif
> +
>   	default:
>   		pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
>   		break;
> @@ -544,6 +554,13 @@ void smp_send_reschedule(int cpu)
>   	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
>   }
>
> +#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
> +void tick_broadcast(const struct cpumask *mask)
> +{
> +	smp_cross_call(mask, IPI_TIMER);
> +}
> +#endif
> +
>   void smp_send_stop(void)
>   {
>   	unsigned long timeout;
>


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