Re: [PATCH v5 4/6] clocksource/drivers/timer-riscv: Use per-CPU timer interrupt

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

On 21/05/2020 15:32, Anup Patel wrote:
> Instead of directly calling RISC-V timer interrupt handler from
> RISC-V local interrupt conntroller driver, this patch implements
> RISC-V timer interrupt as a per-CPU interrupt using per-CPU APIs
> of Linux IRQ subsystem.
> 
> Signed-off-by: Anup Patel <anup.patel@wdc.com>

via which tree do you want this patch to be merged ?

> ---
>  arch/riscv/include/asm/irq.h      |  2 --
>  drivers/clocksource/timer-riscv.c | 30 +++++++++++++++++++++++++++---
>  drivers/irqchip/irq-riscv-intc.c  |  8 --------
>  3 files changed, 27 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
> index a9e5f07a7e9c..9807ad164015 100644
> --- a/arch/riscv/include/asm/irq.h
> +++ b/arch/riscv/include/asm/irq.h
> @@ -10,8 +10,6 @@
>  #include <linux/interrupt.h>
>  #include <linux/linkage.h>
>  
> -void riscv_timer_interrupt(void);
> -
>  #include <asm-generic/irq.h>
>  
>  #endif /* _ASM_RISCV_IRQ_H */
> diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
> index c4f15c4068c0..5fb7c5ba5c91 100644
> --- a/drivers/clocksource/timer-riscv.c
> +++ b/drivers/clocksource/timer-riscv.c
> @@ -14,6 +14,9 @@
>  #include <linux/irq.h>
>  #include <linux/sched_clock.h>
>  #include <linux/io-64-nonatomic-lo-hi.h>
> +#include <linux/irqchip/irq-riscv-intc.h>
> +#include <linux/interrupt.h>
> +#include <linux/of_irq.h>
>  #include <asm/smp.h>
>  #include <asm/sbi.h>
>  
> @@ -39,6 +42,7 @@ static int riscv_clock_next_event(unsigned long delta,
>  	return 0;
>  }
>  
> +static unsigned int riscv_clock_event_irq;
>  static DEFINE_PER_CPU(struct clock_event_device, riscv_clock_event) = {
>  	.name			= "riscv_timer_clockevent",
>  	.features		= CLOCK_EVT_FEAT_ONESHOT,
> @@ -74,30 +78,35 @@ static int riscv_timer_starting_cpu(unsigned int cpu)
>  	struct clock_event_device *ce = per_cpu_ptr(&riscv_clock_event, cpu);
>  
>  	ce->cpumask = cpumask_of(cpu);
> +	ce->irq = riscv_clock_event_irq;
>  	clockevents_config_and_register(ce, riscv_timebase, 100, 0x7fffffff);
>  
> -	csr_set(CSR_IE, IE_TIE);
> +	enable_percpu_irq(riscv_clock_event_irq,
> +			  irq_get_trigger_type(riscv_clock_event_irq));
>  	return 0;
>  }
>  
>  static int riscv_timer_dying_cpu(unsigned int cpu)
>  {
> -	csr_clear(CSR_IE, IE_TIE);
> +	disable_percpu_irq(riscv_clock_event_irq);
>  	return 0;
>  }
>  
>  /* called directly from the low-level interrupt handler */
> -void riscv_timer_interrupt(void)
> +static irqreturn_t riscv_timer_interrupt(int irq, void *dev_id)
>  {
>  	struct clock_event_device *evdev = this_cpu_ptr(&riscv_clock_event);
>  
>  	csr_clear(CSR_IE, IE_TIE);
>  	evdev->event_handler(evdev);
> +
> +	return IRQ_HANDLED;
>  }
>  
>  static int __init riscv_timer_init_dt(struct device_node *n)
>  {
>  	int cpuid, hartid, error;
> +	struct of_phandle_args oirq;
>  
>  	hartid = riscv_of_processor_hartid(n);
>  	if (hartid < 0) {
> @@ -115,6 +124,13 @@ static int __init riscv_timer_init_dt(struct device_node *n)
>  	if (cpuid != smp_processor_id())
>  		return 0;
>  
> +	oirq.np = riscv_of_intc_domain_node();
> +	oirq.args_count = 1;
> +	oirq.args[0] = RV_IRQ_TIMER;
> +	riscv_clock_event_irq = irq_create_of_mapping(&oirq);
> +	if (!riscv_clock_event_irq)
> +		return -ENODEV;
> +
>  	pr_info("%s: Registering clocksource cpuid [%d] hartid [%d]\n",
>  	       __func__, cpuid, hartid);
>  	error = clocksource_register_hz(&riscv_clocksource, riscv_timebase);
> @@ -126,6 +142,14 @@ static int __init riscv_timer_init_dt(struct device_node *n)
>  
>  	sched_clock_register(riscv_sched_clock, 64, riscv_timebase);
>  
> +	error = request_percpu_irq(riscv_clock_event_irq,
> +				    riscv_timer_interrupt,
> +				    "riscv-timer", &riscv_clock_event);
> +	if (error) {
> +		pr_err("registering percpu irq failed [%d]\n", error);
> +		return error;
> +	}
> +
>  	error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
>  			 "clockevents/riscv/timer:starting",
>  			 riscv_timer_starting_cpu, riscv_timer_dying_cpu);
> diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
> index 2f364e6a87f9..d4fbc3543459 100644
> --- a/drivers/irqchip/irq-riscv-intc.c
> +++ b/drivers/irqchip/irq-riscv-intc.c
> @@ -23,20 +23,12 @@ static struct irq_domain *intc_domain;
>  
>  static asmlinkage void riscv_intc_irq(struct pt_regs *regs)
>  {
> -	struct pt_regs *old_regs;
>  	unsigned long cause = regs->cause & ~CAUSE_IRQ_FLAG;
>  
>  	if (unlikely(cause >= BITS_PER_LONG))
>  		panic("unexpected interrupt cause");
>  
>  	switch (cause) {
> -	case RV_IRQ_TIMER:
> -		old_regs = set_irq_regs(regs);
> -		irq_enter();
> -		riscv_timer_interrupt();
> -		irq_exit();
> -		set_irq_regs(old_regs);
> -		break;
>  #ifdef CONFIG_SMP
>  	case RV_IRQ_SOFT:
>  		/*
> 


-- 
<http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog