Re: [PATCH V13 1/4] clocksource: add C-SKY SMP timer

[Guo Ren <ren_guo@c-sky.com>]

Dear Daniel,

Csky subsystem is pulled into linux-4.20, ref: [1]

So could you help merge the C-SKY timer drivers' patches into
linux-4.20? (2 timer drivers and 2 dt-binding-docs)

[1] https://lore.kernel.org/lkml/CAHk-=whq5ebFd2CKE0bybLOY7ttMPxGiXF3WkzFXtkYhAbJqSg@mail.gmail.com/

Best Regards
 Guo Ren

On Mon, Oct 15, 2018 at 01:07:41PM +0800, Guo Ren wrote:
> The driver is for C-SKY SMP timer. It only support oneshot event
> and 32bit overflow for clocksource. Per cpu core has one timer and
> all timers share one clock-counter-input the same clocksource.
> 
> This use mfcr&mtcr instructions to access the regs.
> 
> Signed-off-by: Guo Ren <ren_guo@c-sky.com>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> ---
> Changelog:
>  - Add COMPILE_TEST
>  - Fixup smp boot error, cpuhp_setup_state must after timer_of_init()
>  - Add rollback for timer_of_cleanup.
>  - Use request_percpu_irq separate from time_of.
>  - Remove #define CPUHP_AP_CSKY_TIMER_STARTING.
>  - Add CPUHP_AP_CSKY_TIMER_STARTING in cpuhotplug.h.
>  - Support csky mp timer alpha version.
>  - Just use low-counter with 32bit width as clocksource.
>  - Coding convention with upstream feed-back.
> ---
> ---
>  drivers/clocksource/Kconfig         |  10 +++
>  drivers/clocksource/Makefile        |   1 +
>  drivers/clocksource/timer-mp-csky.c | 173 ++++++++++++++++++++++++++++++++++++
>  include/linux/cpuhotplug.h          |   1 +
>  4 files changed, 185 insertions(+)
>  create mode 100644 drivers/clocksource/timer-mp-csky.c
> 
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index a11f4ba..591c9a8 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -620,4 +620,14 @@ config RISCV_TIMER
>  	  is accessed via both the SBI and the rdcycle instruction.  This is
>  	  required for all RISC-V systems.
>  
> +config CSKY_MP_TIMER
> +	bool "SMP Timer for the C-SKY platform" if COMPILE_TEST
> +	depends on CSKY
> +	select TIMER_OF
> +	help
> +	  Say yes here to enable C-SKY SMP timer driver used for C-SKY SMP
> +	  system.
> +	  csky,mptimer is not only used in SMP system, it also could be used
> +	  single core system. It's not a mmio reg and it use mtcr/mfcr instruction.
> +
>  endmenu
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index db51b24..5ce82d3 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -79,3 +79,4 @@ obj-$(CONFIG_CLKSRC_ST_LPC)		+= clksrc_st_lpc.o
>  obj-$(CONFIG_X86_NUMACHIP)		+= numachip.o
>  obj-$(CONFIG_ATCPIT100_TIMER)		+= timer-atcpit100.o
>  obj-$(CONFIG_RISCV_TIMER)		+= riscv_timer.o
> +obj-$(CONFIG_CSKY_MP_TIMER)		+= timer-mp-csky.o
> diff --git a/drivers/clocksource/timer-mp-csky.c b/drivers/clocksource/timer-mp-csky.c
> new file mode 100644
> index 0000000..a8acc43
> --- /dev/null
> +++ b/drivers/clocksource/timer-mp-csky.c
> @@ -0,0 +1,173 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
> +
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/sched_clock.h>
> +#include <linux/cpu.h>
> +#include <linux/of_irq.h>
> +#include <asm/reg_ops.h>
> +
> +#include "timer-of.h"
> +
> +#define PTIM_CCVR	"cr<3, 14>"
> +#define PTIM_CTLR	"cr<0, 14>"
> +#define PTIM_LVR	"cr<6, 14>"
> +#define PTIM_TSR	"cr<1, 14>"
> +
> +static int csky_mptimer_irq;
> +
> +static int csky_mptimer_set_next_event(unsigned long delta,
> +				       struct clock_event_device *ce)
> +{
> +	mtcr(PTIM_LVR, delta);
> +
> +	return 0;
> +}
> +
> +static int csky_mptimer_shutdown(struct clock_event_device *ce)
> +{
> +	mtcr(PTIM_CTLR, 0);
> +
> +	return 0;
> +}
> +
> +static int csky_mptimer_oneshot(struct clock_event_device *ce)
> +{
> +	mtcr(PTIM_CTLR, 1);
> +
> +	return 0;
> +}
> +
> +static int csky_mptimer_oneshot_stopped(struct clock_event_device *ce)
> +{
> +	mtcr(PTIM_CTLR, 0);
> +
> +	return 0;
> +}
> +
> +static DEFINE_PER_CPU(struct timer_of, csky_to) = {
> +	.flags					= TIMER_OF_CLOCK,
> +	.clkevt = {
> +		.rating				= 300,
> +		.features			= CLOCK_EVT_FEAT_PERCPU |
> +						  CLOCK_EVT_FEAT_ONESHOT,
> +		.set_state_shutdown		= csky_mptimer_shutdown,
> +		.set_state_oneshot		= csky_mptimer_oneshot,
> +		.set_state_oneshot_stopped	= csky_mptimer_oneshot_stopped,
> +		.set_next_event			= csky_mptimer_set_next_event,
> +	},
> +};
> +
> +static irqreturn_t csky_timer_interrupt(int irq, void *dev)
> +{
> +	struct timer_of *to = this_cpu_ptr(&csky_to);
> +
> +	mtcr(PTIM_TSR, 0);
> +
> +	to->clkevt.event_handler(&to->clkevt);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +/*
> + * clock event for percpu
> + */
> +static int csky_mptimer_starting_cpu(unsigned int cpu)
> +{
> +	struct timer_of *to = per_cpu_ptr(&csky_to, cpu);
> +
> +	to->clkevt.cpumask = cpumask_of(cpu);
> +
> +	clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
> +					2, ULONG_MAX);
> +
> +	enable_percpu_irq(csky_mptimer_irq, 0);
> +
> +	return 0;
> +}
> +
> +static int csky_mptimer_dying_cpu(unsigned int cpu)
> +{
> +	disable_percpu_irq(csky_mptimer_irq);
> +
> +	return 0;
> +}
> +
> +/*
> + * clock source
> + */
> +static u64 sched_clock_read(void)
> +{
> +	return (u64)mfcr(PTIM_CCVR);
> +}
> +
> +static u64 clksrc_read(struct clocksource *c)
> +{
> +	return (u64)mfcr(PTIM_CCVR);
> +}
> +
> +struct clocksource csky_clocksource = {
> +	.name	= "csky",
> +	.rating	= 400,
> +	.mask	= CLOCKSOURCE_MASK(32),
> +	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
> +	.read	= clksrc_read,
> +};
> +
> +static int __init csky_mptimer_init(struct device_node *np)
> +{
> +	int ret, cpu, cpu_rollback;
> +	struct timer_of *to = NULL;
> +
> +	/*
> +	 * Csky_mptimer is designed for C-SKY SMP multi-processors and
> +	 * every core has it's own private irq and regs for clkevt and
> +	 * clksrc.
> +	 *
> +	 * The regs is accessed by cpu instruction: mfcr/mtcr instead of
> +	 * mmio map style. So we needn't mmio-address in dts, but we still
> +	 * need to give clk and irq number.
> +	 *
> +	 * We use private irq for the mptimer and irq number is the same
> +	 * for every core. So we use request_percpu_irq() in timer_of_init.
> +	 */
> +	csky_mptimer_irq = irq_of_parse_and_map(np, 0);
> +	if (csky_mptimer_irq <= 0)
> +		return -EINVAL;
> +
> +	ret = request_percpu_irq(csky_mptimer_irq, csky_timer_interrupt,
> +				 "csky_mp_timer", &csky_to);
> +	if (ret)
> +		return -EINVAL;
> +
> +	for_each_possible_cpu(cpu) {
> +		to = per_cpu_ptr(&csky_to, cpu);
> +		ret = timer_of_init(np, to);
> +		if (ret)
> +			goto rollback;
> +	}
> +
> +	clocksource_register_hz(&csky_clocksource, timer_of_rate(to));
> +	sched_clock_register(sched_clock_read, 32, timer_of_rate(to));
> +
> +	ret = cpuhp_setup_state(CPUHP_AP_CSKY_TIMER_STARTING,
> +				"clockevents/csky/timer:starting",
> +				csky_mptimer_starting_cpu,
> +				csky_mptimer_dying_cpu);
> +	if (ret)
> +		return -EINVAL;
> +
> +	return 0;
> +
> +rollback:
> +	for_each_possible_cpu(cpu_rollback) {
> +		if (cpu_rollback == cpu)
> +			break;
> +
> +		to = per_cpu_ptr(&csky_to, cpu_rollback);
> +		timer_of_cleanup(to);
> +	}
> +	return -EINVAL;
> +}
> +TIMER_OF_DECLARE(csky_mptimer, "csky,mptimer", csky_mptimer_init);
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index caf40ad..e0cd2ba 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -126,6 +126,7 @@ enum cpuhp_state {
>  	CPUHP_AP_MIPS_GIC_TIMER_STARTING,
>  	CPUHP_AP_ARC_TIMER_STARTING,
>  	CPUHP_AP_RISCV_TIMER_STARTING,
> +	CPUHP_AP_CSKY_TIMER_STARTING,
>  	CPUHP_AP_KVM_STARTING,
>  	CPUHP_AP_KVM_ARM_VGIC_INIT_STARTING,
>  	CPUHP_AP_KVM_ARM_VGIC_STARTING,
> -- 
> 2.7.4