Commit a7ad38b0 authored by Guo Ren's avatar Guo Ren Committed by Daniel Lezcano
Browse files

clocksource/drivers/c-sky: Add C-SKY SMP timer 



The driver is for C-SKY SMP timer. It only supports oneshot event
and 32bit overflow for clocksource. Per cpu core has one timer and
all timers share one clock-counter-input from the same clocksource.

This use mfcr&mtcr instructions to access the regs.

Signed-off-by: default avatarGuo Ren <ren_guo@c-sky.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
parent 291d0e5d

drivers/clocksource/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -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

drivers/clocksource/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

drivers/clocksource/timer-mp-csky.c

0 → 100644
+173 −0
Original line number Diff line number Diff line 
// 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);

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

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