Commit c92e7ef1 authored by Laurent Vivier's avatar Laurent Vivier Committed by Geert Uytterhoeven
Browse files

clocksource/drivers: Add a goldfish-timer clocksource 

Add a clocksource based on the goldfish-rtc device.

Move the timer register definition to <clocksource/timer-goldfish.h>

This kernel implementation is based on the QEMU upstream implementation:

   https://git.qemu.org/?p=qemu.git;a=blob_plain;f=hw/rtc/goldfish_rtc.c



goldfish-timer is a high-precision signed 64-bit nanosecond timer.
It is part of the 'goldfish' virtual hardware platform used to run
some emulated Android systems under QEMU.
This timer only supports oneshot event.

Signed-off-by: default avatarLaurent Vivier <laurent@vivier.eu>
Acked-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20220406201523.243733-4-laurent@vivier.eu


Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
parent 3378c7f4

drivers/clocksource/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -711,4 +711,11 @@ config MICROCHIP_PIT64B 
	  modes and high resolution. It is used as a clocksource

	  and a clockevent.



config GOLDFISH_TIMER

	bool "Clocksource using goldfish-rtc"

	depends on M68K || COMPILE_TEST

	depends on RTC_DRV_GOLDFISH

	help

	  Support for the timer/counter of goldfish-rtc



endmenu

drivers/clocksource/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -88,3 +88,4 @@ obj-$(CONFIG_GX6605S_TIMER) += timer-gx6605s.o 
obj-$(CONFIG_HYPERV_TIMER)		+= hyperv_timer.o

obj-$(CONFIG_MICROCHIP_PIT64B)		+= timer-microchip-pit64b.o

obj-$(CONFIG_MSC313E_TIMER)		+= timer-msc313e.o

obj-$(CONFIG_GOLDFISH_TIMER)		+= timer-goldfish.o

drivers/clocksource/timer-goldfish.c

0 → 100644
+153 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#include <linux/interrupt.h>

#include <linux/ioport.h>

#include <linux/clocksource.h>

#include <linux/clockchips.h>

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/goldfish.h>

#include <clocksource/timer-goldfish.h>



struct goldfish_timer {

	struct clocksource cs;

	struct clock_event_device ced;

	struct resource res;

	void __iomem *base;

};



static struct goldfish_timer *ced_to_gf(struct clock_event_device *ced)

{

	return container_of(ced, struct goldfish_timer, ced);

}



static struct goldfish_timer *cs_to_gf(struct clocksource *cs)

{

	return container_of(cs, struct goldfish_timer, cs);

}



static u64 goldfish_timer_read(struct clocksource *cs)

{

	struct goldfish_timer *timerdrv = cs_to_gf(cs);

	void __iomem *base = timerdrv->base;

	u32 time_low, time_high;

	u64 ticks;



	/*

	 * time_low: get low bits of current time and update time_high

	 * time_high: get high bits of time at last time_low read

	 */

	time_low = gf_ioread32(base + TIMER_TIME_LOW);

	time_high = gf_ioread32(base + TIMER_TIME_HIGH);



	ticks = ((u64)time_high << 32) | time_low;



	return ticks;

}



static int goldfish_timer_set_oneshot(struct clock_event_device *evt)

{

	struct goldfish_timer *timerdrv = ced_to_gf(evt);

	void __iomem *base = timerdrv->base;



	gf_iowrite32(0, base + TIMER_ALARM_HIGH);

	gf_iowrite32(0, base + TIMER_ALARM_LOW);

	gf_iowrite32(1, base + TIMER_IRQ_ENABLED);



	return 0;

}



static int goldfish_timer_shutdown(struct clock_event_device *evt)

{

	struct goldfish_timer *timerdrv = ced_to_gf(evt);

	void __iomem *base = timerdrv->base;



	gf_iowrite32(0, base + TIMER_IRQ_ENABLED);



	return 0;

}



static int goldfish_timer_next_event(unsigned long delta,

				     struct clock_event_device *evt)

{

	struct goldfish_timer *timerdrv = ced_to_gf(evt);

	void __iomem *base = timerdrv->base;

	u64 now;



	now = goldfish_timer_read(&timerdrv->cs);



	now += delta;



	gf_iowrite32(upper_32_bits(now), base + TIMER_ALARM_HIGH);

	gf_iowrite32(lower_32_bits(now), base + TIMER_ALARM_LOW);



	return 0;

}



static irqreturn_t goldfish_timer_irq(int irq, void *dev_id)

{

	struct goldfish_timer *timerdrv = dev_id;

	struct clock_event_device *evt = &timerdrv->ced;

	void __iomem *base = timerdrv->base;



	gf_iowrite32(1, base + TIMER_CLEAR_INTERRUPT);



	evt->event_handler(evt);



	return IRQ_HANDLED;

}



int __init goldfish_timer_init(int irq, void __iomem *base)

{

	struct goldfish_timer *timerdrv;

	int ret;



	timerdrv = kzalloc(sizeof(*timerdrv), GFP_KERNEL);

	if (!timerdrv)

		return -ENOMEM;



	timerdrv->base = base;



	timerdrv->ced = (struct clock_event_device){

		.name			= "goldfish_timer",

		.features		= CLOCK_EVT_FEAT_ONESHOT,

		.set_state_shutdown	= goldfish_timer_shutdown,

		.set_state_oneshot      = goldfish_timer_set_oneshot,

		.set_next_event		= goldfish_timer_next_event,

	};



	timerdrv->res = (struct resource){

		.name  = "goldfish_timer",

		.start = (unsigned long)base,

		.end   = (unsigned long)base + 0xfff,

	};



	ret = request_resource(&iomem_resource, &timerdrv->res);

	if (ret) {

		pr_err("Cannot allocate '%s' resource\n", timerdrv->res.name);

		return ret;

	}



	timerdrv->cs = (struct clocksource){

		.name		= "goldfish_timer",

		.rating		= 400,

		.read		= goldfish_timer_read,

		.mask		= CLOCKSOURCE_MASK(64),

		.flags		= 0,

		.max_idle_ns	= LONG_MAX,

	};



	clocksource_register_hz(&timerdrv->cs, NSEC_PER_SEC);



	ret = request_irq(irq, goldfish_timer_irq, IRQF_TIMER,

			  "goldfish_timer", timerdrv);

	if (ret) {

		pr_err("Couldn't register goldfish-timer interrupt\n");

		return ret;

	}



	clockevents_config_and_register(&timerdrv->ced, NSEC_PER_SEC,

					1, 0xffffffff);



	return 0;

}

drivers/rtc/rtc-goldfish.c

+1 −12
Original line number Diff line number Diff line
@@ -11,18 +11,7 @@ 
#include <linux/platform_device.h>

#include <linux/rtc.h>

#include <linux/goldfish.h>



#define TIMER_TIME_LOW		0x00	/* get low bits of current time  */

					/*   and update TIMER_TIME_HIGH  */

#define TIMER_TIME_HIGH	0x04	/* get high bits of time at last */

					/*   TIMER_TIME_LOW read         */

#define TIMER_ALARM_LOW	0x08	/* set low bits of alarm and     */

					/*   activate it                 */

#define TIMER_ALARM_HIGH	0x0c	/* set high bits of next alarm   */

#define TIMER_IRQ_ENABLED	0x10

#define TIMER_CLEAR_ALARM	0x14

#define TIMER_ALARM_STATUS	0x18

#define TIMER_CLEAR_INTERRUPT	0x1c

#include <clocksource/timer-goldfish.h>



struct goldfish_rtc {

	void __iomem *base;

include/clocksource/timer-goldfish.h

0 → 100644
+31 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * goldfish-timer clocksource

 * Registers definition for the goldfish-timer device

 */



#ifndef _CLOCKSOURCE_TIMER_GOLDFISH_H

#define _CLOCKSOURCE_TIMER_GOLDFISH_H



/*

 * TIMER_TIME_LOW	 get low bits of current time and update TIMER_TIME_HIGH

 * TIMER_TIME_HIGH	 get high bits of time at last TIMER_TIME_LOW read

 * TIMER_ALARM_LOW	 set low bits of alarm and activate it

 * TIMER_ALARM_HIGH	 set high bits of next alarm

 * TIMER_IRQ_ENABLED	 enable alarm interrupt

 * TIMER_CLEAR_ALARM	 disarm an existing alarm

 * TIMER_ALARM_STATUS	 alarm status (running or not)

 * TIMER_CLEAR_INTERRUPT clear interrupt

 */

#define TIMER_TIME_LOW		0x00

#define TIMER_TIME_HIGH		0x04

#define TIMER_ALARM_LOW		0x08

#define TIMER_ALARM_HIGH	0x0c

#define TIMER_IRQ_ENABLED	0x10

#define TIMER_CLEAR_ALARM	0x14

#define TIMER_ALARM_STATUS	0x18

#define TIMER_CLEAR_INTERRUPT	0x1c



extern int goldfish_timer_init(int irq, void __iomem *base);



#endif /* _CLOCKSOURCE_TIMER_GOLDFISH_H */