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clocksource/drivers: Add a goldfish-timer clocksource
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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: Laurent Vivier <[email protected]>
Acked-by: Daniel Lezcano <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Geert Uytterhoeven <[email protected]>
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vivier authored and geertu committed Apr 11, 2022
1 parent 3378c7f commit c92e7ef
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Showing 5 changed files with 193 additions and 12 deletions.
7 changes: 7 additions & 0 deletions drivers/clocksource/Kconfig
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Expand Up @@ -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
1 change: 1 addition & 0 deletions drivers/clocksource/Makefile
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Expand Up @@ -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
153 changes: 153 additions & 0 deletions drivers/clocksource/timer-goldfish.c
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@@ -0,0 +1,153 @@
// 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;
}
13 changes: 1 addition & 12 deletions drivers/rtc/rtc-goldfish.c
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Expand Up @@ -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;
Expand Down
31 changes: 31 additions & 0 deletions include/clocksource/timer-goldfish.h
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@@ -0,0 +1,31 @@
/* 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 */

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