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Date: Fri, 1 Apr 2022 12:20:17 +0200
From: Laurent Vivier <laurent@...ier.eu>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: Jiaxun Yang <jiaxun.yang@...goat.com>,
Alessandro Zummo <a.zummo@...ertech.it>,
linux-rtc@...r.kernel.org, Stephen Boyd <sboyd@...nel.org>,
Arnd Bergmann <arnd@...db.de>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
linux-m68k@...ts.linux-m68k.org,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Thomas Gleixner <tglx@...utronix.de>,
John Stultz <john.stultz@...aro.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v15 4/5] clocksource/drivers: Add a goldfish-timer
clocksource
Daniel ?
Thanks,
Laurent
Le 10/03/2022 à 10:00, Laurent Vivier a écrit :
> 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 <laurent@...ier.eu>
> ---
> drivers/clocksource/Kconfig | 7 ++
> drivers/clocksource/Makefile | 1 +
> drivers/clocksource/timer-goldfish.c | 153 +++++++++++++++++++++++++++
> drivers/rtc/rtc-goldfish.c | 13 +--
> include/clocksource/timer-goldfish.h | 31 ++++++
> 5 files changed, 193 insertions(+), 12 deletions(-)
> create mode 100644 drivers/clocksource/timer-goldfish.c
> create mode 100644 include/clocksource/timer-goldfish.h
>
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index cfb8ea0df3b1..94f00374cebb 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -721,4 +721,11 @@ 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
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index fa5f624eadb6..12f5d7e8cc2d 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -89,3 +89,4 @@ 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
> diff --git a/drivers/clocksource/timer-goldfish.c b/drivers/clocksource/timer-goldfish.c
> new file mode 100644
> index 000000000000..0512d5eabc82
> --- /dev/null
> +++ b/drivers/clocksource/timer-goldfish.c
> @@ -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;
> +}
> diff --git a/drivers/rtc/rtc-goldfish.c b/drivers/rtc/rtc-goldfish.c
> index eb1929b0cbb6..59c0f38cc08d 100644
> --- a/drivers/rtc/rtc-goldfish.c
> +++ b/drivers/rtc/rtc-goldfish.c
> @@ -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;
> diff --git a/include/clocksource/timer-goldfish.h b/include/clocksource/timer-goldfish.h
> new file mode 100644
> index 000000000000..d39097729b1d
> --- /dev/null
> +++ b/include/clocksource/timer-goldfish.h
> @@ -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 existin 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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