[PATCH v16 3/4] clocksource/drivers: Add a goldfish-timer clocksource

Laurent Vivier
2022-04-06T21:20:28Z

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@vivier.eu>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
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 1589ae7d5abb..06866bfa1826 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -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
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 9c85ee2bb373..b839beb6ea53 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -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
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..05a3a4f610d6
--- /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 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 */
--
2.35.1