1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/interrupt.h>
  4#include <linux/ioport.h>
  5#include <linux/clocksource.h>
  6#include <linux/clockchips.h>
  7#include <linux/module.h>
  8#include <linux/slab.h>
  9#include <linux/goldfish.h>
 10#include <clocksource/timer-goldfish.h>
 11
 12struct goldfish_timer {
 13	struct clocksource cs;
 14	struct clock_event_device ced;
 15	struct resource res;
 16	void __iomem *base;
 17};
 18
 19static struct goldfish_timer *ced_to_gf(struct clock_event_device *ced)
 20{
 21	return container_of(ced, struct goldfish_timer, ced);
 22}
 23
 24static struct goldfish_timer *cs_to_gf(struct clocksource *cs)
 25{
 26	return container_of(cs, struct goldfish_timer, cs);
 27}
 28
 29static u64 goldfish_timer_read(struct clocksource *cs)
 30{
 31	struct goldfish_timer *timerdrv = cs_to_gf(cs);
 32	void __iomem *base = timerdrv->base;
 33	u32 time_low, time_high;
 34	u64 ticks;
 35
 36	/*
 37	 * time_low: get low bits of current time and update time_high
 38	 * time_high: get high bits of time at last time_low read
 39	 */
 40	time_low = gf_ioread32(base + TIMER_TIME_LOW);
 41	time_high = gf_ioread32(base + TIMER_TIME_HIGH);
 42
 43	ticks = ((u64)time_high << 32) | time_low;
 44
 45	return ticks;
 46}
 47
 48static int goldfish_timer_set_oneshot(struct clock_event_device *evt)
 49{
 50	struct goldfish_timer *timerdrv = ced_to_gf(evt);
 51	void __iomem *base = timerdrv->base;
 52
 53	gf_iowrite32(0, base + TIMER_ALARM_HIGH);
 54	gf_iowrite32(0, base + TIMER_ALARM_LOW);
 55	gf_iowrite32(1, base + TIMER_IRQ_ENABLED);
 56
 57	return 0;
 58}
 59
 60static int goldfish_timer_shutdown(struct clock_event_device *evt)
 61{
 62	struct goldfish_timer *timerdrv = ced_to_gf(evt);
 63	void __iomem *base = timerdrv->base;
 64
 65	gf_iowrite32(0, base + TIMER_IRQ_ENABLED);
 66
 67	return 0;
 68}
 69
 70static int goldfish_timer_next_event(unsigned long delta,
 71				     struct clock_event_device *evt)
 72{
 73	struct goldfish_timer *timerdrv = ced_to_gf(evt);
 74	void __iomem *base = timerdrv->base;
 75	u64 now;
 76
 77	now = goldfish_timer_read(&timerdrv->cs);
 78
 79	now += delta;
 80
 81	gf_iowrite32(upper_32_bits(now), base + TIMER_ALARM_HIGH);
 82	gf_iowrite32(lower_32_bits(now), base + TIMER_ALARM_LOW);
 83
 84	return 0;
 85}
 86
 87static irqreturn_t goldfish_timer_irq(int irq, void *dev_id)
 88{
 89	struct goldfish_timer *timerdrv = dev_id;
 90	struct clock_event_device *evt = &timerdrv->ced;
 91	void __iomem *base = timerdrv->base;
 92
 93	gf_iowrite32(1, base + TIMER_CLEAR_INTERRUPT);
 94
 95	evt->event_handler(evt);
 96
 97	return IRQ_HANDLED;
 98}
 99
100int __init goldfish_timer_init(int irq, void __iomem *base)
101{
102	struct goldfish_timer *timerdrv;
103	int ret;
104
105	timerdrv = kzalloc(sizeof(*timerdrv), GFP_KERNEL);
106	if (!timerdrv)
107		return -ENOMEM;
108
109	timerdrv->base = base;
110
111	timerdrv->ced = (struct clock_event_device){
112		.name			= "goldfish_timer",
113		.features		= CLOCK_EVT_FEAT_ONESHOT,
114		.set_state_shutdown	= goldfish_timer_shutdown,
115		.set_state_oneshot      = goldfish_timer_set_oneshot,
116		.set_next_event		= goldfish_timer_next_event,
117	};
118
119	timerdrv->res = (struct resource){
120		.name  = "goldfish_timer",
121		.start = (unsigned long)base,
122		.end   = (unsigned long)base + 0xfff,
123	};
124
125	ret = request_resource(&iomem_resource, &timerdrv->res);
126	if (ret) {
127		pr_err("Cannot allocate '%s' resource\n", timerdrv->res.name);
128		return ret;
129	}
130
131	timerdrv->cs = (struct clocksource){
132		.name		= "goldfish_timer",
133		.rating		= 400,
134		.read		= goldfish_timer_read,
135		.mask		= CLOCKSOURCE_MASK(64),
136		.flags		= 0,
137		.max_idle_ns	= LONG_MAX,
138	};
139
140	clocksource_register_hz(&timerdrv->cs, NSEC_PER_SEC);
141
142	ret = request_irq(irq, goldfish_timer_irq, IRQF_TIMER,
143			  "goldfish_timer", timerdrv);
144	if (ret) {
145		pr_err("Couldn't register goldfish-timer interrupt\n");
146		return ret;
147	}
148
149	clockevents_config_and_register(&timerdrv->ced, NSEC_PER_SEC,
150					1, 0xffffffff);
151
152	return 0;
153}