1// SPDX-License-Identifier: GPL-2.0
2/* drivers/rtc/rtc-goldfish.c
3 *
4 * Copyright (C) 2007 Google, Inc.
5 * Copyright (C) 2017 Imagination Technologies Ltd.
6 */
7
8#include <linux/io.h>
9#include <linux/module.h>
10#include <linux/of.h>
11#include <linux/platform_device.h>
12#include <linux/rtc.h>
13
14#define TIMER_TIME_LOW		0x00	/* get low bits of current time  */
15					/*   and update TIMER_TIME_HIGH  */
16#define TIMER_TIME_HIGH	0x04	/* get high bits of time at last */
17					/*   TIMER_TIME_LOW read         */
18#define TIMER_ALARM_LOW	0x08	/* set low bits of alarm and     */
19					/*   activate it                 */
20#define TIMER_ALARM_HIGH	0x0c	/* set high bits of next alarm   */
21#define TIMER_IRQ_ENABLED	0x10
22#define TIMER_CLEAR_ALARM	0x14
23#define TIMER_ALARM_STATUS	0x18
24#define TIMER_CLEAR_INTERRUPT	0x1c
25
26struct goldfish_rtc {
27	void __iomem *base;
28	int irq;
29	struct rtc_device *rtc;
30};
31
32static int goldfish_rtc_read_alarm(struct device *dev,
33				   struct rtc_wkalrm *alrm)
34{
35	u64 rtc_alarm;
36	u64 rtc_alarm_low;
37	u64 rtc_alarm_high;
38	void __iomem *base;
39	struct goldfish_rtc *rtcdrv;
40
41	rtcdrv = dev_get_drvdata(dev);
42	base = rtcdrv->base;
43
44	rtc_alarm_low = readl(base + TIMER_ALARM_LOW);
45	rtc_alarm_high = readl(base + TIMER_ALARM_HIGH);
46	rtc_alarm = (rtc_alarm_high << 32) | rtc_alarm_low;
47
48	do_div(rtc_alarm, NSEC_PER_SEC);
49	memset(alrm, 0, sizeof(struct rtc_wkalrm));
50
51	rtc_time64_to_tm(rtc_alarm, &alrm->time);
52
53	if (readl(base + TIMER_ALARM_STATUS))
54		alrm->enabled = 1;
55	else
56		alrm->enabled = 0;
57
58	return 0;
59}
60
61static int goldfish_rtc_set_alarm(struct device *dev,
62				  struct rtc_wkalrm *alrm)
63{
64	struct goldfish_rtc *rtcdrv;
65	u64 rtc_alarm64;
66	u64 rtc_status_reg;
67	void __iomem *base;
68
69	rtcdrv = dev_get_drvdata(dev);
70	base = rtcdrv->base;
71
72	if (alrm->enabled) {
73		rtc_alarm64 = rtc_tm_to_time64(&alrm->time) * NSEC_PER_SEC;
74		writel((rtc_alarm64 >> 32), base + TIMER_ALARM_HIGH);
75		writel(rtc_alarm64, base + TIMER_ALARM_LOW);
76		writel(1, base + TIMER_IRQ_ENABLED);
77	} else {
78		/*
79		 * if this function was called with enabled=0
80		 * then it could mean that the application is
81		 * trying to cancel an ongoing alarm
82		 */
83		rtc_status_reg = readl(base + TIMER_ALARM_STATUS);
84		if (rtc_status_reg)
85			writel(1, base + TIMER_CLEAR_ALARM);
86	}
87
88	return 0;
89}
90
91static int goldfish_rtc_alarm_irq_enable(struct device *dev,
92					 unsigned int enabled)
93{
94	void __iomem *base;
95	struct goldfish_rtc *rtcdrv;
96
97	rtcdrv = dev_get_drvdata(dev);
98	base = rtcdrv->base;
99
100	if (enabled)
101		writel(1, base + TIMER_IRQ_ENABLED);
102	else
103		writel(0, base + TIMER_IRQ_ENABLED);
104
105	return 0;
106}
107
108static irqreturn_t goldfish_rtc_interrupt(int irq, void *dev_id)
109{
110	struct goldfish_rtc *rtcdrv = dev_id;
111	void __iomem *base = rtcdrv->base;
112
113	writel(1, base + TIMER_CLEAR_INTERRUPT);
114
115	rtc_update_irq(rtcdrv->rtc, 1, RTC_IRQF | RTC_AF);
116
117	return IRQ_HANDLED;
118}
119
120static int goldfish_rtc_read_time(struct device *dev, struct rtc_time *tm)
121{
122	struct goldfish_rtc *rtcdrv;
123	void __iomem *base;
124	u64 time_high;
125	u64 time_low;
126	u64 time;
127
128	rtcdrv = dev_get_drvdata(dev);
129	base = rtcdrv->base;
130
131	time_low = readl(base + TIMER_TIME_LOW);
132	time_high = readl(base + TIMER_TIME_HIGH);
133	time = (time_high << 32) | time_low;
134
135	do_div(time, NSEC_PER_SEC);
136
137	rtc_time64_to_tm(time, tm);
138
139	return 0;
140}
141
142static int goldfish_rtc_set_time(struct device *dev, struct rtc_time *tm)
143{
144	struct goldfish_rtc *rtcdrv;
145	void __iomem *base;
146	u64 now64;
147
148	rtcdrv = dev_get_drvdata(dev);
149	base = rtcdrv->base;
150
151	now64 = rtc_tm_to_time64(tm) * NSEC_PER_SEC;
152	writel((now64 >> 32), base + TIMER_TIME_HIGH);
153	writel(now64, base + TIMER_TIME_LOW);
154
155	return 0;
156}
157
158static const struct rtc_class_ops goldfish_rtc_ops = {
159	.read_time	= goldfish_rtc_read_time,
160	.set_time	= goldfish_rtc_set_time,
161	.read_alarm	= goldfish_rtc_read_alarm,
162	.set_alarm	= goldfish_rtc_set_alarm,
163	.alarm_irq_enable = goldfish_rtc_alarm_irq_enable
164};
165
166static int goldfish_rtc_probe(struct platform_device *pdev)
167{
168	struct goldfish_rtc *rtcdrv;
169	int err;
170
171	rtcdrv = devm_kzalloc(&pdev->dev, sizeof(*rtcdrv), GFP_KERNEL);
172	if (!rtcdrv)
173		return -ENOMEM;
174
175	platform_set_drvdata(pdev, rtcdrv);
176	rtcdrv->base = devm_platform_ioremap_resource(pdev, 0);
177	if (IS_ERR(rtcdrv->base))
178		return PTR_ERR(rtcdrv->base);
179
180	rtcdrv->irq = platform_get_irq(pdev, 0);
181	if (rtcdrv->irq < 0)
182		return -ENODEV;
183
184	rtcdrv->rtc = devm_rtc_allocate_device(&pdev->dev);
185	if (IS_ERR(rtcdrv->rtc))
186		return PTR_ERR(rtcdrv->rtc);
187
188	rtcdrv->rtc->ops = &goldfish_rtc_ops;
189	rtcdrv->rtc->range_max = U64_MAX / NSEC_PER_SEC;
190
191	err = devm_request_irq(&pdev->dev, rtcdrv->irq,
192			       goldfish_rtc_interrupt,
193			       0, pdev->name, rtcdrv);
194	if (err)
195		return err;
196
197	return rtc_register_device(rtcdrv->rtc);
198}
199
200static const struct of_device_id goldfish_rtc_of_match[] = {
201	{ .compatible = "google,goldfish-rtc", },
202	{},
203};
204MODULE_DEVICE_TABLE(of, goldfish_rtc_of_match);
205
206static struct platform_driver goldfish_rtc = {
207	.probe = goldfish_rtc_probe,
208	.driver = {
209		.name = "goldfish_rtc",
210		.of_match_table = goldfish_rtc_of_match,
211	}
212};
213
214module_platform_driver(goldfish_rtc);
215
216MODULE_LICENSE("GPL v2");
217