1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007-2009 ST-Ericsson AB
4 * Real Time Clock interface for ST-Ericsson AB COH 901 331 RTC.
5 * Author: Linus Walleij <linus.walleij@stericsson.com>
6 * Based on rtc-pl031.c by Deepak Saxena <dsaxena@plexity.net>
7 * Copyright 2006 (c) MontaVista Software, Inc.
8 */
9#include <linux/init.h>
10#include <linux/module.h>
11#include <linux/mod_devicetable.h>
12#include <linux/rtc.h>
13#include <linux/clk.h>
14#include <linux/interrupt.h>
15#include <linux/pm.h>
16#include <linux/platform_device.h>
17#include <linux/io.h>
18#include <linux/slab.h>
19
20/*
21 * Registers in the COH 901 331
22 */
23/* Alarm value 32bit (R/W) */
24#define COH901331_ALARM		0x00U
25/* Used to set current time 32bit (R/W) */
26#define COH901331_SET_TIME	0x04U
27/* Indication if current time is valid 32bit (R/-) */
28#define COH901331_VALID		0x08U
29/* Read the current time 32bit (R/-) */
30#define COH901331_CUR_TIME	0x0cU
31/* Event register for the "alarm" interrupt */
32#define COH901331_IRQ_EVENT	0x10U
33/* Mask register for the "alarm" interrupt */
34#define COH901331_IRQ_MASK	0x14U
35/* Force register for the "alarm" interrupt */
36#define COH901331_IRQ_FORCE	0x18U
37
38/*
39 * Reference to RTC block clock
40 * Notice that the frequent clk_enable()/clk_disable() on this
41 * clock is mainly to be able to turn on/off other clocks in the
42 * hierarchy as needed, the RTC clock is always on anyway.
43 */
44struct coh901331_port {
45	struct rtc_device *rtc;
46	struct clk *clk;
47	void __iomem *virtbase;
48	int irq;
49#ifdef CONFIG_PM_SLEEP
50	u32 irqmaskstore;
51#endif
52};
53
54static irqreturn_t coh901331_interrupt(int irq, void *data)
55{
56	struct coh901331_port *rtap = data;
57
58	clk_enable(rtap->clk);
59	/* Ack IRQ */
60	writel(1, rtap->virtbase + COH901331_IRQ_EVENT);
61	/*
62	 * Disable the interrupt. This is necessary because
63	 * the RTC lives on a lower-clocked line and will
64	 * not release the IRQ line until after a few (slower)
65	 * clock cycles. The interrupt will be re-enabled when
66	 * a new alarm is set anyway.
67	 */
68	writel(0, rtap->virtbase + COH901331_IRQ_MASK);
69	clk_disable(rtap->clk);
70
71	/* Set alarm flag */
72	rtc_update_irq(rtap->rtc, 1, RTC_AF);
73
74	return IRQ_HANDLED;
75}
76
77static int coh901331_read_time(struct device *dev, struct rtc_time *tm)
78{
79	struct coh901331_port *rtap = dev_get_drvdata(dev);
80
81	clk_enable(rtap->clk);
82	/* Check if the time is valid */
83	if (!readl(rtap->virtbase + COH901331_VALID)) {
84		clk_disable(rtap->clk);
85		return -EINVAL;
86	}
87
88	rtc_time64_to_tm(readl(rtap->virtbase + COH901331_CUR_TIME), tm);
89	clk_disable(rtap->clk);
90	return 0;
91}
92
93static int coh901331_set_time(struct device *dev, struct rtc_time *tm)
94{
95	struct coh901331_port *rtap = dev_get_drvdata(dev);
96
97	clk_enable(rtap->clk);
98	writel(rtc_tm_to_time64(tm), rtap->virtbase + COH901331_SET_TIME);
99	clk_disable(rtap->clk);
100
101	return 0;
102}
103
104static int coh901331_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
105{
106	struct coh901331_port *rtap = dev_get_drvdata(dev);
107
108	clk_enable(rtap->clk);
109	rtc_time64_to_tm(readl(rtap->virtbase + COH901331_ALARM), &alarm->time);
110	alarm->pending = readl(rtap->virtbase + COH901331_IRQ_EVENT) & 1U;
111	alarm->enabled = readl(rtap->virtbase + COH901331_IRQ_MASK) & 1U;
112	clk_disable(rtap->clk);
113
114	return 0;
115}
116
117static int coh901331_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
118{
119	struct coh901331_port *rtap = dev_get_drvdata(dev);
120	unsigned long time =  rtc_tm_to_time64(&alarm->time);
121
122	clk_enable(rtap->clk);
123	writel(time, rtap->virtbase + COH901331_ALARM);
124	writel(alarm->enabled, rtap->virtbase + COH901331_IRQ_MASK);
125	clk_disable(rtap->clk);
126
127	return 0;
128}
129
130static int coh901331_alarm_irq_enable(struct device *dev, unsigned int enabled)
131{
132	struct coh901331_port *rtap = dev_get_drvdata(dev);
133
134	clk_enable(rtap->clk);
135	if (enabled)
136		writel(1, rtap->virtbase + COH901331_IRQ_MASK);
137	else
138		writel(0, rtap->virtbase + COH901331_IRQ_MASK);
139	clk_disable(rtap->clk);
140
141	return 0;
142}
143
144static const struct rtc_class_ops coh901331_ops = {
145	.read_time = coh901331_read_time,
146	.set_time = coh901331_set_time,
147	.read_alarm = coh901331_read_alarm,
148	.set_alarm = coh901331_set_alarm,
149	.alarm_irq_enable = coh901331_alarm_irq_enable,
150};
151
152static int __exit coh901331_remove(struct platform_device *pdev)
153{
154	struct coh901331_port *rtap = platform_get_drvdata(pdev);
155
156	if (rtap)
157		clk_unprepare(rtap->clk);
158
159	return 0;
160}
161
162
163static int __init coh901331_probe(struct platform_device *pdev)
164{
165	int ret;
166	struct coh901331_port *rtap;
167
168	rtap = devm_kzalloc(&pdev->dev,
169			    sizeof(struct coh901331_port), GFP_KERNEL);
170	if (!rtap)
171		return -ENOMEM;
172
173	rtap->virtbase  = devm_platform_ioremap_resource(pdev, 0);
174	if (IS_ERR(rtap->virtbase))
175		return PTR_ERR(rtap->virtbase);
176
177	rtap->irq = platform_get_irq(pdev, 0);
178	if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
179			     "RTC COH 901 331 Alarm", rtap))
180		return -EIO;
181
182	rtap->clk = devm_clk_get(&pdev->dev, NULL);
183	if (IS_ERR(rtap->clk)) {
184		ret = PTR_ERR(rtap->clk);
185		dev_err(&pdev->dev, "could not get clock\n");
186		return ret;
187	}
188
189	rtap->rtc = devm_rtc_allocate_device(&pdev->dev);
190	if (IS_ERR(rtap->rtc))
191		return PTR_ERR(rtap->rtc);
192
193	rtap->rtc->ops = &coh901331_ops;
194	rtap->rtc->range_max = U32_MAX;
195
196	/* We enable/disable the clock only to assure it works */
197	ret = clk_prepare_enable(rtap->clk);
198	if (ret) {
199		dev_err(&pdev->dev, "could not enable clock\n");
200		return ret;
201	}
202	clk_disable(rtap->clk);
203
204	platform_set_drvdata(pdev, rtap);
205
206	ret = rtc_register_device(rtap->rtc);
207	if (ret)
208		goto out_no_rtc;
209
210	return 0;
211
212 out_no_rtc:
213	clk_unprepare(rtap->clk);
214	return ret;
215}
216
217#ifdef CONFIG_PM_SLEEP
218static int coh901331_suspend(struct device *dev)
219{
220	struct coh901331_port *rtap = dev_get_drvdata(dev);
221
222	/*
223	 * If this RTC alarm will be used for waking the system up,
224	 * don't disable it of course. Else we just disable the alarm
225	 * and await suspension.
226	 */
227	if (device_may_wakeup(dev)) {
228		enable_irq_wake(rtap->irq);
229	} else {
230		clk_enable(rtap->clk);
231		rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
232		writel(0, rtap->virtbase + COH901331_IRQ_MASK);
233		clk_disable(rtap->clk);
234	}
235	clk_unprepare(rtap->clk);
236	return 0;
237}
238
239static int coh901331_resume(struct device *dev)
240{
241	int ret;
242	struct coh901331_port *rtap = dev_get_drvdata(dev);
243
244	ret = clk_prepare(rtap->clk);
245	if (ret)
246		return ret;
247
248	if (device_may_wakeup(dev)) {
249		disable_irq_wake(rtap->irq);
250	} else {
251		clk_enable(rtap->clk);
252		writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
253		clk_disable(rtap->clk);
254	}
255	return 0;
256}
257#endif
258
259static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
260
261static void coh901331_shutdown(struct platform_device *pdev)
262{
263	struct coh901331_port *rtap = platform_get_drvdata(pdev);
264
265	clk_enable(rtap->clk);
266	writel(0, rtap->virtbase + COH901331_IRQ_MASK);
267	clk_disable_unprepare(rtap->clk);
268}
269
270static const struct of_device_id coh901331_dt_match[] = {
271	{ .compatible = "stericsson,coh901331" },
272	{},
273};
274MODULE_DEVICE_TABLE(of, coh901331_dt_match);
275
276static struct platform_driver coh901331_driver = {
277	.driver = {
278		.name = "rtc-coh901331",
279		.pm = &coh901331_pm_ops,
280		.of_match_table = coh901331_dt_match,
281	},
282	.remove = __exit_p(coh901331_remove),
283	.shutdown = coh901331_shutdown,
284};
285
286module_platform_driver_probe(coh901331_driver, coh901331_probe);
287
288MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
289MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
290MODULE_LICENSE("GPL");
291