1/*
2 * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
3 *
4 * Copyright (C) 2014 STMicroelectronics Limited
5 *
6 * Author: David Paris <david.paris@st.com> for STMicroelectronics
7 *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
8 *
9 * Based on the original driver written by Stuart Menefy.
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public Licence
13 * as published by the Free Software Foundation; either version
14 * 2 of the Licence, or (at your option) any later version.
15 */
16
17#include <linux/clk.h>
18#include <linux/delay.h>
19#include <linux/init.h>
20#include <linux/io.h>
21#include <linux/irq.h>
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/of.h>
25#include <linux/of_irq.h>
26#include <linux/platform_device.h>
27#include <linux/rtc.h>
28
29#include <dt-bindings/mfd/st-lpc.h>
30
31/* Low Power Timer */
32#define LPC_LPT_LSB_OFF		0x400
33#define LPC_LPT_MSB_OFF		0x404
34#define LPC_LPT_START_OFF	0x408
35
36/* Low Power Alarm */
37#define LPC_LPA_LSB_OFF		0x410
38#define LPC_LPA_MSB_OFF		0x414
39#define LPC_LPA_START_OFF	0x418
40
41/* LPC as WDT */
42#define LPC_WDT_OFF		0x510
43#define LPC_WDT_FLAG_OFF	0x514
44
45struct st_rtc {
46	struct rtc_device *rtc_dev;
47	struct rtc_wkalrm alarm;
48	struct resource *res;
49	struct clk *clk;
50	unsigned long clkrate;
51	void __iomem *ioaddr;
52	bool irq_enabled:1;
53	spinlock_t lock;
54	short irq;
55};
56
57static void st_rtc_set_hw_alarm(struct st_rtc *rtc,
58				unsigned long msb, unsigned long  lsb)
59{
60	unsigned long flags;
61
62	spin_lock_irqsave(&rtc->lock, flags);
63
64	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
65
66	writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
67	writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
68	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
69
70	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
71
72	spin_unlock_irqrestore(&rtc->lock, flags);
73}
74
75static irqreturn_t st_rtc_handler(int this_irq, void *data)
76{
77	struct st_rtc *rtc = (struct st_rtc *)data;
78
79	rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);
80
81	return IRQ_HANDLED;
82}
83
84static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)
85{
86	struct st_rtc *rtc = dev_get_drvdata(dev);
87	unsigned long lpt_lsb, lpt_msb;
88	unsigned long long lpt;
89	unsigned long flags;
90
91	spin_lock_irqsave(&rtc->lock, flags);
92
93	do {
94		lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF);
95		lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF);
96	} while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);
97
98	spin_unlock_irqrestore(&rtc->lock, flags);
99
100	lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
101	do_div(lpt, rtc->clkrate);
102	rtc_time_to_tm(lpt, tm);
103
104	return 0;
105}
106
107static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)
108{
109	struct st_rtc *rtc = dev_get_drvdata(dev);
110	unsigned long long lpt;
111	unsigned long secs, flags;
112	int ret;
113
114	ret = rtc_tm_to_time(tm, &secs);
115	if (ret)
116		return ret;
117
118	lpt = (unsigned long long)secs * rtc->clkrate;
119
120	spin_lock_irqsave(&rtc->lock, flags);
121
122	writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
123	writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
124	writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);
125
126	spin_unlock_irqrestore(&rtc->lock, flags);
127
128	return 0;
129}
130
131static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
132{
133	struct st_rtc *rtc = dev_get_drvdata(dev);
134	unsigned long flags;
135
136	spin_lock_irqsave(&rtc->lock, flags);
137
138	memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
139
140	spin_unlock_irqrestore(&rtc->lock, flags);
141
142	return 0;
143}
144
145static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
146{
147	struct st_rtc *rtc = dev_get_drvdata(dev);
148
149	if (enabled && !rtc->irq_enabled) {
150		enable_irq(rtc->irq);
151		rtc->irq_enabled = true;
152	} else if (!enabled && rtc->irq_enabled) {
153		disable_irq(rtc->irq);
154		rtc->irq_enabled = false;
155	}
156
157	return 0;
158}
159
160static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
161{
162	struct st_rtc *rtc = dev_get_drvdata(dev);
163	struct rtc_time now;
164	unsigned long now_secs;
165	unsigned long alarm_secs;
166	unsigned long long lpa;
167
168	st_rtc_read_time(dev, &now);
169	rtc_tm_to_time(&now, &now_secs);
170	rtc_tm_to_time(&t->time, &alarm_secs);
171
172	/* Invalid alarm time */
173	if (now_secs > alarm_secs)
174		return -EINVAL;
175
176	memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
177
178	/* Now many secs to fire */
179	alarm_secs -= now_secs;
180	lpa = (unsigned long long)alarm_secs * rtc->clkrate;
181
182	st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
183	st_rtc_alarm_irq_enable(dev, t->enabled);
184
185	return 0;
186}
187
188static struct rtc_class_ops st_rtc_ops = {
189	.read_time		= st_rtc_read_time,
190	.set_time		= st_rtc_set_time,
191	.read_alarm		= st_rtc_read_alarm,
192	.set_alarm		= st_rtc_set_alarm,
193	.alarm_irq_enable	= st_rtc_alarm_irq_enable,
194};
195
196static int st_rtc_probe(struct platform_device *pdev)
197{
198	struct device_node *np = pdev->dev.of_node;
199	struct st_rtc *rtc;
200	struct resource *res;
201	struct rtc_time tm_check;
202	uint32_t mode;
203	int ret = 0;
204
205	ret = of_property_read_u32(np, "st,lpc-mode", &mode);
206	if (ret) {
207		dev_err(&pdev->dev, "An LPC mode must be provided\n");
208		return -EINVAL;
209	}
210
211	/* LPC can either run as a Clocksource or in RTC or WDT mode */
212	if (mode != ST_LPC_MODE_RTC)
213		return -ENODEV;
214
215	rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
216	if (!rtc)
217		return -ENOMEM;
218
219	spin_lock_init(&rtc->lock);
220
221	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
222	rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res);
223	if (IS_ERR(rtc->ioaddr))
224		return PTR_ERR(rtc->ioaddr);
225
226	rtc->irq = irq_of_parse_and_map(np, 0);
227	if (!rtc->irq) {
228		dev_err(&pdev->dev, "IRQ missing or invalid\n");
229		return -EINVAL;
230	}
231
232	ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,
233			       pdev->name, rtc);
234	if (ret) {
235		dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);
236		return ret;
237	}
238
239	enable_irq_wake(rtc->irq);
240	disable_irq(rtc->irq);
241
242	rtc->clk = clk_get(&pdev->dev, NULL);
243	if (IS_ERR(rtc->clk)) {
244		dev_err(&pdev->dev, "Unable to request clock\n");
245		return PTR_ERR(rtc->clk);
246	}
247
248	clk_prepare_enable(rtc->clk);
249
250	rtc->clkrate = clk_get_rate(rtc->clk);
251	if (!rtc->clkrate) {
252		dev_err(&pdev->dev, "Unable to fetch clock rate\n");
253		return -EINVAL;
254	}
255
256	device_set_wakeup_capable(&pdev->dev, 1);
257
258	platform_set_drvdata(pdev, rtc);
259
260	/*
261	 * The RTC-LPC is able to manage date.year > 2038
262	 * but currently the kernel can not manage this date!
263	 * If the RTC-LPC has a date.year > 2038 then
264	 * it's set to the epoch "Jan 1st 2000"
265	 */
266	st_rtc_read_time(&pdev->dev, &tm_check);
267
268	if (tm_check.tm_year >=  (2038 - 1900)) {
269		memset(&tm_check, 0, sizeof(tm_check));
270		tm_check.tm_year = 100;
271		tm_check.tm_mday = 1;
272		st_rtc_set_time(&pdev->dev, &tm_check);
273	}
274
275	rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev,
276					   &st_rtc_ops, THIS_MODULE);
277	if (IS_ERR(rtc->rtc_dev)) {
278		clk_disable_unprepare(rtc->clk);
279		return PTR_ERR(rtc->rtc_dev);
280	}
281
282	return 0;
283}
284
285static int st_rtc_remove(struct platform_device *pdev)
286{
287	struct st_rtc *rtc = platform_get_drvdata(pdev);
288
289	if (likely(rtc->rtc_dev))
290		rtc_device_unregister(rtc->rtc_dev);
291
292	return 0;
293}
294
295#ifdef CONFIG_PM_SLEEP
296static int st_rtc_suspend(struct device *dev)
297{
298	struct st_rtc *rtc = dev_get_drvdata(dev);
299
300	if (device_may_wakeup(dev))
301		return 0;
302
303	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
304	writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);
305	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
306
307	return 0;
308}
309
310static int st_rtc_resume(struct device *dev)
311{
312	struct st_rtc *rtc = dev_get_drvdata(dev);
313
314	rtc_alarm_irq_enable(rtc->rtc_dev, 0);
315
316	/*
317	 * clean 'rtc->alarm' to allow a new
318	 * .set_alarm to the upper RTC layer
319	 */
320	memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
321
322	writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
323	writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
324	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
325	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
326	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
327
328	return 0;
329}
330#endif
331
332static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
333
334static const struct of_device_id st_rtc_match[] = {
335	{ .compatible = "st,stih407-lpc" },
336	{}
337};
338MODULE_DEVICE_TABLE(of, st_rtc_match);
339
340static struct platform_driver st_rtc_platform_driver = {
341	.driver = {
342		.name = "st-lpc-rtc",
343		.pm = &st_rtc_pm_ops,
344		.of_match_table = st_rtc_match,
345	},
346	.probe = st_rtc_probe,
347	.remove = st_rtc_remove,
348};
349
350module_platform_driver(st_rtc_platform_driver);
351
352MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
353MODULE_AUTHOR("David Paris <david.paris@st.com>");
354MODULE_LICENSE("GPL");
355