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
45 struct 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
st_rtc_set_hw_alarm(struct st_rtc * rtc,unsigned long msb,unsigned long lsb)57 static 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
st_rtc_handler(int this_irq,void * data)75 static 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
st_rtc_read_time(struct device * dev,struct rtc_time * tm)84 static 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_time64_to_tm(lpt, tm);
103
104 return 0;
105 }
106
st_rtc_set_time(struct device * dev,struct rtc_time * tm)107 static 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, secs;
111 unsigned long flags;
112
113 secs = rtc_tm_to_time64(tm);
114
115 lpt = (unsigned long long)secs * rtc->clkrate;
116
117 spin_lock_irqsave(&rtc->lock, flags);
118
119 writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
120 writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
121 writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);
122
123 spin_unlock_irqrestore(&rtc->lock, flags);
124
125 return 0;
126 }
127
st_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * wkalrm)128 static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
129 {
130 struct st_rtc *rtc = dev_get_drvdata(dev);
131 unsigned long flags;
132
133 spin_lock_irqsave(&rtc->lock, flags);
134
135 memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
136
137 spin_unlock_irqrestore(&rtc->lock, flags);
138
139 return 0;
140 }
141
st_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)142 static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
143 {
144 struct st_rtc *rtc = dev_get_drvdata(dev);
145
146 if (enabled && !rtc->irq_enabled) {
147 enable_irq(rtc->irq);
148 rtc->irq_enabled = true;
149 } else if (!enabled && rtc->irq_enabled) {
150 disable_irq(rtc->irq);
151 rtc->irq_enabled = false;
152 }
153
154 return 0;
155 }
156
st_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * t)157 static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
158 {
159 struct st_rtc *rtc = dev_get_drvdata(dev);
160 struct rtc_time now;
161 unsigned long long now_secs;
162 unsigned long long alarm_secs;
163 unsigned long long lpa;
164
165 st_rtc_read_time(dev, &now);
166 now_secs = rtc_tm_to_time64(&now);
167 alarm_secs = rtc_tm_to_time64(&t->time);
168
169 /* Invalid alarm time */
170 if (now_secs > alarm_secs)
171 return -EINVAL;
172
173 memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
174
175 /* Now many secs to fire */
176 alarm_secs -= now_secs;
177 lpa = (unsigned long long)alarm_secs * rtc->clkrate;
178
179 st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
180 st_rtc_alarm_irq_enable(dev, t->enabled);
181
182 return 0;
183 }
184
185 static struct rtc_class_ops st_rtc_ops = {
186 .read_time = st_rtc_read_time,
187 .set_time = st_rtc_set_time,
188 .read_alarm = st_rtc_read_alarm,
189 .set_alarm = st_rtc_set_alarm,
190 .alarm_irq_enable = st_rtc_alarm_irq_enable,
191 };
192
st_rtc_probe(struct platform_device * pdev)193 static int st_rtc_probe(struct platform_device *pdev)
194 {
195 struct device_node *np = pdev->dev.of_node;
196 struct st_rtc *rtc;
197 struct resource *res;
198 uint32_t mode;
199 int ret = 0;
200
201 ret = of_property_read_u32(np, "st,lpc-mode", &mode);
202 if (ret) {
203 dev_err(&pdev->dev, "An LPC mode must be provided\n");
204 return -EINVAL;
205 }
206
207 /* LPC can either run as a Clocksource or in RTC or WDT mode */
208 if (mode != ST_LPC_MODE_RTC)
209 return -ENODEV;
210
211 rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
212 if (!rtc)
213 return -ENOMEM;
214
215 rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
216 if (IS_ERR(rtc->rtc_dev))
217 return PTR_ERR(rtc->rtc_dev);
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 rtc->rtc_dev->ops = &st_rtc_ops;
261 rtc->rtc_dev->range_max = U64_MAX;
262 do_div(rtc->rtc_dev->range_max, rtc->clkrate);
263
264 ret = rtc_register_device(rtc->rtc_dev);
265 if (ret) {
266 clk_disable_unprepare(rtc->clk);
267 return ret;
268 }
269
270 return 0;
271 }
272
273 #ifdef CONFIG_PM_SLEEP
st_rtc_suspend(struct device * dev)274 static int st_rtc_suspend(struct device *dev)
275 {
276 struct st_rtc *rtc = dev_get_drvdata(dev);
277
278 if (device_may_wakeup(dev))
279 return 0;
280
281 writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
282 writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);
283 writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
284
285 return 0;
286 }
287
st_rtc_resume(struct device * dev)288 static int st_rtc_resume(struct device *dev)
289 {
290 struct st_rtc *rtc = dev_get_drvdata(dev);
291
292 rtc_alarm_irq_enable(rtc->rtc_dev, 0);
293
294 /*
295 * clean 'rtc->alarm' to allow a new
296 * .set_alarm to the upper RTC layer
297 */
298 memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
299
300 writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
301 writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
302 writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
303 writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
304 writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
305
306 return 0;
307 }
308 #endif
309
310 static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
311
312 static const struct of_device_id st_rtc_match[] = {
313 { .compatible = "st,stih407-lpc" },
314 {}
315 };
316 MODULE_DEVICE_TABLE(of, st_rtc_match);
317
318 static struct platform_driver st_rtc_platform_driver = {
319 .driver = {
320 .name = "st-lpc-rtc",
321 .pm = &st_rtc_pm_ops,
322 .of_match_table = st_rtc_match,
323 },
324 .probe = st_rtc_probe,
325 };
326
327 module_platform_driver(st_rtc_platform_driver);
328
329 MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
330 MODULE_AUTHOR("David Paris <david.paris@st.com>");
331 MODULE_LICENSE("GPL");
332
