Merge tag 'rtc-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux
[sfrench/cifs-2.6.git] / drivers / rtc / rtc-st-lpc.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
4  *
5  * Copyright (C) 2014 STMicroelectronics Limited
6  *
7  * Author: David Paris <david.paris@st.com> for STMicroelectronics
8  *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
9  *
10  * Based on the original driver written by Stuart Menefy.
11  */
12
13 #include <linux/clk.h>
14 #include <linux/delay.h>
15 #include <linux/init.h>
16 #include <linux/io.h>
17 #include <linux/irq.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/of.h>
21 #include <linux/of_irq.h>
22 #include <linux/platform_device.h>
23 #include <linux/rtc.h>
24
25 #include <dt-bindings/mfd/st-lpc.h>
26
27 /* Low Power Timer */
28 #define LPC_LPT_LSB_OFF         0x400
29 #define LPC_LPT_MSB_OFF         0x404
30 #define LPC_LPT_START_OFF       0x408
31
32 /* Low Power Alarm */
33 #define LPC_LPA_LSB_OFF         0x410
34 #define LPC_LPA_MSB_OFF         0x414
35 #define LPC_LPA_START_OFF       0x418
36
37 /* LPC as WDT */
38 #define LPC_WDT_OFF             0x510
39 #define LPC_WDT_FLAG_OFF        0x514
40
41 struct st_rtc {
42         struct rtc_device *rtc_dev;
43         struct rtc_wkalrm alarm;
44         struct resource *res;
45         struct clk *clk;
46         unsigned long clkrate;
47         void __iomem *ioaddr;
48         bool irq_enabled:1;
49         spinlock_t lock;
50         short irq;
51 };
52
53 static void st_rtc_set_hw_alarm(struct st_rtc *rtc,
54                                 unsigned long msb, unsigned long  lsb)
55 {
56         unsigned long flags;
57
58         spin_lock_irqsave(&rtc->lock, flags);
59
60         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
61
62         writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
63         writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
64         writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
65
66         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
67
68         spin_unlock_irqrestore(&rtc->lock, flags);
69 }
70
71 static irqreturn_t st_rtc_handler(int this_irq, void *data)
72 {
73         struct st_rtc *rtc = (struct st_rtc *)data;
74
75         rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);
76
77         return IRQ_HANDLED;
78 }
79
80 static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)
81 {
82         struct st_rtc *rtc = dev_get_drvdata(dev);
83         unsigned long lpt_lsb, lpt_msb;
84         unsigned long long lpt;
85         unsigned long flags;
86
87         spin_lock_irqsave(&rtc->lock, flags);
88
89         do {
90                 lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF);
91                 lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF);
92         } while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);
93
94         spin_unlock_irqrestore(&rtc->lock, flags);
95
96         lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
97         do_div(lpt, rtc->clkrate);
98         rtc_time64_to_tm(lpt, tm);
99
100         return 0;
101 }
102
103 static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)
104 {
105         struct st_rtc *rtc = dev_get_drvdata(dev);
106         unsigned long long lpt, secs;
107         unsigned long flags;
108
109         secs = rtc_tm_to_time64(tm);
110
111         lpt = (unsigned long long)secs * rtc->clkrate;
112
113         spin_lock_irqsave(&rtc->lock, flags);
114
115         writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
116         writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
117         writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);
118
119         spin_unlock_irqrestore(&rtc->lock, flags);
120
121         return 0;
122 }
123
124 static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
125 {
126         struct st_rtc *rtc = dev_get_drvdata(dev);
127         unsigned long flags;
128
129         spin_lock_irqsave(&rtc->lock, flags);
130
131         memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
132
133         spin_unlock_irqrestore(&rtc->lock, flags);
134
135         return 0;
136 }
137
138 static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
139 {
140         struct st_rtc *rtc = dev_get_drvdata(dev);
141
142         if (enabled && !rtc->irq_enabled) {
143                 enable_irq(rtc->irq);
144                 rtc->irq_enabled = true;
145         } else if (!enabled && rtc->irq_enabled) {
146                 disable_irq(rtc->irq);
147                 rtc->irq_enabled = false;
148         }
149
150         return 0;
151 }
152
153 static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
154 {
155         struct st_rtc *rtc = dev_get_drvdata(dev);
156         struct rtc_time now;
157         unsigned long long now_secs;
158         unsigned long long alarm_secs;
159         unsigned long long lpa;
160
161         st_rtc_read_time(dev, &now);
162         now_secs = rtc_tm_to_time64(&now);
163         alarm_secs = rtc_tm_to_time64(&t->time);
164
165         memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
166
167         /* Now many secs to fire */
168         alarm_secs -= now_secs;
169         lpa = (unsigned long long)alarm_secs * rtc->clkrate;
170
171         st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
172         st_rtc_alarm_irq_enable(dev, t->enabled);
173
174         return 0;
175 }
176
177 static struct rtc_class_ops st_rtc_ops = {
178         .read_time              = st_rtc_read_time,
179         .set_time               = st_rtc_set_time,
180         .read_alarm             = st_rtc_read_alarm,
181         .set_alarm              = st_rtc_set_alarm,
182         .alarm_irq_enable       = st_rtc_alarm_irq_enable,
183 };
184
185 static int st_rtc_probe(struct platform_device *pdev)
186 {
187         struct device_node *np = pdev->dev.of_node;
188         struct st_rtc *rtc;
189         struct resource *res;
190         uint32_t mode;
191         int ret = 0;
192
193         ret = of_property_read_u32(np, "st,lpc-mode", &mode);
194         if (ret) {
195                 dev_err(&pdev->dev, "An LPC mode must be provided\n");
196                 return -EINVAL;
197         }
198
199         /* LPC can either run as a Clocksource or in RTC or WDT mode */
200         if (mode != ST_LPC_MODE_RTC)
201                 return -ENODEV;
202
203         rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
204         if (!rtc)
205                 return -ENOMEM;
206
207         rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
208         if (IS_ERR(rtc->rtc_dev))
209                 return PTR_ERR(rtc->rtc_dev);
210
211         spin_lock_init(&rtc->lock);
212
213         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
214         rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res);
215         if (IS_ERR(rtc->ioaddr))
216                 return PTR_ERR(rtc->ioaddr);
217
218         rtc->irq = irq_of_parse_and_map(np, 0);
219         if (!rtc->irq) {
220                 dev_err(&pdev->dev, "IRQ missing or invalid\n");
221                 return -EINVAL;
222         }
223
224         ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,
225                                pdev->name, rtc);
226         if (ret) {
227                 dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);
228                 return ret;
229         }
230
231         enable_irq_wake(rtc->irq);
232         disable_irq(rtc->irq);
233
234         rtc->clk = clk_get(&pdev->dev, NULL);
235         if (IS_ERR(rtc->clk)) {
236                 dev_err(&pdev->dev, "Unable to request clock\n");
237                 return PTR_ERR(rtc->clk);
238         }
239
240         clk_prepare_enable(rtc->clk);
241
242         rtc->clkrate = clk_get_rate(rtc->clk);
243         if (!rtc->clkrate) {
244                 dev_err(&pdev->dev, "Unable to fetch clock rate\n");
245                 return -EINVAL;
246         }
247
248         device_set_wakeup_capable(&pdev->dev, 1);
249
250         platform_set_drvdata(pdev, rtc);
251
252         rtc->rtc_dev->ops = &st_rtc_ops;
253         rtc->rtc_dev->range_max = U64_MAX;
254         do_div(rtc->rtc_dev->range_max, rtc->clkrate);
255
256         ret = rtc_register_device(rtc->rtc_dev);
257         if (ret) {
258                 clk_disable_unprepare(rtc->clk);
259                 return ret;
260         }
261
262         return 0;
263 }
264
265 #ifdef CONFIG_PM_SLEEP
266 static int st_rtc_suspend(struct device *dev)
267 {
268         struct st_rtc *rtc = dev_get_drvdata(dev);
269
270         if (device_may_wakeup(dev))
271                 return 0;
272
273         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
274         writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);
275         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
276
277         return 0;
278 }
279
280 static int st_rtc_resume(struct device *dev)
281 {
282         struct st_rtc *rtc = dev_get_drvdata(dev);
283
284         rtc_alarm_irq_enable(rtc->rtc_dev, 0);
285
286         /*
287          * clean 'rtc->alarm' to allow a new
288          * .set_alarm to the upper RTC layer
289          */
290         memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
291
292         writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
293         writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
294         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
295         writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
296         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
297
298         return 0;
299 }
300 #endif
301
302 static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
303
304 static const struct of_device_id st_rtc_match[] = {
305         { .compatible = "st,stih407-lpc" },
306         {}
307 };
308 MODULE_DEVICE_TABLE(of, st_rtc_match);
309
310 static struct platform_driver st_rtc_platform_driver = {
311         .driver = {
312                 .name = "st-lpc-rtc",
313                 .pm = &st_rtc_pm_ops,
314                 .of_match_table = st_rtc_match,
315         },
316         .probe = st_rtc_probe,
317 };
318
319 module_platform_driver(st_rtc_platform_driver);
320
321 MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
322 MODULE_AUTHOR("David Paris <david.paris@st.com>");
323 MODULE_LICENSE("GPL");