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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
41struct 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
53static 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
71static 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
80static 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
103static 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
124static 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
138static 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
153static 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
177static 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
185static 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
266static 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
280static 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
302static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
303
304static const struct of_device_id st_rtc_match[] = {
305 { .compatible = "st,stih407-lpc" },
306 {}
307};
308MODULE_DEVICE_TABLE(of, st_rtc_match);
309
310static 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
319module_platform_driver(st_rtc_platform_driver);
320
321MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
322MODULE_AUTHOR("David Paris <david.paris@st.com>");
323MODULE_LICENSE("GPL");