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b5b2bdfc LJ |
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 <[email protected]> for STMicroelectronics | |
7 | * Lee Jones <[email protected]> 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 | ||
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 | ||
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 | ||
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_time_to_tm(lpt, tm); | |
103 | ||
104 | return 0; | |
105 | } | |
106 | ||
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; | |
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 | ||
131 | static 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 | ||
145 | static 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 | ||
160 | static 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 | ||
188 | static 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 | ||
196 | static 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 | ||
742e4097 | 211 | /* LPC can either run as a Clocksource or in RTC or WDT mode */ |
b5b2bdfc LJ |
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 | ||
285 | static 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 | |
296 | static 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 | ||
310 | static 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 | ||
332 | static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume); | |
333 | ||
334 | static const struct of_device_id st_rtc_match[] = { | |
335 | { .compatible = "st,stih407-lpc" }, | |
336 | {} | |
337 | }; | |
338 | MODULE_DEVICE_TABLE(of, st_rtc_match); | |
339 | ||
340 | static 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 | ||
350 | module_platform_driver(st_rtc_platform_driver); | |
351 | ||
352 | MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver"); | |
353 | MODULE_AUTHOR("David Paris <[email protected]>"); | |
354 | MODULE_LICENSE("GPL"); |