mm, page_alloc: set alloc_flags only once in slowpath
[linux/fpc-iii.git] / drivers / rtc / rtc-st-lpc.c
blob74c0a336ceea0650965701f93399814299275bd1
1 /*
2 * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
4 * Copyright (C) 2014 STMicroelectronics Limited
6 * Author: David Paris <david.paris@st.com> for STMicroelectronics
7 * Lee Jones <lee.jones@linaro.org> for STMicroelectronics
9 * Based on the original driver written by Stuart Menefy.
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.
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>
29 #include <dt-bindings/mfd/st-lpc.h>
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
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
41 /* LPC as WDT */
42 #define LPC_WDT_OFF 0x510
43 #define LPC_WDT_FLAG_OFF 0x514
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;
57 static void st_rtc_set_hw_alarm(struct st_rtc *rtc,
58 unsigned long msb, unsigned long lsb)
60 unsigned long flags;
62 spin_lock_irqsave(&rtc->lock, flags);
64 writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
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);
70 writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
72 spin_unlock_irqrestore(&rtc->lock, flags);
75 static irqreturn_t st_rtc_handler(int this_irq, void *data)
77 struct st_rtc *rtc = (struct st_rtc *)data;
79 rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);
81 return IRQ_HANDLED;
84 static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)
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;
91 spin_lock_irqsave(&rtc->lock, flags);
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);
98 spin_unlock_irqrestore(&rtc->lock, flags);
100 lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
101 do_div(lpt, rtc->clkrate);
102 rtc_time_to_tm(lpt, tm);
104 return 0;
107 static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)
109 struct st_rtc *rtc = dev_get_drvdata(dev);
110 unsigned long long lpt;
111 unsigned long secs, flags;
112 int ret;
114 ret = rtc_tm_to_time(tm, &secs);
115 if (ret)
116 return ret;
118 lpt = (unsigned long long)secs * rtc->clkrate;
120 spin_lock_irqsave(&rtc->lock, flags);
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);
126 spin_unlock_irqrestore(&rtc->lock, flags);
128 return 0;
131 static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
133 struct st_rtc *rtc = dev_get_drvdata(dev);
134 unsigned long flags;
136 spin_lock_irqsave(&rtc->lock, flags);
138 memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
140 spin_unlock_irqrestore(&rtc->lock, flags);
142 return 0;
145 static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
147 struct st_rtc *rtc = dev_get_drvdata(dev);
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;
157 return 0;
160 static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
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;
168 st_rtc_read_time(dev, &now);
169 rtc_tm_to_time(&now, &now_secs);
170 rtc_tm_to_time(&t->time, &alarm_secs);
172 /* Invalid alarm time */
173 if (now_secs > alarm_secs)
174 return -EINVAL;
176 memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
178 /* Now many secs to fire */
179 alarm_secs -= now_secs;
180 lpa = (unsigned long long)alarm_secs * rtc->clkrate;
182 st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
183 st_rtc_alarm_irq_enable(dev, t->enabled);
185 return 0;
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,
196 static int st_rtc_probe(struct platform_device *pdev)
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;
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;
211 /* LPC can either run as a Clocksource or in RTC or WDT mode */
212 if (mode != ST_LPC_MODE_RTC)
213 return -ENODEV;
215 rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
216 if (!rtc)
217 return -ENOMEM;
219 spin_lock_init(&rtc->lock);
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);
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;
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;
239 enable_irq_wake(rtc->irq);
240 disable_irq(rtc->irq);
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);
248 clk_prepare_enable(rtc->clk);
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;
256 device_set_wakeup_capable(&pdev->dev, 1);
258 platform_set_drvdata(pdev, rtc);
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"
266 st_rtc_read_time(&pdev->dev, &tm_check);
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);
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);
282 return 0;
285 static int st_rtc_remove(struct platform_device *pdev)
287 struct st_rtc *rtc = platform_get_drvdata(pdev);
289 if (likely(rtc->rtc_dev))
290 rtc_device_unregister(rtc->rtc_dev);
292 return 0;
295 #ifdef CONFIG_PM_SLEEP
296 static int st_rtc_suspend(struct device *dev)
298 struct st_rtc *rtc = dev_get_drvdata(dev);
300 if (device_may_wakeup(dev))
301 return 0;
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);
307 return 0;
310 static int st_rtc_resume(struct device *dev)
312 struct st_rtc *rtc = dev_get_drvdata(dev);
314 rtc_alarm_irq_enable(rtc->rtc_dev, 0);
317 * clean 'rtc->alarm' to allow a new
318 * .set_alarm to the upper RTC layer
320 memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
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);
328 return 0;
330 #endif
332 static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
334 static const struct of_device_id st_rtc_match[] = {
335 { .compatible = "st,stih407-lpc" },
338 MODULE_DEVICE_TABLE(of, st_rtc_match);
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,
346 .probe = st_rtc_probe,
347 .remove = st_rtc_remove,
350 module_platform_driver(st_rtc_platform_driver);
352 MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
353 MODULE_AUTHOR("David Paris <david.paris@st.com>");
354 MODULE_LICENSE("GPL");