xref: /linux/drivers/rtc/rtc-ds1553.c (revision cdd38c5f1ce4398ec58fec95904b75824daab7b5)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * An rtc driver for the Dallas DS1553
4  *
5  * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6  */
7 
8 #include <linux/bcd.h>
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/gfp.h>
12 #include <linux/delay.h>
13 #include <linux/jiffies.h>
14 #include <linux/interrupt.h>
15 #include <linux/rtc.h>
16 #include <linux/platform_device.h>
17 #include <linux/io.h>
18 #include <linux/module.h>
19 
20 #define RTC_REG_SIZE		0x2000
21 #define RTC_OFFSET		0x1ff0
22 
23 #define RTC_FLAGS		(RTC_OFFSET + 0)
24 #define RTC_SECONDS_ALARM	(RTC_OFFSET + 2)
25 #define RTC_MINUTES_ALARM	(RTC_OFFSET + 3)
26 #define RTC_HOURS_ALARM		(RTC_OFFSET + 4)
27 #define RTC_DATE_ALARM		(RTC_OFFSET + 5)
28 #define RTC_INTERRUPTS		(RTC_OFFSET + 6)
29 #define RTC_WATCHDOG		(RTC_OFFSET + 7)
30 #define RTC_CONTROL		(RTC_OFFSET + 8)
31 #define RTC_CENTURY		(RTC_OFFSET + 8)
32 #define RTC_SECONDS		(RTC_OFFSET + 9)
33 #define RTC_MINUTES		(RTC_OFFSET + 10)
34 #define RTC_HOURS		(RTC_OFFSET + 11)
35 #define RTC_DAY			(RTC_OFFSET + 12)
36 #define RTC_DATE		(RTC_OFFSET + 13)
37 #define RTC_MONTH		(RTC_OFFSET + 14)
38 #define RTC_YEAR		(RTC_OFFSET + 15)
39 
40 #define RTC_CENTURY_MASK	0x3f
41 #define RTC_SECONDS_MASK	0x7f
42 #define RTC_DAY_MASK		0x07
43 
44 /* Bits in the Control/Century register */
45 #define RTC_WRITE		0x80
46 #define RTC_READ		0x40
47 
48 /* Bits in the Seconds register */
49 #define RTC_STOP		0x80
50 
51 /* Bits in the Flags register */
52 #define RTC_FLAGS_AF		0x40
53 #define RTC_FLAGS_BLF		0x10
54 
55 /* Bits in the Interrupts register */
56 #define RTC_INTS_AE		0x80
57 
58 struct rtc_plat_data {
59 	struct rtc_device *rtc;
60 	void __iomem *ioaddr;
61 	unsigned long last_jiffies;
62 	int irq;
63 	unsigned int irqen;
64 	int alrm_sec;
65 	int alrm_min;
66 	int alrm_hour;
67 	int alrm_mday;
68 	spinlock_t lock;
69 };
70 
ds1553_rtc_set_time(struct device * dev,struct rtc_time * tm)71 static int ds1553_rtc_set_time(struct device *dev, struct rtc_time *tm)
72 {
73 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
74 	void __iomem *ioaddr = pdata->ioaddr;
75 	u8 century;
76 
77 	century = bin2bcd((tm->tm_year + 1900) / 100);
78 
79 	writeb(RTC_WRITE, pdata->ioaddr + RTC_CONTROL);
80 
81 	writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
82 	writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
83 	writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
84 	writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
85 	writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
86 	writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
87 	writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
88 
89 	/* RTC_CENTURY and RTC_CONTROL share same register */
90 	writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
91 	writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
92 	return 0;
93 }
94 
ds1553_rtc_read_time(struct device * dev,struct rtc_time * tm)95 static int ds1553_rtc_read_time(struct device *dev, struct rtc_time *tm)
96 {
97 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
98 	void __iomem *ioaddr = pdata->ioaddr;
99 	unsigned int year, month, day, hour, minute, second, week;
100 	unsigned int century;
101 
102 	/* give enough time to update RTC in case of continuous read */
103 	if (pdata->last_jiffies == jiffies)
104 		msleep(1);
105 	pdata->last_jiffies = jiffies;
106 	writeb(RTC_READ, ioaddr + RTC_CONTROL);
107 	second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
108 	minute = readb(ioaddr + RTC_MINUTES);
109 	hour = readb(ioaddr + RTC_HOURS);
110 	day = readb(ioaddr + RTC_DATE);
111 	week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
112 	month = readb(ioaddr + RTC_MONTH);
113 	year = readb(ioaddr + RTC_YEAR);
114 	century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
115 	writeb(0, ioaddr + RTC_CONTROL);
116 	tm->tm_sec = bcd2bin(second);
117 	tm->tm_min = bcd2bin(minute);
118 	tm->tm_hour = bcd2bin(hour);
119 	tm->tm_mday = bcd2bin(day);
120 	tm->tm_wday = bcd2bin(week);
121 	tm->tm_mon = bcd2bin(month) - 1;
122 	/* year is 1900 + tm->tm_year */
123 	tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
124 
125 	return 0;
126 }
127 
ds1553_rtc_update_alarm(struct rtc_plat_data * pdata)128 static void ds1553_rtc_update_alarm(struct rtc_plat_data *pdata)
129 {
130 	void __iomem *ioaddr = pdata->ioaddr;
131 	unsigned long flags;
132 
133 	spin_lock_irqsave(&pdata->lock, flags);
134 	writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
135 	       0x80 : bin2bcd(pdata->alrm_mday),
136 	       ioaddr + RTC_DATE_ALARM);
137 	writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
138 	       0x80 : bin2bcd(pdata->alrm_hour),
139 	       ioaddr + RTC_HOURS_ALARM);
140 	writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
141 	       0x80 : bin2bcd(pdata->alrm_min),
142 	       ioaddr + RTC_MINUTES_ALARM);
143 	writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
144 	       0x80 : bin2bcd(pdata->alrm_sec),
145 	       ioaddr + RTC_SECONDS_ALARM);
146 	writeb(pdata->irqen ? RTC_INTS_AE : 0, ioaddr + RTC_INTERRUPTS);
147 	readb(ioaddr + RTC_FLAGS);	/* clear interrupts */
148 	spin_unlock_irqrestore(&pdata->lock, flags);
149 }
150 
ds1553_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)151 static int ds1553_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
152 {
153 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
154 
155 	if (pdata->irq <= 0)
156 		return -EINVAL;
157 	pdata->alrm_mday = alrm->time.tm_mday;
158 	pdata->alrm_hour = alrm->time.tm_hour;
159 	pdata->alrm_min = alrm->time.tm_min;
160 	pdata->alrm_sec = alrm->time.tm_sec;
161 	if (alrm->enabled)
162 		pdata->irqen |= RTC_AF;
163 	ds1553_rtc_update_alarm(pdata);
164 	return 0;
165 }
166 
ds1553_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)167 static int ds1553_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
168 {
169 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
170 
171 	if (pdata->irq <= 0)
172 		return -EINVAL;
173 	alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
174 	alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
175 	alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
176 	alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
177 	alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
178 	return 0;
179 }
180 
ds1553_rtc_interrupt(int irq,void * dev_id)181 static irqreturn_t ds1553_rtc_interrupt(int irq, void *dev_id)
182 {
183 	struct platform_device *pdev = dev_id;
184 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
185 	void __iomem *ioaddr = pdata->ioaddr;
186 	unsigned long events = 0;
187 
188 	spin_lock(&pdata->lock);
189 	/* read and clear interrupt */
190 	if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
191 		events = RTC_IRQF;
192 		if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
193 			events |= RTC_UF;
194 		else
195 			events |= RTC_AF;
196 		rtc_update_irq(pdata->rtc, 1, events);
197 	}
198 	spin_unlock(&pdata->lock);
199 	return events ? IRQ_HANDLED : IRQ_NONE;
200 }
201 
ds1553_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)202 static int ds1553_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
203 {
204 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
205 
206 	if (pdata->irq <= 0)
207 		return -EINVAL;
208 	if (enabled)
209 		pdata->irqen |= RTC_AF;
210 	else
211 		pdata->irqen &= ~RTC_AF;
212 	ds1553_rtc_update_alarm(pdata);
213 	return 0;
214 }
215 
216 static const struct rtc_class_ops ds1553_rtc_ops = {
217 	.read_time		= ds1553_rtc_read_time,
218 	.set_time		= ds1553_rtc_set_time,
219 	.read_alarm		= ds1553_rtc_read_alarm,
220 	.set_alarm		= ds1553_rtc_set_alarm,
221 	.alarm_irq_enable	= ds1553_rtc_alarm_irq_enable,
222 };
223 
ds1553_nvram_read(void * priv,unsigned int pos,void * val,size_t bytes)224 static int ds1553_nvram_read(void *priv, unsigned int pos, void *val,
225 			     size_t bytes)
226 {
227 	struct platform_device *pdev = priv;
228 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
229 	void __iomem *ioaddr = pdata->ioaddr;
230 	u8 *buf = val;
231 
232 	for (; bytes; bytes--)
233 		*buf++ = readb(ioaddr + pos++);
234 	return 0;
235 }
236 
ds1553_nvram_write(void * priv,unsigned int pos,void * val,size_t bytes)237 static int ds1553_nvram_write(void *priv, unsigned int pos, void *val,
238 			      size_t bytes)
239 {
240 	struct platform_device *pdev = priv;
241 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
242 	void __iomem *ioaddr = pdata->ioaddr;
243 	u8 *buf = val;
244 
245 	for (; bytes; bytes--)
246 		writeb(*buf++, ioaddr + pos++);
247 	return 0;
248 }
249 
ds1553_rtc_probe(struct platform_device * pdev)250 static int ds1553_rtc_probe(struct platform_device *pdev)
251 {
252 	unsigned int cen, sec;
253 	struct rtc_plat_data *pdata;
254 	void __iomem *ioaddr;
255 	int ret = 0;
256 	struct nvmem_config nvmem_cfg = {
257 		.name = "ds1553_nvram",
258 		.word_size = 1,
259 		.stride = 1,
260 		.size = RTC_OFFSET,
261 		.reg_read = ds1553_nvram_read,
262 		.reg_write = ds1553_nvram_write,
263 		.priv = pdev,
264 	};
265 
266 	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
267 	if (!pdata)
268 		return -ENOMEM;
269 
270 	ioaddr = devm_platform_ioremap_resource(pdev, 0);
271 	if (IS_ERR(ioaddr))
272 		return PTR_ERR(ioaddr);
273 	pdata->ioaddr = ioaddr;
274 	pdata->irq = platform_get_irq(pdev, 0);
275 
276 	/* turn RTC on if it was not on */
277 	sec = readb(ioaddr + RTC_SECONDS);
278 	if (sec & RTC_STOP) {
279 		sec &= RTC_SECONDS_MASK;
280 		cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
281 		writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
282 		writeb(sec, ioaddr + RTC_SECONDS);
283 		writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
284 	}
285 	if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_BLF)
286 		dev_warn(&pdev->dev, "voltage-low detected.\n");
287 
288 	spin_lock_init(&pdata->lock);
289 	pdata->last_jiffies = jiffies;
290 	platform_set_drvdata(pdev, pdata);
291 
292 	pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
293 	if (IS_ERR(pdata->rtc))
294 		return PTR_ERR(pdata->rtc);
295 
296 	pdata->rtc->ops = &ds1553_rtc_ops;
297 
298 	ret = devm_rtc_register_device(pdata->rtc);
299 	if (ret)
300 		return ret;
301 
302 	if (pdata->irq > 0) {
303 		writeb(0, ioaddr + RTC_INTERRUPTS);
304 		if (devm_request_irq(&pdev->dev, pdata->irq,
305 				ds1553_rtc_interrupt,
306 				0, pdev->name, pdev) < 0) {
307 			dev_warn(&pdev->dev, "interrupt not available.\n");
308 			pdata->irq = 0;
309 		}
310 	}
311 
312 	devm_rtc_nvmem_register(pdata->rtc, &nvmem_cfg);
313 
314 	return 0;
315 }
316 
317 /* work with hotplug and coldplug */
318 MODULE_ALIAS("platform:rtc-ds1553");
319 
320 static struct platform_driver ds1553_rtc_driver = {
321 	.probe		= ds1553_rtc_probe,
322 	.driver		= {
323 		.name	= "rtc-ds1553",
324 	},
325 };
326 
327 module_platform_driver(ds1553_rtc_driver);
328 
329 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
330 MODULE_DESCRIPTION("Dallas DS1553 RTC driver");
331 MODULE_LICENSE("GPL");
332