1 /*
2  * An rtc driver for the Dallas DS1553
3  *
4  * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 
11 #include <linux/bcd.h>
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/gfp.h>
15 #include <linux/delay.h>
16 #include <linux/jiffies.h>
17 #include <linux/interrupt.h>
18 #include <linux/rtc.h>
19 #include <linux/platform_device.h>
20 #include <linux/io.h>
21 #include <linux/module.h>
22 
23 #define RTC_REG_SIZE		0x2000
24 #define RTC_OFFSET		0x1ff0
25 
26 #define RTC_FLAGS		(RTC_OFFSET + 0)
27 #define RTC_SECONDS_ALARM	(RTC_OFFSET + 2)
28 #define RTC_MINUTES_ALARM	(RTC_OFFSET + 3)
29 #define RTC_HOURS_ALARM		(RTC_OFFSET + 4)
30 #define RTC_DATE_ALARM		(RTC_OFFSET + 5)
31 #define RTC_INTERRUPTS		(RTC_OFFSET + 6)
32 #define RTC_WATCHDOG		(RTC_OFFSET + 7)
33 #define RTC_CONTROL		(RTC_OFFSET + 8)
34 #define RTC_CENTURY		(RTC_OFFSET + 8)
35 #define RTC_SECONDS		(RTC_OFFSET + 9)
36 #define RTC_MINUTES		(RTC_OFFSET + 10)
37 #define RTC_HOURS		(RTC_OFFSET + 11)
38 #define RTC_DAY			(RTC_OFFSET + 12)
39 #define RTC_DATE		(RTC_OFFSET + 13)
40 #define RTC_MONTH		(RTC_OFFSET + 14)
41 #define RTC_YEAR		(RTC_OFFSET + 15)
42 
43 #define RTC_CENTURY_MASK	0x3f
44 #define RTC_SECONDS_MASK	0x7f
45 #define RTC_DAY_MASK		0x07
46 
47 /* Bits in the Control/Century register */
48 #define RTC_WRITE		0x80
49 #define RTC_READ		0x40
50 
51 /* Bits in the Seconds register */
52 #define RTC_STOP		0x80
53 
54 /* Bits in the Flags register */
55 #define RTC_FLAGS_AF		0x40
56 #define RTC_FLAGS_BLF		0x10
57 
58 /* Bits in the Interrupts register */
59 #define RTC_INTS_AE		0x80
60 
61 struct rtc_plat_data {
62 	struct rtc_device *rtc;
63 	void __iomem *ioaddr;
64 	unsigned long last_jiffies;
65 	int irq;
66 	unsigned int irqen;
67 	int alrm_sec;
68 	int alrm_min;
69 	int alrm_hour;
70 	int alrm_mday;
71 	spinlock_t lock;
72 };
73 
ds1553_rtc_set_time(struct device * dev,struct rtc_time * tm)74 static int ds1553_rtc_set_time(struct device *dev, struct rtc_time *tm)
75 {
76 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
77 	void __iomem *ioaddr = pdata->ioaddr;
78 	u8 century;
79 
80 	century = bin2bcd((tm->tm_year + 1900) / 100);
81 
82 	writeb(RTC_WRITE, pdata->ioaddr + RTC_CONTROL);
83 
84 	writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
85 	writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
86 	writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
87 	writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
88 	writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
89 	writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
90 	writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
91 
92 	/* RTC_CENTURY and RTC_CONTROL share same register */
93 	writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
94 	writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
95 	return 0;
96 }
97 
ds1553_rtc_read_time(struct device * dev,struct rtc_time * tm)98 static int ds1553_rtc_read_time(struct device *dev, struct rtc_time *tm)
99 {
100 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
101 	void __iomem *ioaddr = pdata->ioaddr;
102 	unsigned int year, month, day, hour, minute, second, week;
103 	unsigned int century;
104 
105 	/* give enough time to update RTC in case of continuous read */
106 	if (pdata->last_jiffies == jiffies)
107 		msleep(1);
108 	pdata->last_jiffies = jiffies;
109 	writeb(RTC_READ, ioaddr + RTC_CONTROL);
110 	second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
111 	minute = readb(ioaddr + RTC_MINUTES);
112 	hour = readb(ioaddr + RTC_HOURS);
113 	day = readb(ioaddr + RTC_DATE);
114 	week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
115 	month = readb(ioaddr + RTC_MONTH);
116 	year = readb(ioaddr + RTC_YEAR);
117 	century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
118 	writeb(0, ioaddr + RTC_CONTROL);
119 	tm->tm_sec = bcd2bin(second);
120 	tm->tm_min = bcd2bin(minute);
121 	tm->tm_hour = bcd2bin(hour);
122 	tm->tm_mday = bcd2bin(day);
123 	tm->tm_wday = bcd2bin(week);
124 	tm->tm_mon = bcd2bin(month) - 1;
125 	/* year is 1900 + tm->tm_year */
126 	tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
127 
128 	return 0;
129 }
130 
ds1553_rtc_update_alarm(struct rtc_plat_data * pdata)131 static void ds1553_rtc_update_alarm(struct rtc_plat_data *pdata)
132 {
133 	void __iomem *ioaddr = pdata->ioaddr;
134 	unsigned long flags;
135 
136 	spin_lock_irqsave(&pdata->lock, flags);
137 	writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
138 	       0x80 : bin2bcd(pdata->alrm_mday),
139 	       ioaddr + RTC_DATE_ALARM);
140 	writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
141 	       0x80 : bin2bcd(pdata->alrm_hour),
142 	       ioaddr + RTC_HOURS_ALARM);
143 	writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
144 	       0x80 : bin2bcd(pdata->alrm_min),
145 	       ioaddr + RTC_MINUTES_ALARM);
146 	writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
147 	       0x80 : bin2bcd(pdata->alrm_sec),
148 	       ioaddr + RTC_SECONDS_ALARM);
149 	writeb(pdata->irqen ? RTC_INTS_AE : 0, ioaddr + RTC_INTERRUPTS);
150 	readb(ioaddr + RTC_FLAGS);	/* clear interrupts */
151 	spin_unlock_irqrestore(&pdata->lock, flags);
152 }
153 
ds1553_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)154 static int ds1553_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
155 {
156 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
157 
158 	if (pdata->irq <= 0)
159 		return -EINVAL;
160 	pdata->alrm_mday = alrm->time.tm_mday;
161 	pdata->alrm_hour = alrm->time.tm_hour;
162 	pdata->alrm_min = alrm->time.tm_min;
163 	pdata->alrm_sec = alrm->time.tm_sec;
164 	if (alrm->enabled)
165 		pdata->irqen |= RTC_AF;
166 	ds1553_rtc_update_alarm(pdata);
167 	return 0;
168 }
169 
ds1553_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)170 static int ds1553_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
171 {
172 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
173 
174 	if (pdata->irq <= 0)
175 		return -EINVAL;
176 	alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
177 	alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
178 	alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
179 	alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
180 	alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
181 	return 0;
182 }
183 
ds1553_rtc_interrupt(int irq,void * dev_id)184 static irqreturn_t ds1553_rtc_interrupt(int irq, void *dev_id)
185 {
186 	struct platform_device *pdev = dev_id;
187 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
188 	void __iomem *ioaddr = pdata->ioaddr;
189 	unsigned long events = 0;
190 
191 	spin_lock(&pdata->lock);
192 	/* read and clear interrupt */
193 	if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
194 		events = RTC_IRQF;
195 		if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
196 			events |= RTC_UF;
197 		else
198 			events |= RTC_AF;
199 		rtc_update_irq(pdata->rtc, 1, events);
200 	}
201 	spin_unlock(&pdata->lock);
202 	return events ? IRQ_HANDLED : IRQ_NONE;
203 }
204 
ds1553_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)205 static int ds1553_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
206 {
207 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
208 
209 	if (pdata->irq <= 0)
210 		return -EINVAL;
211 	if (enabled)
212 		pdata->irqen |= RTC_AF;
213 	else
214 		pdata->irqen &= ~RTC_AF;
215 	ds1553_rtc_update_alarm(pdata);
216 	return 0;
217 }
218 
219 static const struct rtc_class_ops ds1553_rtc_ops = {
220 	.read_time		= ds1553_rtc_read_time,
221 	.set_time		= ds1553_rtc_set_time,
222 	.read_alarm		= ds1553_rtc_read_alarm,
223 	.set_alarm		= ds1553_rtc_set_alarm,
224 	.alarm_irq_enable	= ds1553_rtc_alarm_irq_enable,
225 };
226 
ds1553_nvram_read(void * priv,unsigned int pos,void * val,size_t bytes)227 static int ds1553_nvram_read(void *priv, unsigned int pos, void *val,
228 			     size_t bytes)
229 {
230 	struct platform_device *pdev = priv;
231 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
232 	void __iomem *ioaddr = pdata->ioaddr;
233 	u8 *buf = val;
234 
235 	for (; bytes; bytes--)
236 		*buf++ = readb(ioaddr + pos++);
237 	return 0;
238 }
239 
ds1553_nvram_write(void * priv,unsigned int pos,void * val,size_t bytes)240 static int ds1553_nvram_write(void *priv, unsigned int pos, void *val,
241 			      size_t bytes)
242 {
243 	struct platform_device *pdev = priv;
244 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
245 	void __iomem *ioaddr = pdata->ioaddr;
246 	u8 *buf = val;
247 
248 	for (; bytes; bytes--)
249 		writeb(*buf++, ioaddr + pos++);
250 	return 0;
251 }
252 
ds1553_rtc_probe(struct platform_device * pdev)253 static int ds1553_rtc_probe(struct platform_device *pdev)
254 {
255 	struct resource *res;
256 	unsigned int cen, sec;
257 	struct rtc_plat_data *pdata;
258 	void __iomem *ioaddr;
259 	int ret = 0;
260 	struct nvmem_config nvmem_cfg = {
261 		.name = "ds1553_nvram",
262 		.word_size = 1,
263 		.stride = 1,
264 		.size = RTC_OFFSET,
265 		.reg_read = ds1553_nvram_read,
266 		.reg_write = ds1553_nvram_write,
267 		.priv = pdev,
268 	};
269 
270 	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
271 	if (!pdata)
272 		return -ENOMEM;
273 
274 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
275 	ioaddr = devm_ioremap_resource(&pdev->dev, res);
276 	if (IS_ERR(ioaddr))
277 		return PTR_ERR(ioaddr);
278 	pdata->ioaddr = ioaddr;
279 	pdata->irq = platform_get_irq(pdev, 0);
280 
281 	/* turn RTC on if it was not on */
282 	sec = readb(ioaddr + RTC_SECONDS);
283 	if (sec & RTC_STOP) {
284 		sec &= RTC_SECONDS_MASK;
285 		cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
286 		writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
287 		writeb(sec, ioaddr + RTC_SECONDS);
288 		writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
289 	}
290 	if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_BLF)
291 		dev_warn(&pdev->dev, "voltage-low detected.\n");
292 
293 	spin_lock_init(&pdata->lock);
294 	pdata->last_jiffies = jiffies;
295 	platform_set_drvdata(pdev, pdata);
296 
297 	pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
298 	if (IS_ERR(pdata->rtc))
299 		return PTR_ERR(pdata->rtc);
300 
301 	pdata->rtc->ops = &ds1553_rtc_ops;
302 	pdata->rtc->nvram_old_abi = true;
303 
304 	ret = rtc_register_device(pdata->rtc);
305 	if (ret)
306 		return ret;
307 
308 	if (pdata->irq > 0) {
309 		writeb(0, ioaddr + RTC_INTERRUPTS);
310 		if (devm_request_irq(&pdev->dev, pdata->irq,
311 				ds1553_rtc_interrupt,
312 				0, pdev->name, pdev) < 0) {
313 			dev_warn(&pdev->dev, "interrupt not available.\n");
314 			pdata->irq = 0;
315 		}
316 	}
317 
318 	if (rtc_nvmem_register(pdata->rtc, &nvmem_cfg))
319 		dev_err(&pdev->dev, "unable to register nvmem\n");
320 
321 	return 0;
322 }
323 
324 /* work with hotplug and coldplug */
325 MODULE_ALIAS("platform:rtc-ds1553");
326 
327 static struct platform_driver ds1553_rtc_driver = {
328 	.probe		= ds1553_rtc_probe,
329 	.driver		= {
330 		.name	= "rtc-ds1553",
331 	},
332 };
333 
334 module_platform_driver(ds1553_rtc_driver);
335 
336 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
337 MODULE_DESCRIPTION("Dallas DS1553 RTC driver");
338 MODULE_LICENSE("GPL");
339