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1 /*
2  * A RTC driver for the Simtek STK17TA8
3  *
4  * By Thomas Hommel <thomas.hommel@gefanuc.com>
5  *
6  * Based on the DS1553 driver from
7  * Atsushi Nemoto <anemo@mba.ocn.ne.jp>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  */
13 
14 #include <linux/bcd.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/delay.h>
18 #include <linux/jiffies.h>
19 #include <linux/interrupt.h>
20 #include <linux/rtc.h>
21 #include <linux/platform_device.h>
22 #include <linux/io.h>
23 
24 #define DRV_VERSION "0.1"
25 
26 #define RTC_REG_SIZE		0x20000
27 #define RTC_OFFSET		0x1fff0
28 
29 #define RTC_FLAGS		(RTC_OFFSET + 0)
30 #define RTC_CENTURY		(RTC_OFFSET + 1)
31 #define RTC_SECONDS_ALARM	(RTC_OFFSET + 2)
32 #define RTC_MINUTES_ALARM	(RTC_OFFSET + 3)
33 #define RTC_HOURS_ALARM		(RTC_OFFSET + 4)
34 #define RTC_DATE_ALARM		(RTC_OFFSET + 5)
35 #define RTC_INTERRUPTS		(RTC_OFFSET + 6)
36 #define RTC_WATCHDOG		(RTC_OFFSET + 7)
37 #define RTC_CALIBRATION		(RTC_OFFSET + 8)
38 #define RTC_SECONDS		(RTC_OFFSET + 9)
39 #define RTC_MINUTES		(RTC_OFFSET + 10)
40 #define RTC_HOURS		(RTC_OFFSET + 11)
41 #define RTC_DAY			(RTC_OFFSET + 12)
42 #define RTC_DATE		(RTC_OFFSET + 13)
43 #define RTC_MONTH		(RTC_OFFSET + 14)
44 #define RTC_YEAR		(RTC_OFFSET + 15)
45 
46 #define RTC_SECONDS_MASK	0x7f
47 #define RTC_DAY_MASK		0x07
48 #define RTC_CAL_MASK		0x3f
49 
50 /* Bits in the Calibration register */
51 #define RTC_STOP		0x80
52 
53 /* Bits in the Flags register */
54 #define RTC_FLAGS_AF		0x40
55 #define RTC_FLAGS_PF		0x20
56 #define RTC_WRITE		0x02
57 #define RTC_READ		0x01
58 
59 /* Bits in the Interrupts register */
60 #define RTC_INTS_AIE		0x40
61 
62 struct rtc_plat_data {
63 	struct rtc_device *rtc;
64 	void __iomem *ioaddr;
65 	unsigned long baseaddr;
66 	unsigned long last_jiffies;
67 	int irq;
68 	unsigned int irqen;
69 	int alrm_sec;
70 	int alrm_min;
71 	int alrm_hour;
72 	int alrm_mday;
73 };
74 
stk17ta8_rtc_set_time(struct device * dev,struct rtc_time * tm)75 static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm)
76 {
77 	struct platform_device *pdev = to_platform_device(dev);
78 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
79 	void __iomem *ioaddr = pdata->ioaddr;
80 	u8 flags;
81 
82 	flags = readb(pdata->ioaddr + RTC_FLAGS);
83 	writeb(flags | RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
84 
85 	writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
86 	writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
87 	writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
88 	writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
89 	writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
90 	writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
91 	writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
92 	writeb(bin2bcd((tm->tm_year + 1900) / 100), ioaddr + RTC_CENTURY);
93 
94 	writeb(flags & ~RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
95 	return 0;
96 }
97 
stk17ta8_rtc_read_time(struct device * dev,struct rtc_time * tm)98 static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm)
99 {
100 	struct platform_device *pdev = to_platform_device(dev);
101 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
102 	void __iomem *ioaddr = pdata->ioaddr;
103 	unsigned int year, month, day, hour, minute, second, week;
104 	unsigned int century;
105 	u8 flags;
106 
107 	/* give enough time to update RTC in case of continuous read */
108 	if (pdata->last_jiffies == jiffies)
109 		msleep(1);
110 	pdata->last_jiffies = jiffies;
111 
112 	flags = readb(pdata->ioaddr + RTC_FLAGS);
113 	writeb(flags | RTC_READ, ioaddr + RTC_FLAGS);
114 	second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
115 	minute = readb(ioaddr + RTC_MINUTES);
116 	hour = readb(ioaddr + RTC_HOURS);
117 	day = readb(ioaddr + RTC_DATE);
118 	week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
119 	month = readb(ioaddr + RTC_MONTH);
120 	year = readb(ioaddr + RTC_YEAR);
121 	century = readb(ioaddr + RTC_CENTURY);
122 	writeb(flags & ~RTC_READ, ioaddr + RTC_FLAGS);
123 	tm->tm_sec = bcd2bin(second);
124 	tm->tm_min = bcd2bin(minute);
125 	tm->tm_hour = bcd2bin(hour);
126 	tm->tm_mday = bcd2bin(day);
127 	tm->tm_wday = bcd2bin(week);
128 	tm->tm_mon = bcd2bin(month) - 1;
129 	/* year is 1900 + tm->tm_year */
130 	tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
131 
132 	if (rtc_valid_tm(tm) < 0) {
133 		dev_err(dev, "retrieved date/time is not valid.\n");
134 		rtc_time_to_tm(0, tm);
135 	}
136 	return 0;
137 }
138 
stk17ta8_rtc_update_alarm(struct rtc_plat_data * pdata)139 static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
140 {
141 	void __iomem *ioaddr = pdata->ioaddr;
142 	unsigned long irqflags;
143 	u8 flags;
144 
145 	spin_lock_irqsave(&pdata->rtc->irq_lock, irqflags);
146 
147 	flags = readb(ioaddr + RTC_FLAGS);
148 	writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
149 
150 	writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
151 	       0x80 : bin2bcd(pdata->alrm_mday),
152 	       ioaddr + RTC_DATE_ALARM);
153 	writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
154 	       0x80 : bin2bcd(pdata->alrm_hour),
155 	       ioaddr + RTC_HOURS_ALARM);
156 	writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
157 	       0x80 : bin2bcd(pdata->alrm_min),
158 	       ioaddr + RTC_MINUTES_ALARM);
159 	writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
160 	       0x80 : bin2bcd(pdata->alrm_sec),
161 	       ioaddr + RTC_SECONDS_ALARM);
162 	writeb(pdata->irqen ? RTC_INTS_AIE : 0, ioaddr + RTC_INTERRUPTS);
163 	readb(ioaddr + RTC_FLAGS);	/* clear interrupts */
164 	writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
165 	spin_unlock_irqrestore(&pdata->rtc->irq_lock, irqflags);
166 }
167 
stk17ta8_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)168 static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
169 {
170 	struct platform_device *pdev = to_platform_device(dev);
171 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
172 
173 	if (pdata->irq <= 0)
174 		return -EINVAL;
175 	pdata->alrm_mday = alrm->time.tm_mday;
176 	pdata->alrm_hour = alrm->time.tm_hour;
177 	pdata->alrm_min = alrm->time.tm_min;
178 	pdata->alrm_sec = alrm->time.tm_sec;
179 	if (alrm->enabled)
180 		pdata->irqen |= RTC_AF;
181 	stk17ta8_rtc_update_alarm(pdata);
182 	return 0;
183 }
184 
stk17ta8_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)185 static int stk17ta8_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
186 {
187 	struct platform_device *pdev = to_platform_device(dev);
188 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
189 
190 	if (pdata->irq <= 0)
191 		return -EINVAL;
192 	alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
193 	alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
194 	alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
195 	alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
196 	alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
197 	return 0;
198 }
199 
stk17ta8_rtc_interrupt(int irq,void * dev_id)200 static irqreturn_t stk17ta8_rtc_interrupt(int irq, void *dev_id)
201 {
202 	struct platform_device *pdev = dev_id;
203 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
204 	void __iomem *ioaddr = pdata->ioaddr;
205 	unsigned long events = RTC_IRQF;
206 
207 	/* read and clear interrupt */
208 	if (!(readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF))
209 		return IRQ_NONE;
210 	if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
211 		events |= RTC_UF;
212 	else
213 		events |= RTC_AF;
214 	rtc_update_irq(pdata->rtc, 1, events);
215 	return IRQ_HANDLED;
216 }
217 
stk17ta8_rtc_ioctl(struct device * dev,unsigned int cmd,unsigned long arg)218 static int stk17ta8_rtc_ioctl(struct device *dev, unsigned int cmd,
219 			    unsigned long arg)
220 {
221 	struct platform_device *pdev = to_platform_device(dev);
222 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
223 
224 	if (pdata->irq <= 0)
225 		return -ENOIOCTLCMD; /* fall back into rtc-dev's emulation */
226 	switch (cmd) {
227 	case RTC_AIE_OFF:
228 		pdata->irqen &= ~RTC_AF;
229 		stk17ta8_rtc_update_alarm(pdata);
230 		break;
231 	case RTC_AIE_ON:
232 		pdata->irqen |= RTC_AF;
233 		stk17ta8_rtc_update_alarm(pdata);
234 		break;
235 	default:
236 		return -ENOIOCTLCMD;
237 	}
238 	return 0;
239 }
240 
241 static const struct rtc_class_ops stk17ta8_rtc_ops = {
242 	.read_time	= stk17ta8_rtc_read_time,
243 	.set_time	= stk17ta8_rtc_set_time,
244 	.read_alarm	= stk17ta8_rtc_read_alarm,
245 	.set_alarm	= stk17ta8_rtc_set_alarm,
246 	.ioctl		= stk17ta8_rtc_ioctl,
247 };
248 
stk17ta8_nvram_read(struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t pos,size_t size)249 static ssize_t stk17ta8_nvram_read(struct kobject *kobj,
250 				 struct bin_attribute *attr, char *buf,
251 				 loff_t pos, size_t size)
252 {
253 	struct platform_device *pdev =
254 		to_platform_device(container_of(kobj, struct device, kobj));
255 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
256 	void __iomem *ioaddr = pdata->ioaddr;
257 	ssize_t count;
258 
259 	for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
260 		*buf++ = readb(ioaddr + pos++);
261 	return count;
262 }
263 
stk17ta8_nvram_write(struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t pos,size_t size)264 static ssize_t stk17ta8_nvram_write(struct kobject *kobj,
265 				  struct bin_attribute *attr, char *buf,
266 				  loff_t pos, size_t size)
267 {
268 	struct platform_device *pdev =
269 		to_platform_device(container_of(kobj, struct device, kobj));
270 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
271 	void __iomem *ioaddr = pdata->ioaddr;
272 	ssize_t count;
273 
274 	for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
275 		writeb(*buf++, ioaddr + pos++);
276 	return count;
277 }
278 
279 static struct bin_attribute stk17ta8_nvram_attr = {
280 	.attr = {
281 		.name = "nvram",
282 		.mode = S_IRUGO | S_IWUSR,
283 	},
284 	.size = RTC_OFFSET,
285 	.read = stk17ta8_nvram_read,
286 	.write = stk17ta8_nvram_write,
287 };
288 
stk17ta8_rtc_probe(struct platform_device * pdev)289 static int __init stk17ta8_rtc_probe(struct platform_device *pdev)
290 {
291 	struct rtc_device *rtc;
292 	struct resource *res;
293 	unsigned int cal;
294 	unsigned int flags;
295 	struct rtc_plat_data *pdata;
296 	void __iomem *ioaddr = NULL;
297 	int ret = 0;
298 
299 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
300 	if (!res)
301 		return -ENODEV;
302 
303 	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
304 	if (!pdata)
305 		return -ENOMEM;
306 	if (!request_mem_region(res->start, RTC_REG_SIZE, pdev->name)) {
307 		ret = -EBUSY;
308 		goto out;
309 	}
310 	pdata->baseaddr = res->start;
311 	ioaddr = ioremap(pdata->baseaddr, RTC_REG_SIZE);
312 	if (!ioaddr) {
313 		ret = -ENOMEM;
314 		goto out;
315 	}
316 	pdata->ioaddr = ioaddr;
317 	pdata->irq = platform_get_irq(pdev, 0);
318 
319 	/* turn RTC on if it was not on */
320 	cal = readb(ioaddr + RTC_CALIBRATION);
321 	if (cal & RTC_STOP) {
322 		cal &= RTC_CAL_MASK;
323 		flags = readb(ioaddr + RTC_FLAGS);
324 		writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
325 		writeb(cal, ioaddr + RTC_CALIBRATION);
326 		writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
327 	}
328 	if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF)
329 		dev_warn(&pdev->dev, "voltage-low detected.\n");
330 
331 	if (pdata->irq > 0) {
332 		writeb(0, ioaddr + RTC_INTERRUPTS);
333 		if (request_irq(pdata->irq, stk17ta8_rtc_interrupt,
334 				IRQF_DISABLED | IRQF_SHARED,
335 				pdev->name, pdev) < 0) {
336 			dev_warn(&pdev->dev, "interrupt not available.\n");
337 			pdata->irq = 0;
338 		}
339 	}
340 
341 	rtc = rtc_device_register(pdev->name, &pdev->dev,
342 				  &stk17ta8_rtc_ops, THIS_MODULE);
343 	if (IS_ERR(rtc)) {
344 		ret = PTR_ERR(rtc);
345 		goto out;
346 	}
347 	pdata->rtc = rtc;
348 	pdata->last_jiffies = jiffies;
349 	platform_set_drvdata(pdev, pdata);
350 	ret = sysfs_create_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr);
351 	if (ret)
352 		goto out;
353 	return 0;
354  out:
355 	if (pdata->rtc)
356 		rtc_device_unregister(pdata->rtc);
357 	if (pdata->irq > 0)
358 		free_irq(pdata->irq, pdev);
359 	if (ioaddr)
360 		iounmap(ioaddr);
361 	if (pdata->baseaddr)
362 		release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
363 	kfree(pdata);
364 	return ret;
365 }
366 
stk17ta8_rtc_remove(struct platform_device * pdev)367 static int __devexit stk17ta8_rtc_remove(struct platform_device *pdev)
368 {
369 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
370 
371 	sysfs_remove_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr);
372 	rtc_device_unregister(pdata->rtc);
373 	if (pdata->irq > 0) {
374 		writeb(0, pdata->ioaddr + RTC_INTERRUPTS);
375 		free_irq(pdata->irq, pdev);
376 	}
377 	iounmap(pdata->ioaddr);
378 	release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
379 	kfree(pdata);
380 	return 0;
381 }
382 
383 /* work with hotplug and coldplug */
384 MODULE_ALIAS("platform:stk17ta8");
385 
386 static struct platform_driver stk17ta8_rtc_driver = {
387 	.probe		= stk17ta8_rtc_probe,
388 	.remove		= __devexit_p(stk17ta8_rtc_remove),
389 	.driver		= {
390 		.name	= "stk17ta8",
391 		.owner	= THIS_MODULE,
392 	},
393 };
394 
stk17ta8_init(void)395 static __init int stk17ta8_init(void)
396 {
397 	return platform_driver_register(&stk17ta8_rtc_driver);
398 }
399 
stk17ta8_exit(void)400 static __exit void stk17ta8_exit(void)
401 {
402 	platform_driver_unregister(&stk17ta8_rtc_driver);
403 }
404 
405 module_init(stk17ta8_init);
406 module_exit(stk17ta8_exit);
407 
408 MODULE_AUTHOR("Thomas Hommel <thomas.hommel@gefanuc.com>");
409 MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver");
410 MODULE_LICENSE("GPL");
411 MODULE_VERSION(DRV_VERSION);
412