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 DRV_VERSION "0.3"
24
25#define RTC_REG_SIZE		0x2000
26#define RTC_OFFSET		0x1ff0
27
28#define RTC_FLAGS		(RTC_OFFSET + 0)
29#define RTC_SECONDS_ALARM	(RTC_OFFSET + 2)
30#define RTC_MINUTES_ALARM	(RTC_OFFSET + 3)
31#define RTC_HOURS_ALARM		(RTC_OFFSET + 4)
32#define RTC_DATE_ALARM		(RTC_OFFSET + 5)
33#define RTC_INTERRUPTS		(RTC_OFFSET + 6)
34#define RTC_WATCHDOG		(RTC_OFFSET + 7)
35#define RTC_CONTROL		(RTC_OFFSET + 8)
36#define RTC_CENTURY		(RTC_OFFSET + 8)
37#define RTC_SECONDS		(RTC_OFFSET + 9)
38#define RTC_MINUTES		(RTC_OFFSET + 10)
39#define RTC_HOURS		(RTC_OFFSET + 11)
40#define RTC_DAY			(RTC_OFFSET + 12)
41#define RTC_DATE		(RTC_OFFSET + 13)
42#define RTC_MONTH		(RTC_OFFSET + 14)
43#define RTC_YEAR		(RTC_OFFSET + 15)
44
45#define RTC_CENTURY_MASK	0x3f
46#define RTC_SECONDS_MASK	0x7f
47#define RTC_DAY_MASK		0x07
48
49/* Bits in the Control/Century register */
50#define RTC_WRITE		0x80
51#define RTC_READ		0x40
52
53/* Bits in the Seconds register */
54#define RTC_STOP		0x80
55
56/* Bits in the Flags register */
57#define RTC_FLAGS_AF		0x40
58#define RTC_FLAGS_BLF		0x10
59
60/* Bits in the Interrupts register */
61#define RTC_INTS_AE		0x80
62
63struct rtc_plat_data {
64	struct rtc_device *rtc;
65	void __iomem *ioaddr;
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	spinlock_t lock;
74};
75
76static int ds1553_rtc_set_time(struct device *dev, struct rtc_time *tm)
77{
78	struct platform_device *pdev = to_platform_device(dev);
79	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
80	void __iomem *ioaddr = pdata->ioaddr;
81	u8 century;
82
83	century = bin2bcd((tm->tm_year + 1900) / 100);
84
85	writeb(RTC_WRITE, pdata->ioaddr + RTC_CONTROL);
86
87	writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
88	writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
89	writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
90	writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
91	writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
92	writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
93	writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
94
95	/* RTC_CENTURY and RTC_CONTROL share same register */
96	writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
97	writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
98	return 0;
99}
100
101static int ds1553_rtc_read_time(struct device *dev, struct rtc_time *tm)
102{
103	struct platform_device *pdev = to_platform_device(dev);
104	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
105	void __iomem *ioaddr = pdata->ioaddr;
106	unsigned int year, month, day, hour, minute, second, week;
107	unsigned int century;
108
109	/* give enough time to update RTC in case of continuous read */
110	if (pdata->last_jiffies == jiffies)
111		msleep(1);
112	pdata->last_jiffies = jiffies;
113	writeb(RTC_READ, ioaddr + RTC_CONTROL);
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) & RTC_CENTURY_MASK;
122	writeb(0, ioaddr + RTC_CONTROL);
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
139static void ds1553_rtc_update_alarm(struct rtc_plat_data *pdata)
140{
141	void __iomem *ioaddr = pdata->ioaddr;
142	unsigned long flags;
143
144	spin_lock_irqsave(&pdata->lock, flags);
145	writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
146	       0x80 : bin2bcd(pdata->alrm_mday),
147	       ioaddr + RTC_DATE_ALARM);
148	writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
149	       0x80 : bin2bcd(pdata->alrm_hour),
150	       ioaddr + RTC_HOURS_ALARM);
151	writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
152	       0x80 : bin2bcd(pdata->alrm_min),
153	       ioaddr + RTC_MINUTES_ALARM);
154	writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
155	       0x80 : bin2bcd(pdata->alrm_sec),
156	       ioaddr + RTC_SECONDS_ALARM);
157	writeb(pdata->irqen ? RTC_INTS_AE : 0, ioaddr + RTC_INTERRUPTS);
158	readb(ioaddr + RTC_FLAGS);	/* clear interrupts */
159	spin_unlock_irqrestore(&pdata->lock, flags);
160}
161
162static int ds1553_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
163{
164	struct platform_device *pdev = to_platform_device(dev);
165	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
166
167	if (pdata->irq <= 0)
168		return -EINVAL;
169	pdata->alrm_mday = alrm->time.tm_mday;
170	pdata->alrm_hour = alrm->time.tm_hour;
171	pdata->alrm_min = alrm->time.tm_min;
172	pdata->alrm_sec = alrm->time.tm_sec;
173	if (alrm->enabled)
174		pdata->irqen |= RTC_AF;
175	ds1553_rtc_update_alarm(pdata);
176	return 0;
177}
178
179static int ds1553_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
180{
181	struct platform_device *pdev = to_platform_device(dev);
182	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
183
184	if (pdata->irq <= 0)
185		return -EINVAL;
186	alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
187	alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
188	alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
189	alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
190	alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
191	return 0;
192}
193
194static irqreturn_t ds1553_rtc_interrupt(int irq, void *dev_id)
195{
196	struct platform_device *pdev = dev_id;
197	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
198	void __iomem *ioaddr = pdata->ioaddr;
199	unsigned long events = 0;
200
201	spin_lock(&pdata->lock);
202	/* read and clear interrupt */
203	if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
204		events = RTC_IRQF;
205		if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
206			events |= RTC_UF;
207		else
208			events |= RTC_AF;
209		rtc_update_irq(pdata->rtc, 1, events);
210	}
211	spin_unlock(&pdata->lock);
212	return events ? IRQ_HANDLED : IRQ_NONE;
213}
214
215static int ds1553_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
216{
217	struct platform_device *pdev = to_platform_device(dev);
218	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
219
220	if (pdata->irq <= 0)
221		return -EINVAL;
222	if (enabled)
223		pdata->irqen |= RTC_AF;
224	else
225		pdata->irqen &= ~RTC_AF;
226	ds1553_rtc_update_alarm(pdata);
227	return 0;
228}
229
230static const struct rtc_class_ops ds1553_rtc_ops = {
231	.read_time		= ds1553_rtc_read_time,
232	.set_time		= ds1553_rtc_set_time,
233	.read_alarm		= ds1553_rtc_read_alarm,
234	.set_alarm		= ds1553_rtc_set_alarm,
235	.alarm_irq_enable	= ds1553_rtc_alarm_irq_enable,
236};
237
238static ssize_t ds1553_nvram_read(struct file *filp, struct kobject *kobj,
239				 struct bin_attribute *bin_attr,
240				 char *buf, loff_t pos, size_t size)
241{
242	struct device *dev = container_of(kobj, struct device, kobj);
243	struct platform_device *pdev = to_platform_device(dev);
244	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
245	void __iomem *ioaddr = pdata->ioaddr;
246	ssize_t count;
247
248	for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
249		*buf++ = readb(ioaddr + pos++);
250	return count;
251}
252
253static ssize_t ds1553_nvram_write(struct file *filp, struct kobject *kobj,
254				  struct bin_attribute *bin_attr,
255				  char *buf, loff_t pos, size_t size)
256{
257	struct device *dev = container_of(kobj, struct device, kobj);
258	struct platform_device *pdev = to_platform_device(dev);
259	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
260	void __iomem *ioaddr = pdata->ioaddr;
261	ssize_t count;
262
263	for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
264		writeb(*buf++, ioaddr + pos++);
265	return count;
266}
267
268static struct bin_attribute ds1553_nvram_attr = {
269	.attr = {
270		.name = "nvram",
271		.mode = S_IRUGO | S_IWUSR,
272	},
273	.size = RTC_OFFSET,
274	.read = ds1553_nvram_read,
275	.write = ds1553_nvram_write,
276};
277
278static int ds1553_rtc_probe(struct platform_device *pdev)
279{
280	struct resource *res;
281	unsigned int cen, sec;
282	struct rtc_plat_data *pdata;
283	void __iomem *ioaddr;
284	int ret = 0;
285
286	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
287	if (!pdata)
288		return -ENOMEM;
289
290	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
291	ioaddr = devm_ioremap_resource(&pdev->dev, res);
292	if (IS_ERR(ioaddr))
293		return PTR_ERR(ioaddr);
294	pdata->ioaddr = ioaddr;
295	pdata->irq = platform_get_irq(pdev, 0);
296
297	/* turn RTC on if it was not on */
298	sec = readb(ioaddr + RTC_SECONDS);
299	if (sec & RTC_STOP) {
300		sec &= RTC_SECONDS_MASK;
301		cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
302		writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
303		writeb(sec, ioaddr + RTC_SECONDS);
304		writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
305	}
306	if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_BLF)
307		dev_warn(&pdev->dev, "voltage-low detected.\n");
308
309	spin_lock_init(&pdata->lock);
310	pdata->last_jiffies = jiffies;
311	platform_set_drvdata(pdev, pdata);
312
313	pdata->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
314				  &ds1553_rtc_ops, THIS_MODULE);
315	if (IS_ERR(pdata->rtc))
316		return PTR_ERR(pdata->rtc);
317
318	if (pdata->irq > 0) {
319		writeb(0, ioaddr + RTC_INTERRUPTS);
320		if (devm_request_irq(&pdev->dev, pdata->irq,
321				ds1553_rtc_interrupt,
322				0, pdev->name, pdev) < 0) {
323			dev_warn(&pdev->dev, "interrupt not available.\n");
324			pdata->irq = 0;
325		}
326	}
327
328	ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1553_nvram_attr);
329	if (ret)
330		dev_err(&pdev->dev, "unable to create sysfs file: %s\n",
331			ds1553_nvram_attr.attr.name);
332
333	return 0;
334}
335
336static int ds1553_rtc_remove(struct platform_device *pdev)
337{
338	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
339
340	sysfs_remove_bin_file(&pdev->dev.kobj, &ds1553_nvram_attr);
341	if (pdata->irq > 0)
342		writeb(0, pdata->ioaddr + RTC_INTERRUPTS);
343	return 0;
344}
345
346/* work with hotplug and coldplug */
347MODULE_ALIAS("platform:rtc-ds1553");
348
349static struct platform_driver ds1553_rtc_driver = {
350	.probe		= ds1553_rtc_probe,
351	.remove		= ds1553_rtc_remove,
352	.driver		= {
353		.name	= "rtc-ds1553",
354	},
355};
356
357module_platform_driver(ds1553_rtc_driver);
358
359MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
360MODULE_DESCRIPTION("Dallas DS1553 RTC driver");
361MODULE_LICENSE("GPL");
362MODULE_VERSION(DRV_VERSION);
363