xref: /openbmc/linux/drivers/rtc/rtc-pcf8563.c (revision b6dcefde)
1 /*
2  * An I2C driver for the Philips PCF8563 RTC
3  * Copyright 2005-06 Tower Technologies
4  *
5  * Author: Alessandro Zummo <a.zummo@towertech.it>
6  * Maintainers: http://www.nslu2-linux.org/
7  *
8  * based on the other drivers in this same directory.
9  *
10  * http://www.semiconductors.philips.com/acrobat/datasheets/PCF8563-04.pdf
11  *
12  * This program is free software; you can redistribute it and/or modify
13  * it under the terms of the GNU General Public License version 2 as
14  * published by the Free Software Foundation.
15  */
16 
17 #include <linux/i2c.h>
18 #include <linux/bcd.h>
19 #include <linux/rtc.h>
20 
21 #define DRV_VERSION "0.4.3"
22 
23 #define PCF8563_REG_ST1		0x00 /* status */
24 #define PCF8563_REG_ST2		0x01
25 
26 #define PCF8563_REG_SC		0x02 /* datetime */
27 #define PCF8563_REG_MN		0x03
28 #define PCF8563_REG_HR		0x04
29 #define PCF8563_REG_DM		0x05
30 #define PCF8563_REG_DW		0x06
31 #define PCF8563_REG_MO		0x07
32 #define PCF8563_REG_YR		0x08
33 
34 #define PCF8563_REG_AMN		0x09 /* alarm */
35 #define PCF8563_REG_AHR		0x0A
36 #define PCF8563_REG_ADM		0x0B
37 #define PCF8563_REG_ADW		0x0C
38 
39 #define PCF8563_REG_CLKO	0x0D /* clock out */
40 #define PCF8563_REG_TMRC	0x0E /* timer control */
41 #define PCF8563_REG_TMR		0x0F /* timer */
42 
43 #define PCF8563_SC_LV		0x80 /* low voltage */
44 #define PCF8563_MO_C		0x80 /* century */
45 
46 static struct i2c_driver pcf8563_driver;
47 
48 struct pcf8563 {
49 	struct rtc_device *rtc;
50 	/*
51 	 * The meaning of MO_C bit varies by the chip type.
52 	 * From PCF8563 datasheet: this bit is toggled when the years
53 	 * register overflows from 99 to 00
54 	 *   0 indicates the century is 20xx
55 	 *   1 indicates the century is 19xx
56 	 * From RTC8564 datasheet: this bit indicates change of
57 	 * century. When the year digit data overflows from 99 to 00,
58 	 * this bit is set. By presetting it to 0 while still in the
59 	 * 20th century, it will be set in year 2000, ...
60 	 * There seems no reliable way to know how the system use this
61 	 * bit.  So let's do it heuristically, assuming we are live in
62 	 * 1970...2069.
63 	 */
64 	int c_polarity;	/* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
65 };
66 
67 /*
68  * In the routines that deal directly with the pcf8563 hardware, we use
69  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
70  */
71 static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
72 {
73 	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
74 	unsigned char buf[13] = { PCF8563_REG_ST1 };
75 
76 	struct i2c_msg msgs[] = {
77 		{ client->addr, 0, 1, buf },	/* setup read ptr */
78 		{ client->addr, I2C_M_RD, 13, buf },	/* read status + date */
79 	};
80 
81 	/* read registers */
82 	if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
83 		dev_err(&client->dev, "%s: read error\n", __func__);
84 		return -EIO;
85 	}
86 
87 	if (buf[PCF8563_REG_SC] & PCF8563_SC_LV)
88 		dev_info(&client->dev,
89 			"low voltage detected, date/time is not reliable.\n");
90 
91 	dev_dbg(&client->dev,
92 		"%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
93 		"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
94 		__func__,
95 		buf[0], buf[1], buf[2], buf[3],
96 		buf[4], buf[5], buf[6], buf[7],
97 		buf[8]);
98 
99 
100 	tm->tm_sec = bcd2bin(buf[PCF8563_REG_SC] & 0x7F);
101 	tm->tm_min = bcd2bin(buf[PCF8563_REG_MN] & 0x7F);
102 	tm->tm_hour = bcd2bin(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
103 	tm->tm_mday = bcd2bin(buf[PCF8563_REG_DM] & 0x3F);
104 	tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
105 	tm->tm_mon = bcd2bin(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
106 	tm->tm_year = bcd2bin(buf[PCF8563_REG_YR]);
107 	if (tm->tm_year < 70)
108 		tm->tm_year += 100;	/* assume we are in 1970...2069 */
109 	/* detect the polarity heuristically. see note above. */
110 	pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
111 		(tm->tm_year >= 100) : (tm->tm_year < 100);
112 
113 	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
114 		"mday=%d, mon=%d, year=%d, wday=%d\n",
115 		__func__,
116 		tm->tm_sec, tm->tm_min, tm->tm_hour,
117 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
118 
119 	/* the clock can give out invalid datetime, but we cannot return
120 	 * -EINVAL otherwise hwclock will refuse to set the time on bootup.
121 	 */
122 	if (rtc_valid_tm(tm) < 0)
123 		dev_err(&client->dev, "retrieved date/time is not valid.\n");
124 
125 	return 0;
126 }
127 
128 static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
129 {
130 	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
131 	int i, err;
132 	unsigned char buf[9];
133 
134 	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
135 		"mday=%d, mon=%d, year=%d, wday=%d\n",
136 		__func__,
137 		tm->tm_sec, tm->tm_min, tm->tm_hour,
138 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
139 
140 	/* hours, minutes and seconds */
141 	buf[PCF8563_REG_SC] = bin2bcd(tm->tm_sec);
142 	buf[PCF8563_REG_MN] = bin2bcd(tm->tm_min);
143 	buf[PCF8563_REG_HR] = bin2bcd(tm->tm_hour);
144 
145 	buf[PCF8563_REG_DM] = bin2bcd(tm->tm_mday);
146 
147 	/* month, 1 - 12 */
148 	buf[PCF8563_REG_MO] = bin2bcd(tm->tm_mon + 1);
149 
150 	/* year and century */
151 	buf[PCF8563_REG_YR] = bin2bcd(tm->tm_year % 100);
152 	if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
153 		buf[PCF8563_REG_MO] |= PCF8563_MO_C;
154 
155 	buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;
156 
157 	/* write register's data */
158 	for (i = 0; i < 7; i++) {
159 		unsigned char data[2] = { PCF8563_REG_SC + i,
160 						buf[PCF8563_REG_SC + i] };
161 
162 		err = i2c_master_send(client, data, sizeof(data));
163 		if (err != sizeof(data)) {
164 			dev_err(&client->dev,
165 				"%s: err=%d addr=%02x, data=%02x\n",
166 				__func__, err, data[0], data[1]);
167 			return -EIO;
168 		}
169 	};
170 
171 	return 0;
172 }
173 
174 struct pcf8563_limit
175 {
176 	unsigned char reg;
177 	unsigned char mask;
178 	unsigned char min;
179 	unsigned char max;
180 };
181 
182 static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
183 {
184 	return pcf8563_get_datetime(to_i2c_client(dev), tm);
185 }
186 
187 static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
188 {
189 	return pcf8563_set_datetime(to_i2c_client(dev), tm);
190 }
191 
192 static const struct rtc_class_ops pcf8563_rtc_ops = {
193 	.read_time	= pcf8563_rtc_read_time,
194 	.set_time	= pcf8563_rtc_set_time,
195 };
196 
197 static int pcf8563_probe(struct i2c_client *client,
198 				const struct i2c_device_id *id)
199 {
200 	struct pcf8563 *pcf8563;
201 
202 	int err = 0;
203 
204 	dev_dbg(&client->dev, "%s\n", __func__);
205 
206 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
207 		return -ENODEV;
208 
209 	pcf8563 = kzalloc(sizeof(struct pcf8563), GFP_KERNEL);
210 	if (!pcf8563)
211 		return -ENOMEM;
212 
213 	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
214 
215 	i2c_set_clientdata(client, pcf8563);
216 
217 	pcf8563->rtc = rtc_device_register(pcf8563_driver.driver.name,
218 				&client->dev, &pcf8563_rtc_ops, THIS_MODULE);
219 
220 	if (IS_ERR(pcf8563->rtc)) {
221 		err = PTR_ERR(pcf8563->rtc);
222 		goto exit_kfree;
223 	}
224 
225 	return 0;
226 
227 exit_kfree:
228 	kfree(pcf8563);
229 
230 	return err;
231 }
232 
233 static int pcf8563_remove(struct i2c_client *client)
234 {
235 	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
236 
237 	if (pcf8563->rtc)
238 		rtc_device_unregister(pcf8563->rtc);
239 
240 	kfree(pcf8563);
241 
242 	return 0;
243 }
244 
245 static const struct i2c_device_id pcf8563_id[] = {
246 	{ "pcf8563", 0 },
247 	{ "rtc8564", 0 },
248 	{ }
249 };
250 MODULE_DEVICE_TABLE(i2c, pcf8563_id);
251 
252 static struct i2c_driver pcf8563_driver = {
253 	.driver		= {
254 		.name	= "rtc-pcf8563",
255 	},
256 	.probe		= pcf8563_probe,
257 	.remove		= pcf8563_remove,
258 	.id_table	= pcf8563_id,
259 };
260 
261 static int __init pcf8563_init(void)
262 {
263 	return i2c_add_driver(&pcf8563_driver);
264 }
265 
266 static void __exit pcf8563_exit(void)
267 {
268 	i2c_del_driver(&pcf8563_driver);
269 }
270 
271 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
272 MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
273 MODULE_LICENSE("GPL");
274 MODULE_VERSION(DRV_VERSION);
275 
276 module_init(pcf8563_init);
277 module_exit(pcf8563_exit);
278