1 /*
2  * An I2C driver for the Epson RX8581 RTC
3  *
4  * Author: Martyn Welch <martyn.welch@ge.com>
5  * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
12  * Copyright 2005-06 Tower Technologies
13  */
14 
15 #include <linux/module.h>
16 #include <linux/i2c.h>
17 #include <linux/bcd.h>
18 #include <linux/rtc.h>
19 #include <linux/log2.h>
20 
21 #define DRV_VERSION "0.1"
22 
23 #define RX8581_REG_SC		0x00 /* Second in BCD */
24 #define RX8581_REG_MN		0x01 /* Minute in BCD */
25 #define RX8581_REG_HR		0x02 /* Hour in BCD */
26 #define RX8581_REG_DW		0x03 /* Day of Week */
27 #define RX8581_REG_DM		0x04 /* Day of Month in BCD */
28 #define RX8581_REG_MO		0x05 /* Month in BCD */
29 #define RX8581_REG_YR		0x06 /* Year in BCD */
30 #define RX8581_REG_RAM		0x07 /* RAM */
31 #define RX8581_REG_AMN		0x08 /* Alarm Min in BCD*/
32 #define RX8581_REG_AHR		0x09 /* Alarm Hour in BCD */
33 #define RX8581_REG_ADM		0x0A
34 #define RX8581_REG_ADW		0x0A
35 #define RX8581_REG_TMR0		0x0B
36 #define RX8581_REG_TMR1		0x0C
37 #define RX8581_REG_EXT		0x0D /* Extension Register */
38 #define RX8581_REG_FLAG		0x0E /* Flag Register */
39 #define RX8581_REG_CTRL		0x0F /* Control Register */
40 
41 
42 /* Flag Register bit definitions */
43 #define RX8581_FLAG_UF		0x20 /* Update */
44 #define RX8581_FLAG_TF		0x10 /* Timer */
45 #define RX8581_FLAG_AF		0x08 /* Alarm */
46 #define RX8581_FLAG_VLF		0x02 /* Voltage Low */
47 
48 /* Control Register bit definitions */
49 #define RX8581_CTRL_UIE		0x20 /* Update Interrupt Enable */
50 #define RX8581_CTRL_TIE		0x10 /* Timer Interrupt Enable */
51 #define RX8581_CTRL_AIE		0x08 /* Alarm Interrupt Enable */
52 #define RX8581_CTRL_STOP	0x02 /* STOP bit */
53 #define RX8581_CTRL_RESET	0x01 /* RESET bit */
54 
55 static struct i2c_driver rx8581_driver;
56 
57 /*
58  * In the routines that deal directly with the rx8581 hardware, we use
59  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
60  */
rx8581_get_datetime(struct i2c_client * client,struct rtc_time * tm)61 static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm)
62 {
63 	unsigned char date[7];
64 	int data, err;
65 
66 	/* First we ensure that the "update flag" is not set, we read the
67 	 * time and date then re-read the "update flag". If the update flag
68 	 * has been set, we know that the time has changed during the read so
69 	 * we repeat the whole process again.
70 	 */
71 	data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
72 	if (data < 0) {
73 		dev_err(&client->dev, "Unable to read device flags\n");
74 		return -EIO;
75 	}
76 
77 	do {
78 		/* If update flag set, clear it */
79 		if (data & RX8581_FLAG_UF) {
80 			err = i2c_smbus_write_byte_data(client,
81 				RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF));
82 			if (err != 0) {
83 				dev_err(&client->dev, "Unable to write device "
84 					"flags\n");
85 				return -EIO;
86 			}
87 		}
88 
89 		/* Now read time and date */
90 		err = i2c_smbus_read_i2c_block_data(client, RX8581_REG_SC,
91 			7, date);
92 		if (err < 0) {
93 			dev_err(&client->dev, "Unable to read date\n");
94 			return -EIO;
95 		}
96 
97 		/* Check flag register */
98 		data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
99 		if (data < 0) {
100 			dev_err(&client->dev, "Unable to read device flags\n");
101 			return -EIO;
102 		}
103 	} while (data & RX8581_FLAG_UF);
104 
105 	if (data & RX8581_FLAG_VLF)
106 		dev_info(&client->dev,
107 			"low voltage detected, date/time is not reliable.\n");
108 
109 	dev_dbg(&client->dev,
110 		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
111 		"wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
112 		__func__,
113 		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
114 
115 	tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
116 	tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
117 	tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
118 	tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
119 	tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
120 	tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
121 	tm->tm_year = bcd2bin(date[RX8581_REG_YR]);
122 	if (tm->tm_year < 70)
123 		tm->tm_year += 100;	/* assume we are in 1970...2069 */
124 
125 
126 	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
127 		"mday=%d, mon=%d, year=%d, wday=%d\n",
128 		__func__,
129 		tm->tm_sec, tm->tm_min, tm->tm_hour,
130 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
131 
132 	err = rtc_valid_tm(tm);
133 	if (err < 0)
134 		dev_err(&client->dev, "retrieved date/time is not valid.\n");
135 
136 	return err;
137 }
138 
rx8581_set_datetime(struct i2c_client * client,struct rtc_time * tm)139 static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm)
140 {
141 	int data, err;
142 	unsigned char buf[7];
143 
144 	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
145 		"mday=%d, mon=%d, year=%d, wday=%d\n",
146 		__func__,
147 		tm->tm_sec, tm->tm_min, tm->tm_hour,
148 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
149 
150 	/* hours, minutes and seconds */
151 	buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
152 	buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
153 	buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
154 
155 	buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
156 
157 	/* month, 1 - 12 */
158 	buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
159 
160 	/* year and century */
161 	buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100);
162 	buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
163 
164 	/* Stop the clock */
165 	data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
166 	if (data < 0) {
167 		dev_err(&client->dev, "Unable to read control register\n");
168 		return -EIO;
169 	}
170 
171 	err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
172 		(data | RX8581_CTRL_STOP));
173 	if (err < 0) {
174 		dev_err(&client->dev, "Unable to write control register\n");
175 		return -EIO;
176 	}
177 
178 	/* write register's data */
179 	err = i2c_smbus_write_i2c_block_data(client, RX8581_REG_SC, 7, buf);
180 	if (err < 0) {
181 		dev_err(&client->dev, "Unable to write to date registers\n");
182 		return -EIO;
183 	}
184 
185 	/* get VLF and clear it */
186 	data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
187 	if (data < 0) {
188 		dev_err(&client->dev, "Unable to read flag register\n");
189 		return -EIO;
190 	}
191 
192 	err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,
193 		(data & ~(RX8581_FLAG_VLF)));
194 	if (err != 0) {
195 		dev_err(&client->dev, "Unable to write flag register\n");
196 		return -EIO;
197 	}
198 
199 	/* Restart the clock */
200 	data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
201 	if (data < 0) {
202 		dev_err(&client->dev, "Unable to read control register\n");
203 		return -EIO;
204 	}
205 
206 	err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
207 		(data & ~(RX8581_CTRL_STOP)));
208 	if (err != 0) {
209 		dev_err(&client->dev, "Unable to write control register\n");
210 		return -EIO;
211 	}
212 
213 	return 0;
214 }
215 
rx8581_rtc_read_time(struct device * dev,struct rtc_time * tm)216 static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
217 {
218 	return rx8581_get_datetime(to_i2c_client(dev), tm);
219 }
220 
rx8581_rtc_set_time(struct device * dev,struct rtc_time * tm)221 static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
222 {
223 	return rx8581_set_datetime(to_i2c_client(dev), tm);
224 }
225 
226 static const struct rtc_class_ops rx8581_rtc_ops = {
227 	.read_time	= rx8581_rtc_read_time,
228 	.set_time	= rx8581_rtc_set_time,
229 };
230 
rx8581_probe(struct i2c_client * client,const struct i2c_device_id * id)231 static int __devinit rx8581_probe(struct i2c_client *client,
232 				const struct i2c_device_id *id)
233 {
234 	struct rtc_device *rtc;
235 
236 	dev_dbg(&client->dev, "%s\n", __func__);
237 
238 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
239 		return -ENODEV;
240 
241 	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
242 
243 	rtc = rtc_device_register(rx8581_driver.driver.name,
244 				&client->dev, &rx8581_rtc_ops, THIS_MODULE);
245 
246 	if (IS_ERR(rtc))
247 		return PTR_ERR(rtc);
248 
249 	i2c_set_clientdata(client, rtc);
250 
251 	return 0;
252 }
253 
rx8581_remove(struct i2c_client * client)254 static int __devexit rx8581_remove(struct i2c_client *client)
255 {
256 	struct rtc_device *rtc = i2c_get_clientdata(client);
257 
258 	rtc_device_unregister(rtc);
259 
260 	return 0;
261 }
262 
263 static const struct i2c_device_id rx8581_id[] = {
264 	{ "rx8581", 0 },
265 	{ }
266 };
267 MODULE_DEVICE_TABLE(i2c, rx8581_id);
268 
269 static struct i2c_driver rx8581_driver = {
270 	.driver		= {
271 		.name	= "rtc-rx8581",
272 		.owner	= THIS_MODULE,
273 	},
274 	.probe		= rx8581_probe,
275 	.remove		= __devexit_p(rx8581_remove),
276 	.id_table	= rx8581_id,
277 };
278 
279 module_i2c_driver(rx8581_driver);
280 
281 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
282 MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
283 MODULE_LICENSE("GPL");
284 MODULE_VERSION(DRV_VERSION);
285