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/regmap.h>
19 #include <linux/rtc.h>
20 #include <linux/log2.h>
21 
22 #define RX8581_REG_SC		0x00 /* Second in BCD */
23 #define RX8581_REG_MN		0x01 /* Minute in BCD */
24 #define RX8581_REG_HR		0x02 /* Hour in BCD */
25 #define RX8581_REG_DW		0x03 /* Day of Week */
26 #define RX8581_REG_DM		0x04 /* Day of Month in BCD */
27 #define RX8581_REG_MO		0x05 /* Month in BCD */
28 #define RX8581_REG_YR		0x06 /* Year in BCD */
29 #define RX8581_REG_RAM		0x07 /* RAM */
30 #define RX8581_REG_AMN		0x08 /* Alarm Min in BCD*/
31 #define RX8581_REG_AHR		0x09 /* Alarm Hour in BCD */
32 #define RX8581_REG_ADM		0x0A
33 #define RX8581_REG_ADW		0x0A
34 #define RX8581_REG_TMR0		0x0B
35 #define RX8581_REG_TMR1		0x0C
36 #define RX8581_REG_EXT		0x0D /* Extension Register */
37 #define RX8581_REG_FLAG		0x0E /* Flag Register */
38 #define RX8581_REG_CTRL		0x0F /* Control Register */
39 
40 
41 /* Flag Register bit definitions */
42 #define RX8581_FLAG_UF		0x20 /* Update */
43 #define RX8581_FLAG_TF		0x10 /* Timer */
44 #define RX8581_FLAG_AF		0x08 /* Alarm */
45 #define RX8581_FLAG_VLF		0x02 /* Voltage Low */
46 
47 /* Control Register bit definitions */
48 #define RX8581_CTRL_UIE		0x20 /* Update Interrupt Enable */
49 #define RX8581_CTRL_TIE		0x10 /* Timer Interrupt Enable */
50 #define RX8581_CTRL_AIE		0x08 /* Alarm Interrupt Enable */
51 #define RX8581_CTRL_STOP	0x02 /* STOP bit */
52 #define RX8581_CTRL_RESET	0x01 /* RESET bit */
53 
54 struct rx8581 {
55 	struct regmap		*regmap;
56 	struct rtc_device	*rtc;
57 };
58 
59 /*
60  * In the routines that deal directly with the rx8581 hardware, we use
61  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
62  */
rx8581_rtc_read_time(struct device * dev,struct rtc_time * tm)63 static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
64 {
65 	struct i2c_client *client = to_i2c_client(dev);
66 	unsigned char date[7];
67 	unsigned int data;
68 	int err;
69 	struct rx8581 *rx8581 = i2c_get_clientdata(client);
70 
71 	/* First we ensure that the "update flag" is not set, we read the
72 	 * time and date then re-read the "update flag". If the update flag
73 	 * has been set, we know that the time has changed during the read so
74 	 * we repeat the whole process again.
75 	 */
76 	err = regmap_read(rx8581->regmap, RX8581_REG_FLAG, &data);
77 	if (err < 0)
78 		return err;
79 
80 	if (data & RX8581_FLAG_VLF) {
81 		dev_warn(dev,
82 			 "low voltage detected, date/time is not reliable.\n");
83 		return -EINVAL;
84 	}
85 
86 	do {
87 		/* If update flag set, clear it */
88 		if (data & RX8581_FLAG_UF) {
89 			err = regmap_write(rx8581->regmap, RX8581_REG_FLAG,
90 					  data & ~RX8581_FLAG_UF);
91 			if (err < 0)
92 				return err;
93 		}
94 
95 		/* Now read time and date */
96 		err = regmap_bulk_read(rx8581->regmap, RX8581_REG_SC, date,
97 				       sizeof(date));
98 		if (err < 0)
99 			return err;
100 
101 		/* Check flag register */
102 		err = regmap_read(rx8581->regmap, RX8581_REG_FLAG, &data);
103 		if (err < 0)
104 			return err;
105 	} while (data & RX8581_FLAG_UF);
106 
107 	dev_dbg(dev, "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
108 		"wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
109 		__func__,
110 		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
111 
112 	tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
113 	tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
114 	tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
115 	tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
116 	tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
117 	tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
118 	tm->tm_year = bcd2bin(date[RX8581_REG_YR]) + 100;
119 
120 	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
121 		"mday=%d, mon=%d, year=%d, wday=%d\n",
122 		__func__,
123 		tm->tm_sec, tm->tm_min, tm->tm_hour,
124 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
125 
126 	return 0;
127 }
128 
rx8581_rtc_set_time(struct device * dev,struct rtc_time * tm)129 static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
130 {
131 	struct i2c_client *client = to_i2c_client(dev);
132 	int err;
133 	unsigned char buf[7];
134 	struct rx8581 *rx8581 = i2c_get_clientdata(client);
135 
136 	dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
137 		"mday=%d, mon=%d, year=%d, wday=%d\n",
138 		__func__,
139 		tm->tm_sec, tm->tm_min, tm->tm_hour,
140 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
141 
142 	/* hours, minutes and seconds */
143 	buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
144 	buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
145 	buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
146 
147 	buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
148 
149 	/* month, 1 - 12 */
150 	buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
151 
152 	/* year and century */
153 	buf[RX8581_REG_YR] = bin2bcd(tm->tm_year - 100);
154 	buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
155 
156 	/* Stop the clock */
157 	err = regmap_update_bits(rx8581->regmap, RX8581_REG_CTRL,
158 				 RX8581_CTRL_STOP, RX8581_CTRL_STOP);
159 	if (err < 0)
160 		return err;
161 
162 	/* write register's data */
163 	err = regmap_bulk_write(rx8581->regmap, RX8581_REG_SC,
164 				buf, sizeof(buf));
165 	if (err < 0)
166 		return err;
167 
168 	/* get VLF and clear it */
169 	err = regmap_update_bits(rx8581->regmap, RX8581_REG_FLAG,
170 				 RX8581_FLAG_VLF, 0);
171 	if (err < 0)
172 		return err;
173 
174 	/* Restart the clock */
175 	return regmap_update_bits(rx8581->regmap, RX8581_REG_CTRL,
176 				 RX8581_CTRL_STOP, 0);
177 }
178 
179 static const struct rtc_class_ops rx8581_rtc_ops = {
180 	.read_time	= rx8581_rtc_read_time,
181 	.set_time	= rx8581_rtc_set_time,
182 };
183 
rx8581_probe(struct i2c_client * client,const struct i2c_device_id * id)184 static int rx8581_probe(struct i2c_client *client,
185 			const struct i2c_device_id *id)
186 {
187 	struct rx8581	  *rx8581;
188 	static const struct regmap_config config = {
189 		.reg_bits = 8,
190 		.val_bits = 8,
191 		.max_register = 0xf,
192 	};
193 
194 	dev_dbg(&client->dev, "%s\n", __func__);
195 
196 	rx8581 = devm_kzalloc(&client->dev, sizeof(struct rx8581), GFP_KERNEL);
197 	if (!rx8581)
198 		return -ENOMEM;
199 
200 	i2c_set_clientdata(client, rx8581);
201 
202 	rx8581->regmap = devm_regmap_init_i2c(client, &config);
203 	if (IS_ERR(rx8581->regmap))
204 		return PTR_ERR(rx8581->regmap);
205 
206 	rx8581->rtc = devm_rtc_allocate_device(&client->dev);
207 	if (IS_ERR(rx8581->rtc))
208 		return PTR_ERR(rx8581->rtc);
209 
210 	rx8581->rtc->ops = &rx8581_rtc_ops;
211 	rx8581->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
212 	rx8581->rtc->range_max = RTC_TIMESTAMP_END_2099;
213 	rx8581->rtc->start_secs = 0;
214 	rx8581->rtc->set_start_time = true;
215 
216 	return rtc_register_device(rx8581->rtc);
217 }
218 
219 static const struct i2c_device_id rx8581_id[] = {
220 	{ "rx8581", 0 },
221 	{ }
222 };
223 MODULE_DEVICE_TABLE(i2c, rx8581_id);
224 
225 static const struct of_device_id rx8581_of_match[] = {
226 	{ .compatible = "epson,rx8581" },
227 	{ }
228 };
229 MODULE_DEVICE_TABLE(of, rx8581_of_match);
230 
231 static struct i2c_driver rx8581_driver = {
232 	.driver		= {
233 		.name	= "rtc-rx8581",
234 		.of_match_table = of_match_ptr(rx8581_of_match),
235 	},
236 	.probe		= rx8581_probe,
237 	.id_table	= rx8581_id,
238 };
239 
240 module_i2c_driver(rx8581_driver);
241 
242 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
243 MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
244 MODULE_LICENSE("GPL");
245