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