1 /*
2 * Seiko Instruments S-35390A RTC Driver
3 *
4 * Copyright (c) 2007 Byron Bradley
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <linux/module.h>
13 #include <linux/rtc.h>
14 #include <linux/i2c.h>
15 #include <linux/bitrev.h>
16 #include <linux/bcd.h>
17 #include <linux/slab.h>
18
19 #define S35390A_CMD_STATUS1 0
20 #define S35390A_CMD_STATUS2 1
21 #define S35390A_CMD_TIME1 2
22
23 #define S35390A_BYTE_YEAR 0
24 #define S35390A_BYTE_MONTH 1
25 #define S35390A_BYTE_DAY 2
26 #define S35390A_BYTE_WDAY 3
27 #define S35390A_BYTE_HOURS 4
28 #define S35390A_BYTE_MINS 5
29 #define S35390A_BYTE_SECS 6
30
31 #define S35390A_FLAG_POC 0x01
32 #define S35390A_FLAG_BLD 0x02
33 #define S35390A_FLAG_24H 0x40
34 #define S35390A_FLAG_RESET 0x80
35 #define S35390A_FLAG_TEST 0x01
36
37 struct s35390a {
38 struct i2c_client *client[8];
39 struct rtc_device *rtc;
40 int twentyfourhour;
41 };
42
43 static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
44 {
45 struct i2c_client *client = s35390a->client[reg];
46 struct i2c_msg msg[] = {
47 { client->addr, 0, len, buf },
48 };
49
50 if ((i2c_transfer(client->adapter, msg, 1)) != 1)
51 return -EIO;
52
53 return 0;
54 }
55
56 static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
57 {
58 struct i2c_client *client = s35390a->client[reg];
59 struct i2c_msg msg[] = {
60 { client->addr, I2C_M_RD, len, buf },
61 };
62
63 if ((i2c_transfer(client->adapter, msg, 1)) != 1)
64 return -EIO;
65
66 return 0;
67 }
68
69 static int s35390a_reset(struct s35390a *s35390a)
70 {
71 char buf[1];
72
73 if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf)) < 0)
74 return -EIO;
75
76 if (!(buf[0] & (S35390A_FLAG_POC | S35390A_FLAG_BLD)))
77 return 0;
78
79 buf[0] |= (S35390A_FLAG_RESET | S35390A_FLAG_24H);
80 buf[0] &= 0xf0;
81 return s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
82 }
83
84 static int s35390a_disable_test_mode(struct s35390a *s35390a)
85 {
86 char buf[1];
87
88 if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
89 return -EIO;
90
91 if (!(buf[0] & S35390A_FLAG_TEST))
92 return 0;
93
94 buf[0] &= ~S35390A_FLAG_TEST;
95 return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
96 }
97
98 static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
99 {
100 if (s35390a->twentyfourhour)
101 return BIN2BCD(hour);
102
103 if (hour < 12)
104 return BIN2BCD(hour);
105
106 return 0x40 | BIN2BCD(hour - 12);
107 }
108
109 static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
110 {
111 unsigned hour;
112
113 if (s35390a->twentyfourhour)
114 return BCD2BIN(reg & 0x3f);
115
116 hour = BCD2BIN(reg & 0x3f);
117 if (reg & 0x40)
118 hour += 12;
119
120 return hour;
121 }
122
123 static int s35390a_set_datetime(struct i2c_client *client, struct rtc_time *tm)
124 {
125 struct s35390a *s35390a = i2c_get_clientdata(client);
126 int i, err;
127 char buf[7];
128
129 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
130 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
131 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
132 tm->tm_wday);
133
134 buf[S35390A_BYTE_YEAR] = BIN2BCD(tm->tm_year - 100);
135 buf[S35390A_BYTE_MONTH] = BIN2BCD(tm->tm_mon + 1);
136 buf[S35390A_BYTE_DAY] = BIN2BCD(tm->tm_mday);
137 buf[S35390A_BYTE_WDAY] = BIN2BCD(tm->tm_wday);
138 buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
139 buf[S35390A_BYTE_MINS] = BIN2BCD(tm->tm_min);
140 buf[S35390A_BYTE_SECS] = BIN2BCD(tm->tm_sec);
141
142 /* This chip expects the bits of each byte to be in reverse order */
143 for (i = 0; i < 7; ++i)
144 buf[i] = bitrev8(buf[i]);
145
146 err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
147
148 return err;
149 }
150
151 static int s35390a_get_datetime(struct i2c_client *client, struct rtc_time *tm)
152 {
153 struct s35390a *s35390a = i2c_get_clientdata(client);
154 char buf[7];
155 int i, err;
156
157 err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
158 if (err < 0)
159 return err;
160
161 /* This chip returns the bits of each byte in reverse order */
162 for (i = 0; i < 7; ++i)
163 buf[i] = bitrev8(buf[i]);
164
165 tm->tm_sec = BCD2BIN(buf[S35390A_BYTE_SECS]);
166 tm->tm_min = BCD2BIN(buf[S35390A_BYTE_MINS]);
167 tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
168 tm->tm_wday = BCD2BIN(buf[S35390A_BYTE_WDAY]);
169 tm->tm_mday = BCD2BIN(buf[S35390A_BYTE_DAY]);
170 tm->tm_mon = BCD2BIN(buf[S35390A_BYTE_MONTH]) - 1;
171 tm->tm_year = BCD2BIN(buf[S35390A_BYTE_YEAR]) + 100;
172
173 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
174 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
175 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
176 tm->tm_wday);
177
178 return rtc_valid_tm(tm);
179 }
180
181 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
182 {
183 return s35390a_get_datetime(to_i2c_client(dev), tm);
184 }
185
186 static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
187 {
188 return s35390a_set_datetime(to_i2c_client(dev), tm);
189 }
190
191 static const struct rtc_class_ops s35390a_rtc_ops = {
192 .read_time = s35390a_rtc_read_time,
193 .set_time = s35390a_rtc_set_time,
194 };
195
196 static struct i2c_driver s35390a_driver;
197
198 static int s35390a_probe(struct i2c_client *client)
199 {
200 int err;
201 unsigned int i;
202 struct s35390a *s35390a;
203 struct rtc_time tm;
204 char buf[1];
205
206 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
207 err = -ENODEV;
208 goto exit;
209 }
210
211 s35390a = kzalloc(sizeof(struct s35390a), GFP_KERNEL);
212 if (!s35390a) {
213 err = -ENOMEM;
214 goto exit;
215 }
216
217 s35390a->client[0] = client;
218 i2c_set_clientdata(client, s35390a);
219
220 /* This chip uses multiple addresses, use dummy devices for them */
221 for (i = 1; i < 8; ++i) {
222 s35390a->client[i] = i2c_new_dummy(client->adapter,
223 client->addr + i, "rtc-s35390a");
224 if (!s35390a->client[i]) {
225 dev_err(&client->dev, "Address %02x unavailable\n",
226 client->addr + i);
227 err = -EBUSY;
228 goto exit_dummy;
229 }
230 }
231
232 err = s35390a_reset(s35390a);
233 if (err < 0) {
234 dev_err(&client->dev, "error resetting chip\n");
235 goto exit_dummy;
236 }
237
238 err = s35390a_disable_test_mode(s35390a);
239 if (err < 0) {
240 dev_err(&client->dev, "error disabling test mode\n");
241 goto exit_dummy;
242 }
243
244 err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
245 if (err < 0) {
246 dev_err(&client->dev, "error checking 12/24 hour mode\n");
247 goto exit_dummy;
248 }
249 if (buf[0] & S35390A_FLAG_24H)
250 s35390a->twentyfourhour = 1;
251 else
252 s35390a->twentyfourhour = 0;
253
254 if (s35390a_get_datetime(client, &tm) < 0)
255 dev_warn(&client->dev, "clock needs to be set\n");
256
257 s35390a->rtc = rtc_device_register(s35390a_driver.driver.name,
258 &client->dev, &s35390a_rtc_ops, THIS_MODULE);
259
260 if (IS_ERR(s35390a->rtc)) {
261 err = PTR_ERR(s35390a->rtc);
262 goto exit_dummy;
263 }
264 return 0;
265
266 exit_dummy:
267 for (i = 1; i < 8; ++i)
268 if (s35390a->client[i])
269 i2c_unregister_device(s35390a->client[i]);
270 kfree(s35390a);
271 i2c_set_clientdata(client, NULL);
272
273 exit:
274 return err;
275 }
276
277 static int s35390a_remove(struct i2c_client *client)
278 {
279 unsigned int i;
280
281 struct s35390a *s35390a = i2c_get_clientdata(client);
282 for (i = 1; i < 8; ++i)
283 if (s35390a->client[i])
284 i2c_unregister_device(s35390a->client[i]);
285
286 rtc_device_unregister(s35390a->rtc);
287 kfree(s35390a);
288 i2c_set_clientdata(client, NULL);
289
290 return 0;
291 }
292
293 static struct i2c_driver s35390a_driver = {
294 .driver = {
295 .name = "rtc-s35390a",
296 },
297 .probe = s35390a_probe,
298 .remove = s35390a_remove,
299 };
300
301 static int __init s35390a_rtc_init(void)
302 {
303 return i2c_add_driver(&s35390a_driver);
304 }
305
306 static void __exit s35390a_rtc_exit(void)
307 {
308 i2c_del_driver(&s35390a_driver);
309 }
310
311 MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
312 MODULE_DESCRIPTION("S35390A RTC driver");
313 MODULE_LICENSE("GPL");
314
315 module_init(s35390a_rtc_init);
316 module_exit(s35390a_rtc_exit);
317
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