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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
37static const struct i2c_device_id s35390a_id[] = {
38 { "s35390a", 0 },
39 { }
40};
41MODULE_DEVICE_TABLE(i2c, s35390a_id);
42
43struct s35390a {
44 struct i2c_client *client[8];
45 struct rtc_device *rtc;
46 int twentyfourhour;
47};
48
49static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
50{
51 struct i2c_client *client = s35390a->client[reg];
52 struct i2c_msg msg[] = {
53 { client->addr, 0, len, buf },
54 };
55
56 if ((i2c_transfer(client->adapter, msg, 1)) != 1)
57 return -EIO;
58
59 return 0;
60}
61
62static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
63{
64 struct i2c_client *client = s35390a->client[reg];
65 struct i2c_msg msg[] = {
66 { client->addr, I2C_M_RD, len, buf },
67 };
68
69 if ((i2c_transfer(client->adapter, msg, 1)) != 1)
70 return -EIO;
71
72 return 0;
73}
74
75static int s35390a_reset(struct s35390a *s35390a)
76{
77 char buf[1];
78
79 if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf)) < 0)
80 return -EIO;
81
82 if (!(buf[0] & (S35390A_FLAG_POC | S35390A_FLAG_BLD)))
83 return 0;
84
85 buf[0] |= (S35390A_FLAG_RESET | S35390A_FLAG_24H);
86 buf[0] &= 0xf0;
87 return s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
88}
89
90static int s35390a_disable_test_mode(struct s35390a *s35390a)
91{
92 char buf[1];
93
94 if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
95 return -EIO;
96
97 if (!(buf[0] & S35390A_FLAG_TEST))
98 return 0;
99
100 buf[0] &= ~S35390A_FLAG_TEST;
101 return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
102}
103
104static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
105{
106 if (s35390a->twentyfourhour)
107 return bin2bcd(hour);
108
109 if (hour < 12)
110 return bin2bcd(hour);
111
112 return 0x40 | bin2bcd(hour - 12);
113}
114
115static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
116{
117 unsigned hour;
118
119 if (s35390a->twentyfourhour)
120 return bcd2bin(reg & 0x3f);
121
122 hour = bcd2bin(reg & 0x3f);
123 if (reg & 0x40)
124 hour += 12;
125
126 return hour;
127}
128
129static int s35390a_set_datetime(struct i2c_client *client, struct rtc_time *tm)
130{
131 struct s35390a *s35390a = i2c_get_clientdata(client);
132 int i, err;
133 char buf[7];
134
135 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
136 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
137 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
138 tm->tm_wday);
139
140 buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
141 buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
142 buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
143 buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
144 buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
145 buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
146 buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
147
148
149 for (i = 0; i < 7; ++i)
150 buf[i] = bitrev8(buf[i]);
151
152 err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
153
154 return err;
155}
156
157static int s35390a_get_datetime(struct i2c_client *client, struct rtc_time *tm)
158{
159 struct s35390a *s35390a = i2c_get_clientdata(client);
160 char buf[7];
161 int i, err;
162
163 err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
164 if (err < 0)
165 return err;
166
167
168 for (i = 0; i < 7; ++i)
169 buf[i] = bitrev8(buf[i]);
170
171 tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
172 tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
173 tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
174 tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
175 tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
176 tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
177 tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
178
179 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
180 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
181 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
182 tm->tm_wday);
183
184 return rtc_valid_tm(tm);
185}
186
187static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
188{
189 return s35390a_get_datetime(to_i2c_client(dev), tm);
190}
191
192static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
193{
194 return s35390a_set_datetime(to_i2c_client(dev), tm);
195}
196
197static const struct rtc_class_ops s35390a_rtc_ops = {
198 .read_time = s35390a_rtc_read_time,
199 .set_time = s35390a_rtc_set_time,
200};
201
202static struct i2c_driver s35390a_driver;
203
204static int s35390a_probe(struct i2c_client *client,
205 const struct i2c_device_id *id)
206{
207 int err;
208 unsigned int i;
209 struct s35390a *s35390a;
210 struct rtc_time tm;
211 char buf[1];
212
213 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
214 err = -ENODEV;
215 goto exit;
216 }
217
218 s35390a = kzalloc(sizeof(struct s35390a), GFP_KERNEL);
219 if (!s35390a) {
220 err = -ENOMEM;
221 goto exit;
222 }
223
224 s35390a->client[0] = client;
225 i2c_set_clientdata(client, s35390a);
226
227
228 for (i = 1; i < 8; ++i) {
229 s35390a->client[i] = i2c_new_dummy(client->adapter,
230 client->addr + i);
231 if (!s35390a->client[i]) {
232 dev_err(&client->dev, "Address %02x unavailable\n",
233 client->addr + i);
234 err = -EBUSY;
235 goto exit_dummy;
236 }
237 }
238
239 err = s35390a_reset(s35390a);
240 if (err < 0) {
241 dev_err(&client->dev, "error resetting chip\n");
242 goto exit_dummy;
243 }
244
245 err = s35390a_disable_test_mode(s35390a);
246 if (err < 0) {
247 dev_err(&client->dev, "error disabling test mode\n");
248 goto exit_dummy;
249 }
250
251 err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
252 if (err < 0) {
253 dev_err(&client->dev, "error checking 12/24 hour mode\n");
254 goto exit_dummy;
255 }
256 if (buf[0] & S35390A_FLAG_24H)
257 s35390a->twentyfourhour = 1;
258 else
259 s35390a->twentyfourhour = 0;
260
261 if (s35390a_get_datetime(client, &tm) < 0)
262 dev_warn(&client->dev, "clock needs to be set\n");
263
264 s35390a->rtc = rtc_device_register(s35390a_driver.driver.name,
265 &client->dev, &s35390a_rtc_ops, THIS_MODULE);
266
267 if (IS_ERR(s35390a->rtc)) {
268 err = PTR_ERR(s35390a->rtc);
269 goto exit_dummy;
270 }
271 return 0;
272
273exit_dummy:
274 for (i = 1; i < 8; ++i)
275 if (s35390a->client[i])
276 i2c_unregister_device(s35390a->client[i]);
277 kfree(s35390a);
278
279exit:
280 return err;
281}
282
283static int s35390a_remove(struct i2c_client *client)
284{
285 unsigned int i;
286
287 struct s35390a *s35390a = i2c_get_clientdata(client);
288 for (i = 1; i < 8; ++i)
289 if (s35390a->client[i])
290 i2c_unregister_device(s35390a->client[i]);
291
292 rtc_device_unregister(s35390a->rtc);
293 kfree(s35390a);
294
295 return 0;
296}
297
298static struct i2c_driver s35390a_driver = {
299 .driver = {
300 .name = "rtc-s35390a",
301 },
302 .probe = s35390a_probe,
303 .remove = s35390a_remove,
304 .id_table = s35390a_id,
305};
306
307module_i2c_driver(s35390a_driver);
308
309MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
310MODULE_DESCRIPTION("S35390A RTC driver");
311MODULE_LICENSE("GPL");
312
