GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / rtc / rtc-pcf8583.c
1 /*
2  *  drivers/rtc/rtc-pcf8583.c
3  *
4  *  Copyright (C) 2000 Russell King
5  *  Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix
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  *  Driver for PCF8583 RTC & RAM chip
12  *
13  *  Converted to the generic RTC susbsystem by G. Liakhovetski (2006)
14  */
15 #include <linux/module.h>
16 #include <linux/i2c.h>
17 #include <linux/slab.h>
18 #include <linux/rtc.h>
19 #include <linux/init.h>
20 #include <linux/err.h>
21 #include <linux/errno.h>
22 #include <linux/bcd.h>
23
24 struct rtc_mem {
25         unsigned int    loc;
26         unsigned int    nr;
27         unsigned char   *data;
28 };
29
30 struct pcf8583 {
31         struct rtc_device *rtc;
32         unsigned char ctrl;
33 };
34
35 #define CTRL_STOP       0x80
36 #define CTRL_HOLD       0x40
37 #define CTRL_32KHZ      0x00
38 #define CTRL_MASK       0x08
39 #define CTRL_ALARMEN    0x04
40 #define CTRL_ALARM      0x02
41 #define CTRL_TIMER      0x01
42
43
44 static struct i2c_driver pcf8583_driver;
45
46 #define get_ctrl(x)    ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
47 #define set_ctrl(x, v) get_ctrl(x) = v
48
49 #define CMOS_YEAR       (64 + 128)
50 #define CMOS_CHECKSUM   (63)
51
52 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
53 {
54         unsigned char buf[8], addr[1] = { 1 };
55         struct i2c_msg msgs[2] = {
56                 {
57                         .addr = client->addr,
58                         .flags = 0,
59                         .len = 1,
60                         .buf = addr,
61                 }, {
62                         .addr = client->addr,
63                         .flags = I2C_M_RD,
64                         .len = 6,
65                         .buf = buf,
66                 }
67         };
68         int ret;
69
70         memset(buf, 0, sizeof(buf));
71
72         ret = i2c_transfer(client->adapter, msgs, 2);
73         if (ret == 2) {
74                 dt->tm_year = buf[4] >> 6;
75                 dt->tm_wday = buf[5] >> 5;
76
77                 buf[4] &= 0x3f;
78                 buf[5] &= 0x1f;
79
80                 dt->tm_sec = bcd2bin(buf[1]);
81                 dt->tm_min = bcd2bin(buf[2]);
82                 dt->tm_hour = bcd2bin(buf[3]);
83                 dt->tm_mday = bcd2bin(buf[4]);
84                 dt->tm_mon = bcd2bin(buf[5]) - 1;
85         }
86
87         return ret == 2 ? 0 : -EIO;
88 }
89
90 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
91 {
92         unsigned char buf[8];
93         int ret, len = 6;
94
95         buf[0] = 0;
96         buf[1] = get_ctrl(client) | 0x80;
97         buf[2] = 0;
98         buf[3] = bin2bcd(dt->tm_sec);
99         buf[4] = bin2bcd(dt->tm_min);
100         buf[5] = bin2bcd(dt->tm_hour);
101
102         if (datetoo) {
103                 len = 8;
104                 buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6);
105                 buf[7] = bin2bcd(dt->tm_mon + 1)  | (dt->tm_wday << 5);
106         }
107
108         ret = i2c_master_send(client, (char *)buf, len);
109         if (ret != len)
110                 return -EIO;
111
112         buf[1] = get_ctrl(client);
113         ret = i2c_master_send(client, (char *)buf, 2);
114
115         return ret == 2 ? 0 : -EIO;
116 }
117
118 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
119 {
120         *ctrl = get_ctrl(client);
121         return 0;
122 }
123
124 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
125 {
126         unsigned char buf[2];
127
128         buf[0] = 0;
129         buf[1] = *ctrl;
130         set_ctrl(client, *ctrl);
131
132         return i2c_master_send(client, (char *)buf, 2);
133 }
134
135 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
136 {
137         unsigned char addr[1];
138         struct i2c_msg msgs[2] = {
139                 {
140                         .addr = client->addr,
141                         .flags = 0,
142                         .len = 1,
143                         .buf = addr,
144                 }, {
145                         .addr = client->addr,
146                         .flags = I2C_M_RD,
147                         .len = mem->nr,
148                         .buf = mem->data,
149                 }
150         };
151
152         if (mem->loc < 8)
153                 return -EINVAL;
154
155         addr[0] = mem->loc;
156
157         return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
158 }
159
160 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
161 {
162         unsigned char buf[9];
163         int ret;
164
165         if (mem->loc < 8 || mem->nr > 8)
166                 return -EINVAL;
167
168         buf[0] = mem->loc;
169         memcpy(buf + 1, mem->data, mem->nr);
170
171         ret = i2c_master_send(client, buf, mem->nr + 1);
172         return ret == mem->nr + 1 ? 0 : -EIO;
173 }
174
175 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
176 {
177         struct i2c_client *client = to_i2c_client(dev);
178         unsigned char ctrl, year[2];
179         struct rtc_mem mem = {
180                 .loc = CMOS_YEAR,
181                 .nr = sizeof(year),
182                 .data = year
183         };
184         int real_year, year_offset, err;
185
186         /*
187          * Ensure that the RTC is running.
188          */
189         pcf8583_get_ctrl(client, &ctrl);
190         if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
191                 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
192
193                 dev_warn(dev, "resetting control %02x -> %02x\n",
194                         ctrl, new_ctrl);
195
196                 err = pcf8583_set_ctrl(client, &new_ctrl);
197                 if (err < 0)
198                         return err;
199         }
200
201         if (pcf8583_get_datetime(client, tm) ||
202             pcf8583_read_mem(client, &mem))
203                 return -EIO;
204
205         real_year = year[0];
206
207         /*
208          * The RTC year holds the LSB two bits of the current
209          * year, which should reflect the LSB two bits of the
210          * CMOS copy of the year.  Any difference indicates
211          * that we have to correct the CMOS version.
212          */
213         year_offset = tm->tm_year - (real_year & 3);
214         if (year_offset < 0)
215                 /*
216                  * RTC year wrapped.  Adjust it appropriately.
217                  */
218                 year_offset += 4;
219
220         tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
221
222         return 0;
223 }
224
225 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
226 {
227         struct i2c_client *client = to_i2c_client(dev);
228         unsigned char year[2], chk;
229         struct rtc_mem cmos_year  = {
230                 .loc = CMOS_YEAR,
231                 .nr = sizeof(year),
232                 .data = year
233         };
234         struct rtc_mem cmos_check = {
235                 .loc = CMOS_CHECKSUM,
236                 .nr = 1,
237                 .data = &chk
238         };
239         unsigned int proper_year = tm->tm_year + 1900;
240         int ret;
241
242         /*
243          * The RTC's own 2-bit year must reflect the least
244          * significant two bits of the CMOS year.
245          */
246
247         ret = pcf8583_set_datetime(client, tm, 1);
248         if (ret)
249                 return ret;
250
251         ret = pcf8583_read_mem(client, &cmos_check);
252         if (ret)
253                 return ret;
254
255         ret = pcf8583_read_mem(client, &cmos_year);
256         if (ret)
257                 return ret;
258
259         chk -= year[1] + year[0];
260
261         year[1] = proper_year / 100;
262         year[0] = proper_year % 100;
263
264         chk += year[1] + year[0];
265
266         ret = pcf8583_write_mem(client, &cmos_year);
267
268         if (ret)
269                 return ret;
270
271         ret = pcf8583_write_mem(client, &cmos_check);
272
273         return ret;
274 }
275
276 static const struct rtc_class_ops pcf8583_rtc_ops = {
277         .read_time      = pcf8583_rtc_read_time,
278         .set_time       = pcf8583_rtc_set_time,
279 };
280
281 static int pcf8583_probe(struct i2c_client *client,
282                                 const struct i2c_device_id *id)
283 {
284         struct pcf8583 *pcf8583;
285
286         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
287                 return -ENODEV;
288
289         pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583),
290                                 GFP_KERNEL);
291         if (!pcf8583)
292                 return -ENOMEM;
293
294         i2c_set_clientdata(client, pcf8583);
295
296         pcf8583->rtc = devm_rtc_device_register(&client->dev,
297                                 pcf8583_driver.driver.name,
298                                 &pcf8583_rtc_ops, THIS_MODULE);
299
300         return PTR_ERR_OR_ZERO(pcf8583->rtc);
301 }
302
303 static const struct i2c_device_id pcf8583_id[] = {
304         { "pcf8583", 0 },
305         { }
306 };
307 MODULE_DEVICE_TABLE(i2c, pcf8583_id);
308
309 static struct i2c_driver pcf8583_driver = {
310         .driver = {
311                 .name   = "pcf8583",
312         },
313         .probe          = pcf8583_probe,
314         .id_table       = pcf8583_id,
315 };
316
317 module_i2c_driver(pcf8583_driver);
318
319 MODULE_AUTHOR("Russell King");
320 MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
321 MODULE_LICENSE("GPL");