UPSTREAM Revert 3.9 "rtc: palmas: Add RTC driver Palmas series PMIC"
[linux-3.10.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/errno.h>
21 #include <linux/bcd.h>
22
23 struct rtc_mem {
24         unsigned int    loc;
25         unsigned int    nr;
26         unsigned char   *data;
27 };
28
29 struct pcf8583 {
30         struct rtc_device *rtc;
31         unsigned char ctrl;
32 };
33
34 #define CTRL_STOP       0x80
35 #define CTRL_HOLD       0x40
36 #define CTRL_32KHZ      0x00
37 #define CTRL_MASK       0x08
38 #define CTRL_ALARMEN    0x04
39 #define CTRL_ALARM      0x02
40 #define CTRL_TIMER      0x01
41
42
43 static struct i2c_driver pcf8583_driver;
44
45 #define get_ctrl(x)    ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
46 #define set_ctrl(x, v) get_ctrl(x) = v
47
48 #define CMOS_YEAR       (64 + 128)
49 #define CMOS_CHECKSUM   (63)
50
51 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
52 {
53         unsigned char buf[8], addr[1] = { 1 };
54         struct i2c_msg msgs[2] = {
55                 {
56                         .addr = client->addr,
57                         .flags = 0,
58                         .len = 1,
59                         .buf = addr,
60                 }, {
61                         .addr = client->addr,
62                         .flags = I2C_M_RD,
63                         .len = 6,
64                         .buf = buf,
65                 }
66         };
67         int ret;
68
69         memset(buf, 0, sizeof(buf));
70
71         ret = i2c_transfer(client->adapter, msgs, 2);
72         if (ret == 2) {
73                 dt->tm_year = buf[4] >> 6;
74                 dt->tm_wday = buf[5] >> 5;
75
76                 buf[4] &= 0x3f;
77                 buf[5] &= 0x1f;
78
79                 dt->tm_sec = bcd2bin(buf[1]);
80                 dt->tm_min = bcd2bin(buf[2]);
81                 dt->tm_hour = bcd2bin(buf[3]);
82                 dt->tm_mday = bcd2bin(buf[4]);
83                 dt->tm_mon = bcd2bin(buf[5]) - 1;
84         }
85
86         return ret == 2 ? 0 : -EIO;
87 }
88
89 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
90 {
91         unsigned char buf[8];
92         int ret, len = 6;
93
94         buf[0] = 0;
95         buf[1] = get_ctrl(client) | 0x80;
96         buf[2] = 0;
97         buf[3] = bin2bcd(dt->tm_sec);
98         buf[4] = bin2bcd(dt->tm_min);
99         buf[5] = bin2bcd(dt->tm_hour);
100
101         if (datetoo) {
102                 len = 8;
103                 buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6);
104                 buf[7] = bin2bcd(dt->tm_mon + 1)  | (dt->tm_wday << 5);
105         }
106
107         ret = i2c_master_send(client, (char *)buf, len);
108         if (ret != len)
109                 return -EIO;
110
111         buf[1] = get_ctrl(client);
112         ret = i2c_master_send(client, (char *)buf, 2);
113
114         return ret == 2 ? 0 : -EIO;
115 }
116
117 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
118 {
119         *ctrl = get_ctrl(client);
120         return 0;
121 }
122
123 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
124 {
125         unsigned char buf[2];
126
127         buf[0] = 0;
128         buf[1] = *ctrl;
129         set_ctrl(client, *ctrl);
130
131         return i2c_master_send(client, (char *)buf, 2);
132 }
133
134 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
135 {
136         unsigned char addr[1];
137         struct i2c_msg msgs[2] = {
138                 {
139                         .addr = client->addr,
140                         .flags = 0,
141                         .len = 1,
142                         .buf = addr,
143                 }, {
144                         .addr = client->addr,
145                         .flags = I2C_M_RD,
146                         .len = mem->nr,
147                         .buf = mem->data,
148                 }
149         };
150
151         if (mem->loc < 8)
152                 return -EINVAL;
153
154         addr[0] = mem->loc;
155
156         return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
157 }
158
159 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
160 {
161         unsigned char buf[9];
162         int ret;
163
164         if (mem->loc < 8 || mem->nr > 8)
165                 return -EINVAL;
166
167         buf[0] = mem->loc;
168         memcpy(buf + 1, mem->data, mem->nr);
169
170         ret = i2c_master_send(client, buf, mem->nr + 1);
171         return ret == mem->nr + 1 ? 0 : -EIO;
172 }
173
174 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
175 {
176         struct i2c_client *client = to_i2c_client(dev);
177         unsigned char ctrl, year[2];
178         struct rtc_mem mem = { CMOS_YEAR, sizeof(year), year };
179         int real_year, year_offset, err;
180
181         /*
182          * Ensure that the RTC is running.
183          */
184         pcf8583_get_ctrl(client, &ctrl);
185         if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
186                 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
187
188                 dev_warn(dev, "resetting control %02x -> %02x\n",
189                         ctrl, new_ctrl);
190
191                 if ((err = pcf8583_set_ctrl(client, &new_ctrl)) < 0)
192                         return err;
193         }
194
195         if (pcf8583_get_datetime(client, tm) ||
196             pcf8583_read_mem(client, &mem))
197                 return -EIO;
198
199         real_year = year[0];
200
201         /*
202          * The RTC year holds the LSB two bits of the current
203          * year, which should reflect the LSB two bits of the
204          * CMOS copy of the year.  Any difference indicates
205          * that we have to correct the CMOS version.
206          */
207         year_offset = tm->tm_year - (real_year & 3);
208         if (year_offset < 0)
209                 /*
210                  * RTC year wrapped.  Adjust it appropriately.
211                  */
212                 year_offset += 4;
213
214         tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
215
216         return 0;
217 }
218
219 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
220 {
221         struct i2c_client *client = to_i2c_client(dev);
222         unsigned char year[2], chk;
223         struct rtc_mem cmos_year  = { CMOS_YEAR, sizeof(year), year };
224         struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
225         unsigned int proper_year = tm->tm_year + 1900;
226         int ret;
227
228         /*
229          * The RTC's own 2-bit year must reflect the least
230          * significant two bits of the CMOS year.
231          */
232
233         ret = pcf8583_set_datetime(client, tm, 1);
234         if (ret)
235                 return ret;
236
237         ret = pcf8583_read_mem(client, &cmos_check);
238         if (ret)
239                 return ret;
240
241         ret = pcf8583_read_mem(client, &cmos_year);
242         if (ret)
243                 return ret;
244
245         chk -= year[1] + year[0];
246
247         year[1] = proper_year / 100;
248         year[0] = proper_year % 100;
249
250         chk += year[1] + year[0];
251
252         ret = pcf8583_write_mem(client, &cmos_year);
253
254         if (ret)
255                 return ret;
256
257         ret = pcf8583_write_mem(client, &cmos_check);
258
259         return ret;
260 }
261
262 static const struct rtc_class_ops pcf8583_rtc_ops = {
263         .read_time      = pcf8583_rtc_read_time,
264         .set_time       = pcf8583_rtc_set_time,
265 };
266
267 static int pcf8583_probe(struct i2c_client *client,
268                                 const struct i2c_device_id *id)
269 {
270         struct pcf8583 *pcf8583;
271
272         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
273                 return -ENODEV;
274
275         pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583),
276                                 GFP_KERNEL);
277         if (!pcf8583)
278                 return -ENOMEM;
279
280         i2c_set_clientdata(client, pcf8583);
281
282         pcf8583->rtc = devm_rtc_device_register(&client->dev,
283                                 pcf8583_driver.driver.name,
284                                 &pcf8583_rtc_ops, THIS_MODULE);
285
286         if (IS_ERR(pcf8583->rtc))
287                 return PTR_ERR(pcf8583->rtc);
288
289         return 0;
290 }
291
292 static int pcf8583_remove(struct i2c_client *client)
293 {
294         return 0;
295 }
296
297 static const struct i2c_device_id pcf8583_id[] = {
298         { "pcf8583", 0 },
299         { }
300 };
301 MODULE_DEVICE_TABLE(i2c, pcf8583_id);
302
303 static struct i2c_driver pcf8583_driver = {
304         .driver = {
305                 .name   = "pcf8583",
306                 .owner  = THIS_MODULE,
307         },
308         .probe          = pcf8583_probe,
309         .remove         = pcf8583_remove,
310         .id_table       = pcf8583_id,
311 };
312
313 module_i2c_driver(pcf8583_driver);
314
315 MODULE_AUTHOR("Russell King");
316 MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
317 MODULE_LICENSE("GPL");