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
pcf8583_get_datetime(struct i2c_client * client,struct rtc_time * dt)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
pcf8583_set_datetime(struct i2c_client * client,struct rtc_time * dt,int datetoo)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
pcf8583_get_ctrl(struct i2c_client * client,unsigned char * ctrl)117 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
118 {
119 *ctrl = get_ctrl(client);
120 return 0;
121 }
122
pcf8583_set_ctrl(struct i2c_client * client,unsigned char * ctrl)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
pcf8583_read_mem(struct i2c_client * client,struct rtc_mem * mem)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
pcf8583_write_mem(struct i2c_client * client,struct rtc_mem * mem)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
pcf8583_rtc_read_time(struct device * dev,struct rtc_time * tm)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 printk(KERN_WARNING "RTC: 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
pcf8583_rtc_set_time(struct device * dev,struct rtc_time * tm)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
pcf8583_probe(struct i2c_client * client,const struct i2c_device_id * id)267 static int pcf8583_probe(struct i2c_client *client,
268 const struct i2c_device_id *id)
269 {
270 struct pcf8583 *pcf8583;
271 int err;
272
273 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
274 return -ENODEV;
275
276 pcf8583 = kzalloc(sizeof(struct pcf8583), GFP_KERNEL);
277 if (!pcf8583)
278 return -ENOMEM;
279
280 pcf8583->rtc = rtc_device_register(pcf8583_driver.driver.name,
281 &client->dev, &pcf8583_rtc_ops, THIS_MODULE);
282
283 if (IS_ERR(pcf8583->rtc)) {
284 err = PTR_ERR(pcf8583->rtc);
285 goto exit_kfree;
286 }
287
288 i2c_set_clientdata(client, pcf8583);
289 return 0;
290
291 exit_kfree:
292 kfree(pcf8583);
293 return err;
294 }
295
pcf8583_remove(struct i2c_client * client)296 static int __devexit pcf8583_remove(struct i2c_client *client)
297 {
298 struct pcf8583 *pcf8583 = i2c_get_clientdata(client);
299
300 if (pcf8583->rtc)
301 rtc_device_unregister(pcf8583->rtc);
302 kfree(pcf8583);
303 return 0;
304 }
305
306 static const struct i2c_device_id pcf8583_id[] = {
307 { "pcf8583", 0 },
308 { }
309 };
310 MODULE_DEVICE_TABLE(i2c, pcf8583_id);
311
312 static struct i2c_driver pcf8583_driver = {
313 .driver = {
314 .name = "pcf8583",
315 .owner = THIS_MODULE,
316 },
317 .probe = pcf8583_probe,
318 .remove = __devexit_p(pcf8583_remove),
319 .id_table = pcf8583_id,
320 };
321
pcf8583_init(void)322 static __init int pcf8583_init(void)
323 {
324 return i2c_add_driver(&pcf8583_driver);
325 }
326
pcf8583_exit(void)327 static __exit void pcf8583_exit(void)
328 {
329 i2c_del_driver(&pcf8583_driver);
330 }
331
332 module_init(pcf8583_init);
333 module_exit(pcf8583_exit);
334
335 MODULE_AUTHOR("Russell King");
336 MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
337 MODULE_LICENSE("GPL");
338