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
pcf8583_get_datetime(struct i2c_client * client,struct rtc_time * dt)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
pcf8583_set_datetime(struct i2c_client * client,struct rtc_time * dt,int datetoo)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
pcf8583_get_ctrl(struct i2c_client * client,unsigned char * ctrl)118 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
119 {
120 *ctrl = get_ctrl(client);
121 return 0;
122 }
123
pcf8583_set_ctrl(struct i2c_client * client,unsigned char * ctrl)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
pcf8583_read_mem(struct i2c_client * client,struct rtc_mem * mem)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
pcf8583_write_mem(struct i2c_client * client,struct rtc_mem * mem)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
pcf8583_rtc_read_time(struct device * dev,struct rtc_time * tm)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
pcf8583_rtc_set_time(struct device * dev,struct rtc_time * tm)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
pcf8583_probe(struct i2c_client * client,const struct i2c_device_id * id)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");
322