2 * drivers/rtc/rtc-pcf8583.c
4 * Copyright (C) 2000 Russell King
5 * Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix
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.
11 * Driver for PCF8583 RTC & RAM chip
13 * Converted to the generic RTC susbsystem by G. Liakhovetski (2006)
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>
30 struct rtc_device *rtc;
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
43 static struct i2c_driver pcf8583_driver;
45 #define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
46 #define set_ctrl(x, v) get_ctrl(x) = v
48 #define CMOS_YEAR (64 + 128)
49 #define CMOS_CHECKSUM (63)
51 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
53 unsigned char buf[8], addr[1] = { 1 };
54 struct i2c_msg msgs[2] = {
69 memset(buf, 0, sizeof(buf));
71 ret = i2c_transfer(client->adapter, msgs, 2);
73 dt->tm_year = buf[4] >> 6;
74 dt->tm_wday = buf[5] >> 5;
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;
86 return ret == 2 ? 0 : -EIO;
89 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
95 buf[1] = get_ctrl(client) | 0x80;
97 buf[3] = bin2bcd(dt->tm_sec);
98 buf[4] = bin2bcd(dt->tm_min);
99 buf[5] = bin2bcd(dt->tm_hour);
103 buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6);
104 buf[7] = bin2bcd(dt->tm_mon + 1) | (dt->tm_wday << 5);
107 ret = i2c_master_send(client, (char *)buf, len);
111 buf[1] = get_ctrl(client);
112 ret = i2c_master_send(client, (char *)buf, 2);
114 return ret == 2 ? 0 : -EIO;
117 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
119 *ctrl = get_ctrl(client);
123 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
125 unsigned char buf[2];
129 set_ctrl(client, *ctrl);
131 return i2c_master_send(client, (char *)buf, 2);
134 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
136 unsigned char addr[1];
137 struct i2c_msg msgs[2] = {
139 .addr = client->addr,
144 .addr = client->addr,
156 return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
159 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
161 unsigned char buf[9];
164 if (mem->loc < 8 || mem->nr > 8)
168 memcpy(buf + 1, mem->data, mem->nr);
170 ret = i2c_master_send(client, buf, mem->nr + 1);
171 return ret == mem->nr + 1 ? 0 : -EIO;
174 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
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;
182 * Ensure that the RTC is running.
184 pcf8583_get_ctrl(client, &ctrl);
185 if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
186 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
188 dev_warn(dev, "resetting control %02x -> %02x\n",
191 err = pcf8583_set_ctrl(client, &new_ctrl);
196 if (pcf8583_get_datetime(client, tm) ||
197 pcf8583_read_mem(client, &mem))
203 * The RTC year holds the LSB two bits of the current
204 * year, which should reflect the LSB two bits of the
205 * CMOS copy of the year. Any difference indicates
206 * that we have to correct the CMOS version.
208 year_offset = tm->tm_year - (real_year & 3);
211 * RTC year wrapped. Adjust it appropriately.
215 tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
220 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
222 struct i2c_client *client = to_i2c_client(dev);
223 unsigned char year[2], chk;
224 struct rtc_mem cmos_year = { CMOS_YEAR, sizeof(year), year };
225 struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
226 unsigned int proper_year = tm->tm_year + 1900;
230 * The RTC's own 2-bit year must reflect the least
231 * significant two bits of the CMOS year.
234 ret = pcf8583_set_datetime(client, tm, 1);
238 ret = pcf8583_read_mem(client, &cmos_check);
242 ret = pcf8583_read_mem(client, &cmos_year);
246 chk -= year[1] + year[0];
248 year[1] = proper_year / 100;
249 year[0] = proper_year % 100;
251 chk += year[1] + year[0];
253 ret = pcf8583_write_mem(client, &cmos_year);
258 ret = pcf8583_write_mem(client, &cmos_check);
263 static const struct rtc_class_ops pcf8583_rtc_ops = {
264 .read_time = pcf8583_rtc_read_time,
265 .set_time = pcf8583_rtc_set_time,
268 static int pcf8583_probe(struct i2c_client *client,
269 const struct i2c_device_id *id)
271 struct pcf8583 *pcf8583;
273 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
276 pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583),
281 i2c_set_clientdata(client, pcf8583);
283 pcf8583->rtc = devm_rtc_device_register(&client->dev,
284 pcf8583_driver.driver.name,
285 &pcf8583_rtc_ops, THIS_MODULE);
287 if (IS_ERR(pcf8583->rtc))
288 return PTR_ERR(pcf8583->rtc);
293 static int pcf8583_remove(struct i2c_client *client)
298 static const struct i2c_device_id pcf8583_id[] = {
302 MODULE_DEVICE_TABLE(i2c, pcf8583_id);
304 static struct i2c_driver pcf8583_driver = {
307 .owner = THIS_MODULE,
309 .probe = pcf8583_probe,
310 .remove = pcf8583_remove,
311 .id_table = pcf8583_id,
314 module_i2c_driver(pcf8583_driver);
316 MODULE_AUTHOR("Russell King");
317 MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
318 MODULE_LICENSE("GPL");