Root/drivers/rtc/rtc-rx8581.c

1/*
2 * An I2C driver for the Epson RX8581 RTC
3 *
4 * Author: Martyn Welch <martyn.welch@ge.com>
5 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
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 * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
12 * Copyright 2005-06 Tower Technologies
13 */
14
15#include <linux/module.h>
16#include <linux/i2c.h>
17#include <linux/bcd.h>
18#include <linux/rtc.h>
19#include <linux/log2.h>
20
21#define DRV_VERSION "0.1"
22
23#define RX8581_REG_SC 0x00 /* Second in BCD */
24#define RX8581_REG_MN 0x01 /* Minute in BCD */
25#define RX8581_REG_HR 0x02 /* Hour in BCD */
26#define RX8581_REG_DW 0x03 /* Day of Week */
27#define RX8581_REG_DM 0x04 /* Day of Month in BCD */
28#define RX8581_REG_MO 0x05 /* Month in BCD */
29#define RX8581_REG_YR 0x06 /* Year in BCD */
30#define RX8581_REG_RAM 0x07 /* RAM */
31#define RX8581_REG_AMN 0x08 /* Alarm Min in BCD*/
32#define RX8581_REG_AHR 0x09 /* Alarm Hour in BCD */
33#define RX8581_REG_ADM 0x0A
34#define RX8581_REG_ADW 0x0A
35#define RX8581_REG_TMR0 0x0B
36#define RX8581_REG_TMR1 0x0C
37#define RX8581_REG_EXT 0x0D /* Extension Register */
38#define RX8581_REG_FLAG 0x0E /* Flag Register */
39#define RX8581_REG_CTRL 0x0F /* Control Register */
40
41
42/* Flag Register bit definitions */
43#define RX8581_FLAG_UF 0x20 /* Update */
44#define RX8581_FLAG_TF 0x10 /* Timer */
45#define RX8581_FLAG_AF 0x08 /* Alarm */
46#define RX8581_FLAG_VLF 0x02 /* Voltage Low */
47
48/* Control Register bit definitions */
49#define RX8581_CTRL_UIE 0x20 /* Update Interrupt Enable */
50#define RX8581_CTRL_TIE 0x10 /* Timer Interrupt Enable */
51#define RX8581_CTRL_AIE 0x08 /* Alarm Interrupt Enable */
52#define RX8581_CTRL_STOP 0x02 /* STOP bit */
53#define RX8581_CTRL_RESET 0x01 /* RESET bit */
54
55static struct i2c_driver rx8581_driver;
56
57/*
58 * In the routines that deal directly with the rx8581 hardware, we use
59 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
60 */
61static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm)
62{
63    unsigned char date[7];
64    int data, err;
65
66    /* First we ensure that the "update flag" is not set, we read the
67     * time and date then re-read the "update flag". If the update flag
68     * has been set, we know that the time has changed during the read so
69     * we repeat the whole process again.
70     */
71    data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
72    if (data < 0) {
73        dev_err(&client->dev, "Unable to read device flags\n");
74        return -EIO;
75    }
76
77    do {
78        /* If update flag set, clear it */
79        if (data & RX8581_FLAG_UF) {
80            err = i2c_smbus_write_byte_data(client,
81                RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF));
82            if (err != 0) {
83                dev_err(&client->dev, "Unable to write device "
84                    "flags\n");
85                return -EIO;
86            }
87        }
88
89        /* Now read time and date */
90        err = i2c_smbus_read_i2c_block_data(client, RX8581_REG_SC,
91            7, date);
92        if (err < 0) {
93            dev_err(&client->dev, "Unable to read date\n");
94            return -EIO;
95        }
96
97        /* Check flag register */
98        data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
99        if (data < 0) {
100            dev_err(&client->dev, "Unable to read device flags\n");
101            return -EIO;
102        }
103    } while (data & RX8581_FLAG_UF);
104
105    if (data & RX8581_FLAG_VLF)
106        dev_info(&client->dev,
107            "low voltage detected, date/time is not reliable.\n");
108
109    dev_dbg(&client->dev,
110        "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
111        "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
112        __func__,
113        date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
114
115    tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
116    tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
117    tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
118    tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
119    tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
120    tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
121    tm->tm_year = bcd2bin(date[RX8581_REG_YR]);
122    if (tm->tm_year < 70)
123        tm->tm_year += 100; /* assume we are in 1970...2069 */
124
125
126    dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
127        "mday=%d, mon=%d, year=%d, wday=%d\n",
128        __func__,
129        tm->tm_sec, tm->tm_min, tm->tm_hour,
130        tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
131
132    err = rtc_valid_tm(tm);
133    if (err < 0)
134        dev_err(&client->dev, "retrieved date/time is not valid.\n");
135
136    return err;
137}
138
139static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm)
140{
141    int data, err;
142    unsigned char buf[7];
143
144    dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
145        "mday=%d, mon=%d, year=%d, wday=%d\n",
146        __func__,
147        tm->tm_sec, tm->tm_min, tm->tm_hour,
148        tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
149
150    /* hours, minutes and seconds */
151    buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
152    buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
153    buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
154
155    buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
156
157    /* month, 1 - 12 */
158    buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
159
160    /* year and century */
161    buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100);
162    buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
163
164    /* Stop the clock */
165    data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
166    if (data < 0) {
167        dev_err(&client->dev, "Unable to read control register\n");
168        return -EIO;
169    }
170
171    err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
172        (data | RX8581_CTRL_STOP));
173    if (err < 0) {
174        dev_err(&client->dev, "Unable to write control register\n");
175        return -EIO;
176    }
177
178    /* write register's data */
179    err = i2c_smbus_write_i2c_block_data(client, RX8581_REG_SC, 7, buf);
180    if (err < 0) {
181        dev_err(&client->dev, "Unable to write to date registers\n");
182        return -EIO;
183    }
184
185    /* get VLF and clear it */
186    data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
187    if (data < 0) {
188        dev_err(&client->dev, "Unable to read flag register\n");
189        return -EIO;
190    }
191
192    err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,
193        (data & ~(RX8581_FLAG_VLF)));
194    if (err != 0) {
195        dev_err(&client->dev, "Unable to write flag register\n");
196        return -EIO;
197    }
198
199    /* Restart the clock */
200    data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
201    if (data < 0) {
202        dev_err(&client->dev, "Unable to read control register\n");
203        return -EIO;
204    }
205
206    err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
207        (data & ~(RX8581_CTRL_STOP)));
208    if (err != 0) {
209        dev_err(&client->dev, "Unable to write control register\n");
210        return -EIO;
211    }
212
213    return 0;
214}
215
216static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
217{
218    return rx8581_get_datetime(to_i2c_client(dev), tm);
219}
220
221static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
222{
223    return rx8581_set_datetime(to_i2c_client(dev), tm);
224}
225
226static const struct rtc_class_ops rx8581_rtc_ops = {
227    .read_time = rx8581_rtc_read_time,
228    .set_time = rx8581_rtc_set_time,
229};
230
231static int __devinit rx8581_probe(struct i2c_client *client,
232                const struct i2c_device_id *id)
233{
234    struct rtc_device *rtc;
235
236    dev_dbg(&client->dev, "%s\n", __func__);
237
238    if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
239        return -ENODEV;
240
241    dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
242
243    rtc = rtc_device_register(rx8581_driver.driver.name,
244                &client->dev, &rx8581_rtc_ops, THIS_MODULE);
245
246    if (IS_ERR(rtc))
247        return PTR_ERR(rtc);
248
249    i2c_set_clientdata(client, rtc);
250
251    return 0;
252}
253
254static int __devexit rx8581_remove(struct i2c_client *client)
255{
256    struct rtc_device *rtc = i2c_get_clientdata(client);
257
258    rtc_device_unregister(rtc);
259
260    return 0;
261}
262
263static const struct i2c_device_id rx8581_id[] = {
264    { "rx8581", 0 },
265    { }
266};
267MODULE_DEVICE_TABLE(i2c, rx8581_id);
268
269static struct i2c_driver rx8581_driver = {
270    .driver = {
271        .name = "rtc-rx8581",
272        .owner = THIS_MODULE,
273    },
274    .probe = rx8581_probe,
275    .remove = __devexit_p(rx8581_remove),
276    .id_table = rx8581_id,
277};
278
279module_i2c_driver(rx8581_driver);
280
281MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
282MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
283MODULE_LICENSE("GPL");
284MODULE_VERSION(DRV_VERSION);
285

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