Root/drivers/rtc/rtc-pcf8563.c

1/*
2 * An I2C driver for the Philips PCF8563 RTC
3 * Copyright 2005-06 Tower Technologies
4 *
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
6 * Maintainers: http://www.nslu2-linux.org/
7 *
8 * based on the other drivers in this same directory.
9 *
10 * http://www.semiconductors.philips.com/acrobat/datasheets/PCF8563-04.pdf
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2 as
14 * published by the Free Software Foundation.
15 */
16
17#include <linux/i2c.h>
18#include <linux/bcd.h>
19#include <linux/rtc.h>
20#include <linux/slab.h>
21#include <linux/module.h>
22#include <linux/of.h>
23
24#define DRV_VERSION "0.4.3"
25
26#define PCF8563_REG_ST1 0x00 /* status */
27#define PCF8563_REG_ST2 0x01
28
29#define PCF8563_REG_SC 0x02 /* datetime */
30#define PCF8563_REG_MN 0x03
31#define PCF8563_REG_HR 0x04
32#define PCF8563_REG_DM 0x05
33#define PCF8563_REG_DW 0x06
34#define PCF8563_REG_MO 0x07
35#define PCF8563_REG_YR 0x08
36
37#define PCF8563_REG_AMN 0x09 /* alarm */
38#define PCF8563_REG_AHR 0x0A
39#define PCF8563_REG_ADM 0x0B
40#define PCF8563_REG_ADW 0x0C
41
42#define PCF8563_REG_CLKO 0x0D /* clock out */
43#define PCF8563_REG_TMRC 0x0E /* timer control */
44#define PCF8563_REG_TMR 0x0F /* timer */
45
46#define PCF8563_SC_LV 0x80 /* low voltage */
47#define PCF8563_MO_C 0x80 /* century */
48
49static struct i2c_driver pcf8563_driver;
50
51struct pcf8563 {
52    struct rtc_device *rtc;
53    /*
54     * The meaning of MO_C bit varies by the chip type.
55     * From PCF8563 datasheet: this bit is toggled when the years
56     * register overflows from 99 to 00
57     * 0 indicates the century is 20xx
58     * 1 indicates the century is 19xx
59     * From RTC8564 datasheet: this bit indicates change of
60     * century. When the year digit data overflows from 99 to 00,
61     * this bit is set. By presetting it to 0 while still in the
62     * 20th century, it will be set in year 2000, ...
63     * There seems no reliable way to know how the system use this
64     * bit. So let's do it heuristically, assuming we are live in
65     * 1970...2069.
66     */
67    int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
68    int voltage_low; /* incicates if a low_voltage was detected */
69};
70
71/*
72 * In the routines that deal directly with the pcf8563 hardware, we use
73 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
74 */
75static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
76{
77    struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
78    unsigned char buf[13] = { PCF8563_REG_ST1 };
79
80    struct i2c_msg msgs[] = {
81        { client->addr, 0, 1, buf }, /* setup read ptr */
82        { client->addr, I2C_M_RD, 13, buf }, /* read status + date */
83    };
84
85    /* read registers */
86    if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
87        dev_err(&client->dev, "%s: read error\n", __func__);
88        return -EIO;
89    }
90
91    if (buf[PCF8563_REG_SC] & PCF8563_SC_LV) {
92        pcf8563->voltage_low = 1;
93        dev_info(&client->dev,
94            "low voltage detected, date/time is not reliable.\n");
95    }
96
97    dev_dbg(&client->dev,
98        "%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
99        "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
100        __func__,
101        buf[0], buf[1], buf[2], buf[3],
102        buf[4], buf[5], buf[6], buf[7],
103        buf[8]);
104
105
106    tm->tm_sec = bcd2bin(buf[PCF8563_REG_SC] & 0x7F);
107    tm->tm_min = bcd2bin(buf[PCF8563_REG_MN] & 0x7F);
108    tm->tm_hour = bcd2bin(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
109    tm->tm_mday = bcd2bin(buf[PCF8563_REG_DM] & 0x3F);
110    tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
111    tm->tm_mon = bcd2bin(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
112    tm->tm_year = bcd2bin(buf[PCF8563_REG_YR]);
113    if (tm->tm_year < 70)
114        tm->tm_year += 100; /* assume we are in 1970...2069 */
115    /* detect the polarity heuristically. see note above. */
116    pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
117        (tm->tm_year >= 100) : (tm->tm_year < 100);
118
119    dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
120        "mday=%d, mon=%d, year=%d, wday=%d\n",
121        __func__,
122        tm->tm_sec, tm->tm_min, tm->tm_hour,
123        tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
124
125    /* the clock can give out invalid datetime, but we cannot return
126     * -EINVAL otherwise hwclock will refuse to set the time on bootup.
127     */
128    if (rtc_valid_tm(tm) < 0)
129        dev_err(&client->dev, "retrieved date/time is not valid.\n");
130
131    return 0;
132}
133
134static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
135{
136    struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
137    int i, err;
138    unsigned char buf[9];
139
140    dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
141        "mday=%d, mon=%d, year=%d, wday=%d\n",
142        __func__,
143        tm->tm_sec, tm->tm_min, tm->tm_hour,
144        tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
145
146    /* hours, minutes and seconds */
147    buf[PCF8563_REG_SC] = bin2bcd(tm->tm_sec);
148    buf[PCF8563_REG_MN] = bin2bcd(tm->tm_min);
149    buf[PCF8563_REG_HR] = bin2bcd(tm->tm_hour);
150
151    buf[PCF8563_REG_DM] = bin2bcd(tm->tm_mday);
152
153    /* month, 1 - 12 */
154    buf[PCF8563_REG_MO] = bin2bcd(tm->tm_mon + 1);
155
156    /* year and century */
157    buf[PCF8563_REG_YR] = bin2bcd(tm->tm_year % 100);
158    if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
159        buf[PCF8563_REG_MO] |= PCF8563_MO_C;
160
161    buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;
162
163    /* write register's data */
164    for (i = 0; i < 7; i++) {
165        unsigned char data[2] = { PCF8563_REG_SC + i,
166                        buf[PCF8563_REG_SC + i] };
167
168        err = i2c_master_send(client, data, sizeof(data));
169        if (err != sizeof(data)) {
170            dev_err(&client->dev,
171                "%s: err=%d addr=%02x, data=%02x\n",
172                __func__, err, data[0], data[1]);
173            return -EIO;
174        }
175    };
176
177    return 0;
178}
179
180#ifdef CONFIG_RTC_INTF_DEV
181static int pcf8563_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
182{
183    struct pcf8563 *pcf8563 = i2c_get_clientdata(to_i2c_client(dev));
184    struct rtc_time tm;
185
186    switch (cmd) {
187    case RTC_VL_READ:
188        if (pcf8563->voltage_low)
189            dev_info(dev, "low voltage detected, date/time is not reliable.\n");
190
191        if (copy_to_user((void __user *)arg, &pcf8563->voltage_low,
192                    sizeof(int)))
193            return -EFAULT;
194        return 0;
195    case RTC_VL_CLR:
196        /*
197         * Clear the VL bit in the seconds register in case
198         * the time has not been set already (which would
199         * have cleared it). This does not really matter
200         * because of the cached voltage_low value but do it
201         * anyway for consistency.
202         */
203        if (pcf8563_get_datetime(to_i2c_client(dev), &tm))
204            pcf8563_set_datetime(to_i2c_client(dev), &tm);
205
206        /* Clear the cached value. */
207        pcf8563->voltage_low = 0;
208
209        return 0;
210    default:
211        return -ENOIOCTLCMD;
212    }
213}
214#else
215#define pcf8563_rtc_ioctl NULL
216#endif
217
218static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
219{
220    return pcf8563_get_datetime(to_i2c_client(dev), tm);
221}
222
223static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
224{
225    return pcf8563_set_datetime(to_i2c_client(dev), tm);
226}
227
228static const struct rtc_class_ops pcf8563_rtc_ops = {
229    .ioctl = pcf8563_rtc_ioctl,
230    .read_time = pcf8563_rtc_read_time,
231    .set_time = pcf8563_rtc_set_time,
232};
233
234static int pcf8563_probe(struct i2c_client *client,
235                const struct i2c_device_id *id)
236{
237    struct pcf8563 *pcf8563;
238
239    int err = 0;
240
241    dev_dbg(&client->dev, "%s\n", __func__);
242
243    if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
244        return -ENODEV;
245
246    pcf8563 = kzalloc(sizeof(struct pcf8563), GFP_KERNEL);
247    if (!pcf8563)
248        return -ENOMEM;
249
250    dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
251
252    i2c_set_clientdata(client, pcf8563);
253
254    pcf8563->rtc = rtc_device_register(pcf8563_driver.driver.name,
255                &client->dev, &pcf8563_rtc_ops, THIS_MODULE);
256
257    if (IS_ERR(pcf8563->rtc)) {
258        err = PTR_ERR(pcf8563->rtc);
259        goto exit_kfree;
260    }
261
262    return 0;
263
264exit_kfree:
265    kfree(pcf8563);
266
267    return err;
268}
269
270static int pcf8563_remove(struct i2c_client *client)
271{
272    struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
273
274    if (pcf8563->rtc)
275        rtc_device_unregister(pcf8563->rtc);
276
277    kfree(pcf8563);
278
279    return 0;
280}
281
282static const struct i2c_device_id pcf8563_id[] = {
283    { "pcf8563", 0 },
284    { "rtc8564", 0 },
285    { }
286};
287MODULE_DEVICE_TABLE(i2c, pcf8563_id);
288
289#ifdef CONFIG_OF
290static const struct of_device_id pcf8563_of_match[] __devinitconst = {
291    { .compatible = "nxp,pcf8563" },
292    {}
293};
294MODULE_DEVICE_TABLE(of, pcf8563_of_match);
295#endif
296
297static struct i2c_driver pcf8563_driver = {
298    .driver = {
299        .name = "rtc-pcf8563",
300        .owner = THIS_MODULE,
301        .of_match_table = of_match_ptr(pcf8563_of_match),
302    },
303    .probe = pcf8563_probe,
304    .remove = pcf8563_remove,
305    .id_table = pcf8563_id,
306};
307
308module_i2c_driver(pcf8563_driver);
309
310MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
311MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
312MODULE_LICENSE("GPL");
313MODULE_VERSION(DRV_VERSION);
314

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