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

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