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Linux/drivers/rtc/rtc-pcf2127.c

  1 /*
  2  * An I2C driver for the NXP PCF2127 RTC
  3  * Copyright 2013 Til-Technologies
  4  *
  5  * Author: Renaud Cerrato <r.cerrato@til-technologies.fr>
  6  *
  7  * based on the other drivers in this same directory.
  8  *
  9  * http://www.nxp.com/documents/data_sheet/PCF2127AT.pdf
 10  *
 11  * This program is free software; you can redistribute it and/or modify
 12  * it under the terms of the GNU General Public License version 2 as
 13  * published by the Free Software Foundation.
 14  */
 15 
 16 #include <linux/i2c.h>
 17 #include <linux/bcd.h>
 18 #include <linux/rtc.h>
 19 #include <linux/slab.h>
 20 #include <linux/module.h>
 21 #include <linux/of.h>
 22 
 23 #define DRV_VERSION "0.0.1"
 24 
 25 #define PCF2127_REG_CTRL1       (0x00)  /* Control Register 1 */
 26 #define PCF2127_REG_CTRL2       (0x01)  /* Control Register 2 */
 27 #define PCF2127_REG_CTRL3       (0x02)  /* Control Register 3 */
 28 #define PCF2127_REG_SC          (0x03)  /* datetime */
 29 #define PCF2127_REG_MN          (0x04)
 30 #define PCF2127_REG_HR          (0x05)
 31 #define PCF2127_REG_DM          (0x06)
 32 #define PCF2127_REG_DW          (0x07)
 33 #define PCF2127_REG_MO          (0x08)
 34 #define PCF2127_REG_YR          (0x09)
 35 
 36 static struct i2c_driver pcf2127_driver;
 37 
 38 struct pcf2127 {
 39         struct rtc_device *rtc;
 40         int voltage_low; /* indicates if a low_voltage was detected */
 41 };
 42 
 43 /*
 44  * In the routines that deal directly with the pcf2127 hardware, we use
 45  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 46  */
 47 static int pcf2127_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 48 {
 49         struct pcf2127 *pcf2127 = i2c_get_clientdata(client);
 50         unsigned char buf[10] = { PCF2127_REG_CTRL1 };
 51 
 52         /* read registers */
 53         if (i2c_master_send(client, buf, 1) != 1 ||
 54                 i2c_master_recv(client, buf, sizeof(buf)) != sizeof(buf)) {
 55                 dev_err(&client->dev, "%s: read error\n", __func__);
 56                 return -EIO;
 57         }
 58 
 59         if (buf[PCF2127_REG_CTRL3] & 0x04) {
 60                 pcf2127->voltage_low = 1;
 61                 dev_info(&client->dev,
 62                         "low voltage detected, date/time is not reliable.\n");
 63         }
 64 
 65         dev_dbg(&client->dev,
 66                 "%s: raw data is cr1=%02x, cr2=%02x, cr3=%02x, "
 67                 "sec=%02x, min=%02x, hr=%02x, "
 68                 "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
 69                 __func__,
 70                 buf[0], buf[1], buf[2],
 71                 buf[3], buf[4], buf[5],
 72                 buf[6], buf[7], buf[8], buf[9]);
 73 
 74 
 75         tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
 76         tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
 77         tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
 78         tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
 79         tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
 80         tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 81         tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
 82         if (tm->tm_year < 70)
 83                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 84 
 85         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 86                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 87                 __func__,
 88                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 89                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 90 
 91         /* the clock can give out invalid datetime, but we cannot return
 92          * -EINVAL otherwise hwclock will refuse to set the time on bootup.
 93          */
 94         if (rtc_valid_tm(tm) < 0)
 95                 dev_err(&client->dev, "retrieved date/time is not valid.\n");
 96 
 97         return 0;
 98 }
 99 
100 static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
101 {
102         unsigned char buf[8];
103         int i = 0, err;
104 
105         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
106                 "mday=%d, mon=%d, year=%d, wday=%d\n",
107                 __func__,
108                 tm->tm_sec, tm->tm_min, tm->tm_hour,
109                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
110 
111         /* start register address */
112         buf[i++] = PCF2127_REG_SC;
113 
114         /* hours, minutes and seconds */
115         buf[i++] = bin2bcd(tm->tm_sec);
116         buf[i++] = bin2bcd(tm->tm_min);
117         buf[i++] = bin2bcd(tm->tm_hour);
118         buf[i++] = bin2bcd(tm->tm_mday);
119         buf[i++] = tm->tm_wday & 0x07;
120 
121         /* month, 1 - 12 */
122         buf[i++] = bin2bcd(tm->tm_mon + 1);
123 
124         /* year */
125         buf[i++] = bin2bcd(tm->tm_year % 100);
126 
127         /* write register's data */
128         err = i2c_master_send(client, buf, i);
129         if (err != i) {
130                 dev_err(&client->dev,
131                         "%s: err=%d", __func__, err);
132                 return -EIO;
133         }
134 
135         return 0;
136 }
137 
138 #ifdef CONFIG_RTC_INTF_DEV
139 static int pcf2127_rtc_ioctl(struct device *dev,
140                                 unsigned int cmd, unsigned long arg)
141 {
142         struct pcf2127 *pcf2127 = i2c_get_clientdata(to_i2c_client(dev));
143 
144         switch (cmd) {
145         case RTC_VL_READ:
146                 if (pcf2127->voltage_low)
147                         dev_info(dev, "low voltage detected, date/time is not reliable.\n");
148 
149                 if (copy_to_user((void __user *)arg, &pcf2127->voltage_low,
150                                         sizeof(int)))
151                         return -EFAULT;
152                 return 0;
153         default:
154                 return -ENOIOCTLCMD;
155         }
156 }
157 #else
158 #define pcf2127_rtc_ioctl NULL
159 #endif
160 
161 static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
162 {
163         return pcf2127_get_datetime(to_i2c_client(dev), tm);
164 }
165 
166 static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
167 {
168         return pcf2127_set_datetime(to_i2c_client(dev), tm);
169 }
170 
171 static const struct rtc_class_ops pcf2127_rtc_ops = {
172         .ioctl          = pcf2127_rtc_ioctl,
173         .read_time      = pcf2127_rtc_read_time,
174         .set_time       = pcf2127_rtc_set_time,
175 };
176 
177 static int pcf2127_probe(struct i2c_client *client,
178                                 const struct i2c_device_id *id)
179 {
180         struct pcf2127 *pcf2127;
181 
182         dev_dbg(&client->dev, "%s\n", __func__);
183 
184         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
185                 return -ENODEV;
186 
187         pcf2127 = devm_kzalloc(&client->dev, sizeof(struct pcf2127),
188                                 GFP_KERNEL);
189         if (!pcf2127)
190                 return -ENOMEM;
191 
192         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
193 
194         i2c_set_clientdata(client, pcf2127);
195 
196         pcf2127->rtc = devm_rtc_device_register(&client->dev,
197                                 pcf2127_driver.driver.name,
198                                 &pcf2127_rtc_ops, THIS_MODULE);
199 
200         return PTR_ERR_OR_ZERO(pcf2127->rtc);
201 }
202 
203 static const struct i2c_device_id pcf2127_id[] = {
204         { "pcf2127", 0 },
205         { }
206 };
207 MODULE_DEVICE_TABLE(i2c, pcf2127_id);
208 
209 #ifdef CONFIG_OF
210 static const struct of_device_id pcf2127_of_match[] = {
211         { .compatible = "nxp,pcf2127" },
212         {}
213 };
214 MODULE_DEVICE_TABLE(of, pcf2127_of_match);
215 #endif
216 
217 static struct i2c_driver pcf2127_driver = {
218         .driver         = {
219                 .name   = "rtc-pcf2127",
220                 .owner  = THIS_MODULE,
221                 .of_match_table = of_match_ptr(pcf2127_of_match),
222         },
223         .probe          = pcf2127_probe,
224         .id_table       = pcf2127_id,
225 };
226 
227 module_i2c_driver(pcf2127_driver);
228 
229 MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
230 MODULE_DESCRIPTION("NXP PCF2127 RTC driver");
231 MODULE_LICENSE("GPL");
232 MODULE_VERSION(DRV_VERSION);
233 

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