1 /*
2 * An I2C driver for the PCF85063 RTC
3 * Copyright 2014 Rose Technology
4 *
5 * Author: Søren Andersen <san@rosetechnology.dk>
6 * Maintainers: http://www.nslu2-linux.org/
7 *
8 * based on the other drivers in this same directory.
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14 #include <linux/i2c.h>
15 #include <linux/bcd.h>
16 #include <linux/rtc.h>
17 #include <linux/module.h>
18
19 /*
20 * Information for this driver was pulled from the following datasheets.
21 *
22 * http://www.nxp.com/documents/data_sheet/PCF85063A.pdf
23 * http://www.nxp.com/documents/data_sheet/PCF85063TP.pdf
24 *
25 * PCF85063A -- Rev. 6 — 18 November 2015
26 * PCF85063TP -- Rev. 4 — 6 May 2015
27 */
28
29 #define PCF85063_REG_CTRL1 0x00 /* status */
30 #define PCF85063_REG_CTRL1_STOP BIT(5)
31 #define PCF85063_REG_CTRL2 0x01
32
33 #define PCF85063_REG_SC 0x04 /* datetime */
34 #define PCF85063_REG_SC_OS 0x80
35 #define PCF85063_REG_MN 0x05
36 #define PCF85063_REG_HR 0x06
37 #define PCF85063_REG_DM 0x07
38 #define PCF85063_REG_DW 0x08
39 #define PCF85063_REG_MO 0x09
40 #define PCF85063_REG_YR 0x0A
41
42 static struct i2c_driver pcf85063_driver;
43
pcf85063_stop_clock(struct i2c_client * client,u8 * ctrl1)44 static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
45 {
46 int rc;
47 u8 reg;
48
49 rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
50 if (rc < 0) {
51 dev_err(&client->dev, "Failing to stop the clock\n");
52 return -EIO;
53 }
54
55 /* stop the clock */
56 reg = rc | PCF85063_REG_CTRL1_STOP;
57
58 rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg);
59 if (rc < 0) {
60 dev_err(&client->dev, "Failing to stop the clock\n");
61 return -EIO;
62 }
63
64 *ctrl1 = reg;
65
66 return 0;
67 }
68
pcf85063_start_clock(struct i2c_client * client,u8 ctrl1)69 static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1)
70 {
71 int rc;
72
73 /* start the clock */
74 ctrl1 &= ~PCF85063_REG_CTRL1_STOP;
75
76 rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
77 if (rc < 0) {
78 dev_err(&client->dev, "Failing to start the clock\n");
79 return -EIO;
80 }
81
82 return 0;
83 }
84
pcf85063_rtc_read_time(struct device * dev,struct rtc_time * tm)85 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
86 {
87 struct i2c_client *client = to_i2c_client(dev);
88 int rc;
89 u8 regs[7];
90
91 /*
92 * while reading, the time/date registers are blocked and not updated
93 * anymore until the access is finished. To not lose a second
94 * event, the access must be finished within one second. So, read all
95 * time/date registers in one turn.
96 */
97 rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
98 sizeof(regs), regs);
99 if (rc != sizeof(regs)) {
100 dev_err(&client->dev, "date/time register read error\n");
101 return -EIO;
102 }
103
104 /* if the clock has lost its power it makes no sense to use its time */
105 if (regs[0] & PCF85063_REG_SC_OS) {
106 dev_warn(&client->dev, "Power loss detected, invalid time\n");
107 return -EINVAL;
108 }
109
110 tm->tm_sec = bcd2bin(regs[0] & 0x7F);
111 tm->tm_min = bcd2bin(regs[1] & 0x7F);
112 tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
113 tm->tm_mday = bcd2bin(regs[3] & 0x3F);
114 tm->tm_wday = regs[4] & 0x07;
115 tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
116 tm->tm_year = bcd2bin(regs[6]);
117 tm->tm_year += 100;
118
119 return 0;
120 }
121
pcf85063_rtc_set_time(struct device * dev,struct rtc_time * tm)122 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
123 {
124 struct i2c_client *client = to_i2c_client(dev);
125 int rc;
126 u8 regs[7];
127 u8 ctrl1;
128
129 if ((tm->tm_year < 100) || (tm->tm_year > 199))
130 return -EINVAL;
131
132 /*
133 * to accurately set the time, reset the divider chain and keep it in
134 * reset state until all time/date registers are written
135 */
136 rc = pcf85063_stop_clock(client, &ctrl1);
137 if (rc != 0)
138 return rc;
139
140 /* hours, minutes and seconds */
141 regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
142
143 regs[1] = bin2bcd(tm->tm_min);
144 regs[2] = bin2bcd(tm->tm_hour);
145
146 /* Day of month, 1 - 31 */
147 regs[3] = bin2bcd(tm->tm_mday);
148
149 /* Day, 0 - 6 */
150 regs[4] = tm->tm_wday & 0x07;
151
152 /* month, 1 - 12 */
153 regs[5] = bin2bcd(tm->tm_mon + 1);
154
155 /* year and century */
156 regs[6] = bin2bcd(tm->tm_year - 100);
157
158 /* write all registers at once */
159 rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
160 sizeof(regs), regs);
161 if (rc < 0) {
162 dev_err(&client->dev, "date/time register write error\n");
163 return rc;
164 }
165
166 /*
167 * Write the control register as a separate action since the size of
168 * the register space is different between the PCF85063TP and
169 * PCF85063A devices. The rollover point can not be used.
170 */
171 rc = pcf85063_start_clock(client, ctrl1);
172 if (rc != 0)
173 return rc;
174
175 return 0;
176 }
177
178 static const struct rtc_class_ops pcf85063_rtc_ops = {
179 .read_time = pcf85063_rtc_read_time,
180 .set_time = pcf85063_rtc_set_time
181 };
182
pcf85063_probe(struct i2c_client * client,const struct i2c_device_id * id)183 static int pcf85063_probe(struct i2c_client *client,
184 const struct i2c_device_id *id)
185 {
186 struct rtc_device *rtc;
187 int err;
188
189 dev_dbg(&client->dev, "%s\n", __func__);
190
191 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
192 return -ENODEV;
193
194 err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
195 if (err < 0) {
196 dev_err(&client->dev, "RTC chip is not present\n");
197 return err;
198 }
199
200 rtc = devm_rtc_device_register(&client->dev,
201 pcf85063_driver.driver.name,
202 &pcf85063_rtc_ops, THIS_MODULE);
203
204 return PTR_ERR_OR_ZERO(rtc);
205 }
206
207 static const struct i2c_device_id pcf85063_id[] = {
208 { "pcf85063", 0 },
209 { }
210 };
211 MODULE_DEVICE_TABLE(i2c, pcf85063_id);
212
213 #ifdef CONFIG_OF
214 static const struct of_device_id pcf85063_of_match[] = {
215 { .compatible = "nxp,pcf85063" },
216 {}
217 };
218 MODULE_DEVICE_TABLE(of, pcf85063_of_match);
219 #endif
220
221 static struct i2c_driver pcf85063_driver = {
222 .driver = {
223 .name = "rtc-pcf85063",
224 .of_match_table = of_match_ptr(pcf85063_of_match),
225 },
226 .probe = pcf85063_probe,
227 .id_table = pcf85063_id,
228 };
229
230 module_i2c_driver(pcf85063_driver);
231
232 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
233 MODULE_DESCRIPTION("PCF85063 RTC driver");
234 MODULE_LICENSE("GPL");
235