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