1/*
2 * An rtc/i2c driver for the Dallas DS1672
3 * Copyright 2005-06 Tower Technologies
4 *
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/i2c.h>
13#include <linux/rtc.h>
14#include <linux/module.h>
15
16#define DRV_VERSION "0.4"
17
18/* Registers */
19
20#define DS1672_REG_CNT_BASE	0
21#define DS1672_REG_CONTROL	4
22#define DS1672_REG_TRICKLE	5
23
24#define DS1672_REG_CONTROL_EOSC	0x80
25
26static struct i2c_driver ds1672_driver;
27
28/*
29 * In the routines that deal directly with the ds1672 hardware, we use
30 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
31 * Epoch is initialized as 2000. Time is set to UTC.
32 */
33static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm)
34{
35	unsigned long time;
36	unsigned char addr = DS1672_REG_CNT_BASE;
37	unsigned char buf[4];
38
39	struct i2c_msg msgs[] = {
40		{/* setup read ptr */
41			.addr = client->addr,
42			.len = 1,
43			.buf = &addr
44		},
45		{/* read date */
46			.addr = client->addr,
47			.flags = I2C_M_RD,
48			.len = 4,
49			.buf = buf
50		},
51	};
52
53	/* read date registers */
54	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
55		dev_err(&client->dev, "%s: read error\n", __func__);
56		return -EIO;
57	}
58
59	dev_dbg(&client->dev,
60		"%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
61		__func__, buf[0], buf[1], buf[2], buf[3]);
62
63	time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
64
65	rtc_time_to_tm(time, tm);
66
67	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
68		"mday=%d, mon=%d, year=%d, wday=%d\n",
69		__func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
70		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
71
72	return 0;
73}
74
75static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
76{
77	int xfer;
78	unsigned char buf[6];
79
80	buf[0] = DS1672_REG_CNT_BASE;
81	buf[1] = secs & 0x000000FF;
82	buf[2] = (secs & 0x0000FF00) >> 8;
83	buf[3] = (secs & 0x00FF0000) >> 16;
84	buf[4] = (secs & 0xFF000000) >> 24;
85	buf[5] = 0;		/* set control reg to enable counting */
86
87	xfer = i2c_master_send(client, buf, 6);
88	if (xfer != 6) {
89		dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
90		return -EIO;
91	}
92
93	return 0;
94}
95
96static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
97{
98	return ds1672_get_datetime(to_i2c_client(dev), tm);
99}
100
101static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
102{
103	return ds1672_set_mmss(to_i2c_client(dev), secs);
104}
105
106static int ds1672_get_control(struct i2c_client *client, u8 *status)
107{
108	unsigned char addr = DS1672_REG_CONTROL;
109
110	struct i2c_msg msgs[] = {
111		{/* setup read ptr */
112			.addr = client->addr,
113			.len = 1,
114			.buf = &addr
115		},
116		{/* read control */
117			.addr = client->addr,
118			.flags = I2C_M_RD,
119			.len = 1,
120			.buf = status
121		},
122	};
123
124	/* read control register */
125	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
126		dev_err(&client->dev, "%s: read error\n", __func__);
127		return -EIO;
128	}
129
130	return 0;
131}
132
133/* following are the sysfs callback functions */
134static ssize_t show_control(struct device *dev, struct device_attribute *attr,
135			    char *buf)
136{
137	struct i2c_client *client = to_i2c_client(dev);
138	u8 control;
139	int err;
140
141	err = ds1672_get_control(client, &control);
142	if (err)
143		return err;
144
145	return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
146		       ? "disabled" : "enabled");
147}
148
149static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
150
151static const struct rtc_class_ops ds1672_rtc_ops = {
152	.read_time = ds1672_rtc_read_time,
153	.set_mmss = ds1672_rtc_set_mmss,
154};
155
156static int ds1672_probe(struct i2c_client *client,
157			const struct i2c_device_id *id)
158{
159	int err = 0;
160	u8 control;
161	struct rtc_device *rtc;
162
163	dev_dbg(&client->dev, "%s\n", __func__);
164
165	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
166		return -ENODEV;
167
168	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
169
170	rtc = devm_rtc_device_register(&client->dev, ds1672_driver.driver.name,
171				  &ds1672_rtc_ops, THIS_MODULE);
172
173	if (IS_ERR(rtc))
174		return PTR_ERR(rtc);
175
176	i2c_set_clientdata(client, rtc);
177
178	/* read control register */
179	err = ds1672_get_control(client, &control);
180	if (err) {
181		dev_warn(&client->dev, "Unable to read the control register\n");
182	}
183
184	if (control & DS1672_REG_CONTROL_EOSC)
185		dev_warn(&client->dev, "Oscillator not enabled. "
186			 "Set time to enable.\n");
187
188	/* Register sysfs hooks */
189	err = device_create_file(&client->dev, &dev_attr_control);
190	if (err)
191		dev_err(&client->dev, "Unable to create sysfs entry: %s\n",
192			dev_attr_control.attr.name);
193
194	return 0;
195}
196
197static struct i2c_device_id ds1672_id[] = {
198	{ "ds1672", 0 },
199	{ }
200};
201
202static struct i2c_driver ds1672_driver = {
203	.driver = {
204		   .name = "rtc-ds1672",
205		   },
206	.probe = &ds1672_probe,
207	.id_table = ds1672_id,
208};
209
210module_i2c_driver(ds1672_driver);
211
212MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
213MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
214MODULE_LICENSE("GPL");
215MODULE_VERSION(DRV_VERSION);
216