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/module.h>
13#include <linux/i2c.h>
14#include <linux/rtc.h>
15
16#define DRV_VERSION "0.3"
17
18/* Addresses to scan: none. This chip cannot be detected. */
19static unsigned short normal_i2c[] = { I2C_CLIENT_END };
20
21/* Insmod parameters */
22I2C_CLIENT_INSMOD;
23
24/* Registers */
25
26#define DS1672_REG_CNT_BASE	0
27#define DS1672_REG_CONTROL	4
28#define DS1672_REG_TRICKLE	5
29
30#define DS1672_REG_CONTROL_EOSC	0x80
31
32/* Prototypes */
33static int ds1672_probe(struct i2c_adapter *adapter, int address, int kind);
34
35/*
36 * In the routines that deal directly with the ds1672 hardware, we use
37 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
38 * Epoch is initialized as 2000. Time is set to UTC.
39 */
40static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm)
41{
42	unsigned long time;
43	unsigned char addr = DS1672_REG_CNT_BASE;
44	unsigned char buf[4];
45
46	struct i2c_msg msgs[] = {
47		{ client->addr, 0, 1, &addr },		/* setup read ptr */
48		{ client->addr, I2C_M_RD, 4, buf },	/* read date */
49	};
50
51	/* read date registers */
52	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
53		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
54		return -EIO;
55	}
56
57	dev_dbg(&client->dev,
58		"%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
59		__FUNCTION__, buf[0], buf[1], buf[2], buf[3]);
60
61	time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
62
63	rtc_time_to_tm(time, tm);
64
65	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
66		"mday=%d, mon=%d, year=%d, wday=%d\n",
67		__FUNCTION__, tm->tm_sec, tm->tm_min, tm->tm_hour,
68		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
69
70	return 0;
71}
72
73static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
74{
75	int xfer;
76	unsigned char buf[6];
77
78	buf[0] = DS1672_REG_CNT_BASE;
79	buf[1] = secs & 0x000000FF;
80	buf[2] = (secs & 0x0000FF00) >> 8;
81	buf[3] = (secs & 0x00FF0000) >> 16;
82	buf[4] = (secs & 0xFF000000) >> 24;
83	buf[5] = 0;	/* set control reg to enable counting */
84
85	xfer = i2c_master_send(client, buf, 6);
86	if (xfer != 6) {
87		dev_err(&client->dev, "%s: send: %d\n", __FUNCTION__, xfer);
88		return -EIO;
89	}
90
91	return 0;
92}
93
94static int ds1672_set_datetime(struct i2c_client *client, struct rtc_time *tm)
95{
96	unsigned long secs;
97
98	dev_dbg(&client->dev,
99		"%s: secs=%d, mins=%d, hours=%d, "
100		"mday=%d, mon=%d, year=%d, wday=%d\n",
101		__FUNCTION__,
102		tm->tm_sec, tm->tm_min, tm->tm_hour,
103		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
104
105	rtc_tm_to_time(tm, &secs);
106
107	return ds1672_set_mmss(client, secs);
108}
109
110static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
111{
112	return ds1672_get_datetime(to_i2c_client(dev), tm);
113}
114
115static int ds1672_rtc_set_time(struct device *dev, struct rtc_time *tm)
116{
117	return ds1672_set_datetime(to_i2c_client(dev), tm);
118}
119
120static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
121{
122	return ds1672_set_mmss(to_i2c_client(dev), secs);
123}
124
125static int ds1672_get_control(struct i2c_client *client, u8 *status)
126{
127	unsigned char addr = DS1672_REG_CONTROL;
128
129	struct i2c_msg msgs[] = {
130		{ client->addr, 0, 1, &addr },		/* setup read ptr */
131		{ client->addr, I2C_M_RD, 1, status },	/* read control */
132	};
133
134	/* read control register */
135	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
136		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
137		return -EIO;
138	}
139
140	return 0;
141}
142
143/* following are the sysfs callback functions */
144static ssize_t show_control(struct device *dev, struct device_attribute *attr, char *buf)
145{
146	struct i2c_client *client = to_i2c_client(dev);
147	u8 control;
148	int err;
149
150	err = ds1672_get_control(client, &control);
151	if (err)
152		return err;
153
154	return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
155					? "disabled" : "enabled");
156}
157static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
158
159static const struct rtc_class_ops ds1672_rtc_ops = {
160	.read_time	= ds1672_rtc_read_time,
161	.set_time	= ds1672_rtc_set_time,
162	.set_mmss	= ds1672_rtc_set_mmss,
163};
164
165static int ds1672_attach(struct i2c_adapter *adapter)
166{
167	return i2c_probe(adapter, &addr_data, ds1672_probe);
168}
169
170static int ds1672_detach(struct i2c_client *client)
171{
172	int err;
173	struct rtc_device *rtc = i2c_get_clientdata(client);
174
175 	if (rtc)
176		rtc_device_unregister(rtc);
177
178	if ((err = i2c_detach_client(client)))
179		return err;
180
181	kfree(client);
182
183	return 0;
184}
185
186static struct i2c_driver ds1672_driver = {
187	.driver		= {
188		.name	= "ds1672",
189	},
190	.id		= I2C_DRIVERID_DS1672,
191	.attach_adapter = &ds1672_attach,
192	.detach_client	= &ds1672_detach,
193};
194
195static int ds1672_probe(struct i2c_adapter *adapter, int address, int kind)
196{
197	int err = 0;
198	u8 control;
199	struct i2c_client *client;
200	struct rtc_device *rtc;
201
202	dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);
203
204	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
205		err = -ENODEV;
206		goto exit;
207	}
208
209	if (!(client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
210		err = -ENOMEM;
211		goto exit;
212	}
213
214	/* I2C client */
215	client->addr = address;
216	client->driver = &ds1672_driver;
217	client->adapter	= adapter;
218
219	strlcpy(client->name, ds1672_driver.driver.name, I2C_NAME_SIZE);
220
221	/* Inform the i2c layer */
222	if ((err = i2c_attach_client(client)))
223		goto exit_kfree;
224
225	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
226
227	rtc = rtc_device_register(ds1672_driver.driver.name, &client->dev,
228				&ds1672_rtc_ops, THIS_MODULE);
229
230	if (IS_ERR(rtc)) {
231		err = PTR_ERR(rtc);
232		goto exit_detach;
233	}
234
235	i2c_set_clientdata(client, rtc);
236
237	/* read control register */
238	err = ds1672_get_control(client, &control);
239	if (err)
240		goto exit_devreg;
241
242	if (control & DS1672_REG_CONTROL_EOSC)
243		dev_warn(&client->dev, "Oscillator not enabled. "
244					"Set time to enable.\n");
245
246	/* Register sysfs hooks */
247	err = device_create_file(&client->dev, &dev_attr_control);
248	if (err)
249		goto exit_devreg;
250
251	return 0;
252
253exit_devreg:
254	rtc_device_unregister(rtc);
255
256exit_detach:
257	i2c_detach_client(client);
258
259exit_kfree:
260	kfree(client);
261
262exit:
263	return err;
264}
265
266static int __init ds1672_init(void)
267{
268	return i2c_add_driver(&ds1672_driver);
269}
270
271static void __exit ds1672_exit(void)
272{
273	i2c_del_driver(&ds1672_driver);
274}
275
276MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
277MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
278MODULE_LICENSE("GPL");
279MODULE_VERSION(DRV_VERSION);
280
281module_init(ds1672_init);
282module_exit(ds1672_exit);
283