rtc-isl12022.c revision d6c7428f9c2b1df1356a21837301647cb4f76e60 
1/*
2 * An I2C driver for the Intersil ISL 12022
3 *
4 * Author: Roman Fietze <roman.fietze@telemotive.de>
5 *
6 * Based on the Philips PCF8563 RTC
7 * by Alessandro Zummo <a.zummo@towertech.it>.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version
11 * 2 as published by the Free Software Foundation.
12 */
13
14#include <linux/i2c.h>
15#include <linux/bcd.h>
16#include <linux/rtc.h>
17#include <linux/slab.h>
18
19#define DRV_VERSION "0.1"
20
21/* ISL register offsets */
22#define ISL12022_REG_SC		0x00
23#define ISL12022_REG_MN		0x01
24#define ISL12022_REG_HR		0x02
25#define ISL12022_REG_DT		0x03
26#define ISL12022_REG_MO		0x04
27#define ISL12022_REG_YR		0x05
28#define ISL12022_REG_DW		0x06
29
30#define ISL12022_REG_SR		0x07
31#define ISL12022_REG_INT	0x08
32
33/* ISL register bits */
34#define ISL12022_HR_MIL		(1 << 7)	/* military or 24 hour time */
35
36#define ISL12022_SR_LBAT85	(1 << 2)
37#define ISL12022_SR_LBAT75	(1 << 1)
38
39#define ISL12022_INT_WRTC	(1 << 6)
40
41
42static struct i2c_driver isl12022_driver;
43
44struct isl12022 {
45	struct rtc_device *rtc;
46
47	bool write_enabled;	/* true if write enable is set */
48};
49
50
51static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
52			      uint8_t *data, size_t n)
53{
54	struct i2c_msg msgs[] = {
55		{
56			.addr	= client->addr,
57			.flags	= 0,
58			.len	= 1,
59			.buf	= data
60		},		/* setup read ptr */
61		{
62			.addr	= client->addr,
63			.flags	= I2C_M_RD,
64			.len	= n,
65			.buf	= data
66		}
67	};
68
69	int ret;
70
71	data[0] = reg;
72	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
73	if (ret != ARRAY_SIZE(msgs)) {
74		dev_err(&client->dev, "%s: read error, ret=%d\n",
75			__func__, ret);
76		return -EIO;
77	}
78
79	return 0;
80}
81
82
83static int isl12022_write_reg(struct i2c_client *client,
84			      uint8_t reg, uint8_t val)
85{
86	uint8_t data[2] = { reg, val };
87	int err;
88
89	err = i2c_master_send(client, data, sizeof(data));
90	if (err != sizeof(data)) {
91		dev_err(&client->dev,
92			"%s: err=%d addr=%02x, data=%02x\n",
93			__func__, err, data[0], data[1]);
94		return -EIO;
95	}
96
97	return 0;
98}
99
100
101/*
102 * In the routines that deal directly with the isl12022 hardware, we use
103 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
104 */
105static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
106{
107	uint8_t buf[ISL12022_REG_INT + 1];
108	int ret;
109
110	ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
111	if (ret)
112		return ret;
113
114	if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
115		dev_warn(&client->dev,
116			 "voltage dropped below %u%%, "
117			 "date and time is not reliable.\n",
118			 buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
119	}
120
121	dev_dbg(&client->dev,
122		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
123		"mday=%02x, mon=%02x, year=%02x, wday=%02x, "
124		"sr=%02x, int=%02x",
125		__func__,
126		buf[ISL12022_REG_SC],
127		buf[ISL12022_REG_MN],
128		buf[ISL12022_REG_HR],
129		buf[ISL12022_REG_DT],
130		buf[ISL12022_REG_MO],
131		buf[ISL12022_REG_YR],
132		buf[ISL12022_REG_DW],
133		buf[ISL12022_REG_SR],
134		buf[ISL12022_REG_INT]);
135
136	tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
137	tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
138	tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
139	tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
140	tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
141	tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
142	tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
143
144	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
145		"mday=%d, mon=%d, year=%d, wday=%d\n",
146		__func__,
147		tm->tm_sec, tm->tm_min, tm->tm_hour,
148		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
149
150	/* The clock can give out invalid datetime, but we cannot return
151	 * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
152	if (rtc_valid_tm(tm) < 0)
153		dev_err(&client->dev, "retrieved date and time is invalid.\n");
154
155	return 0;
156}
157
158static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
159{
160	struct isl12022 *isl12022 = i2c_get_clientdata(client);
161	size_t i;
162	int ret;
163	uint8_t buf[ISL12022_REG_DW + 1];
164
165	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
166		"mday=%d, mon=%d, year=%d, wday=%d\n",
167		__func__,
168		tm->tm_sec, tm->tm_min, tm->tm_hour,
169		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
170
171	if (!isl12022->write_enabled) {
172
173		ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
174		if (ret)
175			return ret;
176
177		/* Check if WRTC (write rtc enable) is set factory default is
178		 * 0 (not set) */
179		if (!(buf[0] & ISL12022_INT_WRTC)) {
180			dev_info(&client->dev,
181				 "init write enable and 24 hour format\n");
182
183			/* Set the write enable bit. */
184			ret = isl12022_write_reg(client,
185						 ISL12022_REG_INT,
186						 buf[0] | ISL12022_INT_WRTC);
187			if (ret)
188				return ret;
189
190			/* Write to any RTC register to start RTC, we use the
191			 * HR register, setting the MIL bit to use the 24 hour
192			 * format. */
193			ret = isl12022_read_regs(client, ISL12022_REG_HR,
194						 buf, 1);
195			if (ret)
196				return ret;
197
198			ret = isl12022_write_reg(client,
199						 ISL12022_REG_HR,
200						 buf[0] | ISL12022_HR_MIL);
201			if (ret)
202				return ret;
203		}
204
205		isl12022->write_enabled = 1;
206	}
207
208	/* hours, minutes and seconds */
209	buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
210	buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
211	buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour);
212
213	buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
214
215	/* month, 1 - 12 */
216	buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
217
218	/* year and century */
219	buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
220
221	buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
222
223	/* write register's data */
224	for (i = 0; i < ARRAY_SIZE(buf); i++) {
225		ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
226					 buf[ISL12022_REG_SC + i]);
227		if (ret)
228			return -EIO;
229	};
230
231	return 0;
232}
233
234static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
235{
236	return isl12022_get_datetime(to_i2c_client(dev), tm);
237}
238
239static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
240{
241	return isl12022_set_datetime(to_i2c_client(dev), tm);
242}
243
244static const struct rtc_class_ops isl12022_rtc_ops = {
245	.read_time	= isl12022_rtc_read_time,
246	.set_time	= isl12022_rtc_set_time,
247};
248
249static int isl12022_probe(struct i2c_client *client,
250			  const struct i2c_device_id *id)
251{
252	struct isl12022 *isl12022;
253
254	int ret = 0;
255
256	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
257		return -ENODEV;
258
259	isl12022 = kzalloc(sizeof(struct isl12022), GFP_KERNEL);
260	if (!isl12022)
261		return -ENOMEM;
262
263	dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
264
265	i2c_set_clientdata(client, isl12022);
266
267	isl12022->rtc = rtc_device_register(isl12022_driver.driver.name,
268					    &client->dev,
269					    &isl12022_rtc_ops,
270					    THIS_MODULE);
271
272	if (IS_ERR(isl12022->rtc)) {
273		ret = PTR_ERR(isl12022->rtc);
274		goto exit_kfree;
275	}
276
277	return 0;
278
279exit_kfree:
280	kfree(isl12022);
281
282	return ret;
283}
284
285static int isl12022_remove(struct i2c_client *client)
286{
287	struct isl12022 *isl12022 = i2c_get_clientdata(client);
288
289	rtc_device_unregister(isl12022->rtc);
290	kfree(isl12022);
291
292	return 0;
293}
294
295static const struct i2c_device_id isl12022_id[] = {
296	{ "isl12022", 0 },
297	{ "rtc8564", 0 },
298	{ }
299};
300MODULE_DEVICE_TABLE(i2c, isl12022_id);
301
302static struct i2c_driver isl12022_driver = {
303	.driver		= {
304		.name	= "rtc-isl12022",
305	},
306	.probe		= isl12022_probe,
307	.remove		= isl12022_remove,
308	.id_table	= isl12022_id,
309};
310
311static int __init isl12022_init(void)
312{
313	return i2c_add_driver(&isl12022_driver);
314}
315
316static void __exit isl12022_exit(void)
317{
318	i2c_del_driver(&isl12022_driver);
319}
320
321module_init(isl12022_init);
322module_exit(isl12022_exit);
323
324MODULE_AUTHOR("roman.fietze@telemotive.de");
325MODULE_DESCRIPTION("ISL 12022 RTC driver");
326MODULE_LICENSE("GPL");
327MODULE_VERSION(DRV_VERSION);
328