rtc-isl12022.c revision 0abc920116303e81702a38429a1b61a896e02b37 
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#include <linux/module.h>
19
20#define DRV_VERSION "0.1"
21
22/* ISL register offsets */
23#define ISL12022_REG_SC		0x00
24#define ISL12022_REG_MN		0x01
25#define ISL12022_REG_HR		0x02
26#define ISL12022_REG_DT		0x03
27#define ISL12022_REG_MO		0x04
28#define ISL12022_REG_YR		0x05
29#define ISL12022_REG_DW		0x06
30
31#define ISL12022_REG_SR		0x07
32#define ISL12022_REG_INT	0x08
33
34/* ISL register bits */
35#define ISL12022_HR_MIL		(1 << 7)	/* military or 24 hour time */
36
37#define ISL12022_SR_LBAT85	(1 << 2)
38#define ISL12022_SR_LBAT75	(1 << 1)
39
40#define ISL12022_INT_WRTC	(1 << 6)
41
42
43static struct i2c_driver isl12022_driver;
44
45struct isl12022 {
46	struct rtc_device *rtc;
47
48	bool write_enabled;	/* true if write enable is set */
49};
50
51
52static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
53			      uint8_t *data, size_t n)
54{
55	struct i2c_msg msgs[] = {
56		{
57			.addr	= client->addr,
58			.flags	= 0,
59			.len	= 1,
60			.buf	= data
61		},		/* setup read ptr */
62		{
63			.addr	= client->addr,
64			.flags	= I2C_M_RD,
65			.len	= n,
66			.buf	= data
67		}
68	};
69
70	int ret;
71
72	data[0] = reg;
73	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
74	if (ret != ARRAY_SIZE(msgs)) {
75		dev_err(&client->dev, "%s: read error, ret=%d\n",
76			__func__, ret);
77		return -EIO;
78	}
79
80	return 0;
81}
82
83
84static int isl12022_write_reg(struct i2c_client *client,
85			      uint8_t reg, uint8_t val)
86{
87	uint8_t data[2] = { reg, val };
88	int err;
89
90	err = i2c_master_send(client, data, sizeof(data));
91	if (err != sizeof(data)) {
92		dev_err(&client->dev,
93			"%s: err=%d addr=%02x, data=%02x\n",
94			__func__, err, data[0], data[1]);
95		return -EIO;
96	}
97
98	return 0;
99}
100
101
102/*
103 * In the routines that deal directly with the isl12022 hardware, we use
104 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
105 */
106static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
107{
108	uint8_t buf[ISL12022_REG_INT + 1];
109	int ret;
110
111	ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
112	if (ret)
113		return ret;
114
115	if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
116		dev_warn(&client->dev,
117			 "voltage dropped below %u%%, "
118			 "date and time is not reliable.\n",
119			 buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
120	}
121
122	dev_dbg(&client->dev,
123		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
124		"mday=%02x, mon=%02x, year=%02x, wday=%02x, "
125		"sr=%02x, int=%02x",
126		__func__,
127		buf[ISL12022_REG_SC],
128		buf[ISL12022_REG_MN],
129		buf[ISL12022_REG_HR],
130		buf[ISL12022_REG_DT],
131		buf[ISL12022_REG_MO],
132		buf[ISL12022_REG_YR],
133		buf[ISL12022_REG_DW],
134		buf[ISL12022_REG_SR],
135		buf[ISL12022_REG_INT]);
136
137	tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
138	tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
139	tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
140	tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
141	tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
142	tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
143	tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
144
145	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
146		"mday=%d, mon=%d, year=%d, wday=%d\n",
147		__func__,
148		tm->tm_sec, tm->tm_min, tm->tm_hour,
149		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
150
151	/* The clock can give out invalid datetime, but we cannot return
152	 * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
153	if (rtc_valid_tm(tm) < 0)
154		dev_err(&client->dev, "retrieved date and time is invalid.\n");
155
156	return 0;
157}
158
159static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
160{
161	struct isl12022 *isl12022 = i2c_get_clientdata(client);
162	size_t i;
163	int ret;
164	uint8_t buf[ISL12022_REG_DW + 1];
165
166	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
167		"mday=%d, mon=%d, year=%d, wday=%d\n",
168		__func__,
169		tm->tm_sec, tm->tm_min, tm->tm_hour,
170		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
171
172	if (!isl12022->write_enabled) {
173
174		ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
175		if (ret)
176			return ret;
177
178		/* Check if WRTC (write rtc enable) is set factory default is
179		 * 0 (not set) */
180		if (!(buf[0] & ISL12022_INT_WRTC)) {
181			dev_info(&client->dev,
182				 "init write enable and 24 hour format\n");
183
184			/* Set the write enable bit. */
185			ret = isl12022_write_reg(client,
186						 ISL12022_REG_INT,
187						 buf[0] | ISL12022_INT_WRTC);
188			if (ret)
189				return ret;
190
191			/* Write to any RTC register to start RTC, we use the
192			 * HR register, setting the MIL bit to use the 24 hour
193			 * format. */
194			ret = isl12022_read_regs(client, ISL12022_REG_HR,
195						 buf, 1);
196			if (ret)
197				return ret;
198
199			ret = isl12022_write_reg(client,
200						 ISL12022_REG_HR,
201						 buf[0] | ISL12022_HR_MIL);
202			if (ret)
203				return ret;
204		}
205
206		isl12022->write_enabled = 1;
207	}
208
209	/* hours, minutes and seconds */
210	buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
211	buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
212	buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
213
214	buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
215
216	/* month, 1 - 12 */
217	buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
218
219	/* year and century */
220	buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
221
222	buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
223
224	/* write register's data */
225	for (i = 0; i < ARRAY_SIZE(buf); i++) {
226		ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
227					 buf[ISL12022_REG_SC + i]);
228		if (ret)
229			return -EIO;
230	};
231
232	return 0;
233}
234
235static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
236{
237	return isl12022_get_datetime(to_i2c_client(dev), tm);
238}
239
240static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
241{
242	return isl12022_set_datetime(to_i2c_client(dev), tm);
243}
244
245static const struct rtc_class_ops isl12022_rtc_ops = {
246	.read_time	= isl12022_rtc_read_time,
247	.set_time	= isl12022_rtc_set_time,
248};
249
250static int isl12022_probe(struct i2c_client *client,
251			  const struct i2c_device_id *id)
252{
253	struct isl12022 *isl12022;
254
255	int ret = 0;
256
257	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
258		return -ENODEV;
259
260	isl12022 = kzalloc(sizeof(struct isl12022), GFP_KERNEL);
261	if (!isl12022)
262		return -ENOMEM;
263
264	dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
265
266	i2c_set_clientdata(client, isl12022);
267
268	isl12022->rtc = rtc_device_register(isl12022_driver.driver.name,
269					    &client->dev,
270					    &isl12022_rtc_ops,
271					    THIS_MODULE);
272
273	if (IS_ERR(isl12022->rtc)) {
274		ret = PTR_ERR(isl12022->rtc);
275		goto exit_kfree;
276	}
277
278	return 0;
279
280exit_kfree:
281	kfree(isl12022);
282
283	return ret;
284}
285
286static int isl12022_remove(struct i2c_client *client)
287{
288	struct isl12022 *isl12022 = i2c_get_clientdata(client);
289
290	rtc_device_unregister(isl12022->rtc);
291	kfree(isl12022);
292
293	return 0;
294}
295
296static const struct i2c_device_id isl12022_id[] = {
297	{ "isl12022", 0 },
298	{ "rtc8564", 0 },
299	{ }
300};
301MODULE_DEVICE_TABLE(i2c, isl12022_id);
302
303static struct i2c_driver isl12022_driver = {
304	.driver		= {
305		.name	= "rtc-isl12022",
306	},
307	.probe		= isl12022_probe,
308	.remove		= isl12022_remove,
309	.id_table	= isl12022_id,
310};
311
312module_i2c_driver(isl12022_driver);
313
314MODULE_AUTHOR("roman.fietze@telemotive.de");
315MODULE_DESCRIPTION("ISL 12022 RTC driver");
316MODULE_LICENSE("GPL");
317MODULE_VERSION(DRV_VERSION);
318