rtc-isl12022.c revision 17cc54b20e4a06c081dec6abc9317a69605db541 
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#include <linux/err.h>
20
21#define DRV_VERSION "0.1"
22
23/* ISL register offsets */
24#define ISL12022_REG_SC		0x00
25#define ISL12022_REG_MN		0x01
26#define ISL12022_REG_HR		0x02
27#define ISL12022_REG_DT		0x03
28#define ISL12022_REG_MO		0x04
29#define ISL12022_REG_YR		0x05
30#define ISL12022_REG_DW		0x06
31
32#define ISL12022_REG_SR		0x07
33#define ISL12022_REG_INT	0x08
34
35/* ISL register bits */
36#define ISL12022_HR_MIL		(1 << 7)	/* military or 24 hour time */
37
38#define ISL12022_SR_LBAT85	(1 << 2)
39#define ISL12022_SR_LBAT75	(1 << 1)
40
41#define ISL12022_INT_WRTC	(1 << 6)
42
43
44static struct i2c_driver isl12022_driver;
45
46struct isl12022 {
47	struct rtc_device *rtc;
48
49	bool write_enabled;	/* true if write enable is set */
50};
51
52
53static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
54			      uint8_t *data, size_t n)
55{
56	struct i2c_msg msgs[] = {
57		{
58			.addr	= client->addr,
59			.flags	= 0,
60			.len	= 1,
61			.buf	= data
62		},		/* setup read ptr */
63		{
64			.addr	= client->addr,
65			.flags	= I2C_M_RD,
66			.len	= n,
67			.buf	= data
68		}
69	};
70
71	int ret;
72
73	data[0] = reg;
74	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
75	if (ret != ARRAY_SIZE(msgs)) {
76		dev_err(&client->dev, "%s: read error, ret=%d\n",
77			__func__, ret);
78		return -EIO;
79	}
80
81	return 0;
82}
83
84
85static int isl12022_write_reg(struct i2c_client *client,
86			      uint8_t reg, uint8_t val)
87{
88	uint8_t data[2] = { reg, val };
89	int err;
90
91	err = i2c_master_send(client, data, sizeof(data));
92	if (err != sizeof(data)) {
93		dev_err(&client->dev,
94			"%s: err=%d addr=%02x, data=%02x\n",
95			__func__, err, data[0], data[1]);
96		return -EIO;
97	}
98
99	return 0;
100}
101
102
103/*
104 * In the routines that deal directly with the isl12022 hardware, we use
105 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
106 */
107static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
108{
109	uint8_t buf[ISL12022_REG_INT + 1];
110	int ret;
111
112	ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
113	if (ret)
114		return ret;
115
116	if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
117		dev_warn(&client->dev,
118			 "voltage dropped below %u%%, "
119			 "date and time is not reliable.\n",
120			 buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
121	}
122
123	dev_dbg(&client->dev,
124		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
125		"mday=%02x, mon=%02x, year=%02x, wday=%02x, "
126		"sr=%02x, int=%02x",
127		__func__,
128		buf[ISL12022_REG_SC],
129		buf[ISL12022_REG_MN],
130		buf[ISL12022_REG_HR],
131		buf[ISL12022_REG_DT],
132		buf[ISL12022_REG_MO],
133		buf[ISL12022_REG_YR],
134		buf[ISL12022_REG_DW],
135		buf[ISL12022_REG_SR],
136		buf[ISL12022_REG_INT]);
137
138	tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
139	tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
140	tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
141	tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
142	tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
143	tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
144	tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
145
146	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
147		"mday=%d, mon=%d, year=%d, wday=%d\n",
148		__func__,
149		tm->tm_sec, tm->tm_min, tm->tm_hour,
150		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
151
152	/* The clock can give out invalid datetime, but we cannot return
153	 * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
154	if (rtc_valid_tm(tm) < 0)
155		dev_err(&client->dev, "retrieved date and time is invalid.\n");
156
157	return 0;
158}
159
160static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
161{
162	struct isl12022 *isl12022 = i2c_get_clientdata(client);
163	size_t i;
164	int ret;
165	uint8_t buf[ISL12022_REG_DW + 1];
166
167	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
168		"mday=%d, mon=%d, year=%d, wday=%d\n",
169		__func__,
170		tm->tm_sec, tm->tm_min, tm->tm_hour,
171		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
172
173	if (!isl12022->write_enabled) {
174
175		ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
176		if (ret)
177			return ret;
178
179		/* Check if WRTC (write rtc enable) is set factory default is
180		 * 0 (not set) */
181		if (!(buf[0] & ISL12022_INT_WRTC)) {
182			dev_info(&client->dev,
183				 "init write enable and 24 hour format\n");
184
185			/* Set the write enable bit. */
186			ret = isl12022_write_reg(client,
187						 ISL12022_REG_INT,
188						 buf[0] | ISL12022_INT_WRTC);
189			if (ret)
190				return ret;
191
192			/* Write to any RTC register to start RTC, we use the
193			 * HR register, setting the MIL bit to use the 24 hour
194			 * format. */
195			ret = isl12022_read_regs(client, ISL12022_REG_HR,
196						 buf, 1);
197			if (ret)
198				return ret;
199
200			ret = isl12022_write_reg(client,
201						 ISL12022_REG_HR,
202						 buf[0] | ISL12022_HR_MIL);
203			if (ret)
204				return ret;
205		}
206
207		isl12022->write_enabled = 1;
208	}
209
210	/* hours, minutes and seconds */
211	buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
212	buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
213	buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
214
215	buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
216
217	/* month, 1 - 12 */
218	buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
219
220	/* year and century */
221	buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
222
223	buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
224
225	/* write register's data */
226	for (i = 0; i < ARRAY_SIZE(buf); i++) {
227		ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
228					 buf[ISL12022_REG_SC + i]);
229		if (ret)
230			return -EIO;
231	}
232
233	return 0;
234}
235
236static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
237{
238	return isl12022_get_datetime(to_i2c_client(dev), tm);
239}
240
241static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
242{
243	return isl12022_set_datetime(to_i2c_client(dev), tm);
244}
245
246static const struct rtc_class_ops isl12022_rtc_ops = {
247	.read_time	= isl12022_rtc_read_time,
248	.set_time	= isl12022_rtc_set_time,
249};
250
251static int isl12022_probe(struct i2c_client *client,
252			  const struct i2c_device_id *id)
253{
254	struct isl12022 *isl12022;
255
256	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
257		return -ENODEV;
258
259	isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
260				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 = devm_rtc_device_register(&client->dev,
269					isl12022_driver.driver.name,
270					&isl12022_rtc_ops, THIS_MODULE);
271	return PTR_RET(isl12022->rtc);
272}
273
274static const struct i2c_device_id isl12022_id[] = {
275	{ "isl12022", 0 },
276	{ }
277};
278MODULE_DEVICE_TABLE(i2c, isl12022_id);
279
280static struct i2c_driver isl12022_driver = {
281	.driver		= {
282		.name	= "rtc-isl12022",
283	},
284	.probe		= isl12022_probe,
285	.id_table	= isl12022_id,
286};
287
288module_i2c_driver(isl12022_driver);
289
290MODULE_AUTHOR("roman.fietze@telemotive.de");
291MODULE_DESCRIPTION("ISL 12022 RTC driver");
292MODULE_LICENSE("GPL");
293MODULE_VERSION(DRV_VERSION);
294