1/*
2 * Micro Crystal RV-3029C2 rtc class driver
3 *
4 * Author: Gregory Hermant <gregory.hermant@calao-systems.com>
5 *
6 * based on previously existing rtc class drivers
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 * NOTE: Currently this driver only supports the bare minimum for read
13 * and write the RTC and alarms. The extra features provided by this chip
14 * (trickle charger, eeprom, T° compensation) are unavailable.
15 */
16
17#include <linux/module.h>
18#include <linux/i2c.h>
19#include <linux/bcd.h>
20#include <linux/rtc.h>
21
22/* Register map */
23/* control section */
24#define RV3029C2_ONOFF_CTRL		0x00
25#define RV3029C2_IRQ_CTRL		0x01
26#define RV3029C2_IRQ_CTRL_AIE		(1 << 0)
27#define RV3029C2_IRQ_FLAGS		0x02
28#define RV3029C2_IRQ_FLAGS_AF		(1 << 0)
29#define RV3029C2_STATUS			0x03
30#define RV3029C2_STATUS_VLOW1		(1 << 2)
31#define RV3029C2_STATUS_VLOW2		(1 << 3)
32#define RV3029C2_STATUS_SR		(1 << 4)
33#define RV3029C2_STATUS_PON		(1 << 5)
34#define RV3029C2_STATUS_EEBUSY		(1 << 7)
35#define RV3029C2_RST_CTRL		0x04
36#define RV3029C2_CONTROL_SECTION_LEN	0x05
37
38/* watch section */
39#define RV3029C2_W_SEC			0x08
40#define RV3029C2_W_MINUTES		0x09
41#define RV3029C2_W_HOURS		0x0A
42#define RV3029C2_REG_HR_12_24		(1<<6)  /* 24h/12h mode */
43#define RV3029C2_REG_HR_PM		(1<<5)  /* PM/AM bit in 12h mode */
44#define RV3029C2_W_DATE			0x0B
45#define RV3029C2_W_DAYS			0x0C
46#define RV3029C2_W_MONTHS		0x0D
47#define RV3029C2_W_YEARS		0x0E
48#define RV3029C2_WATCH_SECTION_LEN	0x07
49
50/* alarm section */
51#define RV3029C2_A_SC			0x10
52#define RV3029C2_A_MN			0x11
53#define RV3029C2_A_HR			0x12
54#define RV3029C2_A_DT			0x13
55#define RV3029C2_A_DW			0x14
56#define RV3029C2_A_MO			0x15
57#define RV3029C2_A_YR			0x16
58#define RV3029C2_ALARM_SECTION_LEN	0x07
59
60/* timer section */
61#define RV3029C2_TIMER_LOW		0x18
62#define RV3029C2_TIMER_HIGH		0x19
63
64/* temperature section */
65#define RV3029C2_TEMP_PAGE		0x20
66
67/* eeprom data section */
68#define RV3029C2_E2P_EEDATA1		0x28
69#define RV3029C2_E2P_EEDATA2		0x29
70
71/* eeprom control section */
72#define RV3029C2_CONTROL_E2P_EECTRL	0x30
73#define RV3029C2_TRICKLE_1K		(1<<0)  /*  1K resistance */
74#define RV3029C2_TRICKLE_5K		(1<<1)  /*  5K resistance */
75#define RV3029C2_TRICKLE_20K		(1<<2)  /* 20K resistance */
76#define RV3029C2_TRICKLE_80K		(1<<3)  /* 80K resistance */
77#define RV3029C2_CONTROL_E2P_XTALOFFSET	0x31
78#define RV3029C2_CONTROL_E2P_QCOEF	0x32
79#define RV3029C2_CONTROL_E2P_TURNOVER	0x33
80
81/* user ram section */
82#define RV3029C2_USR1_RAM_PAGE		0x38
83#define RV3029C2_USR1_SECTION_LEN	0x04
84#define RV3029C2_USR2_RAM_PAGE		0x3C
85#define RV3029C2_USR2_SECTION_LEN	0x04
86
87static int
88rv3029c2_i2c_read_regs(struct i2c_client *client, u8 reg, u8 *buf,
89	unsigned len)
90{
91	int ret;
92
93	if ((reg > RV3029C2_USR1_RAM_PAGE + 7) ||
94		(reg + len > RV3029C2_USR1_RAM_PAGE + 8))
95		return -EINVAL;
96
97	ret = i2c_smbus_read_i2c_block_data(client, reg, len, buf);
98	if (ret < 0)
99		return ret;
100	if (ret < len)
101		return -EIO;
102	return 0;
103}
104
105static int
106rv3029c2_i2c_write_regs(struct i2c_client *client, u8 reg, u8 const buf[],
107			unsigned len)
108{
109	if ((reg > RV3029C2_USR1_RAM_PAGE + 7) ||
110		(reg + len > RV3029C2_USR1_RAM_PAGE + 8))
111		return -EINVAL;
112
113	return i2c_smbus_write_i2c_block_data(client, reg, len, buf);
114}
115
116static int
117rv3029c2_i2c_get_sr(struct i2c_client *client, u8 *buf)
118{
119	int ret = rv3029c2_i2c_read_regs(client, RV3029C2_STATUS, buf, 1);
120
121	if (ret < 0)
122		return -EIO;
123	dev_dbg(&client->dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);
124	return 0;
125}
126
127static int
128rv3029c2_i2c_set_sr(struct i2c_client *client, u8 val)
129{
130	u8 buf[1];
131	int sr;
132
133	buf[0] = val;
134	sr = rv3029c2_i2c_write_regs(client, RV3029C2_STATUS, buf, 1);
135	dev_dbg(&client->dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);
136	if (sr < 0)
137		return -EIO;
138	return 0;
139}
140
141static int
142rv3029c2_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
143{
144	u8 buf[1];
145	int ret;
146	u8 regs[RV3029C2_WATCH_SECTION_LEN] = { 0, };
147
148	ret = rv3029c2_i2c_get_sr(client, buf);
149	if (ret < 0) {
150		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
151		return -EIO;
152	}
153
154	ret = rv3029c2_i2c_read_regs(client, RV3029C2_W_SEC , regs,
155					RV3029C2_WATCH_SECTION_LEN);
156	if (ret < 0) {
157		dev_err(&client->dev, "%s: reading RTC section failed\n",
158			__func__);
159		return ret;
160	}
161
162	tm->tm_sec = bcd2bin(regs[RV3029C2_W_SEC-RV3029C2_W_SEC]);
163	tm->tm_min = bcd2bin(regs[RV3029C2_W_MINUTES-RV3029C2_W_SEC]);
164
165	/* HR field has a more complex interpretation */
166	{
167		const u8 _hr = regs[RV3029C2_W_HOURS-RV3029C2_W_SEC];
168		if (_hr & RV3029C2_REG_HR_12_24) {
169			/* 12h format */
170			tm->tm_hour = bcd2bin(_hr & 0x1f);
171			if (_hr & RV3029C2_REG_HR_PM)	/* PM flag set */
172				tm->tm_hour += 12;
173		} else /* 24h format */
174			tm->tm_hour = bcd2bin(_hr & 0x3f);
175	}
176
177	tm->tm_mday = bcd2bin(regs[RV3029C2_W_DATE-RV3029C2_W_SEC]);
178	tm->tm_mon = bcd2bin(regs[RV3029C2_W_MONTHS-RV3029C2_W_SEC]) - 1;
179	tm->tm_year = bcd2bin(regs[RV3029C2_W_YEARS-RV3029C2_W_SEC]) + 100;
180	tm->tm_wday = bcd2bin(regs[RV3029C2_W_DAYS-RV3029C2_W_SEC]) - 1;
181
182	return 0;
183}
184
185static int rv3029c2_rtc_read_time(struct device *dev, struct rtc_time *tm)
186{
187	return rv3029c2_i2c_read_time(to_i2c_client(dev), tm);
188}
189
190static int
191rv3029c2_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
192{
193	struct rtc_time *const tm = &alarm->time;
194	int ret;
195	u8 regs[8];
196
197	ret = rv3029c2_i2c_get_sr(client, regs);
198	if (ret < 0) {
199		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
200		return -EIO;
201	}
202
203	ret = rv3029c2_i2c_read_regs(client, RV3029C2_A_SC, regs,
204					RV3029C2_ALARM_SECTION_LEN);
205
206	if (ret < 0) {
207		dev_err(&client->dev, "%s: reading alarm section failed\n",
208			__func__);
209		return ret;
210	}
211
212	tm->tm_sec = bcd2bin(regs[RV3029C2_A_SC-RV3029C2_A_SC] & 0x7f);
213	tm->tm_min = bcd2bin(regs[RV3029C2_A_MN-RV3029C2_A_SC] & 0x7f);
214	tm->tm_hour = bcd2bin(regs[RV3029C2_A_HR-RV3029C2_A_SC] & 0x3f);
215	tm->tm_mday = bcd2bin(regs[RV3029C2_A_DT-RV3029C2_A_SC] & 0x3f);
216	tm->tm_mon = bcd2bin(regs[RV3029C2_A_MO-RV3029C2_A_SC] & 0x1f) - 1;
217	tm->tm_year = bcd2bin(regs[RV3029C2_A_YR-RV3029C2_A_SC] & 0x7f) + 100;
218	tm->tm_wday = bcd2bin(regs[RV3029C2_A_DW-RV3029C2_A_SC] & 0x07) - 1;
219
220	return 0;
221}
222
223static int
224rv3029c2_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
225{
226	return rv3029c2_i2c_read_alarm(to_i2c_client(dev), alarm);
227}
228
229static int rv3029c2_rtc_i2c_alarm_set_irq(struct i2c_client *client,
230					int enable)
231{
232	int ret;
233	u8 buf[1];
234
235	/* enable AIE irq */
236	ret = rv3029c2_i2c_read_regs(client, RV3029C2_IRQ_CTRL,	buf, 1);
237	if (ret < 0) {
238		dev_err(&client->dev, "can't read INT reg\n");
239		return ret;
240	}
241	if (enable)
242		buf[0] |= RV3029C2_IRQ_CTRL_AIE;
243	else
244		buf[0] &= ~RV3029C2_IRQ_CTRL_AIE;
245
246	ret = rv3029c2_i2c_write_regs(client, RV3029C2_IRQ_CTRL, buf, 1);
247	if (ret < 0) {
248		dev_err(&client->dev, "can't set INT reg\n");
249		return ret;
250	}
251
252	return 0;
253}
254
255static int rv3029c2_rtc_i2c_set_alarm(struct i2c_client *client,
256					struct rtc_wkalrm *alarm)
257{
258	struct rtc_time *const tm = &alarm->time;
259	int ret;
260	u8 regs[8];
261
262	/*
263	 * The clock has an 8 bit wide bcd-coded register (they never learn)
264	 * for the year. tm_year is an offset from 1900 and we are interested
265	 * in the 2000-2099 range, so any value less than 100 is invalid.
266	*/
267	if (tm->tm_year < 100)
268		return -EINVAL;
269
270	ret = rv3029c2_i2c_get_sr(client, regs);
271	if (ret < 0) {
272		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
273		return -EIO;
274	}
275	regs[RV3029C2_A_SC-RV3029C2_A_SC] = bin2bcd(tm->tm_sec & 0x7f);
276	regs[RV3029C2_A_MN-RV3029C2_A_SC] = bin2bcd(tm->tm_min & 0x7f);
277	regs[RV3029C2_A_HR-RV3029C2_A_SC] = bin2bcd(tm->tm_hour & 0x3f);
278	regs[RV3029C2_A_DT-RV3029C2_A_SC] = bin2bcd(tm->tm_mday & 0x3f);
279	regs[RV3029C2_A_MO-RV3029C2_A_SC] = bin2bcd((tm->tm_mon & 0x1f) - 1);
280	regs[RV3029C2_A_DW-RV3029C2_A_SC] = bin2bcd((tm->tm_wday & 7) - 1);
281	regs[RV3029C2_A_YR-RV3029C2_A_SC] = bin2bcd((tm->tm_year & 0x7f) - 100);
282
283	ret = rv3029c2_i2c_write_regs(client, RV3029C2_A_SC, regs,
284					RV3029C2_ALARM_SECTION_LEN);
285	if (ret < 0)
286		return ret;
287
288	if (alarm->enabled) {
289		u8 buf[1];
290
291		/* clear AF flag */
292		ret = rv3029c2_i2c_read_regs(client, RV3029C2_IRQ_FLAGS,
293						buf, 1);
294		if (ret < 0) {
295			dev_err(&client->dev, "can't read alarm flag\n");
296			return ret;
297		}
298		buf[0] &= ~RV3029C2_IRQ_FLAGS_AF;
299		ret = rv3029c2_i2c_write_regs(client, RV3029C2_IRQ_FLAGS,
300						buf, 1);
301		if (ret < 0) {
302			dev_err(&client->dev, "can't set alarm flag\n");
303			return ret;
304		}
305		/* enable AIE irq */
306		ret = rv3029c2_rtc_i2c_alarm_set_irq(client, 1);
307		if (ret)
308			return ret;
309
310		dev_dbg(&client->dev, "alarm IRQ armed\n");
311	} else {
312		/* disable AIE irq */
313		ret = rv3029c2_rtc_i2c_alarm_set_irq(client, 0);
314		if (ret)
315			return ret;
316
317		dev_dbg(&client->dev, "alarm IRQ disabled\n");
318	}
319
320	return 0;
321}
322
323static int rv3029c2_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
324{
325	return rv3029c2_rtc_i2c_set_alarm(to_i2c_client(dev), alarm);
326}
327
328static int
329rv3029c2_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)
330{
331	u8 regs[8];
332	int ret;
333
334	/*
335	 * The clock has an 8 bit wide bcd-coded register (they never learn)
336	 * for the year. tm_year is an offset from 1900 and we are interested
337	 * in the 2000-2099 range, so any value less than 100 is invalid.
338	*/
339	if (tm->tm_year < 100)
340		return -EINVAL;
341
342	regs[RV3029C2_W_SEC-RV3029C2_W_SEC] = bin2bcd(tm->tm_sec);
343	regs[RV3029C2_W_MINUTES-RV3029C2_W_SEC] = bin2bcd(tm->tm_min);
344	regs[RV3029C2_W_HOURS-RV3029C2_W_SEC] = bin2bcd(tm->tm_hour);
345	regs[RV3029C2_W_DATE-RV3029C2_W_SEC] = bin2bcd(tm->tm_mday);
346	regs[RV3029C2_W_MONTHS-RV3029C2_W_SEC] = bin2bcd(tm->tm_mon+1);
347	regs[RV3029C2_W_DAYS-RV3029C2_W_SEC] = bin2bcd((tm->tm_wday & 7)+1);
348	regs[RV3029C2_W_YEARS-RV3029C2_W_SEC] = bin2bcd(tm->tm_year - 100);
349
350	ret = rv3029c2_i2c_write_regs(client, RV3029C2_W_SEC, regs,
351					RV3029C2_WATCH_SECTION_LEN);
352	if (ret < 0)
353		return ret;
354
355	ret = rv3029c2_i2c_get_sr(client, regs);
356	if (ret < 0) {
357		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
358		return ret;
359	}
360	/* clear PON bit */
361	ret = rv3029c2_i2c_set_sr(client, (regs[0] & ~RV3029C2_STATUS_PON));
362	if (ret < 0) {
363		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
364		return ret;
365	}
366
367	return 0;
368}
369
370static int rv3029c2_rtc_set_time(struct device *dev, struct rtc_time *tm)
371{
372	return rv3029c2_i2c_set_time(to_i2c_client(dev), tm);
373}
374
375static const struct rtc_class_ops rv3029c2_rtc_ops = {
376	.read_time	= rv3029c2_rtc_read_time,
377	.set_time	= rv3029c2_rtc_set_time,
378	.read_alarm	= rv3029c2_rtc_read_alarm,
379	.set_alarm	= rv3029c2_rtc_set_alarm,
380};
381
382static struct i2c_device_id rv3029c2_id[] = {
383	{ "rv3029c2", 0 },
384	{ }
385};
386MODULE_DEVICE_TABLE(i2c, rv3029c2_id);
387
388static int rv3029c2_probe(struct i2c_client *client,
389			  const struct i2c_device_id *id)
390{
391	struct rtc_device *rtc;
392	int rc = 0;
393	u8 buf[1];
394
395	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_EMUL))
396		return -ENODEV;
397
398	rc = rv3029c2_i2c_get_sr(client, buf);
399	if (rc < 0) {
400		dev_err(&client->dev, "reading status failed\n");
401		return rc;
402	}
403
404	rtc = devm_rtc_device_register(&client->dev, client->name,
405					&rv3029c2_rtc_ops, THIS_MODULE);
406
407	if (IS_ERR(rtc))
408		return PTR_ERR(rtc);
409
410	i2c_set_clientdata(client, rtc);
411
412	return 0;
413}
414
415static struct i2c_driver rv3029c2_driver = {
416	.driver = {
417		.name = "rtc-rv3029c2",
418	},
419	.probe = rv3029c2_probe,
420	.id_table = rv3029c2_id,
421};
422
423module_i2c_driver(rv3029c2_driver);
424
425MODULE_AUTHOR("Gregory Hermant <gregory.hermant@calao-systems.com>");
426MODULE_DESCRIPTION("Micro Crystal RV3029C2 RTC driver");
427MODULE_LICENSE("GPL");
428