1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * An I2C driver for the Intersil ISL 12026
4 *
5 * Copyright (c) 2018 Cavium, Inc.
6 */
7#include <linux/bcd.h>
8#include <linux/delay.h>
9#include <linux/i2c.h>
10#include <linux/module.h>
11#include <linux/mutex.h>
12#include <linux/nvmem-provider.h>
13#include <linux/of.h>
14#include <linux/rtc.h>
15#include <linux/slab.h>
16
17/* register offsets */
18#define ISL12026_REG_PWR	0x14
19# define ISL12026_REG_PWR_BSW	BIT(6)
20# define ISL12026_REG_PWR_SBIB	BIT(7)
21#define ISL12026_REG_SC		0x30
22#define ISL12026_REG_HR		0x32
23# define ISL12026_REG_HR_MIL	BIT(7)	/* military or 24 hour time */
24#define ISL12026_REG_SR		0x3f
25# define ISL12026_REG_SR_RTCF	BIT(0)
26# define ISL12026_REG_SR_WEL	BIT(1)
27# define ISL12026_REG_SR_RWEL	BIT(2)
28# define ISL12026_REG_SR_MBZ	BIT(3)
29# define ISL12026_REG_SR_OSCF	BIT(4)
30
31/* The EEPROM array responds at i2c address 0x57 */
32#define ISL12026_EEPROM_ADDR	0x57
33
34#define ISL12026_PAGESIZE 16
35#define ISL12026_NVMEM_WRITE_TIME 20
36
37struct isl12026 {
38	struct rtc_device *rtc;
39	struct i2c_client *nvm_client;
40};
41
42static int isl12026_read_reg(struct i2c_client *client, int reg)
43{
44	u8 addr[] = {0, reg};
45	u8 val;
46	int ret;
47
48	struct i2c_msg msgs[] = {
49		{
50			.addr	= client->addr,
51			.flags	= 0,
52			.len	= sizeof(addr),
53			.buf	= addr
54		}, {
55			.addr	= client->addr,
56			.flags	= I2C_M_RD,
57			.len	= 1,
58			.buf	= &val
59		}
60	};
61
62	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
63	if (ret != ARRAY_SIZE(msgs)) {
64		dev_err(&client->dev, "read reg error, ret=%d\n", ret);
65		ret = ret < 0 ? ret : -EIO;
66	} else {
67		ret = val;
68	}
69
70	return ret;
71}
72
73static int isl12026_arm_write(struct i2c_client *client)
74{
75	int ret;
76	u8 op[3];
77	struct i2c_msg msg = {
78		.addr	= client->addr,
79		.flags	= 0,
80		.len	= 1,
81		.buf	= op
82	};
83
84	/* Set SR.WEL */
85	op[0] = 0;
86	op[1] = ISL12026_REG_SR;
87	op[2] = ISL12026_REG_SR_WEL;
88	msg.len = 3;
89	ret = i2c_transfer(client->adapter, &msg, 1);
90	if (ret != 1) {
91		dev_err(&client->dev, "write error SR.WEL, ret=%d\n", ret);
92		ret = ret < 0 ? ret : -EIO;
93		goto out;
94	}
95
96	/* Set SR.WEL and SR.RWEL */
97	op[2] = ISL12026_REG_SR_WEL | ISL12026_REG_SR_RWEL;
98	msg.len = 3;
99	ret = i2c_transfer(client->adapter, &msg, 1);
100	if (ret != 1) {
101		dev_err(&client->dev,
102			"write error SR.WEL|SR.RWEL, ret=%d\n", ret);
103		ret = ret < 0 ? ret : -EIO;
104		goto out;
105	} else {
106		ret = 0;
107	}
108out:
109	return ret;
110}
111
112static int isl12026_disarm_write(struct i2c_client *client)
113{
114	int ret;
115	u8 op[3] = {0, ISL12026_REG_SR, 0};
116	struct i2c_msg msg = {
117		.addr	= client->addr,
118		.flags	= 0,
119		.len	= sizeof(op),
120		.buf	= op
121	};
122
123	ret = i2c_transfer(client->adapter, &msg, 1);
124	if (ret != 1) {
125		dev_err(&client->dev,
126			"write error SR, ret=%d\n", ret);
127		ret = ret < 0 ? ret : -EIO;
128	} else {
129		ret = 0;
130	}
131
132	return ret;
133}
134
135static int isl12026_write_reg(struct i2c_client *client, int reg, u8 val)
136{
137	int ret;
138	u8 op[3] = {0, reg, val};
139	struct i2c_msg msg = {
140		.addr	= client->addr,
141		.flags	= 0,
142		.len	= sizeof(op),
143		.buf	= op
144	};
145
146	ret = isl12026_arm_write(client);
147	if (ret)
148		return ret;
149
150	ret = i2c_transfer(client->adapter, &msg, 1);
151	if (ret != 1) {
152		dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
153		ret = ret < 0 ? ret : -EIO;
154		goto out;
155	}
156
157	msleep(ISL12026_NVMEM_WRITE_TIME);
158
159	ret = isl12026_disarm_write(client);
160out:
161	return ret;
162}
163
164static int isl12026_rtc_set_time(struct device *dev, struct rtc_time *tm)
165{
166	struct i2c_client *client = to_i2c_client(dev);
167	int ret;
168	u8 op[10];
169	struct i2c_msg msg = {
170		.addr	= client->addr,
171		.flags	= 0,
172		.len	= sizeof(op),
173		.buf	= op
174	};
175
176	ret = isl12026_arm_write(client);
177	if (ret)
178		return ret;
179
180	/* Set the CCR registers */
181	op[0] = 0;
182	op[1] = ISL12026_REG_SC;
183	op[2] = bin2bcd(tm->tm_sec); /* SC */
184	op[3] = bin2bcd(tm->tm_min); /* MN */
185	op[4] = bin2bcd(tm->tm_hour) | ISL12026_REG_HR_MIL; /* HR */
186	op[5] = bin2bcd(tm->tm_mday); /* DT */
187	op[6] = bin2bcd(tm->tm_mon + 1); /* MO */
188	op[7] = bin2bcd(tm->tm_year % 100); /* YR */
189	op[8] = bin2bcd(tm->tm_wday & 7); /* DW */
190	op[9] = bin2bcd(tm->tm_year >= 100 ? 20 : 19); /* Y2K */
191	ret = i2c_transfer(client->adapter, &msg, 1);
192	if (ret != 1) {
193		dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
194		ret = ret < 0 ? ret : -EIO;
195		goto out;
196	}
197
198	ret = isl12026_disarm_write(client);
199out:
200	return ret;
201}
202
203static int isl12026_rtc_read_time(struct device *dev, struct rtc_time *tm)
204{
205	struct i2c_client *client = to_i2c_client(dev);
206	u8 ccr[8];
207	u8 addr[2];
208	u8 sr;
209	int ret;
210	struct i2c_msg msgs[] = {
211		{
212			.addr	= client->addr,
213			.flags	= 0,
214			.len	= sizeof(addr),
215			.buf	= addr
216		}, {
217			.addr	= client->addr,
218			.flags	= I2C_M_RD,
219		}
220	};
221
222	/* First, read SR */
223	addr[0] = 0;
224	addr[1] = ISL12026_REG_SR;
225	msgs[1].len = 1;
226	msgs[1].buf = &sr;
227
228	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
229	if (ret != ARRAY_SIZE(msgs)) {
230		dev_err(&client->dev, "read error, ret=%d\n", ret);
231		ret = ret < 0 ? ret : -EIO;
232		goto out;
233	}
234
235	if (sr & ISL12026_REG_SR_RTCF)
236		dev_warn(&client->dev, "Real-Time Clock Failure on read\n");
237	if (sr & ISL12026_REG_SR_OSCF)
238		dev_warn(&client->dev, "Oscillator Failure on read\n");
239
240	/* Second, CCR regs */
241	addr[0] = 0;
242	addr[1] = ISL12026_REG_SC;
243	msgs[1].len = sizeof(ccr);
244	msgs[1].buf = ccr;
245
246	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
247	if (ret != ARRAY_SIZE(msgs)) {
248		dev_err(&client->dev, "read error, ret=%d\n", ret);
249		ret = ret < 0 ? ret : -EIO;
250		goto out;
251	}
252
253	tm->tm_sec = bcd2bin(ccr[0] & 0x7F);
254	tm->tm_min = bcd2bin(ccr[1] & 0x7F);
255	if (ccr[2] & ISL12026_REG_HR_MIL)
256		tm->tm_hour = bcd2bin(ccr[2] & 0x3F);
257	else
258		tm->tm_hour = bcd2bin(ccr[2] & 0x1F) +
259			((ccr[2] & 0x20) ? 12 : 0);
260	tm->tm_mday = bcd2bin(ccr[3] & 0x3F);
261	tm->tm_mon = bcd2bin(ccr[4] & 0x1F) - 1;
262	tm->tm_year = bcd2bin(ccr[5]);
263	if (bcd2bin(ccr[7]) == 20)
264		tm->tm_year += 100;
265	tm->tm_wday = ccr[6] & 0x07;
266
267	ret = 0;
268out:
269	return ret;
270}
271
272static const struct rtc_class_ops isl12026_rtc_ops = {
273	.read_time	= isl12026_rtc_read_time,
274	.set_time	= isl12026_rtc_set_time,
275};
276
277static int isl12026_nvm_read(void *p, unsigned int offset,
278			     void *val, size_t bytes)
279{
280	struct isl12026 *priv = p;
281	int ret;
282	u8 addr[2];
283	struct i2c_msg msgs[] = {
284		{
285			.addr	= priv->nvm_client->addr,
286			.flags	= 0,
287			.len	= sizeof(addr),
288			.buf	= addr
289		}, {
290			.addr	= priv->nvm_client->addr,
291			.flags	= I2C_M_RD,
292			.buf	= val
293		}
294	};
295
296	/*
297	 * offset and bytes checked and limited by nvmem core, so
298	 * proceed without further checks.
299	 */
300	ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
301	if (ret)
302		return ret;
303
304	/* 2 bytes of address, most significant first */
305	addr[0] = offset >> 8;
306	addr[1] = offset;
307	msgs[1].len = bytes;
308	ret = i2c_transfer(priv->nvm_client->adapter, msgs, ARRAY_SIZE(msgs));
309
310	mutex_unlock(&priv->rtc->ops_lock);
311
312	if (ret != ARRAY_SIZE(msgs)) {
313		dev_err(&priv->nvm_client->dev,
314			"nvmem read error, ret=%d\n", ret);
315		return ret < 0 ? ret : -EIO;
316	}
317
318	return 0;
319}
320
321static int isl12026_nvm_write(void *p, unsigned int offset,
322			      void *val, size_t bytes)
323{
324	struct isl12026 *priv = p;
325	int ret;
326	u8 *v = val;
327	size_t chunk_size, num_written;
328	u8 payload[ISL12026_PAGESIZE + 2]; /* page + 2 address bytes */
329	struct i2c_msg msgs[] = {
330		{
331			.addr	= priv->nvm_client->addr,
332			.flags	= 0,
333			.buf	= payload
334		}
335	};
336
337	/*
338	 * offset and bytes checked and limited by nvmem core, so
339	 * proceed without further checks.
340	 */
341	ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
342	if (ret)
343		return ret;
344
345	num_written = 0;
346	while (bytes) {
347		chunk_size = round_down(offset, ISL12026_PAGESIZE) +
348			ISL12026_PAGESIZE - offset;
349		chunk_size = min(bytes, chunk_size);
350		/*
351		 * 2 bytes of address, most significant first, followed
352		 * by page data bytes
353		 */
354		memcpy(payload + 2, v + num_written, chunk_size);
355		payload[0] = offset >> 8;
356		payload[1] = offset;
357		msgs[0].len = chunk_size + 2;
358		ret = i2c_transfer(priv->nvm_client->adapter,
359				   msgs, ARRAY_SIZE(msgs));
360		if (ret != ARRAY_SIZE(msgs)) {
361			dev_err(&priv->nvm_client->dev,
362				"nvmem write error, ret=%d\n", ret);
363			ret = ret < 0 ? ret : -EIO;
364			break;
365		}
366		ret = 0;
367		bytes -= chunk_size;
368		offset += chunk_size;
369		num_written += chunk_size;
370		msleep(ISL12026_NVMEM_WRITE_TIME);
371	}
372
373	mutex_unlock(&priv->rtc->ops_lock);
374
375	return ret;
376}
377
378static void isl12026_force_power_modes(struct i2c_client *client)
379{
380	int ret;
381	int pwr, requested_pwr;
382	u32 bsw_val, sbib_val;
383	bool set_bsw, set_sbib;
384
385	/*
386	 * If we can read the of_property, set the specified value.
387	 * If there is an error reading the of_property (likely
388	 * because it does not exist), keep the current value.
389	 */
390	ret = of_property_read_u32(client->dev.of_node,
391				   "isil,pwr-bsw", &bsw_val);
392	set_bsw = (ret == 0);
393
394	ret = of_property_read_u32(client->dev.of_node,
395				   "isil,pwr-sbib", &sbib_val);
396	set_sbib = (ret == 0);
397
398	/* Check if PWR.BSW and/or PWR.SBIB need specified values */
399	if (!set_bsw && !set_sbib)
400		return;
401
402	pwr = isl12026_read_reg(client, ISL12026_REG_PWR);
403	if (pwr < 0) {
404		dev_warn(&client->dev, "Error: Failed to read PWR %d\n", pwr);
405		return;
406	}
407
408	requested_pwr = pwr;
409
410	if (set_bsw) {
411		if (bsw_val)
412			requested_pwr |= ISL12026_REG_PWR_BSW;
413		else
414			requested_pwr &= ~ISL12026_REG_PWR_BSW;
415	} /* else keep current BSW */
416
417	if (set_sbib) {
418		if (sbib_val)
419			requested_pwr |= ISL12026_REG_PWR_SBIB;
420		else
421			requested_pwr &= ~ISL12026_REG_PWR_SBIB;
422	} /* else keep current SBIB */
423
424	if (pwr >= 0 && pwr != requested_pwr) {
425		dev_dbg(&client->dev, "PWR: %02x\n", pwr);
426		dev_dbg(&client->dev, "Updating PWR to: %02x\n", requested_pwr);
427		isl12026_write_reg(client, ISL12026_REG_PWR, requested_pwr);
428	}
429}
430
431static int isl12026_probe(struct i2c_client *client)
432{
433	struct isl12026 *priv;
434	int ret;
435	struct nvmem_config nvm_cfg = {
436		.name = "isl12026-",
437		.base_dev = &client->dev,
438		.stride = 1,
439		.word_size = 1,
440		.size = 512,
441		.reg_read = isl12026_nvm_read,
442		.reg_write = isl12026_nvm_write,
443	};
444
445	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
446		return -ENODEV;
447
448	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
449	if (!priv)
450		return -ENOMEM;
451
452	i2c_set_clientdata(client, priv);
453
454	isl12026_force_power_modes(client);
455
456	priv->nvm_client = i2c_new_dummy_device(client->adapter, ISL12026_EEPROM_ADDR);
457	if (IS_ERR(priv->nvm_client))
458		return PTR_ERR(priv->nvm_client);
459
460	priv->rtc = devm_rtc_allocate_device(&client->dev);
461	ret = PTR_ERR_OR_ZERO(priv->rtc);
462	if (ret)
463		return ret;
464
465	priv->rtc->ops = &isl12026_rtc_ops;
466	nvm_cfg.priv = priv;
467	ret = devm_rtc_nvmem_register(priv->rtc, &nvm_cfg);
468	if (ret)
469		return ret;
470
471	return devm_rtc_register_device(priv->rtc);
472}
473
474static void isl12026_remove(struct i2c_client *client)
475{
476	struct isl12026 *priv = i2c_get_clientdata(client);
477
478	i2c_unregister_device(priv->nvm_client);
479}
480
481static const struct of_device_id isl12026_dt_match[] = {
482	{ .compatible = "isil,isl12026" },
483	{ }
484};
485MODULE_DEVICE_TABLE(of, isl12026_dt_match);
486
487static struct i2c_driver isl12026_driver = {
488	.driver		= {
489		.name	= "rtc-isl12026",
490		.of_match_table = isl12026_dt_match,
491	},
492	.probe		= isl12026_probe,
493	.remove		= isl12026_remove,
494};
495
496module_i2c_driver(isl12026_driver);
497
498MODULE_DESCRIPTION("ISL 12026 RTC driver");
499MODULE_LICENSE("GPL");
500